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Predictive regression equations were generated to estimate total length of the Argentine seabass (A. patachonicus) using skull and pectoral girdle bones, specific body and otolith lengths. Regressions of skull and pectoral girdle bones, specific body and otolith lengths were all statistically significant. Generating regressions of the bony and external characteristics of the fish body meaningfully increases the ability to analyse the information that can be obtained from the study of the stomach contents of predators of fish from the southwest Atlantic. Fil: Riestra, Cecilia Micaela. Instituto Nacional de Investigaciones y Desarrollo Pesquero; Argentina Fil: Perez Comesaña, Jorge E.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); Argentina Fil: Arias, Karina Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); Argentina Fil: Tamini, Leandro Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); Argentina Fil: Chiaramonte, Gustavo Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Hidrobiológica de Puerto Quequén (sede Quequén); Argentina

The ubiquitous nature of microplastics in aquatic ecosystems may have serious implications for aquatic biota. While microplastic research in freshwater ecosystems is increasing, very few studies have assessed the physical presence of microplastics among top predators. The Eurasian otter (Lutra lutra), a top predator of aquatic ecosystems, is one of the most widely distributed otter species and has a broad habitat niche. The opportunistic collection of otter spraints (i.e., feces) presents a valuable opportunity to assess pollutants of freshwater ecosystems through noninvasive means. Here, we assessed the prevalence, abundance, and concentration of microplastics (100 μm to 5 mm), as well as dietary remains, in 53 spraint samples collected over eight river catchments spanning three regions of Ireland. We found microplastics present in 57% of spraints at an abundance of 1.2 ± 0.1 microplastics (MPs)/spraint (mean ± SE) and a concentration of 3.8 ± 0.6 MPs/g (dry weight). Fibers were the dominant particle type recovered (85%), followed by film (10%). No significant differences in microplastic concentrations were detected between the three regions assessed, or between spraints collected from areas upstream (i.e., “lower” exposure) or downstream (“higher” exposure) of putative microplastic sources, which were defined using spatial vector data. While microplastic concentrations were not explained by spraint condition (i.e., fresh, drying, or dry), spraints collected in autumn had a significantly higher concentration than spring and summer. Furthermore, microplastic abundance or concentration could not be linked to dietary composition based on the items identified. From a trophic perspective, this study showed that the presence of microplastics in the feces of otter is most likely being obtained through its prey (i.e., secondary ingestion). While there may be limitations associated with using spraints as a biomonitoring tool for microplastics in freshwater systems, particularly with respect to otter home range and dietary niche breadth, they could still be employed for a regional assessment of microplastic levels.

Despite the global biodiversity crisis, some ecosystems are showing encouraging signs of recovery, especially in Europe and North America. We do not have a clear understanding of how ecosystems recover from degraded states, of the causes and consequences of such recovery, or of how emerging species interactions affect and are affected by ecological processes. In this thesis, I investigate the patterns and processes emerging from recovering ecosystems by analysing population dynamics, species interactions and animal movement. I explore the spatiotemporal trends of an expanding large mammal community in the Alps and investigate predator-prey interactions between wolves and their main prey. I assess the permeability of the Alpine landscape for recovering populations, by analysing the impact of natural and anthropogenic factors on the movement of a partially migratory ungulate. Studying species interactions in a dynamic and recovering system such as the Alps is challenging. I therefore focus on the Yellowstone ecosystem to analyse the impact of wolf predation on their prey and on other ecological processes. I develop a mechanistic, bio-energetic model of the vegetation-elk-wolf system, to study how energy acquired through resources flows across trophic levels influencing population dynamics and interactions. I then use this model to study how ecological and evolutionary change can affect complex tri-trophic systems. I show that large mammal communities can recover relatively quickly in the right environment, and with the support of conservation and favourable environmental legislation. Nonetheless, humans can still have a significant impact on animal populations by affecting their movement patterns and habitat use. In the Alps, I could not detect an impact of wolf predation on prey populations because the recovery process is still ongoing and the system is highly dynamic. In Yellowstone, on the other hand, I show that wolf predation can have significant effects on the ecosystem, and that complex trophic interactions can respond in unexpected ways to ecological and evolutionary change. My thesis offers advances for investigating complex terrestrial systems, for predicting the potential impacts of environmental change on ecosystems, and for informing future policy and landscape management decisions.

To enhance knowledge of the environmental distribution and temporal trends of dechloranes and their transformation products (TPs) we performed suspect screening of Baltic Sea biota (eelpout, herring, harbor porpoise, guillemot and white-tailed sea eagle). Evaluation of new and “digitally frozen” gas chromatography/high-resolution mass spectrometry data revealed 31 compounds: five dechloranes (Dechlorane [Mirex], Dechlorane 602, Dechlorane 603, and syn-/anti-Dechlorane Plus [DP]), three isomers, and 23 TPs. Six new Dechlorane 603 TPs and two new DP TPs were detected, including one hydroxy-TP. Some TPs occurred at much higher concentrations than the parent compounds (e.g., Dechlorane 603 TPs were >10-fold more abundant than their parent). Concentrations of contaminants in the most contaminated species (white-tailed sea eagle) changed little over the period 1965–2017. Slow declines were detected for most compounds (median, 2% per year), although concentrations of DP and DP-TPs increased by 1% per year. Ten contaminants biomagnify, and the trophic magnification factors for TPs of Mirex, Dechlorane 602 and Dechlorane 603 (8.2 to 17.8) were similar to the parent compounds (6.6 to 12.4) and higher than that of DP (2.4, nonsignificant). The results are discussed in relation to the current review of DP for potential listing under the Stockholm Convention on POPs. Baltic Sea multilevel health impacts on key species of anthropogenic hazardous substances

Pollutants have been identified as one of the major environmental threats to humankind, wildlife and ecosystems, including the Arctic. Organo-halogenated chemicals (OHCs) and mercury (Hg) are transported from anthropogenic sources via long-range transport to the Arctic, where many of these pollutants biomagnify within Arctic food chains, leaving in particular apex predators at the top of food chains vulnerable to potential health effects due to their hazardous properties. From a risk assessment perspective, top predators are valuable sentinels because they integrate chemical exposure across large areas and long time spans and, owing to their position at the top of food chains, reflect pollutant trends and ecosystem fluctuations. Thus, monitoring chemical exposure and understanding its impacts on Arctic predators is crucial for developing science-based recommendations for targeted conservation and management initiatives. The overall objective of the thesis was to assess the exposure of key Arctic marine and terrestrial mammal, bird and fish species to OHCs and Hg as well as their biological effects at the individual and population level. Specifically, we investigated dietary drivers of mercury exposure in two sentinel predator species inhabiting the circumpolar Arctic, namely the Arctic subspecies of the grey wolf (Canis lupus arctos) and the Arctic fox (Vulpes lagopus). In Chapter I, total mercury levels were analysed in the fur of 30 Arctic grey wolves sampled between 1869 – 1998 in Greenland and High Arctic Canada. Diet was evaluated with the help of stable isotope analysis by determining dietary carbon sources (as inferred by δ13C) and trophic level (as inferred by δ15N). As expected, we observed high dietary variation of marine and terrestrial food sources at various trophic positions. Variability in Hg burden in the wolves was significantly driven by biomagnification (δ15N) rather than by carbon source (δ13C) or study site. In Chapter II, various pathogens and Hg levels were evaluated as potential drivers of the Arctic fox population decline during 1970 – 1980 on the distinct, small Mednyi Island belonging to the Russian Commander Islands. We chose a study design that allowed the comparison of Hg fur levels from historical specimens from the Commander Islands representative for the population pre-crash period on Mednyi Island, contemporary Mednyi foxes sampled in 2011, and two unrelated and geographically remote ecotypes represented by inland and coastal Icelandic Arctic fox populations. As expected, Hg levels were significantly higher in foxes inhabiting coastal habitats regardless of geographic location than in those from inland sites and were highest during the pre-crash period in the Mednyi population. This was most likely because the Mednyi population depends solely on marine vertebrates that have been shown to be highly contaminated. Our large-scale health assessment using serological and DNA based pathogen screening techniques suggested a low prevalence of pathogens in contemporary foxes, although it does not allow a proper assessment of the health status of the Mednyi Arctic foxes during or before the crash period. Most likely a complex interplay of stressors explains the high cub mortality observed on Mednyi Island, including high mercury body burden, which renders particularly young foxes vulnerable to infectious diseases. Chapter III evaluates whether fur can be used as a minimally-invasive sampling matrix to reliably determine total Hg levels in soft tissues, specifically in liver and kidney of Arctic foxes. Associations between Hg levels in the fur, liver and kidney of 35 Arctic foxes sampled in 2011-2012 on Iceland were investigated. Observed total Hg concentrations varied considerably among tissues, with liver generally showing higher levels than fur and kidneys, and significant linear and sex-independent relationships based on regressions allowed to reliably extrapolate mercury liver and kidney concentrations from fur levels. Measurements in ecotoxicological studies frequently use different tissues (usually liver), which hinders cross-study comparison. Thus, the derived regression equations improve direct comparison of Hg levels among fur and soft tissues reported for Arctic canids. Chapters I-III show that Arctic wolves from Greenland and High Arctic Canada tend to have relatively low Hg concentrations (< 5 µg g-1 dry weight), whereas coastal Arctic fox populations from Iceland and the Commander Islands had up to 7-fold higher Hg fur levels, while coastal populations had 3-fold higher Hg levels than inland ones. While the health status of the Arctic wolves was most likely not affected, the mercury levels in some of the Arctic foxes exceed putative thresholds for Hg-mediated toxic health effects. Apart from trophic magnification as major driver, the observed inter-population and intra-population variability in Hg levels likely results from a combination of varying ecosystem conditions, changes in emission patterns and biological factors. Although the results of Chapter I-III are limited in terms of conclusive evidence because historic study material and/or sample sizes were scarce and relatively small, respectively, they do provide novel tools and information on temporal and spatial variation in Hg pollution in these understudied Arctic canids. In Chapter IV, exposure levels and health impacts of mercury and OHCs were evaluated in key Arctic marine and terrestrial mammals, birds and fish, using population-specific exposure data published between 2010 and 2019. Various pollutant induced health effects were summarized by each endpoint ranging from molecular to individual and population level effects. We identified quantifiable effects on vitamin metabolism, immune functioning, thyroid and steroid hormone balances, oxidative stress, tissue pathology, and reproduction. On this basis we calculated risk quotients in order to estimate critical body burdens specifically as regard to Hg and polychlorinated biphenyls (PCBs) shown to impair reproduction functions in vertebrates. The outcome was that most Arctic marine mammal species are at no or low risk in terms of health effects or reproductive impairments mediated by Hg or PCB exposure. However, for some species at high marine trophic levels, such as polar bear, narwhal and hooded seal, a segment of the population had body burden indicating a high or severe risk of suffering health effects and reproduction impairments. While bird Hg and PCB concentrations were also above toxicity benchmarks in many areas of the marine environment, terrestrial mammals were not at risk – with the exception of the Arctic foxes from Iceland and Commander Islands analysed in Chapter I – III. Overall, the thesis demonstrates the usefulness of fur samples for monitoring Hg and carbon and nitrogen stable isotopes in Arctic canids. It provides a practical tool for cross-study comparisons of Hg across different tissue types and fur, which will help with interpreting exposure risks of Arctic canids in future studies. It further suggests that absolute exposure to pollutants may be less important than indirect contamination via the feeding ecology and feeding opportunities of canid predators which may in turn affect population health and stability. Although the release of numerous, hazardous OHCs and Hg into the environment have been limited and regulated for a long time, the thesis emphasises that certain Arctic predator species are still highly exposed, which may pose a potential threat to their populations and the integrity of their ecosystems. Since our understanding and assessment methods of the specific risks and chronic impacts of pollutants on wildlife populations are still limited, chemical risk assessment should in future be up-scaled to population level effects. The results of the thesis will complement the existing data that form the basis for science-based recommendations for conservation management and policy measures and were already considered by the Arctic Monitoring and Assessment Program. Finally, to improve the effectiveness of the regulation of the release of pollutants into the environment and to support conservation initiatives for Arctic predators, particularly in view of climate change as a future stressor, further investigations are needed to improve our understanding of the mechanisms and interplay of drivers of pollution and its effects on Arctic wildlife populations and ecosystems.

The COST Action ‘European Raptor Biomonitoring Facility’ (ERBFacility) aims to develop pan-European raptor biomonitoring in support of better chemicals management in Europe, using raptors as sentinel species. This presents a significant challenge involving a range of constraints that must be identified and addressed. The aims of this study were to: (1) carry out a comprehensive review of the constraints that may limit the gathering in the field of raptor samples and contextual data, and assess their relative importance across Europe; and (2) identify and discuss possible solutions to the key constraints that were identified. We applied a participatory approach to identify constraints and to discuss feasible solutions. Thirty-one constraints were identified, which were divided into four categories: legal, methodological, spatial coverage, and skills constraints. To assess the importance of the constraints and their possible solutions, we collected information through scientific workshops and by distributing a questionnaire to stakeholders in all the countries involved in ERBFacility. We obtained 74 answers to the questionnaire, from 24 of the 39 COST participating countries. The most important constraints identified were related to the collection of complex contextual data about sources of contamination, and the low number of existing raptor population national/regional monitoring schemes and ecological studies that could provide raptor samples. Legal constraints, such as permits to allow the collection of invasive samples, and skills constraints, such as the lack of expertise to practice necropsies, were also highlighted. Here, we present solutions for all the constraints identified, thus suggesting the feasibility of establishing a long-term European Raptor Sampling Programme as a key element of the planned European Raptor Biomonitoring Facility., This paper is based on work from COST Action European Raptor Biomonitoring Facility (COST Action CA16224) supported by COST (European Cooperation in Science and Technology), including a grant for a short-term scientific mission awarded to the lead author. COST is funded by the Horizon 2020 Framework Programme of the European Union. Silvia Espín was financially supported by Ministerio de Ciencia, Innovación y Universidades (Juan de la Cierva-Incorporación postdoctoral contract, IJCI-2017-34653).

The Illegal Trade in Wildlife (IWT) is one of the most cumbersome threats currently facing biodiversity, with broad implications for the health and wellbeing of humans and nature. Over the past decade, reports of international illegal trade in jaguars (Panthera onca), with links to demand from Asian wildlife markets, have emerged throughout Latin America, raising the profile of jaguars as the emblem of Latin America’s fight against IWT. This DPhil is among the first to explore the characteristics, prevalence, and drivers of this threat to jaguars, with the goal of providing scientific evidence in support of ongoing and future projects and policies aimed at addressing it. Data collection efforts centred in Mesoamerica and Bolivia, two areas with varying degrees of evidence of international trade, and were based on interviews with enforcement agents and conservation practitioners, and questionnaire surveys with rural communities coexisting with jaguars. In both study areas, the illegal jaguar trade was found to be a prevalent, domestically-focused, and opportunistic activity, driven largely by the confluence of cultural traditions surrounding wildlife uses, forest-dependent livelihoods, and negative perceptions and interactions with jaguars, manifested through human-jaguar conflict. To a lesser degree, the trade was also influenced by a more diverse set of external actors and drivers than originally expected, including tourists of diverse backgrounds, regional immigrants, and traders of Asian-decent. Enabling factors ranged from critical limitations in the enforcement capacity of wildlife authorities, to a high social acceptability of jaguar killing in rural communities. Additionally, the DPhil highlighted biases in how those in charge of addressing the illegal trade in jaguars perceive and use evidence on the trade, with a tendency to disregard its reliability and conservation relevance. To address this issue, the DPhil provides guidelines towards a more objective decision-making on the illegal wildlife trade, and reinforces the need for evidence-based, multifaceted, counter-trafficking approaches that consider the complex interacting domestic and international, cultural and commercial drivers behind the illegal trade in jaguars.

Persistent organic pollutants (POPs) are found in high concentrations in the Artic. Polar bears (Ursus maritimus) are one of the most exposed mammals in the Arctic and are thereby vulnerable to reproductive disruption. The aim of this study was to investigate male polar bear reproduction based on a detailed evaluation of testis histology and to assess possible effects of environmental chemicals on male polar bear reproduction. Reproductive groups that were identified based on histology were as follows: actively reproductive (REP), non-reproductive either with degenerated testes (DEG), undeveloped seminiferous tubules (UND), or morphology in-transition (INT). Categorization into these groups was supported by significant differences in testis and baculum measurements among REP, DEG, and UND, as well as differences in the area and diameter of seminiferous tubules among REP, DEG, and UND. These results show that it is possible to identify the reproductive stage in polar bears even if capture date and or age is lacking. Based on testis morphology we suggest that adult male polar bears from East Greenland have active spermatogenesis in February to June, and inactive degenerated testes in August to January. January to February was the main period of reproductive transition, characterised by a shift between inactive and active spermatogenesis. Baculum and testis size measurements decreased significantly with increasing concentrations of the chlordane metabolite oxychlordane, suggesting a potential impact on male reproductive success. Half of the investigated polar bears in REP group displayed signs of disorganization of the spermatogenesis which might be a sign of disrupted reproduction. However, no correlations with levels of the investigated POPs were detected. Reproductive organ measurements in polar bears differed significantly between REP and DEG groups, which cannot be explained by age, and therefore should be considered when investigating the effect of POPs on male reproduction.

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WOS:000558706200001; International audience; Mesopelagic resources are central to the ecosystem but remain poorly studied mainly due to the lack of observations. This paper investigates the assemblages of micronekton organisms and their habitat in the Natural Park of the Coral Sea around New Caledonia (southwest Pacific) using data from 141 pelagic trawls. A total of 67,130 micronekton individuals (fish, crustaceans, and mollusks) were collected with 252 species identified among 152 genus and 76 families. In the analyses, we focused on 22 species; each were present in more than 33 trawls (i.e., in more than 25% of the total number of trawls) and studied their spatial distribution and vertical dynamic behavior. Community structure was investigated through region of common profile (RCP), an innovative statistical multivariate method allowing the study of both species assemblages and environmental conditions' influence on species occurrence probability. Nine major assemblages were identified, mainly driven by time of the day and sampling depth. Environmental variables, such as mean oxygen concentration, mean temperature, and bathymetry, also influenced micronekton assemblages, inducing a north/south distribution pattern. Three major day-assemblages were identified, distributed over the whole EEZ but segregated by depth: one assemblage in waters shallower than 200 m and the other two in deeper waters, respectively, in the north and the south. The night-assemblages were mostly segregated by depth with two community changes at approximately 80 and 200 m and spatially with a north-south gradient. The predominant northern night assemblages were dominated by crustacean, whereas the southern assemblage mostly by cephalopods and fish species. Generally, the southwest part of the EEZ was the most diverse part. Statistical analyses allowed the prediction of the spatial distribution of each species, and its vertical migration behavior was determined. Based on results, three important areas were identified to be considered for special management measures as part of the Natural Park of the Coral Sea.

In the California Current Ecosystem, krill represent a key link between primary production and higher trophic level species owing to their central position in the food web and tendency to form dense aggregations. However, the strongly advective circulation associated with coastal upwelling may decouple the timing, occurrence, and persistence of krill hotspots from phytoplankton biomass and nutrient sources. Results from a coupled physical‐biological model provide insights into fundamental mechanisms controlling the phenology of krill hotspots in the California Current Ecosystem, and their sensitivity to alongshore changes in coastal upwelling intensity. The simulation indicates that dynamics controlling krill hotspot formation, intensity, and persistence on seasonal and interannual timescales are strongly heterogeneous and related to alongshore variations in upwelling‐favorable winds, primary production, and ocean currents. Furthermore, regions promoting persistent krill hotspot formation coincide with increased observed abundance of top predators, indicating that the model resolves important ecosystem complexity and function., Key Points Krill hotspot formation and persistence are strongly heterogeneous in space and timeKrill hotspots are shaped by local upwelling variability and regional circulationKrill hotspots coincide with observed distributions of marine mammals and seabirds

WOS:000529921100010; International audience; Acoustic data are invaluable information sources for characterizing the distribution and abundance of mid-trophic-level organisms (micronekton). These organisms play a pivotal role in the ecosystem as prey of top predators and as predators of low-trophic-level organisms. Although shipboard-ADCP (acoustic Doppler current profiler) acoustic backscatter signal intensity cannot provide an absolute biomass estimate, it may be a useful proxy to investigate variability in the distribution and relative density of micro-nekton. This study used acoustic recordings data spread across 19 years (1999-2017) from 54 ADCP cruises in New Caledonia's subtropical EEZ (exclusive economic zone) to assess seasonal and interannual variabilities and spatial distribution of micro-nekton. The dataset was composed of two different ADCPs: 150 kHz for the first period, followed by 75 kHz for more recent years. We examined the 20-120 m averaged scattering layer. Using the few cruises with concurrent EK60 measurements, we proposed that the backscatter from the ADCPs and 70 kHz EK60 were sufficiently closely linked to allow the use of the backscatter signal from the ADCPs in a combined dataset over the full time series. We then designed a GAMM (generalized additive mixed model) model that takes into account the two ADCP devices as well as temporal variability. After accounting for the effect of the devices, we showed that the acoustic signal was mainly driven by diel vertical migration, season, year, and ENSO (El Nino-Southern Oscillation). In a second step, a consensus model between two statistical approaches (GAMM and SVM) (support vector machine) was constructed, linking the nighttime 20-120 m backscatter to the oceanographic and geographic environment. This model showed that sea surface temperature was the main factor driving backscatter variability in the EEZ, with intensified backscatter during the austral summer (December to May) in the northern part of the EEZ. We showed that acoustic density differed significantly, spatially and temporally from micronekton biomass predicted for the same period by the SEAPODYM-MTL (mid-trophic level) ecosystem model. The seasonal cycle given by ADCP data lagged behind the SEAPODYM-MTL seasonal cycle by around three months. Reasons to explain these differences and further needs in observation and modeling were explored in the discussion. In addition to providing new insights for micronekton dynamics in this EEZ (i.e., the science needed for ecosystem-based fisheries management), the data should help improve our ability to model this key trophic component.

Place: Hoboken Publisher: Wiley WOS:000601215900001; Marine protected areas (MPAs) are becoming a widely used tool for the conservation of biodiversity and for fishery management; however, most of these areas are designed without prior knowledge of the basic ecological aspects of the species that they are trying to protect. This study investigated the movement of two top predators: the Galapagos shark, Carcharhinus galapagensis, and the yellowtail amberjack, Seriola lalandi, in and around the Motu Motiro Hiva Marine Park (MMHMP) using MiniPAT satellite tags to determine the effectiveness of this MPA for the protection of these species. The Galapagos sharks (n = 4) spent most of their tag deployment periods inside the MMHMP. However, high intraspecific variability was observed in their movement dynamics. Daily individual maximum movements ranged from 17 to 58 km and the maximum distance from Salas y Gomez Island, the only emergent island within the MMHMP, ranged from 31 to 139 km. The maximum linear distance travelled for a female juvenile Galapagos shark (152 cm total length) was 236 km, which is greater than the maximum distance previously documented for juveniles of this species (\textless50 km). For the yellowtail amberjack (n = 1), 91% of the satellite geolocations were within the MMHMP, with a maximum daily distance travelled of 6 km. The maximum distance travelled between points was 111 km and the maximum distance from Salas y Gomez Island was 62 km. All archival tagged fish spent most of their time at depths of This study provides a baseline on the movement of these two top predators in the MMHMP and provides valuable insights for the creation of MPAs in the region and elsewhere.

In order to understand interspecific trophic relationships between top predators, we analyzed diet information for nine bird and two seal species collected in the austral summer from 1996 to 2000 at South Orkney Islands. Overall, the diet of most of the predators was mainly composed of krill and fish. The percentage of re-occurrence of prey among predators ranged from 25.3 to 36.7, and fish, krill and squid re-occurred most frequently. The re-occurrence of fish among predator pairs ranged from 8.1 to 28.1. The species that re-occurred most frequently were the nototheniid fishes Gobionotothen gibberifrons, Nototheniops nudifrons and Nototheniops nybelini, and the myctophid Electrona antarctica. Prey overlap was greatest between Chinstrap (Pygoscelis antarctica) and Adélie (Pygoscelis adeliae) Penguins. Most predator pairs had high overlap of fish prey species. Predators that could forage on demersal and water column prey had yearly variable diets. This variability may be explained by fluctuations in krill availability. In years when krill is scarce (e.g. 2000), these predators diversify their diet by increasing the consumption of fish, which increases the re-occurrence of these preys in the diets. Our samples suggest the recovery of G. gibberifrons stocks around the South Orkney Islands and draw attention to the potential increase of interspecific food competition between predators under scenarios of decreasing krill availability. This information can be used to identify the ecological consequences of fluctuations in krill availability and aid in the management of krill fisheries. Fil: Bertolin, María Lila. Ministerio de Relaciones Exteriores, Comercio Internacional y Culto. Direccion Nacional del Antártico; Argentina Fil: Casaux, Ricardo Jorge. Centro de Investigación Esquel de Montaña y Estepa Patagónica (CIEMEP) CONICET-UNPSJB; Argentina

International audience; In the Gulf of Guinea, bigeye tuna (Thunnus obesus; BET) and yellowfin tuna (Thunnus albacares; YFT) are an important part of commercial fisheries and play a prominent ecological role as top predators. Using fatty acid profiles and carbon and nitrogen stable isotopes, we examined their trophic niche partitioning in this understudied region. Trophic niche overlap was high (> 70%), similar to percentages in other ocean basins. BET occupied a higher trophic position than YFT and fed on deeper prey (high delta N-15 values and high proportions of monounsaturated fatty acids). The trophic position of YFT decreased slightly in the last 15 years (delta N-15 values decreased by similar to 0.5 parts per thousand), suggesting a change in epipelagic communities, as observed in the eastern Pacific Ocean. Ontogenic changes were limited to BET. For both species, the dietary proportion of the diatom marker 20:5(n-3) increased in the seasonal upwelling area, highlighting the influence of seasonal habitat on the diet of tuna. The relatively lipid-rich muscle (similar to 6% dry mass) of Atlantic tropical tuna suggests a richer diet in this region than that of Indian Ocean tropical tuna and (or) differences in energy allocation strategies.

Aquatic food webs have been especially impacted in the last thirty years. This is particularly true for trophic webs with Mobile Generalist Species (MGS), which are species with high mobility (movement and dispersal) and flexibility in both foraging and habitat use. In general, MGS are large-sized species with the ability to move long distances, and they may be top predators (Large Generalist Predator; LGP) or feed lower in the food web than predicted from their size (Giant Secondary Consumers; GSCs). These species groups will play a fundamental role in connecting and rewiring human-impacted food webs, however this may be challenging because the stream network connectivity in most of the world’s largest river basins has been severely fragmented by dams As teias tróficas têm sido impactadas especialmente nos últimos 30 anos. Isto ocorre em especial para teias tróficas com Espécies Generalistas Viajantes (MGS) que são espécies com alta mobilidade (movimento e dispersão) e flexibilidade em forrageamento e uso do habitat. Em geral, MGS são espécies de grande tamanho com habilidade de se mover longas distâncias como predadores de topo (Grande Predador Generalista, LGP) ou de se alimentar em estratos mais baixos da teia trófica do que o predito pelo seu tamanho, são espécies chamadas Consumidoras Secundárias Gigantes (GSC). Estes grupos de espécies terão papel fundamental em conectar e reestruturar as teias tróficas impactadas pelo homem. Entretanto, isto pode ser um desafio devido ao fato que as conectividades das redes hidrográficas nas maiores bacias do mundo têm sido severamente fragmentadas por barramentos

The North Sea is amongst the most intensively utilised sea areas worldwide and the marine habitat occupied by human uses substantially increased during the past years as numerous offshore wind farms (OWFs) were built. The construction of already approved OWFs and the consenting of additional areas for OWFs is still in progress. Due to the importance of apex predators for a healthy marine environment and their role as indicators for the state of the ecosystems it is of utmost importance to increase our knowledge on their habitat use and behaviour and to understand if and how they are affected by anthropogenic activities. In this thesis, fundamental knowledge on the ecology of several important top predator species is provided and applied as baseline information to investigate their reactions towards OWFs constructed in the southern North Sea. To provide a comprehensive view on the different aspects two methods were applied: Visual and digital surveys offer the opportunity to study the species abundance and distribution as well as changes of these on a large spatial and temporal scale. Telemetry of individual animals provides detailed information on their movements and behaviour during specific periods of their annual life cycle and enables to directly observe their reaction to changes in their environment. Five top predator species (including one species group) which differ substantially in their ecological requirements and constraints, e.g. due to their foraging behaviour, were chosen: black-legged kittiwakes (Rissa tridactyla), common guillemots (Uria aalge), the species group of loons (Gavia spp.), northern gannets (Morus bassanus), and grey seals (Halichoerus grypus). As wide ranging and abundant species they are prone to experience interference with OWFs at various locations. However, the reaction of seabirds towards large scale OWFs in the southern North Sea and towards OWFs located close to their breeding colonies, as well as their individual behaviour in response to OWFs were poorly studied so far. Furthermore, although grey seals have become an important part of the ecosystem in the southern North Sea over the last 50 years, information on their habitat use and their reaction towards OWFs was currently missing for the German North Sea. Based on an extensive, long-term and large scale dataset collected by means of visual and digital surveys before and after construction of the OWFs an effect analysis was conducted. Loon distribution was strongly affected by the OWFs located close to one of their most important resting sites during spring migration. The abundance of loons decreased highly significantly by 94.5% inside the OWFs. The associated ship traffic also had a significant negative impact on loons, indicating that OWFs deterred them through the combined effect of ship traffic and the wind turbines themselves. Strong effects of the OWFs located 23-35 km north of Helgoland were furthermore detected for guillemots in spring (63% reduced density in the OWF) and for guillemots and kittiwakes in the breeding season (44% and 45% reduced density in the OWF). Telemetry was applied on breeding gannets and for the first time in German waters on breeding guillemots and weaned grey seal pups. Strong effects were revealed for both seabird species during two breeding seasons. Most individuals strongly avoided the OWFs. Of the tagged guillemots 16% shortly entered the OWFs during two to three occasions and 10% of the gannets frequently entered the wind farms when foraging or commuting between colony and foraging areas. A point process modelling (PPM) approach revealed a significantly reduced resource selection inside the OWFs compared to outside. For gannets resource selection was reduced by 37% and for guillemots by 67%. For guillemots the OWF avoidance was stronger when turbine blades were rotating (76% reduced resource selection). For the grey seal pups a PPM approach revealed that they strongly increased their distance to Helgoland already in the first weeks and generally during the first 70 days at sea. The frequency of the foraging behaviour increased until week four, whereas fast travelling behaviour increased throughout the whole study period. The pups’ individual spatial overlap with OWFs under construction and in operation was revealed but no obvious behavioural response to OWFs was detected. This thesis strongly enhances our knowledge on the ecology of important top predators in the southern North Sea and provides new and detailed information on the effects of OWFs on the studied species. Different reactions towards OWFs were detected and for the seabird species substantial habitat losses were revealed. The here presented findings will contribute fundamentally to future studies on anthropogenic impacts, to environmental monitoring or to conservation and management implications of the respective species and need to be considered during the planning process of future OWFs.

International audience; For many species of marine megafauna, strandings remain the most important source of biological samples. Because of their opportunistic nature however, strandings data have long been under- or misused in the assessment of population conservation status. Even if many national and international regulations promote the use of strandings in monitoring strategies, the interpretation of strandings remains controversial. The aim of this study is to provide a context for the interpretation of marine megafauna stranding data, in order to assess the achievement of specific objectives against Good Environmental Status criteria in the context of the EU Marine Strategy Framework Directive or other regional agreements. The first step is to construct an a priori spatial distribution under a null hypothesis H0. The a priori spatial distribution of theoretical dead animals can either be set uniformly, consistent with current knowledge on abundance of marine vertebrates, or based on management objectives. The drift prediction of these theoretical carcasses would provide a time series of strandings expected under the null hypothesis. The reverse drift of observed strandings would highlight mortality areas of stranded animals. The correction of these areas by the probability of getting stranded according to drift conditions would provide an estimated distribution of dead animals inferred from strandings. The differences between expected and observed situations constitute anomalies and highlight cases where inferred distribution departs from the a priori spatial distribution. This work proposes several population indicators that can be used anywhere in the world and can be applied for all large marine vertebrates found stranded. The integration of these indicators in MSFD and various regional agreements could provide cost-effective and relevant information on protected species. In the context of impaired ecological situations, the complementary use of several population indicators could strengthen the diagnosis made regarding conservation status and hence conservation strategies.

Intrinsic markers, such as stable isotopes, are a powerful approach to trace wildlife movements because they do not require initial marking of the organism. The main limitation of the isotopic method is the lack of knowledge in spatio-temporal patterns and dynamics of stable isotopes in marine environments, especially at local scales. Here, we combine GPS-tracks and isotopic signatures from Cory’s shearwaters as a model species to define isoscapes in the North Atlantic, and assess δ13C and δ15N dynamics, from local to regional spatial scales. Tracking data and blood samples were collected seasonally (during pre-laying and chick-rearing periods) across 6 years (2010–2015) from a total of 191 birds breeding at both neritic and oceanic environments. Tracked birds encompassed a large latitudinal and longitudinal area of the mid-North Atlantic, from the Eastern to Central North Atlantic. Overall, the δ13C and δ15N values of birds’ plasma over the region ranged from -20.2 to -16.2‰, and from 10.8 to 15.5‰, respectively. As expected, strong biogeographic isotopic patterns were found in δ13C values at a regional scale, mostly driven by an inshore/offshore gradient and chlorophyll a concentration. Although a moderate expression of spatial isotopic gradients on δ15N values (i.e., latitudinal and inshore/offshore) in the whole region, these were primarily influenced by temporal drivers (i.e., annual variability). At a local scale (i.e., in a radius of 100 km around the colony, within the neritic environment), both δ13C and δ15N values were very influenced by temporal drivers, suggesting that wide-ranging top consumers are hard to trace locally. This study shows that the δ13C values of marine top consumers are good indicators of the foraging habitat at a regional scale in the mid-North Atlantic, especially in terms of inshore/offshore gradients and areas of higher productivity.

Lethal interactions can shape ecosystem structure, and consequently understanding their causes is ecologically relevant. To improve both empirical and theoretical knowledge on superpredation (i.e. predation on high‐order predators), we studied an eagle owl population, including its main prey and mesopredators, and then we crossed these results with existing theories to provide a reasoning framework. We fitted our field data into four main causes explaining lethal interactions: food stress, opportunistic superpredation, removal of a competitor, and removal of a potential threat. Empirically, superpredation seemed to be mostly determined by the combination of the food‐stress and opportunistic‐superpredation hypotheses, which highlights the complexity of the factors triggering superpredation. Therefore, besides being a response to lower food availability, superpredation may also represent an effective mechanism to remove potential predators and/or competitors, either intentionally or not. Our theoretical framework focused on the decision‐making process in superpredation, considering four inter‐related stages: encountering; attacking; and capturing a mesopredator; as well as consuming a mesopredator once killed. Superpredation almost certainly results from a complex process of decision‐making, accounting for costs and benefits assessed moment‐to‐moment and for each mesopredator individual. It is time to build bridges between theoretical and empirical studies to further understand the mechanisms driving complex interactions among top predators and mesopredators.

The recovery of historic community assemblages on reefs is a primary objective for the management of marine ecosystems. Working under the overall hypothesis that, as fishing pressure increases, the abundance in upper trophic levels decreases followed by intermediate levels, we develop an index that characterizes the comparative health of rocky reefs. Using underwater visual transects to sample rocky reefs in the Gulf of California, Mexico, we sampled 147 reefs across 1200km to test this reef health index (IRH). Five-indicators described 88% of the variation among the reefs along this fishing-intensity gradient: the biomass of piscivores and carnivores were positively associated with reef health; while the relative abundances of zooplanktivores, sea stars, and sea urchins, were negatively correlated with degraded reefs health. The average size of commercial macro-invertebrates and the absolute fish biomass increased significantly with increasing values of the IRH. Higher total fish biomass was found on reefs with complex geomorphology compared to reefs with simple geomorphology (r2=0.14, F=44.05, P

Wildlife exposure to pharmaceuticals can occur through contaminated water, and through the excreta and carcasses of medicated livestock, with potential for bioaccumulation and transfer through food webs. We evaluated whether nestling exposure to pharmaceuticals can occur from food delivered to nests in the golden eagle (Aquila chrysaetos), a top predator and facultative scavenger. Despite the fact that diet analysis suggests an apparently low dependence on livestock carcasses reduced to two piglets remains (1.5% of food remains, n = 134), a high proportion of nestlings (71%, n = 7) showed fluoroquinolone residues in plasma, mostly enrofloxacin, which is exclusively used in veterinary treatments. The occurrence and concentration (54.5 ± 6.6 μg·L) of fluoroquinolones in plasma was similar to those found in the nestlings of three vulture species largely dependent on livestock carcasses obtained at supplementary feeding stations, which are managed for the conservation of their populations. Although the number of analysed eaglets is comparatively small, the fact that enrofloxacin was found in all nests sampled in three breeding seasons suggest an exposure to the drugs similar to that of vultures. An underestimation of the role of carrion, especially from small piglets whose consumption may have gone unnoticed, and the predation of semi-domestic prey and generalist prey exploiting carcasses of medicated livestock, can contribute to explaining the unexpectedly high occurrence of these drugs in eaglets., Funds were provided by the projects CGL2009-12753-C02-01/BOS and CGL2010-15726 of Spanish Ministerio of Economía y Competitividad.

International audience; Global-scale studies of marine food webs are rare, despite their necessity for examining and understanding ecosystem level effects of climate variability. Here we review the progress of an international collaboration that compiled regional diet datasets of multiple top predator fishes from the Indian, Pacific and Atlantic Oceans and developed new statistical methods that can be used to obtain a comprehensive ocean-scale understanding of food webs and climate impacts on marine top predators. We loosely define top predators not as species at the apex of the food web, but rather a guild of large predators near the top of the food web. Specifically, we present a framework for world-wide compilation and analysis of global stomach-contents and stable-isotope data of tunas and other large pelagic predatory fishes. To illustrate the utility of the statistical methods, we show an example using yellowfin tuna in a “test” area in the Pacific Ocean. Stomach-contents data were analyzed using a modified (bagged) classification tree approach, which is being prepared as an R statistical software package. Bulk δ15N values of yellowfin tuna muscle tissue were examined using a Generalized Additive Model, after adjusting for spatial differences in the δ15N values of the baseline primary producers predicted by a global coupled ocean circulation-biogeochemical-isotope model. Both techniques in tandem demonstrated the capacity of this approach to elucidate spatial patterns of variations in both forage species and predator trophic positions and have the potential to predict responses to climate change. We believe this methodology could be extended to all marine top predators. Our results emphasize the necessity for quantitative investigations of global-scale datasets when evaluating changes to the food webs underpinning top ocean predators under long-term climatic variability.

While a global concern about the sustainability of fisheries and the status of marine resources is arising, a better understanding of the available resource at different scales is required to implement an ecosystem-based management. In Reunion Island, local fisheries are still poorly know and the recent shark attack highlighted the lack of fundamental knowledge about the functioning of marine trophic webs. The general aim of this Ph.D thesis is to analyse the feeding relationship between the different predators of multiple habitats. Carried out between January 2012 and December 2014 in collaboration with the fishing stakeholders, the sampling focused on species of commercial interest or interacting with fisheries (bycatches and depredators). Carbon (δ13C) and nitrogen (δ15N) stable isotopes ratio and stomacal content analysis were used to determine the organic matter they depend on, their interspecific relationships and the factors influencing their diets. Results show a wide disparity between species caught in shallow water and the deep ones.Despite their association with the benthic environment, deepwater species (100-600m) indirectly rely on surface primary production through their vertically migrating prey. This dependence on mesopelagic organism induce consequently a high dietary overlap between pairwise species, although alleviated by their presence in different bathymetric areas. Habitat appear to be the main driver of their diet, with a Western/Eastern coasts distinction probably due to different sea current configurations. Deepwater species' isotopic composition is strongly conditioned by both environmental and intrinsic drivers, hence indicating food diet might change during their development and in relation to the reproduction cycles. The wide diversity of the smaller species' diet, Pristipomoides argyrogrammicus, probably contributed to increase its abundance, as reported in captures data when other species decrease.Shallow species are split into three distinct diet categories along a shore-offshore gradient. Both the bull shark (Carcharhinus leucas) and the giant trevally (Caranx ignobilis) rely on the same, coastal, resources whereas the tiger shark (Galeocerdo cuvier) is getting along the edges of the island shelf. The dolphinfish (Coryphaena hippurus) and the wahoo (Acanthocybium solandri) have their diet specialised in a reduced number of prey families, mainly consuming post-larvae of coastal species at their pelagic stage of development. The δ13C we measured in C. leucas blood indicates seasonal variations in its feeding areas' distances to the coast. Moreover, tiger shark are likely to form an homogeneous population composed with generalist individuals conversely to bull sharks which are forming an assorted population of individuals specialized on different resources.Those results tend to promote an habitat-focused approach, more suitable for the management of deepwater species, whereas a species-focused approach would rather be more effective for shallow, highly mobile species.; Dans un contexte mondial de préoccupation sur la durabilité des pêcheries et dans un contexte local de raréfaction des ressources marines, mieux appréhender les facteurs responsables de la répartition des ressources disponibles à différentes échelles est un prérequis crucial à la mise en place d’un système de gestion intégrée, dite écosystémique, des pêches. A La Réunion, la pêcherie locale est encore mal connue et les récentes attaques de requins mettent encore plus en exergue le manque de connaissances fondamentales sur le fonctionnement des réseaux trophiques. L’objectif général de cette thèse est d’étudier les relations alimentaires entre différents prédateurs d’intérêt local, appartenant à plusieurs compartiments écologiques. L’échantillonnage, réalisé entre janvier 2012 et décembre 2014 en partenariat avec la filière pêche, s’est concentré sur les principales espèces d’intérêt commercial ou en interactions avec les pêcheries (captures accessoires et déprédateurs). La détermination des sources de matière organique dont elles dépendent, de leurs relations interspécifiques, ainsi que des facteurs de variation de leurs alimentations, a été réalisée grâce à l’analyse des isotopes stables du carbone (δ13C) et de l’azote (δ15N), ainsi que celle des contenus stomacaux. Les résultats montrent une grande disparité entre espèces capturées en surface et celles capturées entre profondeur.Bien qu’associées au substrat, les espèces profondes (100-600m) dépendent indirectement de la production primaire de surface via leurs proies qui effectuent des migrations verticales dans la colonne d’eau. Cette dépendance aux organismes mésopélagiques induit un chevauchement alimentaire globalement important entre ces espèces, atténué par l’occupation de zones bathymétriques différentes. Leurs régimes alimentaires semblent très dépendant de leur habitat, avec une distinction entre la côte est et la côte ouest de l’île, probablement en lien avec des conditions courantologiques différentes. Leurs compositions isotopiques sont quant à elles fortement influencées à la fois par des facteurs environnementaux et intrinsèques, indiquant l’existence de modifications de leur régime alimentaire au cours de leur développement en lien avec les cycles de reproduction. La grande diversité du régime alimentaire de la plus petite espèce, Pristipomoides argyrogrammicus, a probablement favorisé le développement de celle-ci dont l’abondance augmente dans les captures, ce qui constitue une tendance inverse de celles des autres espèces.Concernant les espèces de surface, celles-ci se répartissent selon un gradient côte-large, formant trois groupes aux régimes alimentaires distincts. Le requin bouledogue (Carcharhinus leucas) et la carangue grosse tête (Caranx ignobilis) exploitent des ressources similaires à proximité de la côte, tandis que le requin tigre (Galeocerdo cuvier) s’alimente sur le bord du plateau insulaire. La dorade coryphène (Coryphaena hippurus) et le thon banane (Acanthocybium solandri) présentent une forte spécialisation sur un nombre limité de familles de proies, consommant majoritairement des stades pélagiques post-larvaires d’espèces côtières. Le δ13C mesuré dans le sang de C. leucas suggère des variations saisonnières de la distance à la côte de ses zones d’alimentation, certainement en lien avec son cycle biologique. Les requins tigre semblent former une population homogène constituée d’individus généralistes tandis que les requins bouledogue forment une population hétérogène d’individus spécialisés sur des ressources différentes.Ces résultats indiquent qu’une approche centrée sur l’habitat conviendrait à la gestion des espèces profondes, tandis qu’une approche centrée sur les espèces serait plus efficiente pour les espèces de surface.

While a global concern about the sustainability of fisheries and the status of marine resources is arising, a better understanding of the available resource at different scales is required to implement an ecosystem-based management. In Reunion Island, local fisheries are still poorly know and the recent shark attack highlighted the lack of fundamental knowledge about the functioning of marine trophic webs. The general aim of this Ph.D thesis is to analyse the feeding relationship between the different predators of multiple habitats. Carried out between January 2012 and December 2014 in collaboration with the fishing stakeholders, the sampling focused on species of commercial interest or interacting with fisheries (bycatches and depredators). Carbon (δ13C) and nitrogen (δ15N) stable isotopes ratio and stomacal content analysis were used to determine the organic matter they depend on, their interspecific relationships and the factors influencing their diets. Results show a wide disparity between species caught in shallow water and the deep ones.Despite their association with the benthic environment, deepwater species (100-600m) indirectly rely on surface primary production through their vertically migrating prey. This dependence on mesopelagic organism induce consequently a high dietary overlap between pairwise species, although alleviated by their presence in different bathymetric areas. Habitat appear to be the main driver of their diet, with a Western/Eastern coasts distinction probably due to different sea current configurations. Deepwater species' isotopic composition is strongly conditioned by both environmental and intrinsic drivers, hence indicating food diet might change during their development and in relation to the reproduction cycles. The wide diversity of the smaller species' diet, Pristipomoides argyrogrammicus, probably contributed to increase its abundance, as reported in captures data when other species decrease.Shallow species are split into three distinct diet categories along a shore-offshore gradient. Both the bull shark (Carcharhinus leucas) and the giant trevally (Caranx ignobilis) rely on the same, coastal, resources whereas the tiger shark (Galeocerdo cuvier) is getting along the edges of the island shelf. The dolphinfish (Coryphaena hippurus) and the wahoo (Acanthocybium solandri) have their diet specialised in a reduced number of prey families, mainly consuming post-larvae of coastal species at their pelagic stage of development. The δ13C we measured in C. leucas blood indicates seasonal variations in its feeding areas' distances to the coast. Moreover, tiger shark are likely to form an homogeneous population composed with generalist individuals conversely to bull sharks which are forming an assorted population of individuals specialized on different resources.Those results tend to promote an habitat-focused approach, more suitable for the management of deepwater species, whereas a species-focused approach would rather be more effective for shallow, highly mobile species.; Dans un contexte mondial de préoccupation sur la durabilité des pêcheries et dans un contexte local de raréfaction des ressources marines, mieux appréhender les facteurs responsables de la répartition des ressources disponibles à différentes échelles est un prérequis crucial à la mise en place d’un système de gestion intégrée, dite écosystémique, des pêches. A La Réunion, la pêcherie locale est encore mal connue et les récentes attaques de requins mettent encore plus en exergue le manque de connaissances fondamentales sur le fonctionnement des réseaux trophiques. L’objectif général de cette thèse est d’étudier les relations alimentaires entre différents prédateurs d’intérêt local, appartenant à plusieurs compartiments écologiques. L’échantillonnage, réalisé entre janvier 2012 et décembre 2014 en partenariat avec la filière pêche, s’est concentré sur les principales espèces d’intérêt commercial ou en interactions avec les pêcheries (captures accessoires et déprédateurs). La détermination des sources de matière organique dont elles dépendent, de leurs relations interspécifiques, ainsi que des facteurs de variation de leurs alimentations, a été réalisée grâce à l’analyse des isotopes stables du carbone (δ13C) et de l’azote (δ15N), ainsi que celle des contenus stomacaux. Les résultats montrent une grande disparité entre espèces capturées en surface et celles capturées entre profondeur.Bien qu’associées au substrat, les espèces profondes (100-600m) dépendent indirectement de la production primaire de surface via leurs proies qui effectuent des migrations verticales dans la colonne d’eau. Cette dépendance aux organismes mésopélagiques induit un chevauchement alimentaire globalement important entre ces espèces, atténué par l’occupation de zones bathymétriques différentes. Leurs régimes alimentaires semblent très dépendant de leur habitat, avec une distinction entre la côte est et la côte ouest de l’île, probablement en lien avec des conditions courantologiques différentes. Leurs compositions isotopiques sont quant à elles fortement influencées à la fois par des facteurs environnementaux et intrinsèques, indiquant l’existence de modifications de leur régime alimentaire au cours de leur développement en lien avec les cycles de reproduction. La grande diversité du régime alimentaire de la plus petite espèce, Pristipomoides argyrogrammicus, a probablement favorisé le développement de celle-ci dont l’abondance augmente dans les captures, ce qui constitue une tendance inverse de celles des autres espèces.Concernant les espèces de surface, celles-ci se répartissent selon un gradient côte-large, formant trois groupes aux régimes alimentaires distincts. Le requin bouledogue (Carcharhinus leucas) et la carangue grosse tête (Caranx ignobilis) exploitent des ressources similaires à proximité de la côte, tandis que le requin tigre (Galeocerdo cuvier) s’alimente sur le bord du plateau insulaire. La dorade coryphène (Coryphaena hippurus) et le thon banane (Acanthocybium solandri) présentent une forte spécialisation sur un nombre limité de familles de proies, consommant majoritairement des stades pélagiques post-larvaires d’espèces côtières. Le δ13C mesuré dans le sang de C. leucas suggère des variations saisonnières de la distance à la côte de ses zones d’alimentation, certainement en lien avec son cycle biologique. Les requins tigre semblent former une population homogène constituée d’individus généralistes tandis que les requins bouledogue forment une population hétérogène d’individus spécialisés sur des ressources différentes.Ces résultats indiquent qu’une approche centrée sur l’habitat conviendrait à la gestion des espèces profondes, tandis qu’une approche centrée sur les espèces serait plus efficiente pour les espèces de surface.

During recent human history, human activities such as overhunting and habitat destruction have severely impacted many large top predator populations around the world. Studies from a variety of ecosystems show that loss or diminishment of top predator populations can have serious consequences for population and community dynamics and ecosystem stability. However, there are relatively few studies of the roles of large top predators in coastal ecosystems, so that we do not yet completely understand what could happen to coastal areas if large top predators are extirpated or significantly reduced in number. This lack of knowledge is surprising given that coastal areas around the globe are highly valued and densely populated by humans, and thus coastal large top predator populations frequently come into conflict with coastal human populations. This paper reviews what is known about the ecological roles of large top predators in coastal systems and presents a synthesis of recent work from three coastal eastern US Long Term Ecological Research (LTER) sites where long-term studies reveal what appear to be common themes relating to the roles of large top predators in coastal systems. We discuss three specific themes: (1) large top predators acting as mobile links between disparate habitats, (2) large top predators potentially affecting nutrient and biogeochemical dynamics through localized behaviors, and (3) individual specialization of large top predator behaviors. We also discuss how research within the LTER network has led to enhanced understanding of the ecological roles of coastal large top predators. Highlighting this work is intended to encourage further investigation of the roles of large top predators across diverse coastal aquatic habitats and to better inform researchers and ecosystem managers about the importance of large top predators for coastal ecosystem health and stability.

Submitted by Guilherme Lemeszenski (guilherme@nead.unesp.br) on 2013-08-22T18:43:16Z No. of bitstreams: 1 S1676-06032013000100006.pdf: 1104545 bytes, checksum: bac8e088463b27cb4a9510f664360023 (MD5) Made available in DSpace on 2013-08-22T18:43:16Z (GMT). No. of bitstreams: 1 S1676-06032013000100006.pdf: 1104545 bytes, checksum: bac8e088463b27cb4a9510f664360023 (MD5) Previous issue date: 2013-03-01 Made available in DSpace on 2013-09-30T19:30:52Z (GMT). No. of bitstreams: 2 S1676-06032013000100006.pdf: 1104545 bytes, checksum: bac8e088463b27cb4a9510f664360023 (MD5) S1676-06032013000100006.pdf.txt: 44386 bytes, checksum: 46ad97fb499a2d225e28514f8c436038 (MD5) Previous issue date: 2013-03-01 Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-20T13:59:38Z No. of bitstreams: 2 S1676-06032013000100006.pdf: 1104545 bytes, checksum: bac8e088463b27cb4a9510f664360023 (MD5) S1676-06032013000100006.pdf.txt: 44386 bytes, checksum: 46ad97fb499a2d225e28514f8c436038 (MD5) Made available in DSpace on 2014-05-20T13:59:38Z (GMT). No. of bitstreams: 2 S1676-06032013000100006.pdf: 1104545 bytes, checksum: bac8e088463b27cb4a9510f664360023 (MD5) S1676-06032013000100006.pdf.txt: 44386 bytes, checksum: 46ad97fb499a2d225e28514f8c436038 (MD5) Previous issue date: 2013-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) ItaFish Transporte e Comercio de Pescados Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Instituto de Pesca (Santos/SP) Este estudo descreve a composição da dieta de peixes pelágicos que vivem no Oceano Atlântico Sudoeste. Como tais espécies pelágicas são consideradas predadoras de topo, o estudo propõe conhecer o que constitui sua principal fonte de alimento. Peixes não são comumente encontrados em seus conteúdos estomacais, em vez disso, os cefalópodes são os alimentos mais comuns. Como pode ser observado, cefalópodes Teuthida compreendem sua dieta principal. O conteúdo estomacal de espécimes de Xiphias gladius, Thunnus albacares, T. obesus, T. alalunga, Isurus oxyrinchus e Alopias superciliosus, capturados durante julho de 2007 a junho de 2009 prela frota atuneira, foram estudados. Cefalópodes Teuthida constituem o principal item alimentar das três espécies de atum, enquanto X. gladius alimenta-se principalmente de cefalópodes Ommastrephidae. Embora as diferenças entre os tipos de cafalópodes existam, eles constituem o principal recurso que estes peixes usam para viver, pelo menos no Oceano Atlântico Sudoeste. This study reveals the food composition of pelagic fishes living in the southwestern Atlantic Ocean. As such more common pelagic species are considered to be top predators, the study proposes to know what constitutes their main food. Fish are not commonly found within their stomach contents, but instead, cephalopods are their most common food. As can be observed, Teuthida cephalopods compose their principal diet. The stomach contents of specimens of Xiphias gladius, Thunnus albacares, T. obesus, T. alalunga, Isurus oxyrinchus and Alopias superciliosus caught during July 2007 to June 2009 by using tuna longliners were studied. Teuthida cephalopods constitute the main food item for the three tuna species, while X. gladius feeds mainly on Ommastrephidae cephalopods. Though the differences among the kinds of cephalopods exist, they constitute the principal resource these fish use to live at least in the southern Atlantic Ocean. Centro Universitário de Araraquara Departamento de Ciências Biológicas e da Saúde Universidade Estadual Paulista Instituto de Biociências Departamento de Zoologia Secretaria de Agricultura e Abastecimento do Estado de São Paulo Agência Paulista de Tecnologia dos Agronegócios Instituto de Pesca Universidade Estadual Paulista Instituto de Biociências Departamento de Zoologia

A fundamental question in ecology is the role of predators in limiting their prey populations. This question can be approached for shallow marine fish communities by comparison of abundance of species inside and outside marine protected areas (MPAs), where fishing restrictions may enforce large abundance differences in large (top) predators. The first step in demonstrating differences in these populations is the development and testing of methods capable of estimating abundance of fast-swimming and alert species which generally are difficult to quantify with traditional net-based sampling or visual census. That the method of experimental fishing with hook and line is capable of sampling predatory fish of a wide range of sizes, from 15 to 125 cm, inside and outside an MPA in the central Adriatic Sea, Kornati National Park, Croatia, was demonstrated in this preliminary study. Evidence of significantly more abundant top predators inside the MPA and a significantly higher mean size of fish overall was found. A total of 11 species of fish were sampled across several benthic habitats, of which six were found only in the MPA. It is concluded that the MPA represents a natural experiment with greater abundance of larger predators than outside, and that experimental fishing can take advantage of these differences to test the hypothesis of top-down regulation of fish communities., Temeljno pitanje u ekologiji je uloga predatora u kontroli populacije plijena. Za zajednice riba u plitkom moru, na ovo pitanje može se odgovoriti uspoređujući brojnost vrsta unutar morskih zaštićenih područja (MPA) i izvan njih, gdje regulacija ribolovnih aktivnosti može značajno utjecati na brojnost velikih (vršnih) predatora. Prvi korak u dokazivanju razlika u navedenim populacijama je razvoj i testiranje metoda uz pomoć kojih je moguće procijeniti brojnost brzih i opreznih vrsta, koje je obično teško kvantificirati korištenjem tradicionalnih metoda poput lova mrežama ili vizualnim cenzusom. U ovom preliminarnom istraživanju je prikazano da se korištenjem metode eksperimentalnog ribolova mogu uzorkovati predatorske vrste riba raznih veličina, od 15 do 125 cm, unutar i izvan morskih zaštićenih područja u srednjem Jadranu (na području Nacionalnog parka Kornati, Hrvatska). Dokazala se značajno veća brojnost vršnih (top) predatora unutar zaštićenog područja kao i značajno veća prosječna veličina riba. Uzorkovano je ukupno 11 različitih vrsta riba na raznim pridnenim staništima, od kojih je 6 zabilježeno isključivo unutar zaštićenog područja. Može se zaključiti da su morska zaštićena područja svojevrsni prirodni eksperiment gdje je brojnost predatorskih vrsta veća nego izvan zaštićenog područja. Osim toga, eksperimentalni ribolov je učinkovita metoda uz pomoć koje se na temelju uočenih razlika može testirati hipoteza o top-down regulaciji zajednica riba.

8 pages, 2 figures, 5 tables, Human stressors are currently impacting both the Amazon and Orinoco river basins and these are likely to increase. However, there is a lack of standardized monitoring programs to track these human stressors in most of the countries that overlap these basins, and no clear ecological indicators have been identified. In this study we investigated the relationships between measures of ecosystem degradation and river dolphins as potential ecological indicators. The presence of human stressors and their distance from the areas surveyed were used to provide an estimate of ecosystem degradation. We tested three ecological indicators of freshwater ecosystem degradation using river dolphins: (i) density of river dolphins, (ii) mean group size of dolphins, and (iii) dolphin sighting rates. We found a strong negative relationship between measures of habitat degradation and river dolphin density estimates in selected locations of the Amazon and Orinoco. Therefore, we suggest that river dolphins are good candidates as ecological indicators, flagship and sentinel species for monitoring the conservation status of large tropical rivers in South America. We suggest that further effort should be directed toward collecting reliable data on human stressors, creating collaborative networks for compiling existing data, and documenting and monitoring current trends in freshwater ecosystem degradation and indicator species in the Amazon and Orinoco basins with the goal of targeting areas for recovery or sustainable management, This work was supported by the Whale and Dolphin Conservation Society (WDCS), Whitley Fund for Nature, Wildlife Conservation Society (WCS), World Wildlife Fund (WWF), Russell E. Train program (WWF), Organization of American States (OAS) Scholarship, National Geographic Society (NGS), Society for Marine Mammalogy Small Grant in Aid of Research, Cetacean Society International (CSI), Humboldt Institute (Colombia), Programa Crédito Beca de Colfuturo, and Dr. Patrick Lett Fund

International audience; This study examined the trophic ecology of three sympatric tropical tuna species (bigeye BET, skipjack SKJ, and yellowfin YFT) sampled in the Western Indian Ocean throughout 2013. Specifically we explored inter-specific resource partitioning and ontogenetic variability using neutral fatty acids and stable isotope analysis of liver and muscle from small (100 cm FL) tuna collected in mixed schools at the surface by purse-seine. Both biochemical tracers were used to calculate trophic niche indices that collectively revealed high potential for resource overlap, especially among small tuna. Resource overlap appeared strongest between BET and YFT, with SKJ tissues having high carbon isotope (delta C-13) values (-17 +/- 0.3 parts per thousand), lower nitrogen isotope (delta N-15) values (11.4 +/- 0.6 parts per thousand), and higher relative proportion of poly-unsaturated fatty acids (PUFA) than the two other species, indicating a different diet. Size was found to be a strong predictor for most biochemical tracers in the three species with delta C-13, delta N-15 and total lipid content in the liver. In the larger species (YFT and BET), proportions of mono-unsaturated fatty acids typically increased with size, while quantities of PUFA decreased. In addition to ontogenetic variability, trophic markers were shown to vary between sampling area and season: higher lipid reserves and delta N-15 values, and lower delta C-13 values occurred during monsoon periods around Seychelles than in the Mozambique Channel (parted from about 1500 km). Our multi-tracer approach reveals the magnitude of potential competitive interactions in mixed tropical tuna schools at both small and large sizes and demonstrates that ontogenetic niche differentiation acts as a major factor of coexistence in tropical tuna

Food web interactions are key to community structure. The introduction of species can be seen as an uncontrolled experiment of the addition of species. Introduced species lead to multiple changes, frequently threatening the native biodiversity. However, little is known about their direct effect on the upper level of the food web. In this study we review empirical data on the predator prey relationship between the introduced lagomorphs and their consumers, and use meta-analytical tools to quantify the strength of their interactions. We expect that exotic lagomorphs will destabilize food webs, affect ecological processes and compromise the conservation of the invaded regions. We found 156 studies on the diet of 43 species of predators that consume lagomorphs as exotic preys in South America and Oceania. We found an average exotic lagomorphspredator link of 20% which indicates a strong interaction, given that the average for the strongest links with native prey (when lagomorphs are not included in the predator diet) is about 24%. Additionally, this last link decreases to 17% when lagomorphs are present. When lagomorphs arrive in a new environment they may become the most important resource for predators, producing an unstable equilibrium in the novel food web. Any disruption of this interaction could have catastrophic consequences for the native diversity by directly impacting predators or indirectly impacting native preys by apparent competition. Eradication or any change in their abundances should be carefully considered in conservation actions since those will have great impacts on predator populations and ultimately in the whole communities

Stable isotope analyses for shortfin mako (Isums oxyrinchus) and blue sharks (Prionace glauca) were conducted to assess their trophic position in two periods of time (before 1980 and after 2000) in the Southeastern Pacific waters (SEP). Both sharks showed that their trophic position decreased over time (P < 0.05). Many factors could be involved in this change such as dietary shifts, prey availability, or indirect fishing effects in SEP waters. Para evaluar los niveles tróficos de los tiburones marrajo (Isurus oxyrinchus) y azulejo (Prionace glauca) en dos períodos de tiempo (previo a 1980 y posterior al 2000) en aguas del Pacífico suroriental (SEP), se realizaron análisis de isótopos estables. Ambos tiburones mostraron un descenso del nivel trófico en el tiempo (P < 0,05). Varios son los factores que pueden estar involucrados en este evento, como los cambios dietarios, la disponibilidad de las presas o los efectos indirectos de la pesquería en aguas del Pacífico suroriental.

International audience; Information on the foraging behaviour of sea snakes has the potential to clarifyadaptive pathways involved in the evolutionary invasion of marine habitats byterrestrial vertebrates. However, logistical obstacles have precluded studies in thisfield. To obtain preliminary data of diving behaviour, we surgically implantedtemperature-depth loggers into two sympatric, amphibious, benthic foraging seakrait species from New Caledonia. Based on logger recovery from three snakes (1Laticauda laticaudata and 2 L. saintgironsi), we obtained data on a total of 1850dives carried out over eight foraging trips and 39.6 days at sea. Almost 99% ofdives were

Human activities influence contaminant concentrations in aquatic organisms. It is increasingly common to monitor the marine environment and establish geographic trends of pollution by measuring contaminant levels in animals from higher trophic levels. Marine mammals are considered to be an ideal model for the assessment of immunological responses to pathogens and contaminants. In fact, living their entire lives (or most of it) in the sea, they act as integrators of the stressors present in the marine environment. Marine mammals may have the potential to predict contaminant effects on health and to be indicators of the status of the marine ecosystem. The impact of infection and environmental stress is here described through the analysis of the immunological processes based on large-scale genomic approaches, highly informative of the interaction of genetic, disease, and environmental factors.

Nature development in The Netherlands is often planned on contaminated soils or sediments. This contamination may present a risk for wildlife species desired at those nature development sites and must be assessed by specific risk assessment methods. In a previous study, we developed a method to predict ecological vulnerability in wildlife species by using autecological data and expert judgment; in the current study, this method is further extended to assess ecological vulnerability of food chains and terrestrial and aquatic habitats typical for The Netherlands. The method is applied to six chemicals: Cd, Cu, Zn, dichlorodiphenyltrichloroethane, chlorpyrifos, and ivermectin. The results indicate that species in different food chains differ in vulnerability, with earthworm-based food chains the most vulnerable. Within and between food chains, vulnerability varied with habitat, particularly at low trophic levels. The concept of habitat vulnerability was applied to a case study of four different habitat types in floodplains contaminated with cadmium and zinc along the river Dommel, The Netherlands. The alder floodplain forest habitat contained the most vulnerable species. The differences among habitats were significant for Cd. We further conclude that the method has good potential for application in mapping of habitat vulnerability. Environ. Toxicol. Chem. 2010;29:2875–2880. © 2010 SETAC

Aerial band transect censuses were carried out parallel with ice thickness profiling surveys in the pack ice of the western Weddell Sea during the ISPOL (Ice Station POLarstern) expedition of R.V. Polarstern from November 2004 to January 2005. Three regions were surveyed: the deep sea of the Weddell Sea, a western continental shelf/slope region where R.V. Polarstern passively drifted with an ice floe (ISPOL), and a northern region (N). Animal densities were compared among regions and in relation to bathymetry and ice thickness distribution. Crabeater seals Lobodon carcinophaga were the most abundant species in all three regions. Their density was significantly lower in the deep sea (0.50 km(-2)) than in the ISPOL (1.00 km(-2)) and northern regions (1.21 km(-2)). Weddell seals Leptonychotes weddellii were not sighted in the deep-sea region, their density elsewhere ranging from 0.03 (N) to 0.08 km(-2) (ISPOL). Leopard seals Hydrurga leptonyx were observed in all three areas, but could only be quantified in the deep-sea (0.05 km(-2)) and northern regions (0.06 km(-2)). The abundance of emperor penguins Aptenodytes forsteri was markedly higher in the northern (0.75 km(-2)) than in the ISPOL (0.13 km(-2)) and the deep-sea region (not quantified). Crabeater seal density was significantly related to ocean depth and modal ice thickness. (C) 2008 Elsevier Ltd. All rights reserved.

14 pages, 5 figures, 3 tables, supplementary material http://dx.doi.org/10.3354/meps11188, Understanding how marine predators interact is a scientific challenge. In marine ecosystems, segregation in feeding habits has been largely described as a common mechanism to allow the coexistence of several competing marine predators. However, little is known about the feeding ecology of most species of chondrichthyans, which play a pivotal role in the structure of marine food webs worldwide. In this study, we examined the trophic ecology of 3 relatively abundant chondrichthyans coexisting in the Mediterranean Sea: the blackmouth catshark Galeus melastomus, the velvet belly lanternshark Etmopterus spinax and the rabbit fish Chimaera monstrosa. To examine their trophic ecology and interspecific differences in food habits, we combined the analysis of stomach content and stable isotopes. Our results highlighted a trophic segregation between C. monstrosa and the other 2 species. G. melastomus showed a diet composed mainly of cephalopods, while E. spinax preyed mainly on shrimps and C. monstrosa on crabs. Interspecific differences in the trophic niche were likely due to different feeding capabilities and body size. Each species showed different isotopic niche space and trophic level. Specifically, C. monstrosa showed a higher trophic level than E. spinax and G. melastomus. The high trophic levels of the 3 species highlighted their important role as predators in the marine food web. Our results illustrate the utility of using complementary approaches that provide information about the feeding behaviour at short (stomach content) and long-term scales (stable isotopes), which could allow more efficient monitoring of marine food-web changes in the study area, M.A.-P. was supported by a predoctoral fellowship of the FPI program (Spanish Ministry of Economy and Competitiveness). J.N. was supported by a research contract of the Marie Curie GIC project BioWeb. M.C. and J.A. are supported by a post-doctoral contract of the Ramon y Cajal Program (Spanish Ministry of Economy and Competiveness), and M.C. was also supported by BioWeb project. This study is a contribution to the project ECOTRANS (CTM2011-26333, Ministerio de Economía y Competitividad, Spain)

Cod, harp seal and minke whale are the main top predators in the Barents Sea ecosystem. In the last decade, the abundance of cod has increased considerably, and is at a record high level. In spite of this, the growth and condition of cod has remained rather stable, although some decrease is seen in size at age of large, mature cod. During the same period, the abundance of harp seals has declined whereas the minke whale stock has been at a stable level. The body condition (blubber thickness) of these two mammal stocks has, however, decreased, with the strongest decrease observed for harp seals. A possible hypothesis for explaining this is that cod outperform the marine mammal stocks in the competition for food. The main advantages for cod are most likely larger availability of food (mainly capelin) during winter-spring than for marine mammals, as well as a wider range of prey species being available to cod than to marine mammals. Harp seals are more dependent on prey items found close to the ice edge than the other two predator stocks are, which could partly explain why the performance of harp seals is worse than that of the two other main top predators in the area.

International audience; We review present understanding of the spatial and temporal diet variability (trophodynamics) of a range of pelagic marine top predators, at both early and adult life history stages. We begin with a review of methodologies used to advance our understanding of the trophodynamics of marine top predators, particularly in relation to climate change. We then explore how these developments are informing our understanding of the major trophic groups in food webs leading to, and including, marine top predators. We examine through specific examples how the impacts of ocean warming may affect pelagic food web relationships from both top-down and bottom-up perspectives. We examine the potential, in the absence of long-term data sets, of using large-scale spatial studies to examine how potential changes in biological oceanography could impact the biomass and composition of prey species, particularly the role of phytoplankton size spectra. We focus on examples from regions where biotic change with respect to climate change is likely. In particular, we detail the effects of climate change on oceanographic and bathymetric "hotspots" and provide the example involving seabirds in the Benguela Current system. We end by urging the development of international collaborations and databases to facilitate comprehensive ocean-scale understanding of climate impacts on marine top predators.

Cod, harp seal and minke whale are the main top predators in the Barents Sea ecosystem. In the last decade, the abundance of cod has increased considerably, and is at a record high level. In spite of this, the growth and condition of cod has remained rather stable, although some decrease is seen in size at age of large, mature cod. During the same period, the abundance of harp seals has declined whereas the minke whale stock has been at a stable level. The body condition (blubber thickness) of these two mammal stocks has, however, decreased, with the strongest decrease observed for harp seals. A possible hypothesis for explaining this is that cod outperform the marine mammal stocks in the competition for food. The main advantages for cod are most likely larger availability of food (mainly capelin) during winter-spring than for marine mammals, as well as a wider range of prey species being available to cod than to marine mammals. Harp seals are more dependent on prey items found close to the ice edge than the other two predator stocks are, which could partly explain why the performance of harp seals is worse than that of the two other main top predators in the area.

We review present understanding of the spatial and temporal diet variability (trophodynamics) of a range of pelagic marine top predators, at both early and adult life history stages. We begin with a review of methodologies used to advance our understanding of the trophodynamics of marine top predators, particularly in relation to climate change. We then explore how these developments are informing our understanding of the major trophic groups in food webs leading to, and including, marine top predators. We examine through specific examples how the impacts of ocean warming may affect pelagic food web relationships from both top-down and bottom-up perspectives. We examine the potential, in the absence of long-term data sets, of using large-scale spatial studies to examine how potential changes in biological oceanography could impact the biomass and composition of prey species, particularly the role of phytoplankton size spectra. We focus on examples from regions where biotic change with respect to climate change is likely. In particular, we detail the effects of climate change on oceanographic and bathymetric "hotspots" and provide the example involving seabirds in the Benguela Current system. We end by urging the development of international collaborations and databases to facilitate comprehensive ocean-scale understanding of climate impacts on marine top predators.

Man-made endocrine disrupting chemicals (EDCs) range across all continents and oceans; some geographic areas are potentially more threatened than others: one of these is the Mediterranean Sea. This basin has limited exchange of water with the Atlantic Ocean and is surrounded by some of the most heavily populated and industrialized countries in the world. Accordingly, levels of some xenobiotics are much higher here than in other seas and oceans. In this research the unexplored hypothesis that Mediterranean top predator species (such as large pelagic fish and marine mammals) are potentially at risk due to EDCs is investigated. Here we illustrate the development of sensitive biomarkers (Vitellogenin, Zona Radiata proteins) for evaluation of toxicological risk in top marine predators (Xiphias gladius, Thunnus thynnus thynnus), and nonlethal techniques, such as nondestructive biomarkers (BPMO activities in skin biopsy), for the hazard assessment of threatened species exposed to EDCs, such as marine mammals (Stenella coeruleoalba, Tursiops truncatus, Delphinus delphis, and Balaenoptera physalus).

Endocrine Disrupting Chemicals (EDCs) have the potential to alter hormone pathways that regulate reproductive processes in wildlife and fisheries. In this research the unexplored hypothesis that Mediterranean top predator species (such as large pelagic fish and marine mammals) are potentially at risk due to EDCs is investigated. In the Mediterranean environment, top predators accumulate high concentrations of polyhalogenated aromatic hydrocarbons (PHAHs) and toxic metals, incurring high toxicological risk. Here we illustrate the need to develop sensitive biomarkers for evaluation of toxicological risk in top marine predators (Xiphias gladius, Thunnus thynnus thynnus) and non-lethal techniques, such as non-destructive biomarkers, for the hazard assessment of threatened species exposed to EDCs, such as marine mammals (Stenella coeruleoalba, Tursiops truncatus, Delphinus delphis and Balaenoptera physalus).

Small-scale distribution patterns of seabirds in the Antarctic Polar Front (APF) were investigated in relation to other biological, physical, and chemical features during the ANT-XIII/2 research cruise of R.V. Polarstern from December 1995 to January 1996. The APF is characterized by steep gradients in sea-surface temperature and salinity. Within the APF, gradient zones were closely associated with elevated levels of primary production, chlorophyll-a (chl-a) concentrations, and zooplankton densities. Even broad-billed prions ('Pachyptila vittata-group'), which dominated the seabird community by 83% in carbon requirements, showed small-scale distributional patterns that were positively related to primary production, chl-a, and total zooplankton densities. The findings demonstrate a close, direct link between fine-scale physical processes in the APF and biological activity through several food web levels up to that of zooplankton-eating seabirds. Broad-billed prions appeared to forage on very small copepods (Oithona spp.) in close association with the front. Fish- and squid-eating predators showed poor correlations with small-scale spatial structures of the APF. However, in a wider band around the APF, most top predators did occur in elevated densities, showing gradual spatio-temporal diffusion of the impact of the APF on higher trophic levels. (C) 2002 Elsevier Science Ltd. All rights reserved.

This project sought to estimate the abundance of vulnerable shark species in Wakatobi, Indonesia. The greatest area of shark biodiversity is in the Indo-West Pacific. In Indonesia, specifically, sharks are one of the most important fishing commodities and are commonly found in almost every Indonesian fishery as target catch or bycatch. As top predators, sharks are integral to the ecosystem yet they are poorly managed and there is an urgent need to improve and develop responsible shark management and recovery plans. To develop these plans, more research is needed on species populations. To conduct a preliminary assessment of shark populations in Wakatobi, a series of interviews were conducted with 2 different groups directly dependent on the marine resources of the region: fishermen and dive guides. Interviews with these two different groups were undertaken in order to acquire information about locations of shark sightings or fisheries catch during their daily activities.

Groupers species are extremely vulnerable to overfishing and many species are threatened worldwide. In recent decades, Mediterranean groupers experienced dramatic population declines. Marine protected areas (MPAs) can protect populations inside their boundaries and provide individuals to adjacent fishing areas through the process of spillover and larval export. This study aims to evaluate the effectiveness of six marine reserves in the Western Mediterranean Sea to protect the populations of three species of grouper, Epinephelus marginatus, Epinephelus costae and Mycteroperca rubra, and to understand in which circumstances MPAs are able to export biomass to neighbouring areas. All the studied MPAs, except one where no grouper was observed, were able to maintain high abundance, biomass and mean weight of groupers. Size classes were more evenly distributed inside than outside MPAs. In two reserves, biomass gradients could be detected through the boundaries of the reserve as an indication of spillover. In some cases, habitat structure appeared to exert a great influence on grouper abundance, biomass and mean individual weight, influencing the gradient shape. Because groupers are generally sedentary animals with a small home range, we suggest that biomass gradients could only occur where groupers attain sufficient abundance inside MPA limits, indicating a strongly density-dependent process. This work was developed in the framework of the EC Project BIOMEX (QLRT-2001-0891). The authors express thanks to the National Council for Technology and Science Development (CNPq-MCT, Brazil, for Brazilian acronym) from the Ministry of Science of Brazil for giving personal financial support to CWH (Proc: 200630/2008-3), and to the Fundación BBVA (Foundation of Bilbao-Viscaya Bank, Spain) for additional support.

SummaryWest African flood-plains have undergone major land-use transformations in the second half of the 20th century. To obtain insight in the effect of flood-plain development for irrigated rice cultivation on the abundance, richness, and diversity of Palearctic and Afrotropical raptors, we conducted monthly transect surveys covering dry and wet seasons in four major habitats on the Waza-Logone flood-plain of Cameroon: dry grasslands, cultivated grasslands, rice fields, and seasonally flooded grasslands resembling natural flood-plain vegetation. We recorded 36 raptor species among 2,533 individuals, dominated by Black Kite Milvus migrans, which comprised 42% of counts. Although richness and diversity were not related to land-use for Palearctic raptors, Afrotropical raptor diversity was higher on the flooded grasslands compared to the newly created cultivated habitats and dry grasslands. The abundance of Afrotropical raptors did not significantly differ across habitats but was lower in rice-fields when Black Kite and Hooded Vulture Necrosyrtes monachus were excluded. Conversely, Palearctic raptor abundance was highest in post-harvest rice fields, demonstrating the importance of the rice fields as foraging habitat for Palearctic raptors. Further transformation of West Africa’s flood-plains is expected, reducing their capacity for Afrotropical raptors, while Palearctic raptors may benefit from expansion of rice-fields, but more research is needed on their vulnerability to pesticide use.

544x376 Normal 0 21 false false false EN-US JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tabla normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman";} Stable isotope analyses for shortfin mako ( Isurus oxyrinchus ) and blue sharks (Prionace glauca) were conducted to assess their trophic position in two periods of time (before 1980 and after 2000) in the Southeastern Pacific waters (SEP). Both sharks showed that their trophic position decreased over time ( P < 0.05). Many factors could be involved in this change such as dietary shifts, prey availability, or indirect fishing effects in SEP waters.

As aves de rapina, como predadores de níveis superiores na rede trófica, necessitam de grandes áreas de vida e ocorrem em baixa densidade populacional. São sensíveis a alteração e degradação do habitat, sendo bons indicadores de qualidade de habitat e biodiversidade. Apesar da importância ecológica pouco se conhece sobre a biologia e ecologia da maioria das 91 espécies que ocorrem na América do Sul, o que nos leva ao objetivo mais amplo desta tese: descrever a composição das taxocenoses de aves de rapina dos campos do sul do Brasil e Uruguai e sua relação com as características topográficas e ambientais. Para tanto, foram realizadas amostragens de aves de rapina em 11 áreas campestres entre outono de 2009 e verão de 2011. Um total de 44 transectos rodoviários foi amostrado sazonalmente, duas vezes ao ano, totalizando 176 amostragens. Ao todo foram observadas 18.424 aves de rapina, pertencentes a 33 espécies. Os transectos rodoviários são amplamente utilizados para a amostragem de aves de rapina, no entanto, nossos resultados sugerem que este método pode subestimar a abundância das espécies. Pontos de contagem parecem ser mais eficazes, principalmente para a amostragem de espécies raras. A distribuição das espécies foi associada à altitude e disponibilidade de habitat, e quatro taxocenoses puderam ser identificadas no sudeste da América do Sul. A taxocenose dos campos de altitude (na ecorregião Floresta Úmida com Araucária) se caracterizou pela presença de espécies florestais, ausentes ou pouco abundantes nas demais áreas. Na ecorregião Savana Uruguaia foram distinguidas outras três taxocenoses: 1) campos da planície costeira do sul do Brasil, com espécies associadas às áreas úmidas e ambientes alterados; 2) campos da Serra do Sudeste, uma taxocenose mista com espécies campestres e florestais, porém pouco abundantes e com maior tolerância a habitat alterados; 3) campos da Savana Uruguaia, taxocenose com predominância de espécies campestres e presença pontual de espécies florestais associadas a matas riparias. Foram registradas quatro espécies de necrófagos obrigatórios (Cathartiformes). A organização da taxocenose dos necrófagos aparenta ser mais influenciada pelas características da paisagem que por relações hierárquicas interespecíficas, mas a distribuição atual pode ter sido influenciada pela caça e envenenamento das espécies, ocorrida no século passado. A abundância das aves de rapina variou sazonalmente. A abundância foi significativamente maior no verão que no inverno, mas variou conforme a espécie. Quatro espécies são migratórias (duas migrantes trans-equatorias e duas intratropicais), três são parcialmente migratórias, mas o padrão de migração e as rotas são pouco conhecidos, e três espécies são nômades ou realizam movimentos irruptivos. Os campos do sudeste da América do Sul tem uma alta diversidade de aves de rapina, influenciada pela topografia, disponibilidade de habitat e sazonalidade, características que devem ser consideradas nas políticas de conservação na região. Raptors, as top predators, have large home ranges and low population densities. They are sensitive to human perturbation and habitat degradation; hence raptors are sentinel species and biodiversity indicators. Despite their ecological importance, the biology and ecology of most of the 91 South American raptors is poorly known. The main objectives of this study were to examine the assemblage composition in grasslands of southern Brazil and Uruguay and to investigate its relation with topography and habitat features. To achieve this, 44 roadside transects were conducted in 11 areas. Each transect was survey four times between autumn/2009 and summer/2011. The 176 transects yielded 18,424 contacts of raptors, belonging to 34 species. Roadside line transect is widely used to survey raptors. However, our results suggest that this method could underestimate the species abundance. Roadside point transect seems to be better, especially to survey rare species. Raptors distribution and assemblage composition were related to altitude and habitat availability, and four assemblages could be identified in southeastern South America. Raptor assemblage at Altitudinal grasslands (in the Araucarian Moist Forest ecoregion) had higher abundances of forest raptors than the other regions. Three assemblages were distinguished in the Uruguayan Savannas ecoregion: 1) south Brazilian coastal plain, with species related wetlands and human modified habitats; 2) Serra do Sudeste grasslands, a mix of forest and grassland raptors assemblage, which showed low abundances and lower sensibility to habitat degradation; 3) Uruguayan Savannas, dominated by grasslands species and few forest species usually found in riparian habitats. Four obligate scavengers (Cathartiformes) were recorded. Landscape features appeared to be more important to the assemblage organization than interspecific hierarchy, but the current distribution and abundance of scavengers could have been driven by species persecution and poisoning in the last century. Raptors abundance changed seasonally. Total abundance was significantly higher during summer than winter, and strategies to deal with seasonality varied between species. Four species are complete migrants (two transequatorial and two intratropical), three are partial migrants, but their routes and migration pattern remain poorly understood; and three species are irruptive or nomadic. The grasslands of southern South America have a high diversity of raptors, influenced by topography, habitat availability and seasonality, features that should be taken into account when divising regional conservation policies.

This report presents the results of extensive work of the smart green infrastructure task force commissioned by the World Bank under the Global Tiger Initiative (GTI). The report benefited from advice, ideas, and information about tigers and tiger-friendly infrastructure development from staff at the World Bank, and from several institutions that promote tiger and biodiversity conservation throughout the world. This study addresses infrastructure's impacts on tigers at international, national, sectoral and project levels in combination with the mitigation hierarchy which is based on avoidance, mitigation, minimization and compensation of impacts. It examines infrastructure policy challenges and opportunities, using lessons learned from case studies, along with regional and in-country analyses. While there are opportunities for improvement in all countries, Russia, India, Bhutan, and Nepal has, in particular, developed good foundations for tiger-related conservation, planning, and policy efforts. Best practices, drawn from case studies in non-tiger range countries, provide additional insights into infrastructure practices that could benefit tiger populations. Avoiding Tiger Conservation Landscapes (TCLs) is the best and cheapest option available to all parties for saving wild tigers.