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As freshwater lakes undergo rapid anthropogenic change, long-term studies reveal key microbial dynamics, evolutionary shifts and biogeochemical interactions, yet the vital role of viruses remains overlooked. Here, leveraging a 20 year time series from Lake Mendota, WI, USA, we characterized 1.3 million viral genomes across time, seasonality and environmental factors. Double-stranded DNA phages from the class Caudoviricetes dominated the community. We identified 574 auxiliary metabolic gene families representing over 140,000 auxiliary metabolic genes, including important genes such as psbA (photosynthesis), pmoC (methane oxidation) and katG (hydrogen peroxide decomposition), which were consistently present and active across decades and seasons. Positive associations and niche differentiation between virus-host pairs, including keystone Cyanobacteria, methanotrophs and Nanopelagicales, emerged during seasonal changes. Inorganic carbon and ammonium influenced viral abundances, underscoring viral roles in both 'top-down' and 'bottom-up' interactions. Evolutionary processes favoured fitness genes, reduced genomic heterogeneity and dominant sub-populations. This study transforms understanding of viral ecology and evolution in Earth's microbiomes., Competing Interests: Competing interests: The authors declare no competing interests., (© 2025. The Author(s), under exclusive licence to Springer Nature Limited.)

This study constitutes a systematic review endeavoring to elucidate the methodologies pertinent to the extraction and analysis of organic contaminants, specifically focusing on crab urine. Although research is limited, crabs serve as invaluable bioindicators and biomonitors due to their unique habitat in sediment-rich areas where aquatic contaminants commonly accumulate. Despite the well-documented harmful effects of substances like PCBs, OCPs, PBDEs, and pesticides on the nervous and endocrine systems, our review found that existing studies have predominantly focused on PAHs such as pyrene, benzo(a)pyrene, and naphthalene oi spilled and unspilled areas. One reason for this research gap is the misconception that collecting crab urine is challenging, a notion perpetuated by the lack of detailed methodologies in the literature. The research gap hinders comparing contamination levels and trends. Limited, infrequent studies highlight the urgent need for comprehensive investigations to enhance understanding of ecological impacts and improve environmental monitoring., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Rivelino Cavalcante reports financial support was provided by Federal University of Ceara Institute of Marine Sciences. Rivelino Cavalcante reports a relationship with National Council for Scientific and Technological Development that includes: funding grants. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: Viruses, the majority of which are uncultivated, are among the most abundant biological entities on Earth. From altering microbial physiology to driving community dynamics, viruses are fundamental members of microbiomes. While the number of studies leveraging viral metagenomics (viromics) for studying uncultivated viruses is growing, standards for viromics research are lacking. Viromics can utilize computational discovery of viruses from total metagenomes of all community members (hereafter metagenomes) or use physical separation of virus-specific fractions (hereafter viromes). However, differences in the recovery and interpretation of viruses from metagenomes and viromes obtained from the same samples remain understudied., Results: Here, we compare viral communities from paired viromes and metagenomes obtained from 60 diverse samples across human gut, soil, freshwater, and marine ecosystems. Overall, viral communities obtained from viromes had greater species richness and total viral genome abundances than those obtained from metagenomes, although there were some exceptions. Despite this, metagenomes still contained many viral genomes not detected in viromes. We also found notable differences in the predicted lytic state of viruses detected in viromes vs metagenomes at the time of sequencing. Other forms of variation observed include genome presence/absence, genome quality, and encoded protein content between viromes and metagenomes, but the magnitude of these differences varied by environment., Conclusions: Overall, our results show that the choice of method can lead to differing interpretations of viral community ecology. We suggest that the choice of whether to target a metagenome or virome to study viral communities should be dependent on the environmental context and ecological questions being asked. However, our overall recommendation to researchers investigating viral ecology and evolution is to pair both approaches to maximize their respective benefits. Video Abstract., (© 2024. The Author(s).)

The Equatorial South Atlantic region, spanning over 1700 km, is currently undergoing extensive exploitation through various activities such as oil extraction, desalination plants, marine mineral explorations, and wind power for green hydrogen production. This undoubtedly also contributes to the exacerbation of pre-existing chronic environmental impacts. This study aims to investigate the concentrations of 60 substances, categorized as Persistent Organic Pollutants (POPs) and Contaminants of Emerging Concern (CECs) from various classes including: polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), organochlorine pesticides (OCPs), as well as Pyrethroids (PPs), Triazines (TPs) and Organophosphates (OPPs) pesticides in consumable fish, shellfish, and crabs. The bivalve (Mytella charruana), crab (Ucides cordatus), and catfish (Sciades herzbergii) samples were collected in areas of ecological, environmental and economic importance. This data was used to estimate concentrations in the organisms, and to calculate cancer and human health risk. The most prevalent pollutant classes in the organisms were OCPs, followed by TPs and PPs. Shellfish and fish samples had more compounds indicating health risks, when compared to crabs. The substances causing cancer risks varied across organisms and study areas. The heightened cancer risks linked to specific compounds in various species highlight the urgent need to address persistent pollutants to prevent long-term health impacts on both humans and wildlife. Compounds such as PPs, TPs, and OPPs pose significant risks of neurotoxicity and endocrine disruption. This study underscores the interconnectedness of environmental and human health in coastal ecosystems, calling for continuous monitoring and adaptive management strategies to protect these fragile environments and the communities that rely on them., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Channel catfish (Ictalurus punctatus) are a food fish extensively reared in aquaculture facilities throughout the world and are also among the most abundant wild catfish species in North America, making them a popular target of anglers. Furthermore, channel catfish are important members of aquatic ecosystems; for example, they serve as a glochidial host for the endangered winged mapleleaf mussel (Quadrula fragosa), making them critical for conserving this species through hatchery-based restoration efforts. During a routine health inspection, a novel aquareovirus was isolated from channel catfish used in mussel propagation efforts at a fish hatchery in Wisconsin. This virus was isolated on brown bullhead cells (ATCC CCL-59) and identified through metagenomic sequencing as a novel member of the family Spinareoviridae, genus Aquareovirus. The virus genome consists of 11 segments, as is typical of the aquareoviruses, with phylogenetic relationships based on RNA-dependent RNA polymerase and major outer capsid protein amino acid sequences showing it to be most closely related to golden shiner virus (aquareovirus C) and aquareovirus C/American grass carp reovirus (aquareovirus G) respectively. The potential of the new virus, which we name genictpun virus 1 (GNIPV-1), to cause disease in channel catfish or other species remains unknown., (© 2024 John Wiley & Sons Ltd. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Microorganisms play vital roles in sulfur cycling through the oxidation of elemental sulfur and reduction of sulfite. These metabolisms are catalyzed by dissimilatory sulfite reductases (Dsr) functioning in either the reductive or reverse, oxidative direction. Dsr-mediated sulfite reduction is an ancient metabolism proposed to have fueled energy metabolism in some of Earth's earliest microorganisms, whereas sulfur oxidation is believed to have evolved later in association with the widespread availability of oxygen on Earth. Organisms are generally believed to carry out either the reductive or oxidative pathway, yet organisms from diverse phyla have been discovered with gene combinations that implicate them in both pathways. A comprehensive investigation into the metabolisms of these phyla regarding Dsr is currently lacking. Here, we selected one of these phyla, the metabolically versatile candidate phylum SAR324, to study the ecology and evolution of Dsr-mediated metabolism. We confirmed that diverse SAR324 encode genes associated with reductive Dsr, oxidative Dsr, or both. Comparative analyses with other Dsr-encoding bacterial and archaeal phyla revealed that organisms encoding both reductive and oxidative Dsr proteins are constrained to a few phyla. Further, DsrAB sequences from genomes belonging to these phyla are phylogenetically positioned at the interface between well-defined oxidative and reductive bacterial clades. The phylogenetic context and dsr gene content in these organisms points to an evolutionary transition event that ultimately gave way to oxidative Dsr-mediated metabolism. Together, this research suggests that SAR324 and other phyla with mixed dsr gene content are associated with the evolution and origins of Dsr-mediated sulfur oxidation., (© The Author(s) 2024. Published by Oxford University Press on behalf of the International Society for Microbial Ecology.)

Background: Viruses, the majority of which are uncultivated, are among the most abundant biological entities on Earth. From altering microbial physiology to driving community dynamics, viruses are fundamental members of microbiomes. While the number of studies leveraging viral metagenomics (viromics) for studying uncultivated viruses is growing, standards for viromics research are lacking. Viromics can utilize computational discovery of viruses from total metagenomes of all community members (hereafter metagenomes) or use physical separation of virus-specific fractions (hereafter viromes). However, differences in the recovery and interpretation of viruses from metagenomes and viromes obtained from the same samples remain understudied., Results: Here, we compare viral communities from paired viromes and metagenomes obtained from 60 diverse samples across human gut, soil, freshwater, and marine ecosystems. Overall, viral communities obtained from viromes were more abundant and species rich than those obtained from metagenomes, although there were some exceptions. Despite this, metagenomes still contained many viral genomes not detected in viromes. We also found notable differences in the predicted lytic state of viruses detected in viromes vs metagenomes at the time of sequencing. Other forms of variation observed include genome presence/absence, genome quality, and encoded protein content between viromes and metagenomes, but the magnitude of these differences varied by environment., Conclusions: Overall, our results show that the choice of method can lead to differing interpretations of viral community ecology. We suggest that the choice of whether to target a metagenome or virome to study viral communities should be dependent on the environmental context and ecological questions being asked. However, our overall recommendation to researchers investigating viral ecology and evolution is to pair both approaches to maximize their respective benefits., Competing Interests: Competing interests The authors declare that they have no competing interests.

Freshwater mussels (Unionida) are globally imperiled, in part due to largely unexplained mass mortality events (MMEs). While recent studies have begun to investigate the possibility that mussel MMEs in the Eastern USA may be caused by infectious diseases, mussels in the Western USA have received relatively little attention in this regard. We conducted a two-year epidemiologic investigation of the role of viruses in ongoing MMEs of the Western pearlshell ( Margaritifera falcata ) and the Western ridged mussel ( Gonidea angulata ) in the Chehalis River and Columbia River watersheds in the Western USA. We characterized viromes of mussel hemolymph from 5 locations in 2018 and 2020 using metagenomic methods and identified 557 viruses based on assembled contiguous sequences, most of which are novel. We also characterized the distribution and diversity of a previously identified mussel Gammarhabdovirus related to pathogenic finfish viruses. Overall, we found few consistent associations between viruses and mussel health status. Variation in mussel viromes was most strongly driven by location, with little influence from date, species, or health status, though these variables together only explained ~1/3 of variation in virome composition. Our results demonstrate that Western freshwater mussels host remarkably diverse viromes, but no single virus or combination of viruses appears to be associated with morbidity or mortality during MMEs. Our findings have implications for the conservation of imperiled freshwater mussels, including efforts to enhance natural populations through captive propagation.

Coastal fish communities are under increasing levels of stress associated with climate variation and anthropogenic activities. However, the high degree of behavioral plasticity of many species within these communities allow them to cope with altered environmental conditions to some extent. Here, we combine meteorological information, data from hydroacoustic surveys, and recordings of goliath grouper sound production to examine the response of coastal fish communities to heavy rainfall events in South Florida, USA, that resulted in the release of excess storm water into surrounding estuaries and coastal waters. We observed a nearly 12,000% increase in water column acoustic backscatter following a heavy rainfall event of September 16th, 2015. Interestingly, estimates of school backscatter, a proxy for biomass, increased by 172% with the onset of the perturbation. Schooling fish density also increased by 182%, as did acoustically derived estimates of mean schooling fish length (21%). Following the perturbed period, school backscatter decreased by 406%, along with schooling density (272%), and mean schooling fish length (35%). Hydrophone and hydroacoustic data also revealed that goliath grouper ( Epinephelus itajara ) spawning aggregations were persistent in the region throughout the duration of the study and continued to exhibit courtship behavior during the perturbed period. Our observations demonstrate the high level of resistance common in coastal species but raises new questions regarding the threshold at which fish communities and reproductive activities are disrupted. As coastal land use continues to increase, and the effects of global climate change become more pronounced, more Before-After Control Impact (BACI) studies will provide improved insight into the overall response of nearshore communities to future perturbations and the cumulative effect of repeated perturbations over extended periods., Competing Interests: The authors declare there are no competing interests., (©2023 Binder et al.)

Recent bacteriological investigations of freshwater mussel mortality events in the southeastern United States have identified a variety of bacteria and differences in bacterial communities between sick and healthy mussels. In particular, Yokenella regensburgei and Aeromonas spp. have been shown to be associated with moribund mussels, although it remains unclear whether these bacteria are causes or consequences of disease. To further understand the role of bacteria in mussel epizootics, we investigated mortality events that occurred in the upper Midwest in the Embarrass River (Wisconsin) and the Huron River (Michigan). For comparison, we also studied mussels from an unaffected population in the St. Croix River (Wisconsin). Diverse bacterial genera were identified from these sites, including Y. regensburgei from moribund mussels in the Embarrass River (Wisconsin). This bacterium has also been consistently isolated during ongoing mortality events in the Clinch River (Virginia). Subsequently, we developed and validated molecular assays for the detection of Yokenella to use in future investigations of mussel mortality events and to identify environmental reservoirs of this bacterium.

Bottlenose dolphins are highly social, renowned for their vocal flexibility, and possess highly enlarged brains relative to their body size. Here, we discuss some of the defining features of bottlenose dolphin social and vocal complexity and place this in the context of their cognitive evolution., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Freshwater mussels (Unionida) are among the world's most imperiled taxa, but the relationship between freshwater mussel mortality events and infectious disease is largely unstudied. We surveyed viromes of a widespread and abundant species (mucket, Actinonaias ligamentina ; syn: Ortmanniana ligamentina ) experiencing a mortality event of unknown etiology in the Huron River, Michigan, in 2019-2020 and compared them to viromes from mucket in a healthy population in the St. Croix River, Wisconsin and a population from the Clinch River, Virginia and Tennessee, where a mortality event was affecting the congeneric pheasantshell ( Actinonaias pectorosa ; syn: Ortmanniana pectorosa ) population. We identified 38 viruses, most of which were associated with mussels collected during the Huron River mortality event. Viral richness and cumulative viral read depths were significantly higher in moribund mussels from the Huron River than in healthy controls from each of the three populations. Our results demonstrate significant increases in the number and intensity of viral infections for freshwater mussels experiencing mortality events, whereas individuals from healthy populations have a substantially reduced virome comprising a limited number of species at low viral read depths.

Efforts to understand human social evolution rely largely on comparisons with nonhuman primates. However, a population of bottlenose dolphins in Shark Bay, Western Australia, combines a chimpanzee-like fission-fusion grouping pattern, mating system, and life history with the only nonhuman example of strategic multilevel male alliances. Unrelated male dolphins form three alliance levels, or "orders", in competition over females: both within-group alliances (i.e., first- and second-order) and between-group alliances (third-order), based on cooperation between two or more second-order alliances against other groups. Both sexes navigate an open society with a continuous mosaic of overlapping home ranges. Here, we use comprehensive association and consortship data to examine fine-scale alliance relationships among 121 adult males. This analysis reveals the largest nonhuman alliance network known, with highly differentiated relationships among individuals. Each male is connected, directly or indirectly, to every other male, including direct connections with adult males outside of their three-level alliance network. We further show that the duration with which males consort females is dependent upon being well connected with third-order allies, independently of the effect of their second-order alliance connections, i.e., alliances between groups increase access to a contested resource, thereby increasing reproductive success. Models of human social evolution traditionally link intergroup alliances to other divergent human traits, such as pair bonds, but our study reveals that intergroup male alliances can arise directly from a chimpanzee-like, promiscuous mating system without one-male units, pair bonds, or male parental care.

Understanding determinants of differential reproductive success is at the core of evolutionary biology because of its connection to fitness. Early work has linked variation in reproductive success to differences in age, 1 rank, 2 or size, 3 , 4 as well as habitat characteristics. 5 More recently, studies in group-living taxa have revealed that social relationships also have measurable effects on fitness. 6-8 The influence of social bonds on fitness is particularly interesting in males who compete over reproductive opportunities. In Shark Bay, Western Australia, groups of 4-14 unrelated male bottlenose dolphins cooperate in second-order alliances to compete with rival alliances over access to females. 9-12 Nested within second-order alliances, pairs or trios of males, which can vary in composition, form first-order alliances to herd estrus females. Using 30 years of behavioral data, we examined how individual social factors, such as first-order alliance stability, social connectivity, and variation in social bond strength within second-order alliances, affect male fitness. Analyzing the reproductive careers of 85 males belonging to 10 second-order alliances, we found that the number of paternities a male achieved was positively correlated with his cumulative social bond strength but negatively correlated with his variation in bond strength. Thus, well-integrated males with more homogeneous social bonds to second-order allies obtained most paternities. Our findings provide novel insights into the fitness benefits of polyadic cooperation among unrelated males and highlight the adaptive value of social bonds in this context., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2022 Elsevier Inc. All rights reserved.)

The Earth's oceans are home to a diverse array of life, from large marine mammals to microscopic organisms. Among the most important are the marine phytoplankton, which comprise the basis of marine food webs, and also produce a large percentage of the Earth's oxygen through photosynthesis. Although the vast majority of phytoplankton are essential to ocean health, several dozen species produce potent toxins, and can form what are called Harmful Algal Blooms (HABs). This activity focuses on the importance of HABs, as well as the types of data scientists collect to understand blooms. In the classroom exercises, students will calculate the proportional abundance (% contribution) of five HAB species present in water samples, and use these data to create pie graphs to depict species composition. Students will then compare these results with levels of HAB toxins in water samples collected over the same time period. Thought questions challenge students to develop hypotheses regarding how changes in the HAB community may relate to observed trends in toxin concentrations. This activity was successfully taught to visually impaired students who were able to complete the pie charts and answer the thought questions., Competing Interests: Declaration of interest statement The authors declare they have no actual or potential competing financial interests.

Freshwater mussels (Unionida) are suffering mass mortality events worldwide, but the causes remain enigmatic. Here, we describe an analysis of bacterial loads, community structure, and inferred metabolic pathways in the hemolymph of pheasantshells ( Actinonaias pectorosa ) from the Clinch River, USA, during a multi-year mass mortality event. Bacterial loads were approximately 2 logs higher in moribund mussels (cases) than in apparently healthy mussels (controls). Bacterial communities also differed between cases and controls, with fewer sequence variants (SVs) and higher relative abundances of the proteobacteria Yokenella regensburgei and Aeromonas salmonicida in cases than in controls. Inferred bacterial metabolic pathways demonstrated a predominance of degradation, utilization, and assimilation pathways in cases and a predominance of biosynthesis pathways in controls. Only two SVs correlated with Clinch densovirus 1, a virus previously shown to be strongly associated with mortality in this system: Deinococcota and Actinobacteriota, which were associated with densovirus-positive and densovirus-negative mussels, respectively. Overall, our results suggest that bacterial invasion and shifts in the bacterial microbiome during unionid mass mortality events may result from primary insults such as viral infection or environmental stressors. If so, bacterial communities in mussel hemolymph may be sensitive, if generalized, indicators of declining mussel health.

Glyphosate is the active ingredient in Roundup formulations. Glyphosate-based herbicides are used globally in agriculture, forestry, horticulture, and in urban settings. Glyphosate can persist for years in our soil, potentially impacting the soil-dwelling arthropods that are primary drivers of a suite of ecosystem services. Furthermore, although glyphosate is not generally classified as neurotoxic to insects, evidence suggests that it may cause nerve damage in other organisms. In a series of experiments, we used food to deliver environmentally realistic amounts of Roundup ready-to-use III, a common 2% glyphosate-based herbicide formulation that lists isopropylamine salt as its active ingredient, to Madagascar hissing cockroaches. We then assessed the impact of contamination on body mass, nerve health, and behavior. Contaminated food contained both 30.6 mg glyphosate and so-called inert ingredients. Food was refreshed weekly for 26-60 days, depending on the experiment. We found that consumption of contaminated food did not impact adult and juvenile survivorship or body weight. However, consumption of contaminated food decreased ventral nerve cord action-potential velocity by 32%, caused a 29% increase in respiration rate, and caused a 74.4% decrease in time spent on a motorized exercise wheel. Such changes in behavior may make cockroaches less capable of fulfilling their ecological service, such as pollinating or decomposing litter. Furthermore, their lack of coordination may make them more susceptible to predation, putting their population at risk. Given the decline of terrestrial insect abundance, understanding common risks to terrestrial insect populations has never been more critical. Results from our experiments add to the growing body of literature suggesting that this popular herbicide can act as a neurotoxin.

Non-consumptive predator effects (NCEs) are now widely recognised for their capacity to shape ecosystem structure and function. Yet, forecasting the propagation of these predator-induced trait changes through particular communities remains a challenge. Accordingly, focusing on plasticity in prey anti-predator behaviours, we conceptualise the multi-stage process by which predators trigger direct and indirect NCEs, review and distil potential drivers of contingencies into three key categories (properties of the prey, predator and setting), and then provide a general framework for predicting both the nature and strength of direct NCEs. Our review underscores the myriad factors that can generate NCE contingencies while guiding how research might better anticipate and account for them. Moreover, our synthesis highlights the value of mapping both habitat domains and prey-specific patterns of evasion success ('evasion landscapes') as the basis for predicting how direct NCEs are likely to manifest in any particular community. Looking ahead, we highlight two key knowledge gaps that continue to impede a comprehensive understanding of non-consumptive predator-prey interactions and their ecosystem consequences; namely, insufficient empirical exploration of (1) context-dependent indirect NCEs and (2) the ways in which direct and indirect NCEs are shaped interactively by multiple drivers of context dependence., (© 2020 John Wiley & Sons Ltd.)

Freshwater mussels (order Unionida) are among the world's most biodiverse but imperiled taxa. Recent unionid mass mortality events around the world threaten ecosystem services such as water filtration, nutrient cycling, habitat stabilization, and food web enhancement, but causes have remained elusive. To examine potential infectious causes of these declines, we studied mussels in Clinch River, Virginia and Tennessee, USA, where the endemic and once-predominant pheasantshell (Actinonaias pectorosa) has suffered precipitous declines since approximately 2016. Using metagenomics, we identified 17 novel viruses in Clinch River pheasantshells. However, only one virus, a novel densovirus (Parvoviridae; Densovirinae), was epidemiologically linked to morbidity. Clinch densovirus 1 was 11.2 times more likely to be found in cases (moribund mussels) than controls (apparently healthy mussels from the same or matched sites), and cases had 2.7 (log 10 ) times higher viral loads than controls. Densoviruses cause lethal epidemic disease in invertebrates, including shrimp, cockroaches, crickets, moths, crayfish, and sea stars. Viral infection warrants consideration as a factor in unionid mass mortality events either as a direct cause, an indirect consequence of physiological compromise, or a factor interacting with other biological and ecological stressors to precipitate mortality.

Linking morphological differences in foraging adaptations to prey choice and feeding strategies has provided major evolutionary insights across taxa. Here, we combine behavioural and morphological approaches to explore and compare the role of the rostrum (bill) and micro-teeth in the feeding behaviour of sailfish ( Istiophorus platypterus ) and striped marlin ( Kajikia audax ) when attacking schooling sardine prey. Behavioural results from high-speed videos showed that sailfish and striped marlin both regularly made rostrum contact with prey but displayed distinct strategies. Marlin used high-speed dashes, breaking schools apart, often contacting prey incidentally or tapping at isolated prey with their rostra; while sailfish used their rostra more frequently and tended to use a slower, less disruptive approach with more horizontal rostral slashes on cohesive prey schools. Capture success per attack was similar between species, but striped marlin had higher capture rates per minute. The rostra of both species are covered with micro-teeth, and micro-CT imaging showed that species did not differ in average micro-tooth length, but sailfish had a higher density of micro-teeth on the dorsal and ventral sides of their rostra and a higher amount of micro-teeth regrowth, suggesting a greater amount of rostrum use is associated with more investment in micro-teeth. Our analysis shows that the rostra of billfish are used in distinct ways and we discuss our results in the broader context of relationships between morphological and behavioural feeding adaptations across species.

The effects of anticoagulant EDTA and sodium heparin (SH) on stable carbon δ 13 C and nitrogen δ 15 N isotopic values of red blood cells (RBC) and blood plasma in juvenile blacktip reef sharks Carcharhinus melanopterus were analysed. Plasma preserved with anticoagulants was not isotopically distinct from plasma stored in no-additive control tubes but RBC δ 15 N values exhibited small enrichments when preserved with EDTA and SH. Results suggest EDTA and SH are viable anticoagulants for stable isotopic analyses of blood fractions but further studies are advised to validate results., (© 2019 The Fisheries Society of the British Isles.)

Acquiring and storing energy is vital to sharks of all age-classes. Viviparous shark embryos receive endogenous maternal energy reserves to sustain the first weeks after birth. Then, in order to maintain body condition, sharks must start foraging. Our goal was to understand whether maternal energy investments vary between blacktip reef sharks (Carcharhinus melanopterus) from two populations and to what extent body condition and the initiation of foraging might be affected by presumably variable maternal investments. A total of 546 young sharks were captured at St. Joseph atoll (Seychelles) and Moorea (French Polynesia) between 2014 and 2018, and indices of body condition and percentage of stomachs containing prey were measured. Maternal investment was found to be site-specific, with significantly larger, heavier, and better conditioned individuals in Moorea. Despite these advantages, as time progressed, Moorea sharks exhibited significant decreases in body condition and were slower to initiate foraging. We suggest that the young sharks' foraging success is independent of the quality of maternal energy resources, and that other factors, such as prey availability, prey quality, and/or anthropogenic stressors are likely responsible for the observed differences across sites. Insights into intraspecific variations in early life-stages may further support site-specific management strategies for young sharks from nearshore habitats.

Overexploitation of key species can negatively impact ecosystem processes, so understanding the ecological roles of individual species is critical for improving ecosystem management. Here, we use coral reefs and the process of herbivory as a model to examine how species identity of consumers influence ecosystem processes to inform management of these consumers. Herbivorous fishes can facilitate the recruitment, growth, and recovery of corals by controlling the fast-growing algae that can outcompete corals for space. However, herbivorous fish guilds are species rich with important differences among species in diet, movement, and habitat preferences. Yet, we lack a general understanding of (1) how these species-specific differences in feeding and behavior scale up to reef-wide rates of ecosystem processes and (2) how species identity and diversity impact these processes. To address these knowledge gaps, we used field observations to derive key species- and size-specific foraging parameters for nine herbivorous parrotfish species on coral reefs in the Florida Keys, USA. We then combined these foraging parameters with fish survey data spanning multiple spatial scales to estimate the rates of three ecosystem processes: area of reef grazed, amount of macroalgae removed, and rate of bioerosion. We found that predicted rates of ecological processes varied dramatically among habitats and among reef zones within habitats, driven primarily by variation in abundance among species with different foraging behaviors. In some cases, assemblages with similar levels of total biomass had different rates of ecological processes, and in others, assemblages with different biomass had similar rates of ecological processes. Importantly, our models of herbivory using species-specific parameters differed from those using genus-level parameters by up to 300% in rates of ecological processes, highlighting the importance of herbivore identity in this system. Our results indicate that there may be little overlap in the roles species play, suggesting that some systems may be vulnerable to loss of ecological function with the reduction or loss of just a few species. This work provides a framework that can be applied across the region to predict how changes in management may affect the ecological impact of these important herbivores., (© 2019 by the Ecological Society of America.)

During a mark-recapture survey from November 2014 until April 2017, 333 neonatal and juvenile blacktip reef sharks Carcharhinus melanopterus and 302 neonatal and juvenile sicklefin lemon sharks Negaprion acutidens were tagged and measured at the uninhabited and isolated St. Joseph Atoll (Republic of Seychelles). Both species demonstrated seasonal reproductive synchronicity and relatively large sizes at birth. Despite the extended times at liberty > 2.5 years, the majority of recaptures were found in close proximity to the initial tagging location (< 500 m). Annual growth rates of C. melanopterus (n = 24) and N. acutidens (n = 62) ranged from 6.6 to 31.7 cm year -1 (mean ± SE; 16.2 ± 1.2 cm year -1 ) and 0.2 to 32.2 cm year -1 (11.8 ± 1 cm year -1 ), respectively and are to date the most variable ever recorded in wild juvenile sharks. High abundances of both species coupled with long-term and repeated recaptures are indicative of a habitat where juveniles can reside for their first years of life. However, large variability in annual growth rates in both species may suggest high intra and interspecific competition induced by a possibly resource limited, isolated habitat., (© 2019 The Fisheries Society of the British Isles.)

The non-essential metal mercury (Hg) can have deleterious effects on health of organisms, and tends to bioaccumulate with age in long-lived organisms and to biomagnify along food webs. Because elasmobranchs are fished for human consumption and their Hg levels are frequently above the maximum Hg concentration recommended for fish consumption, understanding the drivers of Hg concentration is of considerable interest. Total Hg concentrations were analysed in muscle tissues of 14 shark and 2 batoid species (n = 339 individuals) sampled across multiple habitats (coastal, open ocean and bathyal) in the southwestern Indian Ocean. Stable isotope ratios of carbon (δ 13 C) and nitrogen (δ 15 N) were analysed to assess whether relative trophic position and foraging habitats affected Hg concentrations. Hg concentrations increased with δ 15 N and body length, highlighting the mechanisms of bioaccumulation and biomagnification in relation with the trophic position and size of the individuals. Habitats where elasmobranchs were collected also affected their Hg concentrations. Bathyal sharks had high Hg concentrations that were almost similar to those of oceanic species, despite their lower relative trophic position. Higher bioavailability of Hg due to its enhanced methylation in deeper waters was considered as the most likely explanation for this result. These results highlight that multiple factors contribute to mercury accumulation in elasmobranchs., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Limiting climate warming to <2°C requires increased mitigation efforts, including land stewardship, whose potential in the United States is poorly understood. We quantified the potential of natural climate solutions (NCS)-21 conservation, restoration, and improved land management interventions on natural and agricultural lands-to increase carbon storage and avoid greenhouse gas emissions in the United States. We found a maximum potential of 1.2 (0.9 to 1.6) Pg CO 2 e year -1 , the equivalent of 21% of current net annual emissions of the United States. At current carbon market prices (USD 10 per Mg CO 2 e), 299 Tg CO 2 e year -1 could be achieved. NCS would also provide air and water filtration, flood control, soil health, wildlife habitat, and climate resilience benefits.

Indo-Pacific red lionfish (Pterois volitans) have invaded the western Atlantic, and most recently the northern Gulf of Mexico (nGOM), at a rapid pace. Given their generalist habitat affinities and diet, and strong ecological overlap with members of the commercially valuable snapper-grouper complex, increased density and abundance of lionfish could result in significant competitive interactions with nGOM commercially important species. We experimentally investigated the intensity of behavioral interactions between lionfish and indigenous, abundant and economically important juvenile nGOM red snapper (Lutjanus campechanus), and other increasingly abundant juvenile tropical snapper species (gray snapper-L. griseus and lane snapper-L. synagris) in large outdoor mesocosms to examine snapper vulnerabilities to lionfish competition. When paired with lionfish, red snapper swimming activity (i.e., time swimming and roving around experimental tank or at structure habitat during experiments) was significantly lower than in intraspecific control trials, but gray and lane snapper swimming activities in the presence of lionfish did not significantly differ from their intraspecific controls. Additionally in paired trials, red and lane snapper swimming activities were significantly lower than those of lionfish, while no significant difference in swimming activities was observed between lionfish and gray snapper. We found that red snapper prey consumption rates in the presence of lionfish were significantly lower than in their intraspecific 3-individual control trials, but when paired together no significant differences in prey consumption rates between red snapper and lionfish were observed. When paired with lane or gray snapper, lionfish were observed having comparatively higher prey consumption than snappers, or as observed in lionfish intraspecific 1-individual controls. However, lane and gray snapper consumption rates in the presence of lionfish did not significantly differ from those in intraspecific controls. These findings suggest that competition between juvenile snappers and invasive lionfish may be variable, with lionfish exhibiting differing degrees of competitive dominance and snappers exhibiting partial competitive vulnerability and resistance to lionfish. While the degree of intensity at which these interactions may occur in nGOM reefs may differ from those observed in our findings, this study enables greater understanding of the potential ecological effects of red lionfish on native reef fishes., Competing Interests: The authors have declared that no competing interests exist.

What an animal consumes and what an animal digests and assimilates for energetic demands are not always synonymous. Sharks, uniformly accepted as carnivores, have guts that are presumed to be well suited for a high-protein diet. However, the bonnethead shark ( Sphyrna tiburo ), which is abundant in critical seagrass habitats, has been previously shown to consume copious amounts of seagrass (up to 62.1% of gut content mass), although it is unknown if they can digest and assimilate seagrass nutrients. To determine if bonnetheads digest seagrass nutrients, captive sharks were fed a 13 C-labelled seagrass diet. Digestibility analyses, digestive enzyme assays and stable isotope analyses were used to determine the bonnethead shark's capacity for digesting and assimilating seagrass material. Compound-specific stable isotope analysis showed that sharks assimilated seagrass carbon (13.6 ± 6.77‰ δ 13 C mean ± s.d. for all sharks and all amino acid types analysed) with 50 ± 2% digestibility of seagrass organic matter. Additionally, cellulose-component-degrading enzyme activities were detected in shark hindguts. We show that a coastal shark is digesting seagrass with at least moderate efficiency, which has ecological implications due to the stabilizing role of omnivory and nutrient transport within fragile seagrass ecosystems., (© 2018 The Author(s).)

The influence of biotic interactions on microbial community assembly is intensely debated. We hypothesized that keystone taxa, which influence community assembly through strong biotic interactions, are important for regulating microbial community composition. While highly connected microbes have been identified, evidence that these taxa act as keystones is lacking, because keystone status requires influence on whole-community dynamics. We address this gap, showing that small subsets of highly connected keystone taxa (generally 1%-5% of richness) can be optimal predictors of whole-community compositional change. In three long-term data sets, greater connectivity due to the presence of keystone taxa corresponded to lower compositional turnover. We further hypothesized that the influence of keystone taxa would be diminished when environmental disturbance was a strong driver of compositional change. We used two case studies of reference and disturbed communities to investigate how biotic and abiotic forces interact to shape community composition. Most of the same taxa were present in both the reference and disturbed communities, but keystone taxa had much greater explanatory power in the reference communities. Our results suggest that greater biotic connectivity arising from the presence of keystone taxa is stabilizing to community composition, and that keystone taxa can be good indicators of pending community shifts., (© 2018 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.)

In the era of "Anthropocene defaunation," large species are often no longer detected in habitats where they formerly occurred. However, it is unclear whether this apparent missing, or "dark," diversity of megafauna results from local species extirpations or from failure to detect elusive remaining individuals. We find that despite two orders of magnitude less sampling effort, environmental DNA (eDNA) detects 44% more shark species than traditional underwater visual censuses and baited videos across the New Caledonian archipelago (south-western Pacific). Furthermore, eDNA analysis reveals the presence of previously unobserved shark species in human-impacted areas. Overall, our results highlight a greater prevalence of sharks than described by traditional survey methods in both impacted and wilderness areas. This indicates an urgent need for large-scale eDNA assessments to improve monitoring of threatened and elusive megafauna. Finally, our findings emphasize the need for conservation efforts specifically geared toward the protection of elusive, residual populations.

Sharks are a diverse group of mobile predators that forage across varied spatial scales and have the potential to influence food web dynamics. The ecological consequences of recent declines in shark biomass may extend across broader geographic ranges if shark taxa display common behavioural traits. By tracking the original site of photosynthetic fixation of carbon atoms that were ultimately assimilated into muscle tissues of 5,394 sharks from 114 species, we identify globally consistent biogeographic traits in trophic interactions between sharks found in different habitats. We show that populations of shelf-dwelling sharks derive a substantial proportion of their carbon from regional pelagic sources, but contain individuals that forage within additional isotopically diverse local food webs, such as those supported by terrestrial plant sources, benthic production and macrophytes. In contrast, oceanic sharks seem to use carbon derived from between 30° and 50° of latitude. Global-scale compilations of stable isotope data combined with biogeochemical modelling generate hypotheses regarding animal behaviours that can be tested with other methodological approaches.

The ability to predict microbial community dynamics lags behind the quantity of data available in these systems. Most predictive models use only environmental parameters, although a long history of ecological literature suggests that community complexity should also be an informative parameter. Thus, we hypothesize that incorporating information about a community's complexity might improve predictive power in microbial models. Here, we present a new metric, called community 'cohesion,' that quantifies the degree of connectivity of a microbial community. We analyze six long-term (10+ years) microbial data sets using the cohesion metrics and validate our approach using data sets where absolute abundances of taxa are available. As a case study of our metrics' utility, we show that community cohesion is a strong predictor of Bray-Curtis dissimilarity (R 2 =0.47) between phytoplankton communities in Lake Mendota, WI, USA. Our cohesion metrics outperform a model built using all available environmental data collected during a long-term sampling program. The result that cohesion corresponds strongly to Bray-Curtis dissimilarity is consistent across the six long-term time series, including five phytoplankton data sets and one bacterial 16S rRNA gene sequencing data set. We explain here the calculation of our cohesion metrics and their potential uses in microbial ecology.

Stable-isotope analysis supplemented with stomach contents data from published sources was used to quantify the trophic niches, trophic niche overlaps and potential trophic redundancy for the most commonly caught fish species from an East African nearshore seagrass community. This assessment is an important first step in quantifying food-web structure in a region subject to intense fishing activities. Nearshore food webs were driven by at least two isotopically distinct trophic pathways, algal and seagrass, with a greater proportion of the sampled species feeding within the seagrass food web (57%) compared with the algal food web (33%). There was considerable isotopic niche overlap among species (92% of species overlapped with at least one other species). Narrow isotopic niche widths of most (83%) species sampled, low isotopic similarity (only 23% of species exhibited no differences in δ 13 C and δ 15 N) and low predicted trophic redundancy among fishes most commonly caught by fishermen (15%), however, suggest that adjustments to resource management concerning harvesting and gear selectivity may be needed for the persistence of artisanal fishing in northern Tanzania. More detailed trophic studies paired with information on spatio-temporal variation in fish abundance, especially for heavily targeted species, will assist in the development and implementation of management strategies to maintain coastal food-web integrity., (© 2017 The Fisheries Society of the British Isles.)

Food web structure is shaped by interactions within and across trophic levels. As such, understanding how the presence and absence of predators, prey, and competitors affect species foraging patterns is important for predicting the consequences of changes in species abundances, distributions, and behaviors. Here, we used plasma δ 13 C and δ 15 N values from juvenile blacktip reef sharks (Carcharhinus melanopterus) and juvenile sicklefin lemon sharks (Negaprion acutidens) to investigate how species co-occurrence affects their trophic interactions in littoral waters of Moorea, French Polynesia. Co-occurrence led to isotopic niche partitioning among sharks within nurseries, with significant increases in δ 15 N values among sicklefin lemon sharks, and significant decreases in δ 15 N among blacktip reef sharks. Niche segregation likely promotes coexistence of these two predators during early years of growth and development, but data do not suggest coexistence affects life history traits, such as body size, body condition, and ontogenetic niche shifts. Plasticity in trophic niches among juvenile blacktip reef sharks and sicklefin lemon sharks also suggests these predators are able to account for changes in community structure, resource availability, and intra-guild competition, and may fill similar functional roles in the absence of the other species, which is important as environmental change and human impacts persist in coral reef ecosystems., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Both natural and human-related foraging strategies by the common bottlenose dolphin (Tursiops truncatus) have resulted in social segregation in several areas of the world. Bottlenose dolphins near Savannah, Georgia beg at an unprecedented rate and also forage behind commercial shrimp trawlers, providing an opportunity to study the social ramifications of two human-related foraging behaviors within the same group of animals. Dolphins were photo-identified via surveys conducted throughout estuarine waterways around Savannah in the summers of 2009-2011. Mean half-weight indices (HWI) were calculated for each foraging class, and community division by modularity was used to cluster animals based on association indices. Pairs of trawler dolphins had a higher mean HWI (0.20 ± 0.07) than pairs of non-trawler dolphins (0.04 ± 0.02) or mixed pairs (0.02 ± 0.02). In contrast, pairs of beggars, non-beggars, and mixed pairs all had similar means, with HWI between 0.05-0.07. Community division by modularity produced a useful division (0.307) with 6 clusters. Clusters were predominately divided according to trawler status; however, beggars and non-beggars were mixed throughout clusters. Both the mean HWI and social clusters revealed that the social structure of common bottlenose dolphins near Savannah, Georgia was differentiated based on trawler status but not beg status. This finding may indicate that foraging in association with trawlers is a socially learned behavior, while the mechanisms for the propagation of begging are less clear. This study highlights the importance of taking into account the social parameters of a foraging behavior, such as how group size or competition for resources may affect how the behavior spreads. The positive or negative ramifications of homophily may influence whether the behaviors are exhibited by individuals within the same social clusters and should be considered in future studies examining social relationships and foraging behaviors., Competing Interests: The authors have declared that no competing interests exist.

Billfishes are considered to be among the fastest swimmers in the oceans. Previous studies have estimated maximum speed of sailfish and black marlin at around 35 m s -1 but theoretical work on cavitation predicts that such extreme speed is unlikely. Here we investigated maximum speed of sailfish, and three other large marine pelagic predatory fish species, by measuring the twitch contraction time of anaerobic swimming muscle. The highest estimated maximum swimming speeds were found in sailfish (8.3±1.4 m s -1 ), followed by barracuda (6.2±1.0 m s -1 ), little tunny (5.6±0.2 m s -1 ) and dorado (4.0±0.9 m s -1 ); although size-corrected performance was highest in little tunny and lowest in sailfish. Contrary to previously reported estimates, our results suggest that sailfish are incapable of exceeding swimming speeds of 10-15 m s -1 , which corresponds to the speed at which cavitation is predicted to occur, with destructive consequences for fin tissues., Competing Interests: The authors declare no competing or financial interests., (© 2016. Published by The Company of Biologists Ltd.)

A central pursuit of microbial ecology is to accurately model changes in microbial community composition in response to environmental factors. This goal requires a thorough understanding of the drivers of variability in microbial populations. However, most microbial ecology studies focus on the effects of environmental factors on mean population abundances, rather than on population variability. Here, we imposed several experimental disturbances upon periphyton communities and analyzed the variability of populations within disturbed communities compared with those in undisturbed communities. We analyzed both the bacterial and the diatom communities in the periphyton under nine different disturbance regimes, including regimes that contained multiple disturbances. We found several similarities in the responses of the two communities to disturbance; all significant treatment effects showed that populations became less variable as the result of environmental disturbances. Furthermore, multiple disturbances to these communities were often interactive, meaning that the effects of two disturbances could not have been predicted from studying single disturbances in isolation. These results suggest that environmental factors had repeatable effects on populations within microbial communities, thereby creating communities that were more similar as a result of disturbances. These experiments add to the predictive framework of microbial ecology by quantifying variability in microbial populations and by demonstrating that disturbances can place consistent constraints on the abundance of microbial populations. Although models will never be fully predictive due to stochastic forces, these results indicate that environmental stressors may increase the ability of models to capture microbial community dynamics because of their consistent effects on microbial populations. IMPORTANCE There are many reasons why microbial community composition is difficult to model. For example, the high diversity and high rate of change of these communities make it challenging to identify causes of community turnover. Furthermore, the processes that shape community composition can be either deterministic, which cause communities to converge upon similar compositions, or stochastic, which increase variability in community composition. However, modeling microbial community composition is possible only if microbes show repeatable responses to extrinsic forcing. In this study, we hypothesized that environmental stress acts as a deterministic force that shapes microbial community composition. Other studies have investigated if disturbances can alter microbial community composition, but relatively few studies ask about the repeatability of the effects of disturbances. Mechanistic models implicitly assume that communities show consistent responses to stressors; here, we define and quantify microbial variability to test this assumption. Author Video : An author video summary of this article is available.

Due to their high trophic position and long life span, small cetaceans are considered as suitable bioindicators to monitor the presence of contaminants in marine ecosystems. Here, we document the contamination with persistent organic pollutants (POPs) and total mercury (T-Hg) of spinner (Stenella longirostris, n =21) and Indo-Pacific bottlenose dolphins (Tursiops aduncus, n=32) sampled from the coastal waters of La Réunion (south-western Indian Ocean). In addition, seven co-occurring teleost fish species were sampled and analyzed as well. Blubber samples from living dolphins and muscle from teleosts were analyzed for polychlorinated biphenyls (PCBs), DDT and metabolites (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs), hexachlorobenzene (HCB), and polybrominated diphenyl ethers (PBDEs). Methoxylated PBDEs (MeO-PBDEs), reported as having a natural origin, were also analyzed. T-Hg levels were measured in blubber and skin biopsies of the two dolphin species. Stable isotopes δ(13)C and δ(15)N values were determined in skin of the dolphins and in the muscle of teleosts. For PCBs, HCHs and T-Hg, concentrations were significantly higher in T. aduncus than in S. longirostris. For other POP levels, intra-species variability was high. MeO-PBDEs were the dominant compounds (55% of the total POPs) in S. longirostris, while PCBs dominated (50% contribution) in T. aduncus. Other contaminants showed similar profiles between the two species. Given the different patterns of POPs and T-Hg contamination and the δ(15)N values observed among analyzed teleosts, dietary and foraging habitat preferences most likely explain the contrasted contaminant profiles observed in the two dolphin species. Levels of each class of contaminants were significantly higher in males than females. Despite their spatial and temporal overlap in the waters of La Réunion, S. longirostris and T. aduncus are differently exposed to contaminant accumulation., (Copyright © 2016 Elsevier Inc. All rights reserved.)