163 results on '"Neil Hammerschlag"'
Search Results
2. Tiger sharks support the characterization of the world’s largest seagrass ecosystem
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Austin J. Gallagher, Jacob W. Brownscombe, Nourah A. Alsudairy, Andrew B. Casagrande, Chuancheng Fu, Lucy Harding, S. David Harris, Neil Hammerschlag, Wells Howe, Antonio Delgado Huertas, Sami Kattan, Andrew S. Kough, Andre Musgrove, Nicholas L. Payne, Adrian Phillips, Brendan D. Shea, Oliver N. Shipley, U. Rashid Sumaila, Mohammad S. Hossain, and Carlos M. Duarte
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Science - Abstract
This study characterizes the world’s largest seagrass ecosystem in The Bahamas by integrating spatial estimates with remote sensing and performing extensive ground-truthing of benthic habitat with 2,542 diver surveys, as well as data obtained from instrument-equipped tiger sharks, which have strong fidelity to seagrass ecosystems.
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- 2022
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3. Acoustic tracking of a threatened juvenile shark species, the smooth hammerhead (Sphyrna zygaena), reveals vulnerability to exploitation at the boundary of a marine reserve
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Patricia S. Albano, Chris Fallows, Monique Fallows, Lacey H. Williams, Taryn Murray, Oliver Sedgwick, and Neil Hammerschlag
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elasmobranchs ,marine protected areas ,conservation management ,spatial protection ,South Africa ,acoustic telemetry ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
The coastal waters of South Africa are habitat to a diverse composition of sharks that are vulnerable to exploitation, many of which are endemic and/or classified by the International Union for Conservation of Nature (IUCN) Red List as Threatened or Data Deficient. Accordingly, this region has been identified as a global research and conservation priority for elasmobranchs. The De Hoop Marine Protected Area (MPA), in the Western Cape Province of South Africa, provides 288 km2 of no-take protection within its boundaries. However, the region experiences heavy commercial fishing, with two vessels actively operating as dedicated shark longliners (as of 2022). When crossing MPA boundaries, sharks are susceptible to capture by these vessels. Utilizing passive acoustic telemetry, the present study evaluated the movements of a threatened juvenile shark species, the smooth hammerhead (Sphyrna zygaena), both inside and adjacent to the De Hoop MPA, and along the greater coastline. Movement data from 20 tagged sharks were used to explore the effects of spatial, environmental, and management variables on their residency and movement patterns. Results indicate a high reliance of sharks on unprotected waters immediately adjacent to the MPA’s eastern boundary, an area of high biological productivity due to its proximity to the mouth of an estuary. Although some tagged sharks did move regionally along the South African coastline, individuals spent 95% of their days detected just outside the eastern boundary of the MPA, rendering them vulnerable to commercial shark longlining occurring there. These findings have conservation implications for smooth hammerhead sharks in South Africa and present an opportunity to revisit management practices that may optimize spatial protection for an important life stage of this threatened species.
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- 2023
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4. 3D visualization processes for recreating and studying organismal form
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Duncan J. Irschick, Fredrik Christiansen, Neil Hammerschlag, Johnson Martin, Peter T. Madsen, Jeanette Wyneken, Annabelle Brooks, Adrian Gleiss, Sabrina Fossette, Cameron Siler, Tony Gamble, Frank Fish, Ursula Siebert, Jaymin Patel, Zhan Xu, Evangelos Kalogerakis, Joshua Medina, Atreyi Mukherji, Mark Mandica, Savvas Zotos, Jared Detwiler, Blair Perot, and George Lauder
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Ecology ,Biological sciences ,Zoology ,Evolutionary biology ,Science - Abstract
Summary: The study of biological form is a vital goal of evolutionary biology and functional morphology. We review an emerging set of methods that allow scientists to create and study accurate 3D models of living organisms and animate those models for biomechanical and fluid dynamic analyses. The methods for creating such models include 3D photogrammetry, laser and CT scanning, and 3D software. New multi-camera devices can be used to create accurate 3D models of living animals in the wild and captivity. New websites and virtual reality/augmented reality devices now enable the visualization and sharing of these data. We provide examples of these approaches for animals ranging from large whales to lizards and show applications for several areas: Natural history collections; body condition/scaling, bioinspired robotics, computational fluids dynamics (CFD), machine learning, and education. We provide two datasets to demonstrate the efficacy of CFD and machine learning approaches and conclude with a prospectus.
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- 2022
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5. How continuing mortality affects recovery potential for prohibited sharks: The case of white sharks in South Africa
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Heather D. Bowlby, Neil Hammerschlag, Dylan T. Irion, and Enrico Gennari
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life history ,threats ,shark conservation ,recovery ability ,white shark (Carcharodon carcharias) ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
It can be difficult to determine whether a prohibition to exploitation ensures effective conservation or recovery for species that remain exposed to fishing effort and other sources of mortality throughout their range. Here we used simulation modeling of four life history scenarios (different productivity and population size) to contextualize potential population response to multiple levels of mortality, using white sharks (Carcharodon carcharias) in South Africa as a case study. The species has been protected since 1991, yet substantial uncertainty about population dynamics persists and recent declines at two aggregation sites have renewed conservation concern. All scenarios indicated that annual removals in the 10s of individuals would substantially limit the potential for and magnitude of any abundance increase following prohibition. Because average known removals from the KwaZulu-Natal Sharks Board’s Bather Protection Program have typically remained higher than these thresholds, they likely eliminated much of the conservation benefit derived from prohibition. The only life history scenario to achieve appreciable increase when simulated removals were similar to published averages assumed maturation occurred at a much younger age than currently understood. Our results demonstrate why general application of life history-based simulations can provide a useful mechanism to evaluate the biological plausibility of life history information and abundance trends, and to explore the scope for population response to recovery actions. For South Africa, our results suggest that even known levels of white shark removals, which likely underestimate total removals within their range, may be sufficient to drive abundance decline and new mitigation measures may be required to ensure population recovery.
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- 2022
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6. The role of context in elucidating drivers of animal movement
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Nicolas Lubitz, Michael Bradley, Marcus Sheaves, Neil Hammerschlag, Ryan Daly, and Adam Barnett
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animal movement ,birds ,context ,elasmobranchs ,environmental change ,intra‐specific variability ,Ecology ,QH540-549.5 - Abstract
Abstract Despite its consequences for ecological processes and population dynamics, intra‐specific variability is frequently overlooked in animal movement studies. Consequently, the necessary resolution to reveal drivers of individual movement decisions is often lost as animal movement data are aggregated to infer average or population patterns. Thus, an empirical understanding of why a given movement pattern occurs remains patchy for many taxa, especially in marine systems. Nonetheless, movement is often rationalized as being driven by basic life history requirements, such as acquiring energy (feeding), reproduction, predator‐avoidance, and remaining in suitable environmental conditions. However, these life history requirements are central to every individual within a species and thus do not sufficiently account for the high intra‐specific variability in movement behavior and hence fail to fully explain the occurrence of multiple movement strategies within a species. Animal movement appears highly context dependent as, for example, within the same location, the behavior of both resident and migratory individuals is driven by life history requirements, such as feeding or reproduction, however different movement strategies are utilized to fulfill them. A systematic taxa‐wide approach that, instead of averaging population patterns, incorporates and utilizes intra‐specific variability to enable predictions as to which movement patterns can be expected under a certain context, is needed. Here, we use intra‐specific variability in elasmobranchs as a case study to introduce a stepwise approach for studying animal movement drivers that is based on a context‐dependence framework. We examine relevant literature to illustrate how this context‐focused approach can aid in reliably identifying drivers of a specific movement pattern. Ultimately, incorporating behavioral variability in the study of movement drivers can assist in making predictions about behavioral responses to environmental change, overcoming tagging biases, and establishing more efficient conservation measures.
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- 2022
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7. Age-Dependent Dispersal and Relatedness in Tiger Sharks (Galeocerdo cuvier)
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Margaret A. McClain, Neil Hammerschlag, Austin J. Gallagher, J. Marcus Drymon, R. Dean Grubbs, Tristan L. Guttridge, Matthew J. Smukall, Bryan S. Frazier, and Toby S. Daly-Engel
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philopatry ,site fidelity ,kinship ,microsatellites ,movement patterns ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Understanding dispersal in large marine fauna is necessary for conservation, but movement patterns often vary widely by sex and life stage. In sharks, genetic studies have shown evidence of widespread male-biased dispersal, though tagging and tracking studies on the same populations show both sexes using site fidelity, including philopatry, and moving similar distances. We used a suite of microsatellite loci and DNA samples from 362 previously-tagged tiger sharks (Galeocerdo cuvier) in the northwestern Atlantic, including a large number of residential juveniles, to evaluate reproductive dispersal in light of demographic and published tracking data. We found that lumping size classes together resulted in genetic panmixia across sites, but systematic removal of large individuals showed significant population-level differentiation and three separate population clusters among juveniles less than 260 cm total length. Tests for relatedness found that 8.9% of our sample set was composed of first-order related pairs (N = 16), including several full siblings from different litters, a sign of multi-cycle genetic monogamy which carries implications for effective population size. By mapping genetic assignments of juveniles, we identified a signature of fine-scale genetic structure suggesting broad biparental site fidelity to reproductive habitat in the northeast Gulf of Mexico, which is concordant with both genetic and tracking data. Taken together, these findings demonstrate how lumping individuals from different life stages in genetic studies may obscure fine-scale genetic structure, confounding future conservation efforts.
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- 2022
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8. Metal concentrations in coastal sharks from The Bahamas with a focus on the Caribbean Reef shark
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Oliver N. Shipley, Cheng-Shiuan Lee, Nicholas S. Fisher, James K. Sternlicht, Sami Kattan, Erica R. Staaterman, Neil Hammerschlag, and Austin J. Gallagher
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Medicine ,Science - Abstract
Abstract Over the last century anthropogenic activities have rapidly increased the influx of metals and metalloids entering the marine environment, which can bioaccumulate and biomagnify in marine top consumers. This may elicit sublethal effects on target organisms, having broad implications for human seafood consumers. We provide the first assessment of metal (Cd, Pb, Cr, Mn, Co, Cu, Zn, As, Ag, and THg) and metalloid (As) concentrations in the muscle tissue of coastal sharks from The Bahamas. A total of 36 individual sharks from six species were evaluated, spanning two regions/study areas, with a focus on the Caribbean reef shark (Carcharhinus perezi), and to a lesser extent the tiger shark (Galeocerdo cuvier). This is due their high relative abundance and ecological significance throughout coastal Bahamian and regional ecosystems. Caribbean reef sharks exhibited some of the highest metal concentrations compared to five other species, and peaks in the concentrations of Pb, Cr, Cu were observed as individuals reached sexual maturity. Observations were attributed to foraging on larger, more piscivorous prey, high longevity, as well a potential slowing rate of growth. We observed correlations between some metals, which are challenging to interpret but may be attributed to trophic level and ambient metal conditions. Our results provide the first account of metal concentrations in Bahamian sharks, suggesting individuals exhibit high concentrations which may potentially cause sublethal effects. Finally, these findings underscore the potential toxicity of shark meat and have significant implications for human consumers.
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- 2021
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9. A scalable, satellite-transmitted data product for monitoring high-activity events in mobile aquatic animals
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Rachel A. Skubel, Kenady Wilson, Yannis P. Papastamatiou, Hannah J. Verkamp, James A. Sulikowski, Daniel Benetti, and Neil Hammerschlag
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Biotelemetry ,Biologging ,Accelerometers ,Activity ,Sharks ,Behavior ,Ecology ,QH540-549.5 ,Animal biochemistry ,QP501-801 - Abstract
Abstract A growing number of studies are using accelerometers to examine activity level patterns in aquatic animals. However, given the amount of data generated from accelerometers, most of these studies use loggers that archive acceleration data, thus requiring physical recovery of the loggers or acoustic transmission from within a receiver array to obtain the data. These limitations have restricted the duration of tracking (ranging from hours to days) and/or type of species studied (e.g., relatively sessile species or those returning to predictable areas). To address these logistical challenges, we present and test a satellite-transmitted metric for the remote monitoring of changes in activity, measured via a pop-off satellite archival tag (PSAT) with an integrated accelerometer. Along with depth, temperature, and irradiance for geolocation, the PSAT transmits activity data as a time-series (ATS) with a user-programmable resolution. ATS is a count of high-activity events, relative to overall activity/mobility during a summary period. An algorithm is used to identify the high-activity events from accelerometer data and reports the data as a count per time-series interval. Summary statistics describing the data used to identify high-activity events accompany the activity time-series. In this study, we first tested the ATS activity metric through simulating PSAT output from accelerometer data logger archives, comparing ATS to vectorial dynamic body acceleration. Next, we deployed PSATs with ATS under captive conditions with cobia (Rachycentron canadum). Lastly, we deployed seven pop-off satellite archival tags (PSATs) able to collect and transmit ATS in the wild on adult sandbar sharks (Carcharhinus plumbeus). In the captive trials, we identified both resting and non-resting behavior for species and used logistic regression to compare ATS values with observed activity levels. In captive cobia, ATS was a significant predictor of observed activity levels. For 30-day wild deployments on sandbar sharks, satellites received 57.4–73.2% of the transmitted activity data. Of these ATS datapoints, between 21.9 and 41.2% of records had a concurrent set of temperature, depth, and light measurements. These results suggest that ATS is a practical metric for remotely monitoring and transmitting relative high-activity data in large-bodied aquatic species with variable activity levels, under changing environmental conditions, and across broad spatiotemporal scales.
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- 2020
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10. Social Network Analysis Reveals the Subtle Impacts of Tourist Provisioning on the Social Behavior of a Generalist Marine Apex Predator
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David M. P. Jacoby, Bethany S. Fairbairn, Bryan S. Frazier, Austin J. Gallagher, Michael R. Heithaus, Steven J. Cooke, and Neil Hammerschlag
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behavioral ecology ,ecotourism ,gregariousness ,predators ,shark diving ,social affiliations ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Shark dive ecotourism is a lucrative industry in many regions around the globe. In some cases, sharks are provisioned using bait, prompting increased research on how baited dives influence shark behavior and yielding mixed results. Effects on patterns of habitat use and movement seemly vary across species and locations. It is unknown, however, whether wide-ranging, marine apex predators respond to provisioning by changing their patterns of grouping or social behavior. We applied a tiered analytical approach (aggregation-gregariousness-social preferences) examining the impact of provisioning on the putative social behavior of tiger sharks (Galeocerdo cuvier) at a dive tourism location in The Bahamas. Using network inference on three years of acoustic tracking data from 48 sharks, we tested for non-random social structure between non-provisioned and provisioned monitoring sites resulting in 12 distinct networks. Generally considered a solitary nomadic predator, we found evidence of sociality in tiger sharks, which varied spatiotemporally. We documented periods of both random (n = 7 networks) and non-random aggregation (n = 5 networks). Three of five non-random aggregations were at locations unimpacted by provisioning regardless of season, one occurred at an active provisioning site during the dry season and one at the same receivers during the wet season when provision activity is less prevalent. Aggregations lasted longer and occurred more frequently at provisioning sites, where gregariousness was also more variable. While differences in gregariousness among individuals was generally predictive of non-random network structure, individual site preferences, size and sex were not. Within five social preference networks, constructed using generalized affiliation indices, network density was lower at provisioning sites, indicating lower connectivity at these locations. We found no evidence of size assortment on preferences. Our data suggest that sociality may occur naturally within the Tiger Beach area, perhaps due to the unusually high density of individuals there. This study demonstrates the existence of periodic social behavior, but also considerable variation in association between tiger sharks, which we argue may help to mitigate any long-term impacts of provisioning on this population. Finally, we illustrate the utility of combining telemetry and social network approaches for assessing the impact of human disturbance on wildlife behavior.
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- 2021
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11. Spatial Connectivity and Drivers of Shark Habitat Use Within a Large Marine Protected Area in the Caribbean, The Bahamas Shark Sanctuary
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Austin J. Gallagher, Oliver N. Shipley, Maurits P. M. van Zinnicq Bergmann, Jacob W. Brownscombe, Craig P. Dahlgren, Michael G. Frisk, Lucas P. Griffin, Neil Hammerschlag, Sami Kattan, Yannis P. Papastamatiou, Brendan D. Shea, Steven T. Kessel, and Carlos M. Duarte
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shark ,acoustic telemetry ,marine protected area ,MPA ,seagrass ,coral reef ,Science ,General. Including nature conservation, geographical distribution ,QH1-199.5 - Abstract
Marine protected areas (MPAs) have emerged as potentially important conservation tools for the conservation of biodiversity and mitigation of climate impacts. Among MPAs, a large percentage has been created with the implicit goal of protecting shark populations, including 17 shark sanctuaries which fully protect sharks throughout their jurisdiction. The Commonwealth of the Bahamas represents a long-term MPA for sharks, following the banning of commercial longlining in 1993 and subsequent designation as a shark sanctuary in 2011. Little is known, however, about the long-term behavior and space use of sharks within this protected area, particularly among reef-associated sharks for which the sanctuary presumably offers the most benefit. We used acoustic telemetry to advance our understanding of the ecology of such sharks, namely Caribbean reef sharks (Carcharhinus perezi) and tiger sharks (Galeocerdo cuvier), over two discrete islands (New Providence and Great Exuma) varying in human activity level, over 2 years. We evaluated which factors influenced the likelihood of detection of individuals, analyzed patterns of movement and occurrence, and identified variability in habitat selection among species and regions, using a dataset of 23 Caribbean reef sharks and 15 tiger sharks which were passively monitored in two arrays with a combined total of 13 acoustic receivers. Caribbean reef sharks had lower detection probabilities than tiger sharks, and exhibited relatively low habitat connectivity and high residency, while tiger sharks demonstrated wider roaming behavior across much greater space. Tiger sharks were associated with shallow seagrass habitats where available, but frequently transited between and connected different habitat types. Our data support the notion that large MPAs afford greater degrees of protection for highly resident species such as Caribbean reef sharks, yet still may provide substantial benefits for more migratory species such as tiger sharks. We discuss these findings within the context of species-habitat linkages, ecosystem services, and the establishment of future MPAs.
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- 2021
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12. Movement patterns and habitat use of tiger sharks (Galeocerdo cuvier) across ontogeny in the Gulf of Mexico.
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Matthew J Ajemian, J Marcus Drymon, Neil Hammerschlag, R J David Wells, Garrett Street, Brett Falterman, Jennifer A McKinney, William B Driggers, Eric R Hoffmayer, Christopher Fischer, and Gregory W Stunz
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Medicine ,Science - Abstract
The tiger shark (Galeocerdo cuvier) is globally distributed with established coastal and open-ocean movement patterns in many portions of its range. While all life stages of tiger sharks are known to occur in the Gulf of Mexico (GoM), variability in habitat use and movement patterns over ontogeny have never been quantified in this large marine ecosystem. To address this data gap we fitted 56 tiger sharks with Smart Position and Temperature transmitting tags between 2010 and 2018 and examined seasonal and spatial distribution patterns across the GoM. Additionally, we analyzed overlap of core habitats (i.e., 50% kernel density estimates) among individuals relative to large benthic features (oil and gas platforms, natural banks, bathymetric breaks). Our analyses revealed significant ontogenetic and seasonal differences in distribution patterns as well as across-shelf (i.e., regional) and sex-linked variability in movement rates. Presumably sub-adult and adult sharks achieved significantly higher movement rates and used off-shelf deeper habitats at greater proportions than juvenile sharks, particularly during the fall and winter seasons. Further, female maximum rate of movement was higher than males when accounting for size. Additionally, we found evidence of core regions encompassing the National Oceanographic and Atmospheric Administration designated Habitat Areas of Particular Concern (i.e., shelf-edge banks) during cooler months, particularly by females, as well as 2,504 oil and gas platforms. These data provide a baseline for future assessments of environmental impacts, such as climate variability or oil spills, on tiger shark movements and distribution in the region. Future research may benefit from combining alternative tracking tools, such as acoustic telemetry and genetic approaches, which can facilitate long-term assessment of the species' movement dynamics and better elucidate the ecological significance of the core habitats identified here.
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- 2020
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13. The value of using measurements of geomagnetic field in addition to irradiance and sea surface temperature to estimate geolocations of tagged aquatic animals
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A. Peter Klimley, Marco Flagg, Neil Hammerschlag, and Alex Hearn
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Geolocation ,Irradiance ,Geomagnetic intensity ,Archival tags ,Ecology ,QH540-549.5 ,Animal biochemistry ,QP501-801 - Abstract
Abstract In this commentary, we describe how geomagnetic intensity can be used to estimate latitude, discuss its strengths and weaknesses, and argue for its potential use along with irradiance measurements for estimating the latitude of a migratory fish carrying an archival tag. We conclude this commentary by suggesting that researchers and tag manufacturers estimate positions using as many inputs as possible, environmental irradiance, sea surface temperature, and geomagnetic field. Each environmental property will provide a better estimate of position at different times of the year and locations on earth. We contend that one geolocation estimation approach is not better than another, as each functions optimally under different circumstances and thus should be used accordingly.
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- 2017
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14. Considerations for effective science communication
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Steven J. Cooke, Austin J. Gallagher, Natalie M. Sopinka, Vivian M. Nguyen, Rachel A. Skubel, Neil Hammerschlag, Sarah Boon, Nathan Young, and Andy J. Danylchuk
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science engagement ,science outreach ,communication science ,evaluation of science communication ,academic cultures ,professional development ,Education ,Science - Abstract
It is increasingly common for scientists to engage in sharing science-related knowledge with diverse knowledge users—an activity called science communication. Given that many scientists now seek information on how to communicate effectively, we have generated a list of 16 important considerations for those interested in science communication: (1) Define what science communication means to you and your research; (2) Know—and listen to—your target audience; (3) Consider a diverse but coordinated communication portfolio; (4) Draft skilled players and build a network; (5) Create and seize opportunities; (6) Be creative when you communicate; (7) Focus on the science in science communication; (8) Be an honest broker; (9) Understand the science of science communication; (10) Think like an entrepreneur; (11) Don’t let your colleagues stop you; (12) Integrate science communication into your research program; (13) Recognize how science communication enhances your science; (14) Request science communication funds from grants; (15) Strive for bidirectional communication; and (16) Evaluate, reflect, and be prepared to adapt. It is our ambition that the ideas shared here will encourage readers to engage in science communication and increase the effectiveness of those already active in science communication, stimulating them to share their experiences with others.
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- 2017
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15. Residency and movement patterns of an apex predatory shark (Galeocerdo cuvier) at the Galapagos Marine Reserve.
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David Acuña-Marrero, Adam N H Smith, Neil Hammerschlag, Alex Hearn, Marti J Anderson, Hannah Calich, Matthew D M Pawley, Chris Fischer, and Pelayo Salinas-de-León
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Medicine ,Science - Abstract
The potential effectiveness of marine protected areas (MPAs) as a conservation tool for large sharks has been questioned due to the limited spatial extent of most MPAs in contrast to the complex life history and high mobility of many sharks. Here we evaluated the movement dynamics of a highly migratory apex predatory shark (tiger shark Galeocerdo cuvier) at the Galapagos Marine Reserve (GMR). Using data from satellite tracking passive acoustic telemetry, and stereo baited remote underwater video, we estimated residency, activity spaces, site fidelity, distributional abundances and migration patterns from the GMR and in relation to nesting beaches of green sea turtles (Chelonia mydas), a seasonally abundant and predictable prey source for large tiger sharks. Tiger sharks exhibited a high degree of philopatry, with 93% of the total satellite-tracked time across all individuals occurring within the GMR. Large sharks (> 200 cm TL) concentrated their movements in front of the two most important green sea turtle-nesting beaches in the GMR, visiting them on a daily basis during nocturnal hours. In contrast, small sharks (< 200 cm TL) rarely visited turtle-nesting areas and displayed diurnal presence at a third location where only immature sharks were found. Small and some large individuals remained in the three study areas even outside of the turtle-nesting season. Only two sharks were satellite-tracked outside of the GMR, and following long-distance migrations, both individuals returned to turtle-nesting beaches at the subsequent turtle-nesting season. The spatial patterns of residency and site fidelity of tiger sharks suggest that the presence of a predictable source of prey and suitable habitats might reduce the spatial extent of this large shark that is highly migratory in other parts of its range. This highly philopatric behaviour enhances the potential effectiveness of the GMR for their protection.
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- 2017
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16. Cyanobacterial Neurotoxin β-N-Methylamino-L-alanine (BMAA) in Shark Fins
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John Pablo, Deborah C. Mash, Sandra A. Banack, Neil Hammerschlag, Margaret Basile, and Kiyo Mondo
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β-N-methylamino-L-alanine ,neurotoxin ,neurodegenerative disease ,cyanobacteria ,elasmobranch ,conservation ,Biology (General) ,QH301-705.5 - Abstract
Sharks are among the most threatened groups of marine species. Populations are declining globally to support the growing demand for shark fin soup. Sharks are known to bioaccumulate toxins that may pose health risks to consumers of shark products. The feeding habits of sharks are varied, including fish, mammals, crustaceans and plankton. The cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) has been detected in species of free-living marine cyanobacteria and may bioaccumulate in the marine food web. In this study, we sampled fin clips from seven different species of sharks in South Florida to survey the occurrence of BMAA using HPLC-FD and Triple Quadrupole LC/MS/MS methods. BMAA was detected in the fins of all species examined with concentrations ranging from 144 to 1836 ng/mg wet weight. Since BMAA has been linked to neurodegenerative diseases, these results may have important relevance to human health. We suggest that consumption of shark fins may increase the risk for human exposure to the cyanobacterial neurotoxin BMAA.
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- 2012
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17. How long is too long in contemporary peer review? Perspectives from authors publishing in conservation biology journals.
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Vivian M Nguyen, Neal R Haddaway, Lee F G Gutowsky, Alexander D M Wilson, Austin J Gallagher, Michael R Donaldson, Neil Hammerschlag, and Steven J Cooke
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Medicine ,Science - Abstract
Delays in peer reviewed publication may have consequences for both assessment of scientific prowess in academics as well as communication of important information to the knowledge receptor community. We present an analysis on the perspectives of authors publishing in conservation biology journals regarding their opinions on the importance of speed in peer-review as well as how to improve review times. Authors were invited to take part in an online questionnaire, of which the data was subjected to both qualitative (open coding, categorizing) and quantitative analyses (generalized linear models). We received 637 responses to a total of 6,547 e-mail invitations sent. Peer-review speed was generally perceived as slow, with authors experiencing a typical turnaround time of 14 weeks while their perceived optimal review time is six weeks. Male and younger respondents seem to have higher expectations of review speed than females and older respondents. Majority of participants attributed lengthy review times to the 'stress' on the peer-review system (i.e., reviewer and editor fatigue), while editor persistence and journal prestige were believed to speed up the review process. Negative consequences of lengthy review times appear to be greater for early career researchers and can also have impact on author morale (e.g. motivation or frustration). Competition among colleagues were also of concern to respondents. Incentivizing peer review was among the top suggested alterations to the system along with training graduate students in peer review, increased editorial persistence, and changes to the norms of peer-review such as opening the peer-review process to the public. It is clear that authors surveyed in this study view the peer-review system as under stress and we encourage scientists and publishers to push the envelope for new peer review models.
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- 2015
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18. White sharks (Carcharodon carcharias) scavenging on whales and its potential role in further shaping the ecology of an apex predator.
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Chris Fallows, Austin J Gallagher, and Neil Hammerschlag
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Medicine ,Science - Abstract
Scavenging, a result of a temporary pulse of resources, occurs in virtually all ecosystems containing carnivores, and is an important energy transfer pathway that can impact ecosystem structure and function, and this ecological significance has largely been considered from a terrestrial standpoint; however, little is known about the role of scavenging in shaping the behavioral ecology of marine species, specifically apex predators. Here we present findings from multiple opportunistic observations of white sharks scavenging on whale carcasses in False Bay, South Africa. Observations of white sharks scavenging over successive days provided evidence of strategic and selective scavenging by this species. Moreover, extended daily observations permitted recordings of unique social, aggregative, and feeding behaviors. We further compare these data against observations of natural predation by sharks on seals in the study area. We discuss these data in relation to environmental conditions, shark social interactions, migration patterns, whale biology, and behaviorally-mediated trophic cascades. While the appearance of a whale carcass is largely a stochastic event, we propose that white shark scavenging on whales may represent an underestimated, yet significant component to the overall foraging ecology of this species, especially as individuals attain sexual maturity.
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- 2013
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19. Cyanobacterial Neurotoxin BMAA and Mercury in Sharks
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Neil Hammerschlag, David A. Davis, Kiyo Mondo, Matthew S. Seely, Susan J. Murch, William Broc Glover, Timothy Divoll, David C. Evers, and Deborah C. Mash
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β-N-methylamino- ,l-alanine%22">">l-alanine ,conservation ,cyanobacteria ,total mercury ,methylmercury ,neurodegenerative disease ,neurotoxin ,sharks ,Medicine - Abstract
Sharks have greater risk for bioaccumulation of marine toxins and mercury (Hg), because they are long-lived predators. Shark fins and cartilage also contain β-N-methylamino-l-alanine (BMAA), a ubiquitous cyanobacterial toxin linked to neurodegenerative diseases. Today, a significant number of shark species have found their way onto the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Many species of large sharks are threatened with extinction due in part to the growing high demand for shark fin soup and, to a lesser extent, for shark meat and cartilage products. Recent studies suggest that the consumption of shark parts may be a route to human exposure of marine toxins. Here, we investigated BMAA and Hg concentrations in fins and muscles sampled in ten species of sharks from the South Atlantic and Pacific Oceans. BMAA was detected in all shark species with only seven of the 55 samples analyzed testing below the limit of detection of the assay. Hg concentrations measured in fins and muscle samples from the 10 species ranged from 0.05 to 13.23 ng/mg. These analytical test results suggest restricting human consumption of shark meat and fins due to the high frequency and co-occurrence of two synergistic environmental neurotoxic compounds.
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- 2016
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20. A comparison of spatial and movement patterns between sympatric predators: bull sharks (Carcharhinus leucas) and Atlantic tarpon (Megalops atlanticus).
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Neil Hammerschlag, Jiangang Luo, Duncan J Irschick, and Jerald S Ault
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Medicine ,Science - Abstract
BACKGROUND: Predators can impact ecosystems through trophic cascades such that differential patterns in habitat use can lead to spatiotemporal variation in top down forcing on community dynamics. Thus, improved understanding of predator movements is important for evaluating the potential ecosystem effects of their declines. METHODOLOGY/PRINCIPAL FINDINGS: We satellite-tagged an apex predator (bull sharks, Carcharhinus leucas) and a sympatric mesopredator (Atlantic tarpon, Megalops atlanticus) in southern Florida waters to describe their habitat use, abundance and movement patterns. We asked four questions: (1) How do the seasonal abundance patterns of bull sharks and tarpon compare? (2) How do the movement patterns of bull sharks and tarpon compare, and what proportion of time do their respective primary ranges overlap? (3) Do tarpon movement patterns (e.g., straight versus convoluted paths) and/or their rates of movement (ROM) differ in areas of low versus high bull shark abundance? and (4) Can any general conclusions be reached concerning whether tarpon may mitigate risk of predation by sharks when they are in areas of high bull shark abundance? CONCLUSIONS/SIGNIFICANCE: Despite similarities in diet, bull sharks and tarpon showed little overlap in habitat use. Bull shark abundance was high year-round, but peaked in winter; while tarpon abundance and fishery catches were highest in late spring. However, presence of the largest sharks (>230 cm) coincided with peak tarpon abundance. When moving over deep open waters (areas of high shark abundance and high food availability) tarpon maintained relatively high ROM in directed lines until reaching shallow structurally-complex areas. At such locations, tarpon exhibited slow tortuous movements over relatively long time periods indicative of foraging. Tarpon periodically concentrated up rivers, where tracked bull sharks were absent. We propose that tarpon trade-off energetic costs of both food assimilation and osmoregulation to reduce predation risk by bull sharks.
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- 2012
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- View/download PDF
21. Physiological state predicts space use of sharks at a tourism provisioning site
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Bianca S. Rangel, Renata G. Moreira, Mitchell J. Rider, James A. Sulikowski, Austin J. Gallagher, Michael R. Heithaus, Steven J. Cooke, Les Kaufman, and Neil Hammerschlag
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REPRODUÇÃO ,Animal Science and Zoology ,Ecology, Evolution, Behavior and Systematics - Published
- 2022
22. Urban Living Affects the Nutrition of Sharks
- Author
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Bianca S. Rangel, Renata G. Moreira, and Neil Hammerschlag
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General Medicine - Abstract
It is common to see some wild animals in the city, like squirrels and raccoons, but have you ever thought about sharks in the city? While you will not see a shark hanging out on the streets of downtown, you may see one swimming along the shorelines of major seaside cities! Although living in coastal cities can bring many benefits to sharks, such as abundant food and protection from large predators, sharks can be negatively affected by pollution and fishing. We studied blacktip sharks living near the city of Miami, Florida, to see if urban living affected their diets and their health. We found that blacktip sharks living close the city (nicknamed urban sharks) were fatter than non-urban sharks. Urban sharks also showed signs of eating more saturated fats, which are unhealthy when in excess in an animal’s body. This shows us that urban sharks are likely eating more food of lower quality, which can have negative consequences for their health.
- Published
- 2023
23. A novel intrauterine satellite transmitter to identify parturition in large sharks
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James A. Sulikowski and Neil Hammerschlag
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Multidisciplinary - Abstract
Determining where and when animals give birth is critical for establishing effective conservation management that protects vulnerable life stages (e.g., pregnant females and newborns) and places (e.g., nursery grounds). To date, this information has been elusive in the case of highly migratory sharks in the wild. Here, we report on the deployment a of novel intrauterine satellite tag implanted in two highly mobile apex predators, the tiger shark ( Galeocerdo cuvier ) and the scalloped hammerhead ( Sphyrna lewini ), that remotely documented the location and timing of birth by a highly migratory oceanic animal in the wild. This novel technology will be especially valuable for the protection of threatened and endangered shark species, where protection of pupping and nursery grounds is a conservation priority.
- Published
- 2023
24. Reviewing Cd, Hg and Pb Assessments and Effects in Elasmobranchs
- Author
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Natascha Wosnick, Aline Cristina Prado, Mariana Martins, Liza Merly, Ana Paula Chaves, Neil Hammerschlag, Oliver Shipley, and Rachel Ann Hauser-Davis
- Published
- 2023
25. Loss of an apex predator in the wild induces physiological and behavioural changes in prey
- Author
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Neil Hammerschlag, Chris Fallows, Michael Meÿer, Simon Mduduzi Seakamela, Samantha Orndorff, Steve Kirkman, Deon Kotze, and Scott Creel
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South Africa ,Food Chain ,Seals, Earless ,Predatory Behavior ,Sharks ,Animals ,Global Change Biology ,General Agricultural and Biological Sciences ,Agricultural and Biological Sciences (miscellaneous) - Abstract
Predators can impact prey via predation or risk effects, which can initiate trophic cascades. Given widespread population declines of apex predators, understanding and predicting the associated ecological consequences is a priority. When predation risk is relatively unpredictable or uncontrollable by prey, the loss of predators is hypothesized to release prey from stress; however, there are few tests of this hypothesis in the wild. A well-studied predator–prey system between white sharks (Carcharodon carcharias) and Cape fur seals (Arctocephalus pusillus pusillus) in False Bay, South Africa, has previously demonstrated elevated faecal glucocorticoid metabolite concentrations (fGCMs) in seals exposed to high levels of predation risk from white sharks. A recent decline and disappearance of white sharks from the system has coincided with a pronounced decrease in seal fGCM concentrations. Seals have concurrently been rafting further from shore and over deeper water, a behaviour that would have previously rendered them vulnerable to attack. These results show rapid physiological and behavioural responses by seals to release from predation stress. To our knowledge, this represents the first demonstration in the wild of physiological changes in prey from predator decline, and such responses are likely to increase given the scale and pace of apex predator declines globally.
- Published
- 2023
26. Preliminary investigation of reproductive hormone profiles in the blacktip shark (
- Author
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Hannah J. Verkamp, Neil Hammerschlag, James Quinlan, Joseph A. Langan, and James A. Sulikowski
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Ecology ,Aquatic Science ,Oceanography ,Ecology, Evolution, Behavior and Systematics - Abstract
Accurate reproductive information is crucial for the effective management of sharks. Here, we used non-lethal methods to evaluate reproductive hormone profiles of blacktip sharks (Carcharhinus limbatus) off the coast of southern Florida (FL) as part of a preliminary investigation of this species’ reproductive patterns in the region. Circulating testosterone concentrations in males ranged from 0.04 to 320.7 ng mL−1, and concentrations peaked during months previously shown to represent peak spermatogenic activity. In females, circulating concentrations of oestradiol (E2) ranged from 12.5 to 941.4 pg mL−1, and progesterone (P4) ranged from 30.1 to 821.2 pg mL−1. E2 peaked during months with peak vitellogenic and ovulatory activity in previous studies; P4 displayed less variability among months. In general, changes in monthly hormone concentrations align well with the timing of reproductive events in C. limbatus in other regions. However, because of low monthly sample sizes and a lack of reproductive status confirmation, the female profiles raise interesting questions about this population’s reproductive cycle that could be explored in future studies. Additional studies should collect larger monthly samples and incorporate supplementary data to provide more insight into the reproductive cycle of this species in southern FL.
- Published
- 2022
27. Ocean warming alters the distributional range, migratory timing, and spatial protections of an apex predator, the tiger shark ( Galeocerdo cuvier )
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Neil Hammerschlag, Laura H. McDonnell, Mitchell J. Rider, Garrett M. Street, Elliott L. Hazen, Lisa J. Natanson, Camilla T. McCandless, Melanie R. Boudreau, Austin J. Gallagher, Malin L. Pinsky, and Ben Kirtman
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Global and Planetary Change ,Ecology ,Climate Change ,Oceans and Seas ,Fisheries ,Sharks ,Animals ,Humans ,Environmental Chemistry ,Ecosystem ,General Environmental Science - Abstract
Given climate change threats to ecosystems, it is critical to understand the responses of species to warming. This is especially important in the case of apex predators since they exhibit relatively high extinction risk, and changes to their distribution could impact predator-prey interactions that can initiate trophic cascades. Here we used a combined analysis of animal tracking, remotely sensed environmental data, habitat modeling, and capture data to evaluate the effects of climate variability and change on the distributional range and migratory phenology of an ectothermic apex predator, the tiger shark (Galeocerdo cuvier). Tiger sharks satellite tracked in the western North Atlantic between 2010 and 2019 revealed significant annual variability in the geographic extent and timing of their migrations to northern latitudes from ocean warming. Specifically, tiger shark migrations have extended farther poleward and arrival times to northern latitudes have occurred earlier in the year during periods with anomalously high sea-surface temperatures. A complementary analysis of nearly 40 years of tiger shark captures in the region revealed decadal-scale changes in the distribution and timing of shark captures in parallel with long-term ocean warming. Specifically, areas of highest catch densities have progressively increased poleward and catches have occurred earlier in the year off the North American shelf. During periods of anomalously high sea-surface temperatures, movements of tracked sharks shifted beyond spatial management zones that had been affording them protection from commercial fishing and bycatch. Taken together, these study results have implications for fisheries management, human-wildlife conflict, and ecosystem functioning.
- Published
- 2022
28. Physiological markers suggest energetic and nutritional adjustments in male sharks linked to reproduction
- Author
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Neil Hammerschlag, James A. Sulikowski, Bianca de Sousa Rangel, and Renata Guimarães Moreira
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biology ,Period (gene) ,media_common.quotation_subject ,Zoology ,chemical and pharmacologic phenomena ,Pelagic zone ,biology.organism_classification ,Blacktip shark ,ACASALAMENTO ,Carcharhinus ,Mating ,Reproduction ,Nurse shark ,human activities ,Ecology, Evolution, Behavior and Systematics ,Testosterone ,media_common - Abstract
Energetic condition is one of the most important factors that influence fitness and reproductive performance in vertebrates. Yet, we lack evidence on how energetic states change in response to reproduction in large marine vertebrates. In the present study, we used a non-lethal approach to assess relationships among reproductive stage, circulating steroid hormones (testosterone and relative corticosteroid levels), plasma fatty acids, and the ketone body β-hydroxybutyrate in male sharks of two species with divergent ecologies, the benthic nurse shark (Ginglymostoma cirratum) and the epipelagic blacktip shark (Carcharhinus limbatus). We found higher relative corticosteroid levels in adult nurse sharks during the pre-mating period and in blacktip sharks during the mating period. Higher levels of β-hydroxybutyrate were found in adult nurse sharks during the mating period, but concentrations of this ketone body did not significantly vary across reproductive stages in blacktip sharks. We also detected reduced percentages of essential fatty acids during the mating period of both nurse and blacktip sharks. Taken together, our findings suggest that nurse and blacktip sharks differ in their energetic strategy to support reproduction, however, they likely rely on physiologically important fatty acids during mating, to support spermatogenesis.
- Published
- 2021
29. Movescapes and eco‐evolutionary movement strategies in marine fish: Assessing a connectivity hotspot
- Author
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Jayne M. Gardiner, Susan K. Lowerre-Barbieri, Debra L. Abercrombie, Mitchell J. Rider, Matt Perkinson, Joel Bickford, Matthew J. Smukall, Jacob W. Brownscombe, Andy J. Danylchuk, Lucas P. Griffin, Neil Hammerschlag, Steven J. Cooke, Gregg R. Poulakis, Barbara A. Block, R. Dean Grubbs, Joy M. Young, Danielle Morley, Tristan L. Guttridge, Carissa L. Gervasi, Gregory B. Skomal, Kim Bassos-Hull, Alejandro Acosta, Andrea M. Kroetz, Jennifer S. Rehage, Frederick G. Whoriskey, Maurits P. M. van Zinnicq Bergmann, Claudia Friess, Grace A. Casselberry, Dustin T. Addis, and Aaron J. Adams
- Subjects
Hotspot (Wi-Fi) ,Geography ,Eco evolutionary ,business.industry ,Movement (music) ,Environmental resource management ,Space use ,Marine fish ,Management, Monitoring, Policy and Law ,Aquatic Science ,Oceanography ,business ,Ecology, Evolution, Behavior and Systematics - Published
- 2021
30. Diving into the vertical dimension of elasmobranch movement ecology
- Author
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Samantha Andrzejaczek, Tim C.D. Lucas, Maurice C. Goodman, Nigel E. Hussey, Amelia J. Armstrong, Aaron Carlisle, Daniel M. Coffey, Adrian C. Gleiss, Charlie Huveneers, David M. P. Jacoby, Mark G. Meekan, Johann Mourier, Lauren R. Peel, Kátya Abrantes, André S. Afonso, Matthew J. Ajemian, Brooke N. Anderson, Scot D. Anderson, Gonzalo Araujo, Asia O. Armstrong, Pascal Bach, Adam Barnett, Mike B. Bennett, Natalia A. Bezerra, Ramon Bonfil, Andre M. Boustany, Heather D. Bowlby, Ilka Branco, Camrin D. Braun, Edward J. Brooks, Judith Brown, Patrick J. Burke, Paul Butcher, Michael Castleton, Taylor K. Chapple, Olivier Chateau, Maurice Clarke, Rui Coelho, Enric Cortes, Lydie I. E. Couturier, Paul D. Cowley, Donald A. Croll, Juan M. Cuevas, Tobey H. Curtis, Laurent Dagorn, Jonathan J. Dale, Ryan Daly, Heidi Dewar, Philip D. Doherty, Andrés Domingo, Alistair D. M. Dove, Michael Drew, Christine L. Dudgeon, Clinton A. J. Duffy, Riley G. Elliott, Jim R. Ellis, Mark V. Erdmann, Thomas J. Farrugia, Luciana C. Ferreira, Francesco Ferretti, John D. Filmalter, Brittany Finucci, Chris Fischer, Richard Fitzpatrick, Fabien Forget, Kerstin Forsberg, Malcolm P. Francis, Bryan R. Franks, Austin J. Gallagher, Felipe Galvan-Magana, Mirta L. García, Troy F. Gaston, Bronwyn M. Gillanders, Matthew J. Gollock, Jonathan R. Green, Sofia Green, Christopher A. Griffiths, Neil Hammerschlag, Abdi Hasan, Lucy A. Hawkes, Fabio Hazin, Matthew Heard, Alex Hearn, Kevin J. Hedges, Suzanne M. Henderson, John Holdsworth, Kim N. Holland, Lucy A. Howey, Robert E. Hueter, Nicholas E. Humphries, Melanie Hutchinson, Fabrice R. A. Jaine, Salvador J. Jorgensen, Paul E. Kanive, Jessica Labaja, Fernanda O. Lana, Hugo Lassauce, Rebecca S. Lipscombe, Fiona Llewellyn, Bruno C. L. Macena, Ronald Mambrasar, Jaime D. McAllister, Sophy R. McCully Phillips, Frazer McGregor, Matthew N. McMillan, Lianne M. McNaughton, Sibele A. Mendonça, Carl G. Meyer, Megan Meyers, John A. Mohan, John C. Montgomery, Gonzalo Mucientes, Michael K. Musyl, Nicole Nasby-Lucas, Lisa J. Natanson, John B. O’Sullivan, Paulo Oliveira, Yannis P. Papastamtiou, Toby A. Patterson, Simon J. Pierce, Nuno Queiroz, Craig A. Radford, Andy J. Richardson, Anthony J. Richardson, David Righton, Christoph A. Rohner, Mark A. Royer, Ryan A. Saunders, Matthias Schaber, Robert J. Schallert, Michael C. Scholl, Andrew C. Seitz, Jayson M. Semmens, Edy Setyawan, Brendan D. Shea, Rafid A. Shidqi, George L. Shillinger, Oliver N. Shipley, Mahmood S. Shivji, Abraham B. Sianipar, Joana F. Silva, David W. Sims, Gregory B. Skomal, Lara L. Sousa, Emily J. Southall, Julia L. Y. Spaet, Kilian M. Stehfest, Guy Stevens, Joshua D. Stewart, James A. Sulikowski, Ismail Syakurachman, Simon R. Thorrold, Michele Thums, David Tickler, Mariana T. Tolloti, Kathy A. Townsend, Paulo Travassos, John P. Tyminski, Jeremy J. Vaudo, Drausio Veras, Laurent Wantiez, Sam B. Weber, R.J. David Wells, Kevin C. Weng, Bradley M. Wetherbee, Jane E. Williamson, Matthew J. Witt, Serena Wright, Kelly Zilliacus, Barbara A. Block, David J. Curnick, Andrzejaczek, Samantha [0000-0002-9929-7312], Lucas, Tim CD [0000-0003-4694-8107], Goodman, Maurice C [0000-0002-6874-2313], Hussey, Nigel E [0000-0002-9050-6077], Armstrong, Amelia J [0000-0001-8103-4314], Carlisle, Aaron [0000-0003-0796-6564], Coffey, Daniel M [0000-0001-5983-0146], Huveneers, Charlie [0000-0001-8937-1358], Jacoby, David MP [0000-0003-2729-3811], Meekan, Mark G [0000-0002-3067-9427], Mourier, Johann [0000-0001-9019-1717], Peel, Lauren R [0000-0001-6960-5663], Abrantes, Kátya [0000-0001-7430-8428], Afonso, André S [0000-0001-9129-278X], Ajemian, Matthew J [0000-0002-2725-4030], Anderson, Brooke N [0000-0003-4299-3496], Araujo, Gonzalo [0000-0002-4708-3638], Armstrong, Asia O [0000-0002-9307-0598], Barnett, Adam [0000-0001-7430-8428], Bennett, Mike B [0000-0001-8051-0040], Bezerra, Natalia A [0000-0002-4203-8408], Bonfil, Ramon [0000-0002-5753-464X], Boustany, Andre M [0000-0001-5501-7190], Bowlby, Heather D [0000-0002-2532-3725], Branco, Ilka [0000-0001-8136-2596], Braun, Camrin D [0000-0002-9317-9489], Brooks, Edward J [0000-0001-5206-7133], Burke, Patrick J [0000-0002-7217-0215], Butcher, Paul [0000-0001-7338-6037], Castleton, Michael [0000-0001-9639-6967], Chapple, Taylor K [0000-0002-0357-0223], Chateau, Olivier [0000-0003-1153-6284], Coelho, Rui [0000-0003-3813-5157], Cortes, Enric [0000-0001-6001-2482], Couturier, Lydie IE [0000-0002-3885-3397], Cuevas, Juan M [0000-0003-0086-5963], Curtis, Tobey H [0000-0003-0164-7335], Dale, Jonathan J [0000-0001-8565-3841], Daly, Ryan [0000-0002-4409-6951], Dewar, Heidi [0000-0002-8202-1387], Doherty, Philip D [0000-0001-7561-3731], Domingo, Andrés [0000-0002-1793-7663], Dove, Alistair DM [0000-0003-3239-4772], Drew, Michael [0000-0002-5109-7792], Dudgeon, Christine L [0000-0001-5059-7886], Duffy, Clinton AJ [0000-0002-3352-1609], Elliott, Riley G [0000-0003-0234-5953], Erdmann, Mark V [0000-0002-3644-8347], Farrugia, Thomas J [0000-0001-9052-8826], Ferreira, Luciana C [0000-0001-6755-2799], Ferretti, Francesco [0000-0001-9510-3552], Finucci, Brittany [0000-0003-1315-2946], Forget, Fabien [0000-0002-4845-4277], Forsberg, Kerstin [0000-0002-1233-9381], Franks, Bryan R [0000-0003-4016-9225], Gallagher, Austin J [0000-0003-1515-3440], García, Mirta L [0000-0003-0143-7397], Gaston, Troy F [0000-0003-0049-0831], Gillanders, Bronwyn M [0000-0002-7680-2240], Green, Jonathan R [0000-0001-7671-6716], Green, Sofia [0000-0002-2878-5984], Griffiths, Christopher A [0000-0001-7203-0426], Hammerschlag, Neil [0000-0001-9002-9082], Hawkes, Lucy A [0000-0002-6696-1862], Hearn, Alex [0000-0002-4986-098X], Hedges, Kevin J [0000-0002-2219-2360], Holland, Kim N [0000-0003-4663-7026], Howey, Lucy A [0000-0001-7381-4871], Humphries, Nicholas E [0000-0003-3741-1594], Hutchinson, Melanie [0000-0001-7042-0658], Jaine, Fabrice RA [0000-0002-9304-5034], Jorgensen, Salvador J [0000-0002-4331-1648], Kanive, Paul E [0000-0003-2430-6920], Labaja, Jessica [0000-0001-6916-7050], Lana, Fernanda O [0000-0001-7235-069X], Lassauce, Hugo [0000-0001-9636-6522], Lipscombe, Rebecca S [0000-0001-9602-643X], Llewellyn, Fiona [0000-0003-4309-8311], Macena, Bruno CL [0000-0001-5010-8560], McCully Phillips, Sophy R [0000-0003-3110-5916], McGregor, Frazer [0000-0002-7441-4404], McMillan, Matthew N [0000-0001-6348-184X], Mendonça, Sibele A [0000-0002-1981-5950], Mohan, John A [0000-0002-2758-163X], Mucientes, Gonzalo [0000-0001-6650-3020], Musyl, Michael K [0000-0003-4719-9259], Nasby-Lucas, Nicole [0000-0001-8355-9392], Natanson, Lisa J [0000-0002-2903-6037], O'Sullivan, John B [0000-0002-1689-2141], Oliveira, Paulo [0000-0001-7697-2111], Papastamtiou, Yannis P [0000-0002-6091-6841], Patterson, Toby A [0000-0002-7150-9205], Pierce, Simon J [0000-0002-9375-5175], Queiroz, Nuno [0000-0002-3860-7356], Radford, Craig A [0000-0001-7949-9497], Richardson, Andy J [0000-0003-2598-5080], Richardson, Anthony J [0000-0002-9289-7366], Righton, David [0000-0001-8643-3672], Rohner, Christoph A [0000-0001-8760-8972], Royer, Mark A [0000-0002-6938-7536], Schaber, Matthias [0000-0003-1032-4626], Schallert, Robert J [0000-0002-3584-2668], Scholl, Michael C [0000-0002-6014-1759], Semmens, Jayson M [0000-0003-1742-6692], Setyawan, Edy [0000-0001-6629-5997], Shea, Brendan D [0000-0001-7771-0586], Shillinger, George L [0000-0001-5168-4551], Shipley, Oliver N [0000-0001-5163-3471], Sianipar, Abraham B [0000-0003-4049-3893], Silva, Joana F [0000-0002-2897-1410], Sims, David W [0000-0002-0916-7363], Sousa, Lara L [0000-0002-4392-3572], Southall, Emily J [0000-0001-7246-278X], Spaet, Julia LY [0000-0001-8703-1472], Stevens, Guy [0000-0002-2056-9830], Sulikowski, James A [0000-0002-3646-5200], Thums, Michele [0000-0002-8669-8440], Tickler, David [0000-0001-7722-0771], Tolloti, Mariana T [0000-0001-6895-2479], Townsend, Kathy A [0000-0002-2581-2158], Travassos, Paulo [0000-0001-8667-5292], Tyminski, John P [0000-0001-8251-7385], Vaudo, Jeremy J [0000-0002-6826-3822], Veras, Drausio [0000-0001-5627-6848], Wantiez, Laurent [0000-0001-5024-2057], Weber, Sam B [0000-0003-1447-4082], Wells, RJ David [0000-0002-1306-0614], Weng, Kevin C [0000-0002-7069-7152], Wetherbee, Bradley M [0000-0002-3753-8950], Williamson, Jane E [0000-0003-3627-4508], Witt, Matthew J [0000-0002-9498-5378], Zilliacus, Kelly [0000-0001-9166-5611], Block, Barbara A [0000-0001-5181-3616], Curnick, David J [0000-0002-3093-1282], Apollo - University of Cambridge Repository, Zoological Society of London - ZSL (UNITED KINGDOM), Centre de recherches insulaires et observatoire de l'environnement (CRIOBE), Université de Perpignan Via Domitia (UPVD)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), and Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)
- Subjects
Multidisciplinary ,[SDV]Life Sciences [q-bio] ,Violacea Bonaparte ,3103 Ecology ,Pelagic stingray ,Scalloped hammerhead shark ,41 Environmental Sciences ,Western North Pacific ,Reproductive-biology ,Habitat Use ,Carcharhinus-falciformis ,Galeocerdo-cuvier ,Sexual segregation ,Sphyna-lewini ,31 Biological Sciences - Abstract
20 pages, 3 tables, 5 figures.-- Samantha Andrzejaczek ... et al.-- Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC), Knowledge of the three-dimensional movement patterns of elasmobranchs is vital to understand their ecological roles and exposure to anthropogenic pressures. To date, comparative studies among species at global scales have mostly focused on horizontal movements. Our study addresses the knowledge gap of vertical movements by compiling the first global synthesis of vertical habitat use by elasmobranchs from data obtained by deployment of 989 biotelemetry tags on 38 elasmobranch species. Elasmobranchs displayed high intra- and interspecific variability in vertical movement patterns. Substantial vertical overlap was observed for many epipelagic elasmobranchs, indicating an increased likelihood to display spatial overlap, biologically interact, and share similar risk to anthropogenic threats that vary on a vertical gradient. We highlight the critical next steps toward incorporating vertical movement into global management and monitoring strategies for elasmobranchs, emphasizing the need to address geographic and taxonomic biases in deployments and to concurrently consider both horizontal and vertical movements, Data analysis was funded by the Bertarelli Foundation through the Marine Science program through grants to D.J.C., B.A.B., and S.A. D.J.C. is also funded through Research England, UK. S.A. and B.A.B. thank the Moore Foundation and the Packard Foundation. F.G.-M. thanks the Instituto Politecnico Nacional for fellowships (COFAA, EDI). S.B.W. thanks funding from the Darwin Initiative (DPLUS046). A.D.M.D. acknowledges funding from the Research and Conservation Budget at Georgia Aquarium, including philanthropic gifts from several anonymous donors. K.F. acknowledges funding from the Rolex Awards for Enterprise and the Whitley Fund for Nature
- Published
- 2022
31. Dietary and reproductive biomarkers in a generalist apex predator reveal differences in nutritional ecology across life stages
- Author
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James A. Sulikowski, Neil Hammerschlag, Bianca de Sousa Rangel, and Renata Guimarães Moreira
- Subjects
0106 biological sciences ,Ecology ,biology ,010604 marine biology & hydrobiology ,media_common.quotation_subject ,Zoology ,Aquatic Science ,Generalist and specialist species ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Life stage ,TUBARÕES ,Reproduction ,Ecology, Evolution, Behavior and Systematics ,Nutritional ecology ,Tiger shark ,Apex predator ,media_common - Abstract
Knowledge of the nutritional requirements of apex predators is key for determining ecological interactions. However, an understanding of how diet is influenced by reproduction, and the consequences of foraging variation on the nutritional status of a predator, is limited. Here, we used short-term dietary markers (plasma and whole-blood fatty acids) integrated with reproductive hormones (17β-estradiol and testosterone) and ultrasonography as a non-lethal approach to investigate the effect of life stage on nutritional status and trophic dynamics of female tiger sharks Galeocerdo cuvier. Despite their generalist feeding behavior, female tiger sharks fed on different food sources and/or modulated their fatty acid metabolism depending on the reproductive context. This suggests some adjustment in their nutritional requirements associated with changes in their reproductive state. Plasma and whole-blood fatty acids indicated distinct dietary sources across life stages, with a high dependence on coastal/benthic food resources during juvenile life stages, and on pelagic/oceanic and reef-associated food resources during adult life stages. Higher percentages of highly unsaturated omega-3 fatty acids found in females during their reproductive cycles suggest the dependency on these fatty acids as a source of metabolic energy during reproduction. A high percentage of arachidonic acid (ARA) found in plasma of gravid females suggests the possibility of a selective diet of ARA-rich prey species and/or selective mobilization of ARA from stored energy during gestation. Based on our findings, we propose a conceptual model of expected changes in nutritional and trophic markers across life stages of female tiger sharks.
- Published
- 2021
32. Estimated life-history traits and movements of the Caribbean reef shark (Carcharhinus perezi) in The Bahamas based on tag-recapture data
- Author
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Brendan S. Talwar, Darcy Bradley, Christopher Berry, Mark E. Bond, Ian A. Bouyoucos, Annabelle M. L. Brooks, Candace Y. A. Fields, Austin J. Gallagher, Tristan L. Guttridge, Annie E. Guttridge, Neil Hammerschlag, Ian Hamilton, Bryan A. Keller, Steven T. Kessel, Philip Matich, Owen R. O’Shea, Yannis P. Papastamatiou, Cameron Raguse, Eric V. C. Schneider, Oliver N. Shipley, Matthew J. Smukall, Maurits P. M. van Zinnicq Bergmann, and Edward J. Brooks
- Subjects
Ecology ,Aquatic Science ,Ecology, Evolution, Behavior and Systematics - Published
- 2022
33. Regional-scale variability in the movement ecology of marine fishes revealed by an integrative acoustic tracking network
- Author
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Angela B. Collins, Kim Bassos-Hull, Breanna C. DeGroot, Lucas P. Griffin, Andy J. Danylchuk, Frederick G. Whoriskey, M. Randall, EC Bohaboy, Jayne M. Gardiner, Colin P. Shea, Joy M. Young, Rachel M. Scharer, Matthew J. Smukall, Gregory B. Skomal, ME Price, Susan K. Lowerre-Barbieri, RD Grubbs, Jennifer S. Rehage, C. Purtlebaugh, William F. Patterson, GA Alvarez, Tonya R. Wiley, A. Hill, Ryan W. Schloesser, CT Peterson, S. Walters Burnsed, Joel Bickford, C. Friess, Neil Hammerschlag, AG Fox, Andrea M. Kroetz, Robert D. Ellis, H. Menendez, P. M. O’Donnell, Krystan A. Wilkinson, JV Locascio, and Gregg R. Poulakis
- Subjects
0106 biological sciences ,Ecology ,Scale (ratio) ,Movement (music) ,010604 marine biology & hydrobiology ,Ecology (disciplines) ,Acoustic tracking ,Aquatic Science ,010603 evolutionary biology ,01 natural sciences ,Geography ,Oceanography ,Ecosystem monitoring ,Ecology, Evolution, Behavior and Systematics - Abstract
Marine fish movement plays a critical role in ecosystem functioning and is increasingly studied with acoustic telemetry. Traditionally, this research has focused on single species and small spatial scales. However, integrated tracking networks, such as the Integrated Tracking of Aquatic Animals in the Gulf of Mexico (iTAG) network, are building the capacity to monitor multiple species over larger spatial scales. We conducted a synthesis of passive acoustic monitoring data for 29 species (889 transmitters), ranging from large top predators to small consumers, monitored along the west coast of Florida, USA, over 3 yr (2016-2018). Space use was highly variable, with some groups using all monitored areas and others using only the area where they were tagged. The most extensive space use was found for Atlantic tarpon Megalops atlanticus and bull sharks Carcharhinus leucas. Individual detection patterns clustered into 4 groups, ranging from occasionally detected long-distance movers to frequently detected juvenile or adult residents. Synchronized, alongshore, long-distance movements were found for Atlantic tarpon, cobia Rachycentron canadum, and several elasmobranch species. These movements were predominantly northbound in spring and southbound in fall. Detections of top predators were highest in summer, except for nearshore Tampa Bay where the most detections occurred in fall, coinciding with large red drum Sciaenops ocellatus spawning aggregations. We discuss the future of collaborative telemetry research, including current limitations and potential solutions to maximize its impact for understanding movement ecology, conducting ecosystem monitoring, and supporting fisheries management.
- Published
- 2021
34. Multi-year movements of adult and subadult bull sharks (Carcharhinus leucas): philopatry, connectivity, and environmental influences
- Author
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Mitchell J. Rider, Neil Hammerschlag, and Laura H. McDonnell
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0106 biological sciences ,Wet season ,biology ,Environmental change ,Range (biology) ,010604 marine biology & hydrobiology ,Aquatic Science ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Fishery ,Bycatch ,Geography ,Habitat ,Carcharhinus ,Philopatry ,Bay ,Ecology, Evolution, Behavior and Systematics - Abstract
Understanding the movement ecology of marine species is important for conservation management and monitoring their responses to environmental change. In this study, adult and subadult bull sharks (Carcharhinus leucas; n = 16) were acoustically tagged in Biscayne Bay, Florida (USA), where they were tracked locally via an array of 40 passive acoustic receivers, as well as regionally via cooperative acoustic telemetry networks, with individuals tracked up to 4.5 years. Detection data were used to assess philopatry, regional connectivity, and environmental correlates of shark habitat use. Spatial range varied per individual; however, most individuals displayed high residency to Biscayne Bay, exhibiting strong philopatric behavior to the tagging area. A generalized linear mixed model revealed a seasonal pattern in habitat use, with mature females displaying high residency in Biscayne Bay during the colder dry season (November to February) and lower residencies during the warmer wet season (June to October). These seasonal patterns were supported by catch data from long-term fishery-independent shark surveys in the study area. During summer months when residencies of C. leucas declined in Biscayne Bay, their residencies increased in other regions (e.g., Florida Gulf Coast), demonstrative of seasonal migrations. Connectivity between areas of high use (Biscayne Bay and Florida Gulf Coast) was demonstrated by some individuals traveling between these areas. Results from generalized additive mixed models suggest that these movement patterns could be partially driven by seasonal changes in environmental variables as well as an individual’s life stage, including reproductive status.
- Published
- 2021
35. Saws and the city: smalltooth sawfish Pristis pectinata encounters, recovery potential, and research priorities in urbanized coastal waters off Miami, Florida, USA
- Author
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Lindsay M Phenix, Austin J. Gallagher, George H. Burgess, Laura H. McDonnell, Joan A. Browder, Helen Albertson, Neil Hammerschlag, and Thomas L. Jackson
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0106 biological sciences ,Acoustic array ,Ecology ,biology ,010604 marine biology & hydrobiology ,Endangered species ,Miami ,Smalltooth sawfish ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,lcsh:QK1-989 ,Fishery ,Urban ecology ,Geography ,lcsh:Botany ,lcsh:Zoology ,lcsh:QL1-991 ,Nature and Landscape Conservation - Abstract
As coastal urbanization increases globally, the subsequent effects on marine animals, especially endangered species, inhabiting nearshore waters have become a research priority. The smalltooth sawfish Pristis pectinata, once abundant in US waters, now only persists in a few parts of its former range, including South Florida. Many areas utilized by smalltooth sawfish are estuarine systems or other shallow coastal habitats, making this species particularly vulnerable to threats associated with coastal development. To date, P. pectinata has been understudied in the waters in and around Biscayne Bay, Florida, a coastal waterway subjected to the urbanization of adjacent Miami-Dade County. Here, we summarize data from reported smalltooth sawfish encounters dating as far back as 1895 (N = 90) and detail opportune recordings (incidental catches, acoustic detections, and baited remote underwater videos) of sub-adults and adults (N = 14 individuals) in Biscayne Bay and the adjacent reef tract. These data demonstrate historical and increased contemporary use of the study area by this imperiled species, suggesting potential local and regional recovery. Most documented sawfish occurrences were near the urban center, indicating a need to understand the effects of coastal urbanization on sawfish and on the species' recovery potential. We suggest priorities for future research on P. pectinata in the study area that will assist in addressing regional management goals and contribute to understanding the ecology of smalltooth sawfish under environmental change.
- Published
- 2020
36. Variation of body condition and plasma energy substrates with life stage, sex, and season in wild‐sampled nurse sharks <scp> Ginglymostoma cirratum </scp>
- Author
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Neil Hammerschlag, Austin J. Gallagher, Liza Merly, and Shannon G. Moorhead
- Subjects
Male ,0106 biological sciences ,Wet season ,Ontogeny ,Context (language use) ,Aquatic Science ,Biology ,010603 evolutionary biology ,01 natural sciences ,Intraspecific competition ,Plasma ,Sex Factors ,Nursing ,Dry season ,medicine ,Animals ,Triglycerides ,Ecology, Evolution, Behavior and Systematics ,010604 marine biology & hydrobiology ,Age Factors ,Seasonality ,medicine.disease ,Body Composition ,Florida ,Sharks ,Ketone bodies ,Female ,Seasons ,Energy Metabolism ,Blood Chemical Analysis ,Body condition - Abstract
Reported here are the relationships among morphological (i.e., body condition) and biochemical (i.e., plasma concentrations of triglycerides, cholesterol, free fatty acids, and ketone bodies and ketone body ratios) parameters related to energy storage and use, as well as the variation of such parameters, for 107 free-ranging nurse sharks Ginglymostoma cirratum sampled off South Florida. Immature G. cirratum exhibited a higher variance in body condition, plasma free fatty acid concentrations and ketone body ratios compared to adults. Mature female G. cirratum had significantly higher body condition than mature males, driven by a seasonal increase in mature female body condition during the wet season. Mature male G. cirratum showed a decrease in the ketone body β-hydroxybutyric acid during the dry season. Taken together, this study provides a baseline assessment of body condition and internal physiological state for a data-poor marine species and demonstrates significant ontogenetic, sexual and seasonal variation in G. cirratum energetic state. As concluded by other studies of energy metabolism in free-ranging sharks, this research highlights the importance of considering intraspecific patterns and sampling context for inferring the drivers of variation.
- Published
- 2020
37. Evaluating spatial management options for tiger shark (Galeocerdo cuvier) conservation in US Atlantic Waters
- Author
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Alexia Morgan, Neil Hammerschlag, James A. Sulikowski, and Hannah J. Calich
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0106 biological sciences ,food.ingredient ,Ecology ,biology ,010604 marine biology & hydrobiology ,Aquatic Science ,Oceanography ,Galeocerdo ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Fishery ,food ,Geography ,Spatial management ,Marine protected area ,Ecology, Evolution, Behavior and Systematics ,Tiger shark - Abstract
There has been debate in the literature over the use and success of spatial management zones (i.e. marine protected areas and time/area closures) as policy tools for commercially exploited sharks. The tiger shark (Galeocerdo cuvier) is a highly migratory predator found worldwide in warm temperate and tropical seas, which is caught in multiple US fisheries. We used a spatially explicit modelling approach to investigate the impact of varying spatial management options in the Western North Atlantic Ocean on tiger shark biomass, catch, and distribution, and impacts to other species in the ecosystem. Results suggest that under current management scenarios, tiger shark biomass will increase over time. Model outputs indicate that protecting additional habitats will have relatively minimal impacts on tiger shark biomass, as would increasing or decreasing protections in areas not highly suitable for tiger sharks. However, increasing spatial management protections in highly suitable habitats is predicted to have a positive effect on their biomass. Results also predict possible spill-over effects from current spatial protections. Our results provide insights for evaluating differing management strategies on tiger shark abundance patterns and suggest that management zones may be an effective conservation tool for highly migratory species if highly suitable habitat is protected.
- Published
- 2020
38. Serum Protein Electrophoresis Reference Intervals for Six Species of Wild-Sampled Sharks in South Florida
- Author
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Samantha L Shinder, Carolyn Cray, Neil Hammerschlag, and Liza Merly
- Subjects
Animal Science and Zoology ,Plant Science - Abstract
Serum proteins found in the blood have been used as diagnostic markers in both human and animal medicine. Evaluating proteins in the blood of sharks may be a valuable way to assess shark health. The purpose of this study was to perform serum protein electrophoresis from non-lethal blood samples of wild sharks and establish baseline values for six species off South Florida: blacknose (Carcharhinus acronotus), blacktip (C. limbatus), bull (C. leucas), lemon (Negaprion brevirostris), sandbar (C. plumbeus), and tiger shark (Galeocerdo cuvier). Two hundred and fifty-one serum samples were collected between 2015–2018 along with sex determination and morphometric measurements. Agarose gel analysis was performed using mammalian protein fraction delimits albumin, alpha 1-globulins, alpha 2-globulins, beta globulins, and gamma globulins alternatively defined as fractions 1–5. Reference electrophoretic profiles were established for each species, revealing the dominance of protein fractions 3 and 4. The fraction 3:4 ratio was determined for each shark and reference intervals for total solids, protein fractions, and fraction 3:4 ratio are reported for each species. There were no significant differences in total solids or protein fractions between males and females of any species. In both blacktip sharks and bull sharks, total solids were positively correlated with body size, but not in the other species evaluated. In blacknose sharks, the fraction 3:4 ratio was positively correlated with body condition. Results suggest that there may be differences in total solids values across dry and wet seasons for some species. Newly established reference intervals can now be utilized in future research to evaluate the health of captive sharks and to investigate the health status of individuals in the wild as well as relate health measures to environmental conditions.
- Published
- 2022
39. Consequences of 'Natural' Disasters on Aquatic Life and Habitats
- Author
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Steven J. Cooke, Diana M.P. Galassi, Bronwyn M. Gillanders, Sean J. Landsman, Neil Hammerschlag, Austin J. Gallagher, Erika J. Eliason, Clifford E. Kraft, Mark K. Taylor, Charlie M. Crisafulli, Dan H. Shugar, and Robert J. Lennox
- Subjects
General Environmental Science - Abstract
“Natural” disasters (also known as geophysical disasters) involve physical processes that have a direct or indirect impact on humans. These events occur rapidly and may have severe consequences for resident flora and fauna as their habitat undergoes dramatic and sudden change. Although most studies have focused on the impact of natural disasters on humans and terrestrial systems, geophysical disasters can also impact aquatic ecosystems. Here, we provide a synthesis on the effects of the most common and destructive geophysical disasters on aquatic systems (life and habitat). Our approach spanned realms (i.e., freshwater, estuarine, and marine) and taxa (i.e., plants, vertebrates, invertebrates, and microbes) and included floods, droughts, wildfires, hurricanes/cyclones/typhoons, tornadoes, dust storms, ice storms, avalanches (snow), landslides, volcanic eruptions, earthquakes (including limnic eruptions), tsunamis, and cosmic events. Many geophysical disasters have dramatic effects on aquatic systems. The evidence base is somewhat limited for some natural disasters because transient events (e.g., tornadoes and floods) are difficult to study. Most natural disaster studies focus on geology/geomorphology and hazard assessment for humans and infrastructure. However, the destruction of aquatic systems can impact humans indirectly through loss of food security, cultural services, or livelihoods. Many geophysical disasters interact in complex ways (e.g., wildfires often lead to landslides and flooding) and can be magnified or otherwise mediated by human activities. Our synthesis reveals that geophysical events influence aquatic ecosystems, often in negative ways, yet systems can be resilient provided that effects are not compounded by anthropogenic stressors. It is difficult to predict or prevent geophysical disasters but understanding how aquatic ecosystems are influenced by geophysical events is important given the inherent connection between peoples and aquatic ecosystems.
- Published
- 2022
40. Effects of Urbanization on the Nutritional Ecology of a Highly Active Coastal Shark: Preliminary Insights from Trophic Markers and Body Condition
- Author
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Bianca S. Rangel, Neil Hammerschlag, Luiz A. Martinelli, and Renata Guimarães Moreira
- Subjects
History ,Environmental Engineering ,Ecology ,Polymers and Plastics ,Urbanization ,Pollution ,Industrial and Manufacturing Engineering ,Isotopes ,Seafood ,Sharks ,Animals ,Environmental Chemistry ,Business and International Management ,Waste Management and Disposal - Abstract
The synergistic effects of coastal urbanization have dramatically impacted biological communities. Yet, few studies have investigated how urbanization can influence the diet quality and trophic ecology of coastal sharks. In a preliminary study, we examined for spatial variation in the nutritional ecology of a highly active marine predator, the blacktip (Carcharhinus limbatus) exposed to regional differences in coastal urbanization in southeast Florida. We used medium-term nutritional indicators (i.e., body condition and whole blood stable isotopes [δ
- Published
- 2022
41. Serum Protein Analysis of Nurse Sharks
- Author
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Carolyn Cray, Liza Merly, Neil Hammerschlag, and Leila AtallahBenson
- Subjects
Male ,040301 veterinary sciences ,Alpha (ethology) ,Fraction (chemistry) ,Aquatic Science ,0403 veterinary science ,Nursing ,Reference Values ,medicine ,Animals ,Whole blood ,biology ,medicine.diagnostic_test ,Erythropoietin-producing hepatocellular (Eph) receptor ,Albumin ,Blood Proteins ,04 agricultural and veterinary sciences ,Blood Protein Electrophoresis ,biology.organism_classification ,Blood proteins ,Serum protein electrophoresis ,Florida ,Sharks ,040102 fisheries ,0401 agriculture, forestry, and fisheries ,Female ,Nurse shark - Abstract
Serum protein electrophoresis (EPH) is used to assess relative concentrations of blood proteins in clinical and biological studies. Serum EPH fractions have been determined for elasmobranchs using mammalian albumin, alpha 1-, alpha 2-, beta-, and gamma-globulin fractions, and have been deemed fractions 1 through 5, respectively. However, serum EPH fraction concentration reference intervals (RIs) have not been widely established for different elasmobranch species. In this study, RIs for fractions 1 through 5 were determined from 45 wild-caught Nurse Sharks Ginglymostoma cirratum (27 females and 23 males) in South Florida. Serum samples were isolated from whole blood following caudal venipuncture. Body condition was also measured in the field to assess the relative health of the individuals sampled. There was no relationship between body condition and serum EPH fraction concentrations. In addition, there was no difference in body condition or serum EPH fraction concentrations between females and males. Total solids and total protein values were significantly different (P < 0.001). Nurse Shark serum EPH fraction 1 was found within the mammalian albumin migrating band distance and was negligible. Fraction 2 showed no peak in the mammalian alpha 1-globulin range. A thin, medium peak in the mammalian alpha 2-globulin range represented fraction 3. In the mammalian beta-globulin range, fraction 4 consisted of the majority of protein observed. It was represented by a smooth, broad peak. A short, medium broad peak in the mammalian gamma-globulin range represented fraction 5. The Nurse Shark serum EPH fraction RIs provided in this study may be utilized to clinically evaluate the health of Nurse Sharks in captivity and in the wild, and to compare the health of their populations around the world experiencing various anthropogenic stressors and other environmental impacts.
- Published
- 2020
42. Application of three-dimensional acoustic telemetry to assess the effects of rapid recompression on reef fish discard mortality
- Author
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Neil Hammerschlag, Tristan L. Guttridge, William F. Patterson, Erin Collings Bohaboy, and Maurits P. M. van Zinnicq Bergmann
- Subjects
0106 biological sciences ,Ecology ,Coral reef fish ,010604 marine biology & hydrobiology ,04 agricultural and veterinary sciences ,Aquatic Science ,Oceanography ,01 natural sciences ,Predation ,Fishery ,Recreational fishing ,Geography ,Telemetry ,040102 fisheries ,0401 agriculture, forestry, and fisheries ,Ecology, Evolution, Behavior and Systematics - Abstract
Geopositioning underwater acoustic telemetry was used to test whether rapid recompression with weighted return-to-depth (descender) devices reduced discard mortality of red snapper (n = 141) and gray triggerfish (n = 26) captured and released at 30–60 m depths at two 15 km2 study sites in the northern Gulf of Mexico. Cox proportional hazards modelling indicated red snapper released with descender devices had significantly lower discard mortality within the first 2 d (95% CI = 18.8–41.8% for descender-released vs. 44.0–72.4% for surface-released, unvented fish), while there was no significant effect of descender devices on discard mortality of gray triggerfish. Predation by large pelagic predators was estimated to account 83% of red snapper and 100% of gray triggerfish discard mortality. Discard mortality due to predation has likely been overlooked in previous mark-recapture, laboratory, and enclosure studies, suggesting cryptic population losses due to predation on discards may be underestimated for red snapper and gray triggerfish. Large-area three-dimensional positioning acoustic telemetry arrays combined with collaboration and data sharing among acoustic telemetry researchers have the potential to advance our knowledge of the processes affecting discard mortality in reef fishes and other taxa.
- Published
- 2019
43. Comprehensive analytical approaches reveal species-specific search strategies in sympatric apex predatory sharks
- Author
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Carlos M. Duarte, Neil Hammerschlag, Hannah J. Calich, Víctor M. Eguíluz, Jorge P. Rodríguez, Ana M. M. Sequeira, Charitha Pattiaratchi, Australian Government, Ministerio de Ciencia e Innovación (España), Australian Research Council, European Commission, Batchelor Foundation, Disney Conservation Fund, Wells Fargo, Guy Harvey Ocean Foundation, and West Coast Inland Navigation District
- Subjects
Satellite tracking ,Ecology ,Miami ,Carcharhinus leucas ,Movement ecology ,Geography ,Apex (mollusc) ,Sympatric speciation ,Sphyrna mokarran ,Galeocerdo cuvier ,Statistical physics ,Atlantic Ocean ,Ecology, Evolution, Behavior and Systematics - Abstract
Animals follow specific movement patterns and search strategies to maximize encounters with essential resources (e.g. prey, favourable habitat) while minimizing exposures to suboptimal conditions (e.g. competitors, predators). While describing spatiotemporal patterns in animal movement from tracking data is common, understanding the associated search strategies employed continues to be a key challenge in ecology. Moreover, studies in marine ecology commonly focus on singular aspects of species' movements, however using multiple analytical approaches can further enable researchers to identify ecological phenomena and resolve fundamental ecological questions relating to movement. Here, we used a set of statistical physics-based methods to analyze satellite tracking data from three co-occurring apex predators (tiger, great hammerhead and bull sharks) that predominantly inhabit productive coastal regions of the northwest Atlantic Ocean and Gulf of Mexico. We analyzed data from 96 sharks and calculated a range of metrics, including each species' displacements, turning angles, dispersion, space-use and community-wide movement patterns to characterize each species' movements and identify potential search strategies. Our comprehensive approach revealed high interspecific variability in shark movement patterns and search strategies. Tiger sharks displayed near-random movements consistent with a Brownian strategy commonly associated with movements through resource-rich habitats. Great hammerheads showed a mixed-movement strategy including Brownian and resident-type movements, suggesting adaptation to widespread and localized high resource availability. Bull sharks followed a resident movement strategy with restricted movements indicating localized high resource availability. We hypothesize that the species-specific search strategies identified here may help foster the co-existence of these sympatric apex predators. Following this comprehensive approach provided novel insights into spatial ecology and assisted with identifying unique movement and search strategies. Similar future studies of animal movement will help characterize movement patterns and also enable the identification of search strategies to help elucidate the ecological drivers of movement and to understand species' responses to environmental change., HC was supported by an Australian Government RTP scholarship at UWA. JPR received funding from the Juan de la Cierva-formación program (Subprograma Estatal de Formación en I+D+i, Ministerio de Ciencia e Innovación, Spain). AMMS was funded by a 2020 Pew Fellowship in Marine Conservation. This research was supported by an Australian Research Council Discovery Project (Grant DP210103091), and the Ministry of Science and Innovation (Spain) and FEDER through project SPASIMM [FIS2016-80067-P (AEI/FEDER, UE)]. Tagging research was supported by grants to NH from The Batchelor Foundation, Disney Conservation Fund, Wells Fargo, Guy Harvey Ocean Foundation, and the West Coast Inland Navigation District.
- Published
- 2021
44. Reply to: Shark mortality cannot be assessed by fishery overlap alone
- Author
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Emily R. Nelson, Demian D. Chapman, Robert E. Hueter, Fabien Forget, Michele Thums, Mark G. Meekan, Laurent Dagorn, Pedro Afonso, Marcus Sheaves, Robert Harcourt, Charlie Huveneers, Jaime D. McAllister, Marisa Vedor, Alison V. Towner, James S. E. Lea, Sarika Singh, Ramón Bonfil, Nigel E. Hussey, Hector M. Guzman, Eric Clua, Felipe Ladino, Matthew Heard, Diego Bernal, Alex Hearn, John R. M. Chisholm, Warrick S. Lyon, Neil Hammerschlag, Laurenne B. Snyders, Taylor K. Chapple, Paulo Travassos, Sam B. Weber, Frederic Vandeperre, Estelle Crochelet, Clare A. Keating Daly, Patricia Zarate, Enrico Gennari, Cesar Peñaherrera-Palma, Mark E. Bond, Luciana C. Ferreira, Nuno Queiroz, Timothy D. White, Johan A. Gustafson, Graeme C. Hays, Luke Harman, David M. P. Jacoby, Jonathan Green, Francesco Ferretti, Lance K. B. Jordan, Fiona Llewellyn, André S. Afonso, Bonnie J. Holmes, Ryan Johnson, Simon D. Goldsworthy, Ana M. M. Sequeira, Natalia P. A. Bezerra, Steven E. Campana, Malcolm J. Smale, Bradley M. Wetherbee, J.B. Brown, Ana Rita Couto, Michael L. Berumen, Christopher R. Clarke, James T. Ketchum, Austin J. Gallagher, Nicolas E. Humphries, Ivo da Costa, Matthew Gollock, Sean Williams, Ryan Daly, Paul J. Rogers, Simon Pierce, Sandra Bessudo Lion, Samantha J. Simpson, Kilian M. Stehfest, Eduardo Espinoza, Emily J. Southall, Thomas K. Doyle, Marc Soria, Mariana Travassos Tolotti, Yannis P. Papastamatiou, Francois Poisson, Michael E. Byrne, Kátya G. Abrantes, Yuuki Y. Watanabe, Dylan T. Irion, Annabelle Brooks, Anna MacDonnell, Clinton A. J. Duffy, Warren Joyce, Alison A. Kock, Jayson M. Semmens, Michael A. Meÿer, Bruno C. L. Macena, G. Chris Fischer, Richard Fitzpatrick, Mauricio Hoyos, Camrin D. Braun, Carlos M. Duarte, Gonzalo Araujo, Fábio H. V. Hazin, Lara L. Sousa, Jorge Fontes, Mark Fowler, David Rowat, David Acuña-Marrero, Pieter Koen, Gonzalo Mucientes, Randall Arauz, John C. Holdsworth, Aaron B. Carlisle, John J. Morris, Thor Erikson, Adam Barnett, Barry D. Bruce, Daniel Devia Cortés, António M. Santos, Michael E. Drew, Jesse E. M. Cochran, Francisco J. Abascal, Edward J. Brooks, Fernanda O. Lana, Mahmood S. Shivji, Xabier Irigoien, Darrell Anders, Tristan L. Guttridge, Melita Samoilys, David W. Sims, Oliver J. D. Jewell, Lina Maria Quintero, Gregory B. Skomal, Christoph A. Rohner, Barbara A. Block, Pascal Bach, Malcolm P. Francis, German Soler, Debra L. Abercrombie, Simon R. Thorrold, A. Peter Klimley, John P. Tyminski, Russell W. Bradford, John D. Filmalter, Antonin V. Blaison, Heather Marshall, Víctor M. Eguíluz, Jeremy J. Vaudo, George L. Shillinger, Lucy A. Howey, Andrew J. Richardson, Universidade do Porto, Departamento de Oceanografia e Pescas [Horta], Instituto do Mar - Universidade dos Açores (IMAR-UAc), MARine Biodiversity Exploitation and Conservation (UMR MARBEC), Centre National de la Recherche Scientifique (CNRS)-Université de Montpellier (UM)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Institut de Recherche pour le Développement (IRD), King Abdullah University of Science and Technology, Joint Institute for Marine and Atmospheric Research (JIMAR), University of Hawai‘i [Mānoa] (UHM), University of Iceland [Reykjavik], School of Marine and Atmospheric Sciences [Stony Brook] (SoMAS), Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY), Virginia Polytechnic Institute and State University [Blacksburg], South African Institute for Aquatic Biodiversity (SAIAB), South African Institute for Aquatic Biodiversity, Zoological Society of London - ZSL (UNITED KINGDOM), Physique et mécanique des milieux hétérogenes (UMR 7636) (PMMH), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Flinders University of South Australia, James Cook University (JCU), Nova Southeastern University (NSU), Biology Department (WHOI), Woods Hole Oceanographic Institution (WHOI), Universidade Federal Rural de Pernambuco (UFRPE), Universidade dos Açores, Institute for Marine and Antarctic Studies [Horbat] (IMAS), University of Tasmania [Hobart, Australia] (UTAS), Australian Institute of Marine Science (AIMS), Macquarie University [Sydney], Australian Institute of Marine Science [Perth] (AIMS Perth), Ikerbasque - Basque Foundation for Science, and King Abdullah University of Science and Technology (KAUST)
- Subjects
0106 biological sciences ,Conservation of Natural Resources ,Automatic Identification System ,[SDE.MCG]Environmental Sciences/Global Changes ,Fishing ,Fisheries ,010603 evolutionary biology ,01 natural sciences ,survival ,ecological risk-assessment ,law.invention ,Longline fishing ,caught ,law ,Animals ,14. Life underwater ,Multidisciplinary ,010604 marine biology & hydrobiology ,Regression analysis ,Pelagic zone ,Catch per unit effort ,Fishery ,Geography ,Habitat ,Seafood ,Sharks ,Conservation biology ,[SDE.BE]Environmental Sciences/Biodiversity and Ecology - Abstract
REPLYING TO H. Murua et al. Nature https://doi.org/10.1038/s41586-021-03396-4 (2021) Our previously published paper1 provided global fine-scale spatiotemporal estimates (1° × 1°; monthly) of overlap and fishing exposure risk (FEI) between satellite-tracked shark space use and automatic identification system (AIS) longline fishing effort. We did not assess shark mortality directly, but in addition to replying to the Comment by Murua et al.2, we confirm—using regression analysis of spatially matched data—that fishing-induced pelagic shark mortality (catch per unit effort (CPUE)) is greater where FEI is higher. We focused on assessing shark horizontal spatiotemporal overlap and exposure risk with fisheries because spatial overlap is a major driver of fishing capture susceptibility and previous shark ecological risk assessments (ERAs) assumed a homogenous shark density within species-range distributions3,4,5 or used coarse-scale modelled occurrence data, rather than more ecologically realistic risk estimates in heterogeneous habitats that were selected by sharks over time. Furthermore, our shark spatial exposure risk implicitly accounts for other susceptibility factors with equal or similar probabilities to those commonly used in shark ERAs3,5.
- Published
- 2021
45. Predator-prey landscapes of large sharks and game fishes in the Florida Keys
- Author
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Lucas P. Griffin, Grace A. Casselberry, Susan K. Lowerre‐Barbieri, Alejandro Acosta, Aaron J. Adams, Steven J. Cooke, Alex Filous, Claudia Friess, Tristan L. Guttridge, Neil Hammerschlag, Vital Heim, Danielle Morley, Mitchell J. Rider, Gregory B. Skomal, Matthew J. Smukall, Andy J. Danylchuk, and Jacob W. Brownscombe
- Subjects
Ecology ,Predatory Behavior ,Fishes ,Florida ,Sharks ,Animals ,Ecosystem - Abstract
Interspecific interactions can play an essential role in shaping wildlife populations and communities. To date, assessments of interspecific interactions, and more specifically predator-prey dynamics, in aquatic systems over broad spatial and temporal scales (i.e., hundreds of kilometers and multiple years) are rare due to constraints on our abilities to measure effectively at those scales. We applied new methods to identify space-use overlap and potential predation risk to Atlantic tarpon (Megalops atlanticus) and permit (Trachinotus falcatus) from two known predators, great hammerhead (Sphyrna mokarran) and bull (Carcharhinus leucas) sharks, over a 3-year period using acoustic telemetry in the coastal region of the Florida Keys (USA). By examining spatiotemporal overlap, as well as the timing and order of arrival at specific locations compared to random chance, we show that potential predation risk from great hammerhead and bull sharks to Atlantic tarpon and permit are heterogeneous across the Florida Keys. Additionally, we find that predator encounter rates with these game fishes are elevated at specific locations and times, including a prespawning aggregation site in the case of Atlantic tarpon. Further, using machine learning algorithms, we identify environmental variability in overlap between predators and their potential prey, including location, habitat, time of year, lunar cycle, depth, and water temperature. These predator-prey landscapes provide insights into fundamental ecosystem function and biological conservation, especially in the context of emerging fishery-related depredation issues in coastal marine ecosystems.
- Published
- 2021
46. Space use patterns of sharks in relation to boat activity in an urbanized coastal waterway
- Author
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Jerald S. Ault, Neil Hammerschlag, Joan A. Browder, Austin J. Gallagher, Thomas L. Jackson, Erica Staaterman, Christopher R. Sasso, Mitchell J. Rider, and Oliver S. Kirsebom
- Subjects
biology ,Aerial survey ,Sphyrna ,Aquatic ecosystem ,Space use ,General Medicine ,Interspecific competition ,Aquatic Science ,Great hammerhead ,Oceanography ,biology.organism_classification ,Pollution ,Fishery ,Geography ,Carcharhinus ,Florida ,Sharks ,Animals ,Telemetry ,Bay ,Ecosystem ,Ships - Abstract
Aquatic ecosystems face numerous anthropogenic threats associated with coastal urbanization, with boat activity being among the most prevalent. The present study aimed to evaluate a potential relationship between boat activity and shark space use in Biscayne Bay, Florida (USA), a coastal waterway exposed to high levels of boating. Spatiotemporal patterns in boat density and traffic were determined from aerial surveys and underwater acoustic recorders, respectively. These data were then compared with residency patterns of bull (Carcharhinus leucas), nurse (Ginglymostoma cirratum) and great hammerhead (Sphyrna mokarran) sharks quantified through passive acoustic telemetry. Results were mixed, with no detectable relationship between boat density and shark residency for any of the species. Hourly presence of G. cirratum decreased with increasing boat traffic, a relationship not seen in the other two species. Explanations for these results include habituation of sharks to the high levels of chronic boat activity in the study area and interspecific differences in hearing sensitivity.
- Published
- 2021
47. A standardisation framework for bio-logging data to advance ecological research and conservation
- Author
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Michael J. Weise, Melinda Holland, Vardis Tsontos, Francesca Cagnacci, Megan K. McKinzie, Elliott L. Hazen, Adrian C. Gleiss, Robert Harcourt, Samantha E. Simmons, Mônica M. C. Muelbert, Malcolm O'Toole, Peggy Newman, Clint Blight, Brendal Townsend, Jonathan Pye, Frederick G. Whoriskey, Mark A. Hindell, Daniel P. Costa, Ian D. Jonsen, Christian Rutz, Daniel C. Dunn, Chari Pattiaratchi, Theresa R. Keates, Graeme C. Hays, Carlos M. Duarte, Kim N. Holland, David W. Sims, Camrin D. Braun, Fabrice R. A. Jaine, Bill Woodward, Holger Dettki, Ana M. M. Sequeira, Neil Hammerschlag, Ivica Janeković, Víctor M. Eguíluz, Xavier Hoenner, Laura H. McDonnell, Clive R. McMahon, Michelle R. Heupel, Michael A. Fedak, Steven J. Bograd, Sarah C. Davidson, University of St Andrews. Scottish Oceans Institute, University of St Andrews. Sea Mammal Research Unit, University of St Andrews. School of Biology, University of St Andrews. Centre for Biological Diversity, University of St Andrews. Centre for Social Learning & Cognitive Evolution, The Pew Charitable Trusts, and Harvard University
- Subjects
0106 biological sciences ,Bio-logging template ,bio-logging template, data accessibility and interoperability, data standards, metadata templates, movement ecology, sensors, telemetry, tracking ,Process (engineering) ,Computer science ,QH301 Biology ,Interoperability ,010603 evolutionary biology ,01 natural sciences ,bio-logging template ,data accessibility and interoperability ,data standards ,metadata templates ,movement ecology ,sensors ,telemetry ,tracking ,Movement ecology ,QH301 ,Settore BIO/07 - ECOLOGIA ,ddc:570 ,Data standards ,Telemetry ,14. Life underwater ,SDG 14 - Life Below Water ,Ecology, Evolution, Behavior and Systematics ,NetCDF ,GC ,GE ,Ecology ,Data accessibility and interoperability ,Sensors ,010604 marine biology & hydrobiology ,Ecological Modeling ,Tracking ,Metadata templates ,DAS ,computer.file_format ,15. Life on land ,Discoverability ,Data flow diagram ,Workflow ,13. Climate action ,Animal ecology ,GC Oceanography ,Raw data ,computer ,GE Environmental Sciences - Abstract
Bio-logging data obtained by tagging animals are key to addressing global conservation challenges. However, the many thousands of existing bio-logging datasets are not easily discoverable, universally comparable, nor readily accessible through existing repositories and across platforms, slowing down ecological research and effective management. A set of universal standards is needed to ensure discoverability, interoperability and effective translation of bio-logging data into research and management recommendations. We propose a standardisation framework adhering to existing data principles (FAIR: Findable, Accessible, Interoperable and Reusable; and TRUST: Transparency, Responsibility, User focus, Sustainability and Technology) and involving the use of simple templates to create a data flow from manufacturers and researchers to compliant repositories, where automated procedures should be in place to prepare data availability into four standardised levels: (a) decoded raw data, (b) curated data, (c) interpolated data and (d) gridded data. Our framework allows for integration of simple tabular arrays (e.g. csv files) and creation of sharable and interoperable network Common Data Form (netCDF) files containing all the needed information for accuracy-of-use, rightful attribution (ensuring data providers keep ownership through the entire process) and data preservation security. We show the standardisation benefits for all stakeholders involved, and illustrate the application of our framework by focusing on marine animals and by providing examples of the workflow across all data levels, including filled templates and code to process data between levels, as well as templates to prepare netCDF files ready for sharing. Adoption of our framework will facilitate collection of Essential Ocean Variables (EOVs) in support of the Global Ocean Observing System (GOOS) and inter-governmental assessments (e.g. the World Ocean Assessment), and will provide a starting point for broader efforts to establish interoperable bio-logging data formats across all fields in animal ecology., A.M.M.S. was funded by a 2020 Pew Fellowship in Marine Conservation, and also supported by AIMS. C.R. was the recipient of a Radcliffe Fellowship at the Radcliffe Institute for Advanced Study, Harvard University.
- Published
- 2021
48. Diverse resource-use strategies in a large-bodied marine predator guild: evidence from differential use of resource subsidies and intraspecific isotopic variation
- Author
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Austin J. Gallagher, David S. Shiffman, Oliver N. Shipley, Leslie S. Kaufman, and Neil Hammerschlag
- Subjects
Resource (biology) ,Variation (linguistics) ,Ecology ,Guild ,Subsidy ,Differential (mechanical device) ,Aquatic Science ,Biology ,Predator ,Ecology, Evolution, Behavior and Systematics ,Intraspecific competition ,Isotope analysis - Published
- 2019
49. Ecosystem Function and Services of Aquatic Predators in the Anthropocene
- Author
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Neil Hammerschlag, Andrew Sih, Steven J. Cooke, Rachel A. Skubel, Alexander S. Flecker, Oswald J. Schmitz, Duncan J. Irschick, Austin J. Gallagher, Trisha B. Atwood, and Kevin D. Lafferty
- Subjects
0106 biological sciences ,Food Chain ,Ecology ,Environmental change ,business.industry ,Climate Change ,010604 marine biology & hydrobiology ,Environmental resource management ,Fisheries ,010603 evolutionary biology ,01 natural sciences ,Ecosystem services ,Adaptive management ,Geography ,Habitat ,Anthropocene ,Humans ,Ecosystem ,Trophic cascade ,business ,Ecology, Evolution, Behavior and Systematics ,Tourism - Abstract
Arguments for the need to conserve aquatic predator (AP) populations often focus on the ecological and socioeconomic roles they play. Here, we summarize the diverse ecosystem functions and services connected to APs, including regulating food webs, cycling nutrients, engineering habitats, transmitting diseases/parasites, mediating ecological invasions, affecting climate, supporting fisheries, generating tourism, and providing bioinspiration. In some cases, human-driven declines and increases in AP populations have altered these ecosystem functions and services. We present a social ecological framework for supporting adaptive management decisions involving APs in response to social and environmental change. We also identify outstanding questions to guide future research on the ecological functions and ecosystem services of APs in a changing world.
- Published
- 2019
50. Intraspecific differences in relative isotopic niche area and overlap of co-occurring sharks
- Author
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Neil Hammerschlag, Michael R. Heithaus, Les Kaufman, and David S. Shiffman
- Subjects
0106 biological sciences ,Ecology ,010604 marine biology & hydrobiology ,Niche ,Aquatic Science ,Biology ,biology.organism_classification ,010603 evolutionary biology ,01 natural sciences ,Intraspecific competition ,Food web ,Blacktip shark ,Sympatric speciation ,Carcharhinus ,Ecology, Evolution, Behavior and Systematics ,Trophic level ,Isotope analysis - Abstract
Few studies have assessed whether patterns of resource partitioning among sympatric marine predators vary between different habitats. This type of data is important for understanding food web functioning as well as for supporting an ecosystem-based fisheries management plan. In this study, we used δ13C and δ15N stable isotope analysis to assess the relative isotopic niche area (i.e., which species has the largest and smallest isotopic niche area within a study site) and core isotopic niche overlap between 299 sharks of 11 co-occurring shark species that vary in size, diet and behavior in three coastal study areas in South Florida. Overall, results show that the relative isotopic niche area and patterns of core isotopic niche overlap between some sympatric shark species varied between sites, suggesting plasticity in resource use and competitive interactions between shark species (e.g., 85% of blacktip shark Carcharhinus limbatus standard ellipse area overlapped with the blacknose shark C. acronotus ellipse in Biscayne Bay, but there was no overlap between these species’ ellipses in nearby Florida Bay). Therefore, patterns of resource use and trophic interactions documented among species from one site may not be applicable to a neighboring location. These findings may have implications for food web models that incorporate trophic data from different areas for a species when local data are unavailable.
- Published
- 2019
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