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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.

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.

To fuel the high energetic demands of reproduction, vertebrates employ different tactics of resource use. Large sharks exhibit long gestation periods and have relatively few well-developed young, which likely incurs high energetic costs. However, information on the relationship between the reproductive and energetic states for most shark species is lacking. In the present study, we used a noninvasive approach to assess relationships among reproductive stage, plasma triglyceride levels, body condition, and circulating reproductive hormones in free-ranging female tiger sharks (Galeocerdo cuvier). A total of 57 sharks were sampled (19 immature, 15 mature/nongravid, and 23 gravid). Circulating plasma triglycerides did not significantly differ among female tiger sharks of different reproductive stages, but body condition values were significantly higher for mature/nongravid sharks ([Formula: see text]) compared with gravid ([Formula: see text]) and immature ([Formula: see text]) sharks. For gravid and mature/nongravid sharks, no significant correlations existed among values of reproductive hormones, plasma triglycerides, and body condition. However, for immature sharks, estradiol values were negatively correlated with body condition values. Additionally, progesterone levels were positively correlated with testosterone levels in immature females. Our results suggest that this large generalist predator may not necessarily be easily characterized as a pure capital breeder, as has been previously hypothesized for ectotherms, but may rely on a mix of energy stores and opportunistic feeding to support reproduction. We present several hypotheses to explain these patterns and discuss our results in terms of energetic reproductive strategies.

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.

Relational values are values that arise from a relationship with nature, encompassing sense of place, feelings of well-being (mental and physical health), and cultural, community, or personal identities. With sharks, such values are formed by diverse groups that interact with these animals and their ecosystems, either physically or virtually, whether scientist, student, fisher, or media-consumer. Further, these user groups may overlap or conflict over management plans, media portrayals of sharks, and their conservation status. Although scientists have not explicitly aimed to assess relational values through sharks, qualitative studies of shark fishers, tourism operators, tourists, and the public, as well as historical and archaeological accounts, can be interpreted through an analytical lens to reveal values which can also be defined as relational. To this end, this review considers studies capturing relational values alongside those on economic value (increasingly, sharks’ value is appraised by their financial value by way of shark tourism) and the social and cultural roles of sharks. Based on these studies and the broader relational values literature, we then outline a workflow for how relational values can be leveraged in scientific inquiry, equitable resource management, and education. We conclude that via collaborative assessments of relational values, with implicit inclusion of all values from sharks and acknowledgement of their importance of to all parties involved in user conflicts, the relational values framework can lead to constructive dialogue on polarizing conservation and management issues. By illuminating shared values, and/or revealing dichotomies of values ascribed towards certain areas or objects, this framework can provide inroads to mediation, seeking to conserve or even restore relationships with nature and their derived values insomuch as is possible. This approach can yield unexpected knowledge, solutions, and compromises in an increasingly complex conservation landscape.

Given the conservation status and ecological, cultural, and commercial importance of chondrichthyan fishes, it is valuable to evaluate the extent to which research attention is spread across taxa and geographic locations and to assess the degree to which scientific research is appropriately addressing the challenges they face. Here we review trends in research effort over three decades (1985–2016) through content analysis of every abstract (n = 2,701) presented at the annual conference of the American Elasmobranch Society (AES), the oldest and largest professional society focused on the scientific study and management of these fishes. The most common research areas of AES abstracts were reproductive biology, movement/telemetry, age and growth, population genetics, and diet/feeding ecology, with different areas of focus for different study species or families. The most commonly studied species were large and charismatic (e.g., White Shark, Carcharodon carcharias), easily accessible to long-term established field research programs (e.g., Lemon Shark, Negaprion brevirostris, and Sandbar Shark, Carcharhinus plumbeus), or easily kept in aquaria for lab-based research (e.g., Bonnethead Shark, Sphyrna tiburo). Nearly 90% of all described chondrichthyan species have never been mentioned in an AES abstract, including some of the most threatened species in the Americas. The proportion of female* first authors has increased over time, though many current female* Society members are graduate students. Nearly half of all research presented at AES occurred in the waters of the United States rather than in the waters of developing nations where there are more threatened species and few resources for research or management. Presentations based on research areas such as paleontology and aquarium-based research have declined in frequency over time, and identified research priorities such as social science and interdisciplinary research are poorly represented. Possible research gaps and future research priorities for the study of chondrichthyan fishes are also discussed.

This study presents the energy, water, and carbon (C) flux dynamics of a young afforested temperate white pine (Pinus strobus L.) forest in southern Ontario, Canada during the initial fourteen years (2003–2016) of establishment. Energy fluxes, namely, net radiation (Rn), latent heat (LE), and sensible heat (H) flux increased over time, due to canopy development. Annual values of ground heat flux (G) peaked in 2007 and then gradually declined in response to canopy closure. The forest became a consistent C-sink only 5 years after establishment owing in part to low respiratory fluxes from the former agricultural, sandy soils with low residual soil organic matter. Mean annual values of gross ecosystem productivity (GEP), ecosystem respiration (RE), and net ecosystem productivity (NEP) ranged from 494 to 1913, 515 to 1774 and −126 to 216 g C m−2 year−1 respectively, over the study period. Annual evapotranspiration (ET) values ranged from 328 to 429 mm year−1 over the same period. Water use efficiency (WUE) increased with stand age with a mean WUE value of 3.92 g C kg−1 H2O from 2008 to 2016. Multivariable linear regression analysis conducted using observed data suggested that the overall, C and water dynamics of the stand were primarily driven by radiation and temperature, both of which explained 77%, 48%, 28%, and 76% of the variability in GEP, RE, NEP, and ET, respectively. However, late summer droughts, which were prevalent in the region, reduced NEP. The reduction in NEP was enhanced when summer drought events were accompanied by increased heat such as those in 2005, 2012 and 2016. This study contributes to our understanding of the energy, water and C dynamics of afforested temperate conifer plantations and how these forests may respond to changing climate conditions during the crucial initial stage of their life cycle. Our findings also demonstrate the potential of pine plantation stands to sequester atmospheric CO2 in eastern North America.

This study analysed age-related water-use dynamics across three temperate conifer forest plantations (aged 11, 39 and 74 years, as of 2013, henceforth referred to as TP02, TP74 and TP39, respectively, where the last two digits represent the year of planting) in southern Ontario, Canada, from 2008 to 2013. Eddy covariance-measured mean evapotranspiration over the growing season (April–October) was 438 ± 19, 392 ± 19 and 323 ± 25 mm at TP39, TP74 and TP02, respectively. Daytime bulk surface conductance was highest and most variable at the TP39 site (8.5 ± 4.0 mm s−1), followed by the TP74 (7.0 ± 2.8 mm s−1) and TP02 (5.4 ± 2.5 mm s−1) sites. Evapotranspiration at all the forests was sensitive to air temperature and tended to decrease with increasing atmospheric dryness. The youngest forest's evapotranspiration was most conservative, which led to an increase in water-use efficiency throughout the study period, in particular during drought events. The oldest forest was the least restrictive in its water use during drought, which led to lower water-use efficiency during such events as compared with the younger forests. The oldest forest was thinned in early 2012, when about one third of trees were commercially harvested. No significant change in evapotranspiration or water-use efficiency was observed at this site following thinning; however, daytime bulk surface conductance declined. Our results suggested that changes in stand structure with forest ageing, such as reduction in stem density and increase in sapwood area, were responsible for differences in soil water demand during drought and non-drought periods, leading to differences in forest water use. Hence, forest age, because of its structural implications, is an important control on stand-level water-use efficiency and forests' response to drought events. Our study suggested that younger forests may be best suited to maximize growth and carbon uptake efficiency under rising air temperatures and increasing precipitation variability as predicted by climate models for eastern North America. Copyright © 2015 John Wiley & Sons, Ltd.

Copyright © 2016 John Wiley & Sons, Ltd. Forest plantations are commonly used to restore the ecological and hydrological functionality of landscapes. In this study, we investigated the hydrological response of a 74-year-old pine plantation forest in southern Ontario, Canada to a selective thinning, wherein 30% of trees were harvested in winter of 2012. Tree-level and ecosystem-level water fluxes were monitored from 2011 to 2013 using sapflow and eddy-covariance techniques, and were compared with an adjacent 39-year-old pine plantation forest that was not thinned. In the 74-year-old forest, transpiration declined after thinning in the 2012 growing season, while tree-level water transport increased despite a severe drought. Time lag between sapflow and ecosystem evapotranspiration showed that the older stand had a significantly shorter time lag when compared to the younger stand, particularly in the thinning year. Linear regression modeling indicated that this was likely due to higher soil moisture status in the older stand versus the younger forest. Hydraulic redistribution of soil water was apparent during drought periods in both forests and did not appear to be negatively affected by the thinning treatment in the older forest. We conclude that selective low density thinning did not negatively impact the forest's response to seasonal drought, and that the availability of more soil moisture as a result of thinning may improve the resilience of the forest to future climatic extreme events such as drought.

We evaluated concentrations of plasma lipids in four large, free-ranging shark species via non-lethal biopsies for the purposes of improving our understanding of their nutritional ecology and for assessing the utility of biopsies in future monitoring studies of the energetics and metabolism in shark populations., Evaluating how predators metabolize energy is increasingly useful for conservation physiology, as it can provide information on their current nutritional condition. However, obtaining metabolic information from mobile marine predators is inherently challenging owing to their relative rarity, cryptic nature and often wide-ranging underwater movements. Here, we investigate aspects of energy metabolism in four free-ranging shark species (n = 281; blacktip, bull, nurse, and tiger) by measuring three metabolic parameters [plasma triglycerides (TAG), free fatty acids (FFA) and cholesterol (CHOL)] via non-lethal biopsy sampling. Plasma TAG, FFA and total CHOL concentrations (in millimoles per litre) varied inter-specifically and with season, year, and shark length varied within a species. The TAG were highest in the plasma of less active species (nurse and tiger sharks), whereas FFA were highest among species with relatively high energetic demands (blacktip and bull sharks), and CHOL concentrations were highest in bull sharks. Although temporal patterns in all metabolites were varied among species, there appeared to be peaks in the spring and summer, with ratios of TAG/CHOL (a proxy for condition) in all species displaying a notable peak in summer. These results provide baseline information of energy metabolism in large sharks and are an important step in understanding how the metabolic parameters can be assessed through non-lethal sampling in the future. In particular, this study emphasizes the importance of accounting for intra-specific and temporal variability in sampling designs seeking to monitor the nutritional condition and metabolic responses of shark populations.

It is commonly assumed that elasmobranchs (sharks, skates, and rays) are most active during dark periods (dawn, dusk, night). However, this assertion has not been critically evaluated. It is also unclear whether dark periods are primarily utilized for the performance of important life-history events, such as mating. If this were the case, low-light periods would be of significance to elasmobranch conservation as some anthropogenic activities (night fishing, lighting) could disproportionately impact fitness of species that are more active in the dark. Here, we review and summarize previous studies on elasmobranch behavior during nocturnal and crepuscular periods focusing on patterns of movement, habitat use, foraging, and reproduction. A review of 166 studies provided mixed results for widely-assumed increased elasmobranch activity when dark. Frequency of foraging and horizontal movement (distance travelled, activity space) were reported as greater only during crepuscular periods in the majority (>50%) of reviewed studies (28 of 43 and 78 of 125 studies, respectively), a pattern not evident during night. No pervasive patterns emerged for increased habitat use or reproductive behaviors during dark. We did not find any particular habitat type consistently supporting increased activity during dark, nor did we find evidence that higher trophic level elasmobranchs were more active when dark. Thus, generalizations about increased elasmobranch activity during dark periods are currently not supported. While research on the behavior of elasmobranchs during dark periods has been increasing, many knowledge gaps remain and we present a set of research priorities to assist in the development of future investigations.