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Body size is of fundamental importance to our understanding of extinct organisms. Physiology, ecology and life history are all strongly influenced by body size and shape, which ultimately determine how a species interacts with its environment. Reconstruction of body size and form in extinct animals provides insight into the dynamics underlying community composition and faunal turnover in past ecosystems and broad macroevolutionary trends. Many extinct animals are known only from incomplete remains, necessitating the use of anatomical proxies to reconstruct body size and form. Numerous limitations affecting the appropriateness of these proxies are often overlooked, leading to controversy and downstream inaccuracies in studies for which reconstructions represent key input data. In this perspective, we discuss four prominent case studies (Dunkleosteus, Helicoprion, Megalodon and Perucetus) in which proxy taxa have been used to estimate body size and shape from fragmentary remains. We synthesise the results of these and other studies to discuss nuances affecting the validity of taxon selection when reconstructing extinct organisms, as well as mitigation measures that can ensure the selection of the most appropriate proxy. We argue that these precautionary measures are necessary to maximise the robustness of reconstructions in extinct taxa for better evolutionary and ecological inferences. [ABSTRACT FROM AUTHOR]

The presence of wild fish in and around aquaculture habitats is often assumed a response to food resources within these habitats, either from input feed, the presence of cultured species, and/or the assemblage of biofouling that naturally colonises aquaculture structures. The nutritional quality of the food resources consumed by wild fish in aquaculture habitats is also important in determining their nutritional condition and subsequent productivity. Few studies have investigated the nutritional quality of prey in aquaculture habitats, and these have mostly focused on fed aquaculture by tracking manufactured fish pellets into the diets of wild fish. However, in non‐fed aquaculture, the assemblage of cultured and biofouling species may also provide a nutritional benefit to fish feeding in these habitats. The Australasian snapper, Chrysophrys auratus, are commonly present as adults within coastal mussel farms in New Zealand and tend to become a resident species. This study investigated the nutritional quality of the gut contents of snapper in soft‐sediment habitats within and outside of New Zealand green‐lipped mussel farms. Total lipid, protein, carbohydrate and total calorific content were measured from the gut contents of snapper sampled from mussel farm and natural (i.e. control) habitats. Snapper in mussel farms had double the dietary intake of lipid (16% vs. 8%) from consuming lipid‐rich bivalves and barnacles which are in abundance in mussel farms. Higher lipid intake can contribute to improved nutritional condition, reproduction and growth in snapper. However, the higher dietary lipid intake of snapper in mussel farms did not increase their overall body condition (i.e. Fulton condition index). This may be due to the coarse nature of this measure, or the use of the additional lipid in more rapid somatic growth or reproductive outputs, possibilities that warrant examination through further research. Overall, this study shows for the first time the potential ecosystem benefits of shellfish aquaculture in provisioning nutritionally valuable prey for coastal fish populations. [ABSTRACT FROM AUTHOR]

Over one third of shark and ray (henceforth elasmobranch) species are threatened by global extinction. Overfishing, driven largely by human consumption of various products is a key threat to >95% of threatened elasmobranch species. The local consumption of elasmobranch meat is an emerging driver of these fisheries particularly in the Global South. Very little data exists on local elasmobranch meat consumption and restaurants offer a useful insight into patterns of consumption. We examined local elasmobranch consumption in India, which has the world's third highest elasmobranch catches. We surveyed 2649 seafood restaurants across 10 coastal states and found that two states alone accounted for 70% of all restaurants serving shark meat. Nine percent of all seafood restaurants advertised elasmobranch meat. 251.6 tonnes, equivalent to 9.8% of India's annual landings, is sold every year in India's restaurants. The drivers of these sales are local cultural affinities and regional cuisines, with evidence of new and evolving consumption pathways, in states like Goa. In Goa, the state with the highest prevalence of elasmobranch meat on restaurant menus, consumption by locals, as well as consumption of "baby sharks" by tourists was driving the demand for elasmobranch meat. Small‐bodied and juvenile sharks of threatened species are at risk from local meat consumption. Elasmobranch meat consumption can be reduced by targeting interventions in the regional hotspots of maximum consumption, substituting other types of seafood as alternatives in regional cuisines, bycatch reduction, increased price and seafood consumer awareness campaigns. Preliminary findings suggest that focusing on the health implications of eating species that concentrate heavy metals will produce the greatest decreases in elasmobranch meat sales at India's restaurants. [ABSTRACT FROM AUTHOR]

Losses in freshwater fish diversity might produce a loss in important ecological services provided by fishes in particular habitats. An important gap in our understanding of ecosystem services by fishes is the influence of individuals from different size classes, which is predicted based on known ontogenetic shifts in metabolic demand and diet. I used 20 experimental stream mesocosms located at Konza Prairie Biological Station (KPBS), KS, USA, to assess the influence of fish size on ecosystem properties. Mesocosms included two macrohabitats: one riffle upstream from one pool filled with consistent pebble and gravel substrate. There were four experimental and one control treatment, each replicated four times (N = 20). I used two size classes of central stonerollers (Campostoma anomalum) and southern redbelly dace (Chrosomus erythrogaster). Five ecosystem properties were assessed: algal filament length (cm), benthic chlorophyll a (μg/cm2), benthic organic matter (g/m2), macroinvertebrate biomass (g/m2), and stream metabolism (g O2/m2/day−1). Size structure of fish populations affected some, but not all, ecosystem properties, and these effects were dependent upon species identity. Size structure of both species had effects on algal filament lengths where stonerollers of both size classes reduced algal filaments, but only small redbelly dace kept filaments short. A better understanding of the relationship between these prairie stream minnows and their small stream habitats could be useful to both predict changes in stream properties if species are lost (redbelly dace are a Species In Need of Conservation) or size structure shifts. [ABSTRACT FROM AUTHOR]

Amidst global declines in elasmobranch populations resulting predominantly from overfishing, the need to gather data regarding shark ecology is greater than ever. Many species remain data deficient or at risk of going extinct before sufficient conservation measures can be applied. In this review, we summarise existing knowledge regarding the biology and ecology of the Pacific sharpnose shark Rhizoprionodon longurio (Jordan & Hilbert, 1882), a small‐bodied carcharhinid shark found in coastal waters of the Eastern Tropical Pacific Ocean that is of both commercial and ecological importance. We compare ecological parameters of this species with its closest extant relatives and identify major knowledge gaps and avenues for future research. In particular, additional studies investigating the behavioural and sensory ecology, as well as potential migratory patterns of the species are needed. Such studies will not only improve our understanding of R. longurio, but provide insight into the extent to which the numerous studies performed on a close relative—Rhizoprionodon terraenovae—provide an accurate representation of the biology and ecology of Rhizoprionodon and carcharhinids more generally. [ABSTRACT FROM AUTHOR]

Designing appropriate management plans requires knowledge of both the dispersal ability and what has shaped the current distribution of the species under consideration. Here, we investigated the evolutionary history of the endangered gray reef shark (Carcharhinus amblyrhynchos) across its range by sequencing thousands of RADseq loci in 173 individuals in the Indo‐Pacific (IP). We first bring evidence of the occurrence of a range expansion (RE) originating close to the Indo‐Australian Archipelago (IAA) where two stepping‐stone waves (east and westward) colonized almost the entire IP. Coalescent modeling additionally highlighted a homogenous connectivity (Nm ~ 10 per generation) throughout the range, and isolation by distance model suggested the absence of barriers to dispersal despite the affinity of C. amblyrhynchos to coral reefs. This coincides with long‐distance swims previously recorded, suggesting that the strong genetic structure at the IP scale (FST ~ 0.56 between its ends) is the consequence of its broad current distribution and organization in a large number of demes. Our results strongly suggest that management plans for the gray reef shark should be designed on a range‐wide rather than a local scale due to its continuous genetic structure. We further contrasted these results with those obtained previously for the sympatric but strictly lagoon‐associated Carcharhinus melanopterus, known for its restricted dispersal ability. Carcharhinus melanopterus exhibits a similar RE dynamic but is characterized by a stronger genetic structure and a nonhomogeneous connectivity largely dependent on local coral reefs availability. This sheds new light on shark evolution, emphasizing the roles of IAA as source of biodiversity and of life‐history traits in shaping the extent of genetic structure and diversity. [ABSTRACT FROM AUTHOR]

Copyright of People & Nature is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aim: Marine vertebrates play key functional roles on reef ecosystems. Despite their phylogenetic distance, different vertebrate lineages could play similar functions on reefs, which has been overlooked by current research on marine functional biogeography. We provide the first comprehensive assessment of the functional structure and inventory of ecosystem functions delivered by 224 vertebrates—marine mammals, sea turtles, sharks, rays and bony fish—in Atlantic Ocean reefs. Location: Atlantic Ocean reefs. Methods: We compiled six species‐level traits and investigated geographical patterns of functional richness (FRic), functional uniqueness (FUn) and specialization (FSpe) in 83 assemblages. Additionally, we simulate the effects of marine vertebrate species' extinction on functional diversity metrics. Results: Sharks, rays and bony fish species had the highest overlap in functional space (30.94%), while turtles overlapped mainly with bony fishes (1.76%). The functional structure of vertebrate assemblages is not homogeneous across the Atlantic. While functional richness peaks in the Caribbean (a "functional hotspot"), this region depicts low‐to‐intermediate functional uniqueness and functional specialization levels. Despite the large proportion of threatened top predator species (53.1%), mainly large‐bodied sharks, it is the loss of mesopredator species that will severely impact (up to 94% of functional loss) the functional space of vertebrate assemblages in Atlantic Ocean reefs. Main conclusions: Our study reveals that functional richness patterns of vertebrate assemblages differ across Atlantic Ocean reefs. Despite the low values of functional uniqueness and specialization in some reef assemblages, reef functioning can still be compromised due to species' extinctions. The impact of mesopredators' loss over the functional structure of vertebrate assemblages is worrisome since this group holds a considerable proportion of threatened species (20.1%) and is next in line considering the anthropogenic impacts over high trophic level species. [ABSTRACT FROM AUTHOR]

Sharks play a key role in the structure and functioning of marine ecosystems. More ecological information is essential to implement responsible management and conservation actions on this fauna, particularly at a regional level for threatened species. Mustelus mustelus is widely found in the eastern Atlantic Ocean and catalogued as "Vulnerable" by the IUCN European assessment. In this study, data on the distribution and population structure of this species across the islands of the Canarian archipelago, located along an east to west gradient in the north‐eastern Atlantic, were collected by taking advantage of "Local Ecological Knowledge," in terms of sightings in coastal waters and long‐term imprints on the local gastronomic heritage, and decadal fisheries landings. Both sources of quantitative data (sightings and fisheries landings) demonstrated that adults of M. mustelus has a significantly larger presence in the eastern and central, than in the western islands of the archipelago. This is also reflected on local gastronomic legacies, with a larger number of recipes in the eastern and central islands. Adult smooth‐hound sharks were significantly more observed in sandy and sandy‐rocky bottoms, with individuals seen throughout the entire year, whereas juveniles aggregate on very shallow waters in spring and summer. Such aggregations require a special management strategy, as they play a key role in critical life stages; these sites should be protected from human perturbations. We also suggest a temporal fishing ban between April and October, when individuals tend to concentrate on nearshore waters. Because of the large differences in presence of this shark among the Canary Islands, management of the species should be adapted to the specific peculiarities of each island, rather than adopting a management policy at the entire archipelago‐scale. Overall, this study sets the basis for further investigation to promote conservation of this vulnerable shark in the study region. [ABSTRACT FROM AUTHOR]

Increasing fishing pressure has negatively impacted elasmobranch populations globally. Despite high levels of historical and current fishing pressure, the Bay of Bengal region remains data‐poor. Focusing on Bangladesh, we conducted a socio‐ecological study to characterize elasmobranch fisheries and evaluate their impact on threatened species. The results demonstrate that several globally threatened elasmobranch species are frequently captured, and some of them have experienced substantial population declines (e.g., wedgefishes, sawfishes, large carcharhinid sharks) over the past decade. A decrease in elasmobranch diversity, abundance, and size of caught specimens was also reported, which was attributed to increased fishing intensity, destructive practices (e.g., bottom trawling), and an accessible elasmobranch market. While catch and trade of more than 90 elasmobranchs are regulated under Bangladesh's law, non‐compliance is widespread. Likely causes include a dearth of awareness, practical alternative livelihoods, and technical facilities, and the complex nature of the fisheries. Encouraging and facilitating the engagement of fishers in science (data collection), local governance (policy‐making), and field implementation (bycatch mitigation) is vital. These interventions must be rooted in sustainable approaches and co‐designed with fishers, with appropriate training available. Development of this work through enhanced engagement with fishers has the potential to transform the elasmobranch fishery situation in Bangladesh and could be used as a model for data‐poor regions. [ABSTRACT FROM AUTHOR]

Background: The interplay of animal dispersal and environmental heterogeneity is fundamental for the distribution of biodiversity on earth. In the ocean, the interaction of physical barriers and dispersal has primarily been examined for organisms with planktonic larvae. Animals that lack a planktonic life stage and depend on active dispersal are however likely to produce distinctive patterns. Methods: We used available literature on population genetics and phylogeography of elasmobranchs (sharks, rays and skates) to examine how marine barriers and dispersal ecology shape genetic connectivity in animals with active dispersal. We provide a global geographical overview of barriers extracted from the literature and synthesize the geographical and hydrological factors, spatial and temporal scales to characterize different types of barriers. The three most studied barriers were used to analyse the effect of elasmobranch dispersal potential and barrier type on genetic connectivity. Results: We characterized nine broad types of marine barriers, with the three most common barriers being related to ocean bathymetry. The maximum depth of occurrence, maximum body size and habitat of each species were used as proxies for dispersal potential, and were important predictors of genetic connectivity with varying effect depending on barrier type. Environmental tolerance and reproductive behaviour may also play a crucial role in population connectivity in animals with active dispersal. However, we find that studies commonly lack appropriate study designs based on a priori hypotheses to test the effect of physical barriers while accounting for animal behaviour. Main conclusions: Our synthesis highlights the relative contribution of different barrier types in shaping elasmobranch populations. We provide a new perspective on how barriers and dispersal ecology interact to rearrange genetic variation of marine animals with active dispersal. We illustrate methodological sources that can bias the detection of barriers and provide potential solutions for future research in the field. [ABSTRACT FROM AUTHOR]

Indirect interactions mediated by shared enemies or mutualists (i.e. apparent competition) can influence whether invasive plants harm or benefit co‐occurring species. However, studies to date have largely examined single pairwise interactions, limiting our understanding of the interplay among different types of interactions and whether indirect impacts systematically favour native or exotic species. Predicting indirect interaction strength has also proven challenging, and it remains unclear whether the strengths of different indirect interactions are correlated.We conducted a field experiment in a grassland invaded by Scotch broom Cytisus scoparius to compare the strength of its indirect impacts, via both soil fungi and herbivores, on 21 native and exotic legume species growing in pots buried in the ground. Direct interactions of plants with soil fungi were controlled using nylon mesh pot windows of differing porosity (1 or 38 µm) to prevent or allow soil fungi hyphal growth. Arthropod herbivores were controlled through spraying pyrethrum pesticide. To assess indirect impacts, interactions were compared between plants adjacent to or 50 m away from an extensive Scotch broom invasion. We measured plant performance (survival, height and biomass), arthropod and hare herbivory, and rhizobia nodulation.Despite increasing arthropod herbivory of both native and exotic plant species, Scotch broom had a net positive impact on their survival and growth, through sheltering them from abiotic stress, and indirectly via beneficial soil fungi and release from hare browsing. Soil fungi also increased arthropod herbivory, decreased rhizobia nodulation and disproportionately promoted the growth of exotic plants. Overall, exotic plants experienced stronger interactions, which favoured them with beneficial soil fungi and rhizobia but not hare browsing. Finally, indirect interaction strength was not correlated among indirect interactions mediated by different interaction partners.Synthesis. We demonstrate that invaders affect their competitors through multiple interacting indirect pathways that were stronger than direct 'nurse plant' effects, emphasizing the importance of a community‐level approach to studying biological invasions. Exotic species experienced stronger positive and negative impacts than natives, but were facilitated overall, potentially contributing to exotic dominance in communities. [ABSTRACT FROM AUTHOR]

The U.S. Congress is currently discussing the Shark Fin Sales Elimination Act to eliminate shark fin trade at the federal level. This bill was introduced in 2017 and has been proceeding very slowly in Congress because of mixed reviews from the scientific community. Debate exists on whether shark conservation and management are effectively addressed with tightened trade controls for imported shark products or blanket bans that outright end U.S. participation in the shark fin trade. Here we contribute to this debate with a review and analysis of economic, nutritional, ethical, and legal arguments, as well as of the shark fisheries status and shark fin trade. We show that the United States has a limited commercial interest in shark fisheries and contributes to the shark fin trade mainly as a facilitator. A fin trade ban has few tangible economic drawbacks but would have a considerable conservation impact. While making all shark fisheries sustainable is the ultimate goal, in practice this objective is far from achievable everywhere in the world. Conversely, banning shark fin trade is an interim measure that nations like the United States can take with negligible cost and can truly impact the biggest driver of shark exploitation globally. [ABSTRACT FROM AUTHOR]

During their evolutionary history, modern sharks developed different tooth mineralization patterns that resulted in very distinct histological patterns of the tooth crown (histotypes). To date, three different tooth histotypes have been distinguished: (i) orthodont teeth, which have a central hollow pulp cavity in the crown, encapsulated by a prominent layer of dentine (orthodentine); (ii) pseudoosteodont teeth, which have their pulp cavities secondarily replaced by a dentinal core of porous dentine (osteodentine), encased by orthodentine; and (iii) osteodont teeth, which lack orthodentine and the whole tooth crown of which consists of osteodentine. The aim of the present study was to trace evolutionary trends of tooth mineralization patterns in modern sharks and to find evidence for the presence of phylogenetic or functional signals. High resolution micro‐computed tomography images were generated for the teeth of members of all nine extant shark orders and the putative stem group †Synechodontiformes, represented here by three taxa, to examine the tooth histology non‐destructively. Pseudoosteodonty is the predominant state among modern sharks and represents unambiguously the plesiomorphic condition. Orthodonty evolved several times independently in modern sharks, while the osteodont tooth histotype is only developed in lamniform sharks. The two shark orders Heterodontiformes and Pristiophoriformes showed highly modified tooth histologies, with Pristiophorus exhibiting a histology only known from batomorphs (i.e. rays and skates), and Heterodontus showing a histological difference between anterior and posterior teeth, indicating a link between its tooth morphology, histology and durophagous lifestyle. The tooth histotype concept has proven to be a useful tool to reflect links between histology, function and its taxonomic value for distinct taxa; however, a high degree of variation, especially in the pseudoosteodont tooth histotype, demonstrates that the current histotype concept is too simplistic to fully resolve these relationships. The vascularization pattern of the dentine might offer new future research pathways for better understanding functional and phylogenetic signals in the tooth histology of modern sharks. [ABSTRACT FROM AUTHOR]

Across their North American range, grizzly bears (Ursus arctos) occupy a special place in human imagination, as icons of nature's rugged and raw power, to representations of safety risks and economic costs of living with carnivores. Different bear representations can also be found across news media, from controversial and sensational descriptions of attacks, tragic events and conflicts, to scientific accounts of conservation research. News media certainly has the power to pique curiosity, spark debate, or elicit emotional responses through framing and repetition of content. In turn, news stories can influence how people might interpret and internalize information about grizzly bears. Using media content analysis, we examined newsprint stories on grizzly bears across their North American range between 2000 and 2016, to understand message framing and attention cycle, as well as attitudinal expression and representative anecdote conveyed to the readership. We found that human–bear conflict stories are over‐reported compared to other narratives, where a single incidence garners more attention than a story about new scientific findings. We also found articles that included hunting frames largely originated in Alberta, likely due to the threatened species listing and hunting moratorium. Attitudinal expressions included ecological, negative or neutral, and moral sentiments toward bears. The most common representative anecdote conveyed to the readership reflected the dire state faced by grizzly bears. The bear eco‐gossip expressed in the articles we reviewed, which included clear protagonists and antagonists and the occasional man‐bites‐bear surprise, appears to be the diet of manufactured information fed to the public. Results of our study can help scientists and conservationists understand how news media portrays grizzly bears to the public and how this might influence public sentiment toward their conservation, but also identifies the roles that scientists, conservationists and journalists together can play in crafting effective, factual and engaging news stories about bears. [ABSTRACT FROM AUTHOR]

Copyright of Methods in Ecology & Evolution is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Specialised predators foraging in the boundaries of adjacent ecosystems can control or redirect the flow of subsidies through trophic interception. Ecologically diverse predators can capture terrestrial invertebrates that fall on the water surface and, consequently, influence the flow of energy to aquatic environments. In this study, we show that the movement of prey triggers ripples on the surface of the water, and these stimuli are detected by bulldog bats (Noctilio albiventris, Noctilionidae) during foraging. Thus, the bats located live crickets (Gryllus assimilis, Gryllidae) on average of 15 times faster when compared to the location of dead or artificial crickets (i.e. without movements or ripples on the water surface). The bats also inspected (i.e. touched with their feet) all floating objects on the water surface. During this behaviour, the characteristics of the object (i.e. texture) were critical for bats to distinguish between debris (e.g. leaves and sticks) and the resource (i.e. insect carcasses) that floated on the water surface. In addition, when we compare the efficiency of predators (i.e. bats and fishes) in capturing this resource, our findings suggest that bats are extremely effective (i.e. consumed 100% of the available prey), since the fishes consumed only 40% of the available crickets on the surface of the water over a 60‐s period. These results bring novel information about the influence of prey‐based stimuli on the behaviour of its predators and, consequently, on the flow of nutrients between terrestrial and aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Copyright of Conservation Biology is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)