@article {9642, title = {Hydro-morphological features and functional structure of fish assemblages mediate species isotopic niches in estuaries}, journal = {Estuarine, Coastal and Shelf Science}, volume = {299}, year = {2024}, month = {Jan-04-2024}, pages = {108686}, abstract = {Despite the popularity of stable isotope analysis (Carbon and Nitrogen), the drivers of species isotopic niches and their consequences on food web functioning remained poorly described, especially in estuaries. Here, we hypothesised that species niche characteristics are influenced by ecosystem hydro-morphological features and the functional structure of fish assemblages. The trophic niches of four fish species (Dicentrarchus labrax, Pomatoschistus minutus, Sprattus\ and\ Platichthys flesus) and overlap between them were compared during two consecutive autumns in eight estuarine ecosystems of the northeast Atlantic Ocean. Our findings demonstrated a relative steadiness of trophic positions of fish in estuaries, despite a high level of interspecific variability. The seabass generally occupied the higher trophic position, followed by the sand goby, while the flounder and sprat were at the lowest position in the food web. Species isotopic niches and overlap were mediated by some estuarine features, including estuary size and intertidal extent, but also by biotic interactions at the intra- and inter-specific levels, as reflected by the influence of fish abundance and functional diversity metrics. Our results support the statement that the intertidal area is a pivotal factor in regulating trophic interactions, by promoting niche partitioning and diversification of trophic resources between species. Moreover, niche size and dietary divergence of species decreased with increasing regularity of trophic strategies within assemblages, suggesting that species occupied more restricted trophic niches when they were less subjected to competition for the same food resources. These findings emphasize the importance of local conditions and the functional composition of assemblages in modulating the trophic resources consumed by fish in estuarine environments.}, keywords = {Estuary, functional diversity, Isotopic niche, stable isotope, Trophic competition}, issn = {02727714}, doi = {10.1016/j.ecss.2024.108686}, url = {https://www.sciencedirect.com/science/article/pii/S0272771424000738}, author = {Teichert, Nils and Liz{\'e}, Anne and Lepage, Mario and Cabral, Henrique and Trancart, Thomas and Acou, Anthony and Larregieu, Marie and Feunteun, Eric and Carpentier, Alexandre} } @article {9606, title = {Northeast Atlantic elasmobranch community on the move: Functional reorganization in response to climate change}, journal = {Global Change Biology}, volume = {30}, year = {2024}, month = {Jan-01-2024}, abstract = {While spatial distribution shifts have been documented in many marine fishes under global change, the responses of elasmobranchs have rarely been studied, which may have led to an underestimation of their potential additional threats. Given their irreplaceable role in ecosystems and their high extinction risk, we used a 24-year time series (1997{\textendash}2020) of scientific bottom trawl surveys to examine the effects of climate change on the spatial distribution of nine elasmobranch species within Northeast Atlantic waters. Using a hierarchical modeling of species communities, belonging to the joint species distribution models, we found that suitable habitats for four species increased on average by a factor of 1.6 and, for six species, shifted north-eastwards and/or to deeper waters over the past two decades. By integrating species traits, we showed changes in habitat suitability led to changes in the elasmobranchs trait composition. Moreover, communities shifted to deeper waters and their mean trophic level decreased. We also note an increase in the mean community size at maturity concurrent with a decrease in fecundity. Because skates and sharks are functionally unique and dangerously vulnerable to both climate change and fishing, we advocate for urgent considerations of species traits in management measures. Their use would make it better to identify species whose loss could have irreversible impacts in face of the myriad of anthropogenic threats.}, issn = {1354-1013}, doi = {10.1111/gcb.v30.110.1111/gcb.17157}, url = {https://onlinelibrary.wiley.com/toc/13652486/30/1https://onlinelibrary.wiley.com/doi/10.1111/gcb.17157https://onlinelibrary.wiley.com/doi/pdf/10.1111/gcb.17157}, author = {Coulon, No{\'e}mie and Elliott, Sophie and Teichert, Nils and Auber, Arnaud and McLean, Matthew and Barreau, Thomas and Feunteun, Eric and Carpentier, Alexandre} } @article {9643, title = {Quantifying larval dispersal portfolio in seabass nurseries using otolith chemical signatures}, journal = {Marine Environmental Research}, volume = {196}, year = {2024}, month = {Jan-04-2024}, pages = {106426}, abstract = {The temporal asynchronies in larvae production from different spawning areas are fundamental components for ensuring stability and resilience of marine metapopulations. Such a concept, named portfolio effect, supposes that diversifying larval dispersal histories should minimize the risk of recruitment failure by increasing the probability that at least some larvae successfully settle in nursery. Here, we used a reconstructive approach based on otolith chemistry to quantify the larval dispersal portfolio of the European seabass,\ Dicentrarchus labrax, across six estuarine nursery areas of the northeast Atlantic Ocean. The analysis of natal and trajectory signatures indicated that larvae hatch in distinct environments and then dispersed in water masses featured by contrasting chemical signatures. While some trace elements appeared affected by temporal changes (Mn and Sr), others varied spatially during the larval stage but remained poorly affected by temporal fluctuation and fish physiology (Ba, Cu, Rb and Zn). We then proposed two diversity metrics based on richness and variations of chemical signatures among populations to reflect spatio-temporal diversity in natal origins and larval trajectories (i.e., estimates of dispersal portfolio). Along the French coast, the diversity estimates were maximum in nurseries located at proximity of offshore spawning sites and featured by complex offshore hydrodynamic contexts, such as the Mont St-Michel bay. Finally, our findings indicate that the dispersal portfolio was positively related with the local abundance of seabass juveniles, supporting the assumption that heterogeneity in dispersal history contributes to promote recruitment success in nurseries.}, keywords = {Connectivity, dispersion, Dynamic time warping, Fish nursery, Larval life history, Otolith chemistry}, issn = {01411136}, doi = {10.1016/j.marenvres.2024.106426}, url = {https://www.sciencedirect.com/science/article/pii/S0141113624000874}, author = {Teichert, Nils and Tabouret, H{\'e}l{\`e}ne and Liz{\'e}, Anne and Daverat, Fran{\c c}oise and Acou, Anthony and Trancart, Thomas and Virag, Laure-Sarah and Pecheyran, Christophe and Feunteun, Eric and Carpentier, Alexandre} } @article {9640, title = {Accounting for variability in life-history traits for the definition of amphidromous goby fry fisheries closure periods}, journal = {Cybium}, volume = {47}, year = {2023}, month = {10/2023}, pages = {391-399}, abstract = {Amphidromous goby fry (post-larvae and young juveniles) are traditionally fished when they arrive in rivers after their larval development at sea. In Reunion Island (Indian Ocean) two species of amphidromous goby are mainly targeted by the fisheries: the endemic\ Cotylopus acutipinnis\ and the cosmopolitan\ Sicyopterus lagocephalus. Despite the lack of quantitative data on these fisheries, their impact on populations\ is expected to be important because the catches can represent several tonnes per year. Consequently, fishery regulation changes have been proposed that increase the duration of the existing fisheries closure period of two weeks in March. We developed an approach to identify key periods for fisheries closure, including assessment of the proposed management scenario and several alternative protection scenarios, based on the maximization of fry abundance and on the variability of four life-history traits: (i) fry size and (ii) age at arrival in rivers, (iii) the time the juveniles spend in river before maturation and (iv) their migration behaviour. This approach is in seeking to preserve a high level of phenotypic diversity, which is predicted to promote population resilience. We conducted a multiple-criteria decision analysis to rank 4096 alternatives of fisheries closure periods, ranging from zero to 12 months, based on their propensity to maintain fry abundance and life history trait diversity. Finally, according to the type of fisheries closure period (discontinuous or continuous) and the proportion of annual abundance and variability of life-history traits preserved during the period (50\% or 75\%), we propose four different fisheries closures lasting from six to nine months.}, keywords = {amphidromy, Bichiques, Conservation, diadromy, Indian Ocean, Management, recruitment}, doi = {10.26028/cybium/2023-018}, url = {https://sfi-cybium.fr/fr/accounting-variability-life-history-traits-definition-amphidromous-goby-fry-fisheries-closure}, author = {Lagarde, Rapha{\"e}l and Valade, Pierre and Teichert, Nils} } @article {9085, title = {Biogeographical snapshot of life-history traits of European silver eels: insights from otolith microchemistry}, journal = {Aquatic Sciences}, volume = {85}, year = {2023}, month = {Jan-04-2023}, abstract = {Life-history traits of eels display a high level of phenotypic plasticity in response to large-scale biogeographical drivers, as well as local conditions encountered during the continental phase. Here, we provided a biogeographical snapshot of the variability of life-history traits of eels (Anguilla anguilla), across a large proportion of their natural distribution range. Silver eels (n = 99) were collected across eleven European catchments to investigate how life-history traits vary along geographical and saline habitats, as it was inferred from the Sr:Ca ratio in otoliths. Among 13 life-history traits tested, 3 of them such as total length, body or liver weight were related to geographical coordinates. Overall, eels grow faster in southern Europe and migrate earlier suggesting that the silvering process is related to the local growth conditions more than fish age. The salinity profiles revealed by the otoliths{\textquoteright} Sr:Ca ratios indicate that eels with a brackish life-history generally grow faster, reach larger size-at-age, and have a better condition than eels living in freshwater. This observation associated with the lower abundance of the sanguivorous swimbladder nematode, Anguillicola crassus, confirms the importance of brackish areas for sustaining the eel production. A large proportion of the observed variation of life-history traits remained unexplained by the biogeographical trends and salinity condition, which suggests that other drivers act at the catchment scale.
}, keywords = {Anguilla anguilla, Biogeography, Brackish habitat, otolith, phenotypic plasticity, Sr:Ca ratio}, issn = {1015-1621}, doi = {10.1007/s00027-023-00940-4}, url = {https://link.springer.com/10.1007/s00027-023-00940-4}, author = {Teichert, Nils and Bourillon, Bastien and Suzuki, Kyoko and Acou, Anthony and Alexandre Carpentier and Kuroki, Mari and Righton, David and Thomas Trancart and Virag, Laure-Sarah and Walker, Alan and Otake, Tsuguo and Eric Feunteun} } @article {9004, title = {Decoupling carry-over effects from environment in fish nursery grounds}, journal = {Science of The Total Environment}, volume = {857}, year = {2023}, month = {Jan-01-2023}, pages = {159487}, abstract = {Life-history trait expression not only depends on the current environmental constraints, but also on the past ones that shaped traits expressed earlier in life. Such an effect, named carry-over, can occur in fish nursery grounds when juvenile performances after settlement are influenced by their larval traits in combination with conditions experienced in nurseries. To date, the impacts of environmental and human stressors on post-settlement traits have been assessed, but independently from larval traits, so that the contributions of environmental versus carry-over constraints remain unquantified. Here, we used a reconstructive approach based on otolith microstructure to investigate how carry-over and environment affect life-history traits of the European seabass,\ Dicentrarchus labrax. In the northeast Atlantic Ocean, seabass juveniles were collected in six French estuarine nursery areas with contrasted environmental conditions (water temperature, salinity, food availability, and anthropogenic impacts), and five of their life-history traits across ontogenetic stages were measured (pelagic growth, larval duration, size at settlement, post-settlement growth and body condition). Piecewise structural equation model emphasized the strong co-variation of larval traits in response to food availability and temperature in the pelagic environment, stressing that fast growing larvae are characterized by shorter pelagic larval duration, but larger size at recruitment. However, the magnitude of carry-over effects greatly varied between traits, revealing that larval trait impacts on post-settlement traits remained minor as compared to the nursery environment. In estuarine nurseries, our findings suggest that resource allocation results from a trade-off between somatic growth and energy storage. Fish juveniles exposed to anthropogenic stress or risk of food limitation tended to predominantly invest in storage, whereas individuals in favourable conditions allocated their resources in somatic growth. These findings highlight the importance of heterogeneity in pelagic and nursery environments in understanding trait variations and population dynamic of estuarine dependent fish.}, issn = {00489697}, doi = {10.1016/j.scitotenv.2022.159487}, url = {https://linkinghub.elsevier.com/retrieve/pii/S004896972206586X}, author = {Teichert, Nils and Liz{\'e}, Anne and Cabral, Henrique and Acou, Anthony and Trancart, Thomas and Virag, Laure-Sarah and Feunteun, Eric and Alexandre Carpentier} } @article {9361, title = {The goby fish Sicydium spp. as valuable sentinel species towards the chemical stress in freshwater bodies of West Indies}, journal = {Aquatic Toxicology}, volume = {261}, year = {2023}, month = {Jan-08-2023}, pages = {106623}, abstract = {Implementation of the European Water Framework Directive in tropical areas such as the French West Indies (FWI) requires to select relevant aquatic sentinel species for investigating the ecological status of surface waters. The present work aimed to study the biological response of the widespread fish Sicydium spp. towards river chemical quality in Guadeloupe island through a set of proper biomarkers. During a 2-year survey, the hepatic EROD activity, the micronucleus formation and the level of primary DNA strand breaks in erythrocytes were measured respectively as an enzymatic biomarker of exposure and genotoxicity endpoints in fish living upstream and downstream of two chemically-contrasted rivers. Hepatic EROD activity was shown to be variable along the time but always significantly higher in fish from the most contaminated river (Rivi{\`e}re aux Herbes) compared to the low contaminated one (Grande Rivi{\`e}re de Vieux-Habitants). Fish size did not influence EROD activity. Female fish exhibited a lower EROD activity compared to males depending on the catching period. We observed significant temporal variation in micronucleus frequency and primary DNA damage level measured in fish erythrocytes that did not depend on the fish size. Micronucleus frequency and to a lesser extent DNA damage were significantly higher in fish from the Rivi{\`e}re aux Herbes compared to the Grande Rivi{\`e}re de Vieux-Habitants. Our results argue for the interest of using Sicydium spp. as sentinel species to assess river quality and chemical pressures in FWI.}, issn = {0166445X}, doi = {10.1016/j.aquatox.2023.106623}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0166445X23002266}, author = {Bony, S. and Labeille, M. and Lefrancois, E. and Noury, P. and Olivier, J.M. and Santos, R. and Teichert, Nils and Besnard, A. and Devaux, A.} } @article {9641, title = {Isotopic niches of diadromous fishes inform on interspecific competition in an obstructed catchment}, journal = {Frontiers in Ecology and Evolution}, volume = {11}, year = {2023}, month = {Apr-11-2025}, abstract = {Competition arises when species share a limited resource, but this can be avoided through niche partitioning. Despite the large body of literature on diadromous fishes, very few studies have focused on niche partitioning when competing for resources. Diadromous fishes are suffering a global decline throughout their range in part due to their peculiar life history traits as they migrate from the sea to freshwater to spawn or the reverse. They are particularly sensitive to river fragmentation induced by barriers. Dams for instance are expected to alter the spatial distribution and resource exploitation of diadromous fishes as well as other organisms. Here, we studied the ecological niche of six taxa of diadromous fishes, temporally co-occurring in the same land{\textendash}sea continuum obstructed by two river dams. We used Bayesian mixing models run on C and N isotopes to infer the various habitats used and the origin of the trophic carbon in muscle and scale tissues of diadromous fishes. Results showed that the sub-adults of\ Anguilla anguilla, juveniles of\ Petromyzon marinus, and\ Salmo trutta\ exploit mainly the freshwater, or marine part for adults of\ Lampetra fluviatilis, whereas juveniles of\ Platichthys flesus\ and Mugilidae use all the habitats of the land{\textendash}sea continuum. In the freshwater habitat, the microphytobenthos and biofilm are the main sources of carbon used, while in the marine habitat, the basal carbon sources are more diverse. The analyses of niche overlaps between diadromous fishes demonstrate that the widest isotopic niches, observed for\ A. anguilla\ and\ P. flesus, also have more impact within the community. Results are discussed in terms of intra- and interspecific competition between these diadromous fishes and their generalist/specialist strategies in an obstructed catchment.}, doi = {10.3389/fevo.2023.124245210.3389/fevo.2023.1242452.s001}, url = {https://www.frontiersin.org/articles/10.3389/fevo.2023.1242452/fullhttps://www.frontiersin.org/articles/10.3389/fevo.2023.1242452/fullhttps://www.frontiersin.org/articles/10.3389/fevo.2023.1242452/supplementary-material/10.3389/fevo.2023.1242452.s001}, author = {Liz{\'e}, Anne and Teichert, Nils and Roussel, Jean-Marc and Acou, Anthony and Feunteun, Eric and Carpentier, Alexandre} } @article {9006, title = {Anthropogenic Contaminants Shape the Fitness of the Endangered European Eel: A Machine Learning Approach}, journal = {Fishes}, volume = {7}, year = {2022}, month = {Jan-10-2022}, pages = {274}, abstract = {European eel is thought to be a symbol of the effects of global change on aquatic biodiversity. The species has persisted for millions of years and faced drastic environmental fluctuations thanks to its phenotypic plasticity. However, the species has recently declined to historically low levels under synergistic human pressures. Sublethal chemical contamination has been shown to alter reproductive capacity, but the impacts and required actions are not fully addressed by conservation plans. This paper proposes a modelling approach to quantify the effects of sublethal contamination by anthropogenic pollutants on the expression of life history traits and related fitness of the critically endangered European eel.\ Material and Methods: We sampled female silver eels from eight different catchments across Europe previously shown to be representative of the spectrum of environmental variability and contamination. We measured 11 fitness-related life history traits within four main categories: fecundity, adaptability and plasticity, migratory readiness, and spawning potential. We used machine learning in models to explore the phenotypic reaction (expression of these life history traits) according to geographical parameters, parasite burdens (the introduced nematode\ Anguillicoloides crassus) and anthropogenic contaminants (persistent organic pollutants (POPs) in muscular tissue and trace elements (TEs) in gonads, livers and muscles). Finally, we simulated, the effects of two management scenarios{\textemdash}contamination reduction and contamination increase{\textemdash}on the fecundity and recruitment.\ Results: Contamination in our sampling was shown to have a stronger control on life history traits than do geographic and environmental factors that are currently described in the literature. We modelled different contamination scenarios to assess the benefit of mitigation: these scenarios suggest that reducing pollutants concentrations to the lowest values that occurred in our sampling design would double the fecundity of eels compared to the current situation.\ Discussion: Remediation of contamination could represent a viable management option for increasing the resilience of eel populations, with much more effects than solely reducing fishing mortality. More broadly, our work provides an innovative way for quantitative assessment of the reaction norms of species{\textquoteright} biological traits and related fecundity to contamination by organic and inorganic pollutions thus opening new management and conservation pathways to revert the erosion of biodiversity.}, doi = {10.3390/fishes7050274}, url = {https://www.mdpi.com/2410-3888/7/5/274}, author = {Bourillon, Bastien and Feunteun, Eric and Acou, Anthony and Trancart, Thomas and Teichert, Nils and Belpaire, Claude and Dufour, Sylvie and Bustamante, Paco and Aarestrup, Kim and Walker, Alan and Righton, David} } @book {8753, title = {Chapter 6 - Fishes and Estuarine Environmental Health}, year = {2022}, pages = {332 - 379}, publisher = {Wiley}, organization = {Wiley}, edition = {1}, abstract = {This chapter addresses the use of fish as indicators of environmental health. The main anthropogenic pressures impacting estuarine fishes are reviewed, as well as the main types of responses by fishes at different levels of biological organisation. Fishes have been widely used to assess estuarine health through different methodological approaches, namely comparisons with historical data or reference conditions, experimental approaches, environmental impact or risk assessment methods, as well as qualitative or quantitative indicators and models. A large number of multi-metric indices based on fish have been proposed and are routinely used in environmental assessments, although to disentangle natural variability from anthropogenic pressures in a multi-stress context of global change is still a major challenge.}, isbn = {9781444336672}, doi = {10.1002/978111970534510.1002/9781119705345.ch6}, url = {https://onlinelibrary.wiley.com/doi/book/10.1002/9781119705345}, author = {Cabral, Henrique N. and Borja, Angel and Fonseca, Vanessa F. and Harrison, Trevor D. and Teichert, Nils and Lepage, Mario and Leal, Miguel C.}, editor = {Whitfield, Alan K. and Able, Kenneth W. and Blaber, Stephen J.M. and Elliott, Michael} } @article {9003, title = {European flounder foraging movements in an estuarine nursery seascape inferred from otolith microchemistry and stable isotopes}, journal = {Marine Environmental Research}, volume = {182}, year = {2022}, month = {Jan-12-2022}, pages = {105797}, abstract = {Despite the importance of estuarine nurseries in the regulation of many fish stocks, temporal and spatial movements and habitat use patterns of juvenile fish remain poorly understood. Overall, combining several movement metrics allowed us to characterize dispersal patterns of juvenile flounder,\ Platichthys flesus,\ along an estuarine seascape. Specifically, we investigated otolith microchemistry signatures (Sr:Ca and Ba:Ca ratios) and stable isotope ratios (δ13C and δ15N) in muscles of these juveniles, during three consecutive years to assess inter-annual fluctuations in their home range and isotopic niches. The morphological condition and lipid content of individuals were lower in years of high as compared to low dispersal along the estuarine gradient. We discuss these results in relation to the ecosystem productivity and intra- and inter-specific competition level, which in turn affects movements and foraging behaviors of juvenile flounders.}, issn = {01411136}, doi = {10.1016/j.marenvres.2022.105797}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0141113622002422}, author = {Teichert, Nils and Liz{\'e}, Anne and Tabouret, H{\'e}l{\`e}ne and Roussel, Jean-Marc and Bareille, Gilles and Trancart, Thomas and Acou, Anthony and Virag, Laure-Sarah and Pecheyran, Christophe and Alexandre Carpentier and Feunteun, Eric} } @article {8752, title = {Modelling past migrations to determine efficient management rules favouring silver eel escapement from a large regulated Floodplain Lake}, journal = {Journal for Nature Conservation}, volume = {67}, year = {2022}, month = {Jan-06-2022}, pages = {126192}, abstract = {As human activities caused a dramatic decline of European eel population since the 1970\ s, the European Union has set targets to ensure a 40\%\ escapement\ to the sea of the silver eel biomass by considerably reducing anthropogenic impact. Thus, human obstacles to fish migration like dams and hydropower plants should enable efficient management measures ensuring safe passage for eels during the migration. In order to provide a quick and efficient assessment of eel conservation measure applied to the\ sluice gates\ of a large\ floodplain\ lake, we implemented a novel evaluation method using predictions on past migration seasons when no management measure were applied. For this purpose, we collected acoustic\ telemetry\ monitoring data over three migration seasons and fitted a predictive model based on Boosted Regression Trees (BRTs) to describe the influence of environmental parameters on migration. The water level difference over two days proved to be decisive, along with early migration occasions in the season, as an increase of at least 10\ cm water level was associated with a sharp increase of migration probability. We then used the BRT model to predict migration occasions at the dam over 8 past seasons and forecast the impact on escapement of management measures if they had been applied. Thanks to this original prospective assessment of dam management measures, we identified an enhanced opening decision rule, capable of increasing the eel escapement for each year of the study. The management measure is particularly efficient during the years with poor hydrological conditions (i.e. droughts), that is the periods with the lowest initial escapement rates. Finally, efficient management measures to increase silver eel escapement were based on increasing the number of\ gate opening\ days by only a few days per year (c.a. 15\%). However, the management measure only focused on silver eel migration, so that further investigations should consider the impacts of other threats occurring during the life cycle. This study also provides a highly operational approach for fast evaluation of conservation measures, avoiding lengthy and expensive monitoring campaigns of classical ex-post assessments.}, keywords = {Eel conservation, fish migration, Predictive model, Reservoir management}, issn = {16171381}, doi = {10.1016/j.jnc.2022.126192}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1617138122000656}, author = {Bourgeaux, Jacques and Teichert, Nils and Gillier, Jean-Marc and Danet, Valentin and Eric Feunteun and Acou, Anthony and Charrier, Fabien and Mazel, Virgile and Alexandre Carpentier and Trancart, Thomas} } @article {8599, title = {A multi-approach study to reveal eel life-history traits in an obstructed catchment before dam removal}, journal = {Hydrobiologia}, year = {2022}, month = {Sep-03-2022}, abstract = {River fragmentation is expected to impact not only movement patterns and distribution of eels within catchment, but also their life-history traits. Here, we used otolith multi-elemental signatures to reconstruct life sequences of European silver eels within an obstructed catchment, just before the removal of hydropower dams. Beyond providing an initial state, we hypothesized that otolith signatures can provide crucial information on the way eels use the watershed. Indeed, their spatial distribution is expected to shape life-history traits, including condition coefficient, trophic level, growth rate, or infection by metazoan parasites. While Sr:Ca and Ba:Ca ratios were complementary in tracing fish movements between freshwater and estuary, the Ba:Ca variations allowed to discriminate three freshwater sectors. The eels assigned to the midstream sector were more mobile and exhibited lower growth rates, probably in response to higher competition at the vicinity of dams. While most eels are currently produced by downstream and midstream sectors, eels assigned to upper reaches of connected tributaries generally display higher richness in native parasite and higher body condition and lipid reserve, known to promote the success of migration and reproduction. In the near future, the dam removals will represent an outstanding experimental framework for evaluating impacts of catchment reconnection.}, keywords = {LA-ICP-MS, life-history trait, metazoan parasites, otolith microchemistry, phenotypic plasticity, river barrier}, issn = {0018-8158}, doi = {10.1007/s10750-022-04833-9}, url = {https://link.springer.com/10.1007/s10750-022-04833-9}, author = {Teichert, Nils and Liz{\'e}, Anne and Tabouret, H{\'e}l{\`e}ne and G{\'e}rard, Claudia and Bareille, Gilles and Acou, Anthony and Alexandre Carpentier and Trancart, Thomas and Virag, Laure-Sarah and Robin, Emma and Druet, Morgan and Prod{\textquoteright}Homme, Jordan and Eric Feunteun} } @article {9005, title = {A possible strong impact of tidal power plant on silver eels{\textquoteright} migration}, journal = {Estuarine, Coastal and Shelf Science}, volume = {278}, year = {2022}, month = {Jan-11-2022}, pages = {108116}, abstract = {Very few\ tidal power\ plants exist in the world. The first one was built in the Rance\ estuary\ (Brittany, France) in 1966 and the second one in South Korea. However, with the increasing demand in renewable energy, other tidal power plant projects are being studied.

These power plants are larger than unidirectional fluvial hydropower plants and strongly modify the natural\ tidal cycle\ in estuarine systems. As such, their effect on megafaunal movements might strongly differ from those caused by unidirectional fluvial hydropower plants and should be specifically considered and studied before the development of similar constructions.

In this study, an acoustic\ telemetry\ array was deployed to track 25 silver eels released 16\ km upstream of the Rance tidal power dam. Only 1/3 of the tagged eels passed the dam and reached the sea. Data suggested that eels interrupted their migration up to 5\ km upstream of the dam. We assume that the noise and tidal disturbance generated by the dam could lead to a disruption of a high proportion of silver eels{\textquoteright} reproductive migration.}, issn = {02727714}, doi = {10.1016/j.ecss.2022.108116}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0272771422003742}, author = {Trancart, Thomas and Teichert, Nils and Lamoureux, J{\'e}zabel and Gharnit, Elouana and Acou, Anthony and de Oliveira, Eric and Roy, Romain and Feunteun, Eric} } @article {7823, title = {Influence of environmental conditions on the distribution of burrows of the mud crab, Scylla serrata, in a fringing mangrove ecosystem}, journal = {Regional Studies in Marine Science}, volume = {43}, year = {2021}, month = {Jan-03-2021}, pages = {101684}, abstract = {Mud crab, Scylla serrata, is a common mangrove species in the Indian Ocean. Over the last decades, fishing pressure has greatly increased especially in Madagascar. Therefore, improving the knowledge of mud crab biology and ecology is crucial to guide conservation and restoration plans. This study aimed at describing the distribution of burrows of the mud crab in a mangrove in southwestern Madagascar. Burrows fulfill an essential functional role by limiting the exposure of crab to environmental stress, such as desiccation during low tide, and predation. A total of 140 burrows were observed and available conditions were described at 168 random sampling points at low tide in three different mangrove zones, during the dry season (July 2014). Twelve environmental factors were recorded to reflect the position within the mangrove, the substrate composition and the surrounding floristic structure. A multivariate ordination analysis highlighted an overall association between burrows and specific habitat conditions. Boosted regression trees then indicated that the burrows distribution was predominantly explained by the avoidance of hard substrates. The occurrence of burrows was positively related to the upper intertidal zone of the mangrove where the water level was below 100 cm. Although the tree density had a positive effect, the occurrence of burrows was higher for low percentage of shade (\<40\%). These results provide insight for identifying mangrove areas that have an essential functional role for the conservation of mud crab populations.}, keywords = {Crustacean, Floristic structure, Habitat conditions, Mangrove crab, Substratum composition}, issn = {23524855}, doi = {10.1016/j.rsma.2021.101684}, url = {https://linkinghub.elsevier.com/retrieve/pii/S2352485521000761}, author = {Leoville, Alexandre and Lagarde, Rapha{\"e}l and Grondin, Henri and Faivre, La{\"e}titia and Rasoanirina, Elisa and Teichert, Nils} } @article {8754, title = {La protection des milieux aquatiques. Vuln{\'e}rabilit{\'e} et sensibilit{\'e} fonctionnelle des communaut{\'e}s de poissons}, journal = {Sciences Eaux \& Territoires}, volume = {N{\textdegree} 37}, year = {2021}, month = {Jan-12-2022}, pages = {76 - 81}, abstract = {Les approches en {\'e}cologie fonctionnelle ouvrent aujourd{\textquoteright}hui de nouvelles perspectives dans le domaine du diagnostic {\'e}cologique. C{\textquoteright}est le cas par exemple du crit{\`e}re de la redondance fonctionnelle que les auteurs de cet article ont appliqu{\'e} aux communaut{\'e}s de poissons pour {\'e}valuer leur sensibilit{\'e} fonctionnelle {\`a} la perte d{\textquoteright}esp{\`e}ces, et au-del{\`a}, mesurer l{\textquoteright}influence d{\textquoteright}un d{\'e}clin potentiel de diversit{\'e} sur le fonctionnement de l{\textquoteright}{\'e}cosyst{\`e}me. L{\textquoteright}int{\'e}gration de ce type d{\textquoteright}indice, en compl{\'e}ment des crit{\`e}res habituels, est utile pour d{\'e}finir des plans de gestion ou des sites prioritaires {\`a} prot{\'e}ger face {\`a} des perturbations environnementales, en se concentrant sur les processus {\'e}cosyst{\'e}miques.}, issn = {2109-3016}, doi = {10.3917/set.037.0076}, url = {https://www.cairn.info/revue-sciences-eaux-et-territoires-2021-3-page-76.htm?ref=doi}, author = {Teichert, Nils and Lepage, Mario and Hette-Tronquart, Nicolas and Argillier, Christine} } @article {7824, title = {Temporary turbine and reservoir level management to improve downstream migration of juvenile salmon through a hydropower complex}, journal = {Knowledge \& Management of Aquatic Ecosystems}, year = {2021}, month = {Jan-01-2021}, pages = {4}, abstract = {Developing management rules to improve downstream migration of salmon smolts in large hydropower plants is essential to limit mortality and migration delay. A 2-year telemetry study was conducted to assess the efficiency of temporary measures to enhance the safety and speed of juvenile salmon passage through the Pout{\`e}s dam (Allier River, France). 124 smolts were tracked through the reservoir and downstream of the dam, during implementation of turbine modulation and/or shutdown during night and reservoir level lowering. Level lowering significantly reduced median residence time from 3.4 days to 4.4 hours. However, even with high spill during turbine modulation, the risk of smolt being drawn toward the turbines was increased at low reservoir level due to the site{\textquoteright}s configuration, greater proximity to the surface and weak repulsive effect of the rack. Moreover, results revealed that a substantial proportion of smolts can migrate during daytime and twilight during floods, even at the beginning of the migration period. Thus targeted turbine shutdown has a good potential to protect smolts, but implementation requires studies taking account of site specificities and a flexible approach.}, keywords = {Atlantic salmon, downstream migration, migratory delay, operational management, Turbine shutdown}, doi = {10.1051/kmae/2021004}, url = {https://www.kmae-journal.org/10.1051/kmae/2021004}, author = {T{\'e}tard, St{\'e}phane and Roy, Romain and Teichert, Nils and Rancon, Jocelyn and Courret, Dominique} } @article {7825, title = {Water temperature influences larval survival of the amphidromous goby Sicyopterus lagocephalus}, journal = {Ecology of Freshwater Fish}, year = {2021}, month = {May-02-2022}, abstract = {Water warming induced by human activities can impact fish larvae survival, notably because it influences larval development and prey abundances. Amphidromous gobies of the subfamily Sicydiinae are particularly sensitive to this threat as the newly hatched free embryos are poorly developed and the first feeding opportunity only occurs after they reach the ocean. Here, we studied how water temperature (21, 23, 25, 29 and 31{\textdegree}C) impacts early development stages of Sicyopterus lagocephalus in both freshwater and marine aquaria (salinity 35). We monitored survival time, larval condition and the occurrence of critical developmental events such as mouth opening, yolk sac and oil globule resorption. In freshwater, the survival exceeded 150 hours at 21{\textdegree}C, while it dropped below 50 hours at 31{\textdegree}C. In seawater, the larval development of unfed larvae was significantly affected by temperature, survival time being greatly reduced in warmer waters. Accounting for the observed duration between mouth opening and the resorption of the oil globule, we estimated that larvae need to find suitable prey in seawater within a short time: around 30 hours during the peak of reproduction in summer. Otherwise, their endogenous reserves become depleted and their condition degrades. This study emphasises the sensitivity of free embryos to stream flow alterations, which contributes to the increase in water temperature and to the slowing down of larvae drift to the ocean. We conclude that once in seawater the temperature and feeding conditions experienced by amphidromous larvae are critical for survival.}, keywords = {amphidromy, Early life history, larval survival, mixed feeding period, starvation, water warming}, issn = {0906-6691}, doi = {10.1111/eff.12602}, url = {https://onlinelibrary.wiley.com/doi/10.1111/eff.12602}, author = {Teichert, Nils and Lagarde, Rapha{\"e}l and Occelli, Nicolas and Ponton, Dominique and Gaudin, Philippe} } @article {7116, title = {Development of an accurate model to predict the phenology of Atlantic salmon smolt spring migration}, journal = {Aquatic Conservation: Marine and Freshwater Ecosystems}, year = {2020}, month = {Apr-07-2021}, abstract = {Changes in migration timing, resulting from the alteration in river continuity or the effect of climate change, can have major consequences on the population dynamics of diadromous fish. Forecasting the phenology of fish migration is thus critically important to implement management actions aimed at protecting fish during their migration.
In this study, an 11-year monitoring survey of Atlantic salmon smolts (Salmo salar\ ) from the Ourthe River, Belgium, was analysed within a European Special Area of Conservation to improve the understanding of environment-induced spring migration. A logistic model was fitted to forecast smolt migration and to calculate phenological indicators for management, i.e. the onset, end, and duration of migration, while accounting for the influence of photoperiod, water temperature, and hydrological conditions.
The results indicated that the photo-thermal units accumulated by smolts above a 7{\textdegree}C temperature threshold was a relevant proxy to reflect the synergistic effect between temperature and photoperiod on smolt migration. After integrating the effect of river flow pulses, the model accurately explained the inter-annual changes in migration timing (R2\ = 0.95). The model predictions provide decisive management information to identify sensitive periods during which mitigation measures (e.g. hydropower turbine shutdown, river discharge management) should be conducted to promote smolt survival.
The model was used to predict phenological characteristics under future scenarios of climate change. The results suggest a joint effect of hydrological alterations and water warming. Temperature increases of 1{\textendash}4{\textdegree}C were associated with earlier initiation of migration, 6{\textendash}51 days earlier, and spring flood events greatly influenced the duration of the migration period. Accordingly, the combined effects of human-induced modifications of the hydrological regimes and increasing temperatures could result in a mismatch between the smolt and favourable survival conditions in the marine environment.}, issn = {1052-7613}, doi = {10.1002/aqc.3382}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/aqc.3382}, author = {Teichert, Nils and Benitez, Jean-Philippe and Dierckx, Arnaud and T{\'e}tard, St{\'e}phane and Oliveira, Eric and Thomas Trancart and Eric Feunteun and Ovidio, Micha{\"e}l} } @article {6961, title = {Influence of larval and juvenile life history on age at first maturity in two tropical amphidromous fish species}, journal = {Ecology of Freshwater Fish}, volume = {29}, year = {2020}, month = {Feb-01-2022}, pages = {63 - 73}, issn = {0906-6691}, doi = {10.1111/eff.v29.110.1111/eff.12488}, url = {https://onlinelibrary.wiley.com/toc/16000633/29/1}, author = {Lagarde, Rapha{\"e}l and Teichert, Nils and Grondin, Henri and Hue, Thomas and Gaudin, Philippe and Ponton, Dominique} } @article {6952, title = {Looking for environmental and endocrine factors inducing the transformation of Sicyopterus lagocephalus (Pallas 1770) (Teleostei: Gobiidae: Sicydiinae) freshwater prolarvae into marine larvae}, journal = {Aquatic Ecology}, volume = {54}, year = {2020}, month = {Jan-03-2020}, pages = {163 - 180}, issn = {1386-2588}, doi = {10.1007/s10452-019-09734-z}, url = {http://link.springer.com/10.1007/s10452-019-09734-z}, author = {Ellien, C{\'e}line and Causse, Romain and Werner, Ugo and Teichert, Nils and Rousseau, Karine} } @article {7117, title = {Predicting species richness and abundance of tropical post-larval fish using machine learning}, journal = {Marine Ecology Progress Series}, volume = {645}, year = {2020}, month = {Sep-07-2020}, pages = {125 - 139}, abstract = {No previous studies predicted post-larval fish species richness and abundance combining molecular tools, machine learning, and past-days Remotely Sensed Oceanic Conditions (RSOCs) at different scales. Previous studies aimed at modeling species richness and abundance of marine fishes have mostly used environmental variables recorded locally during sampling. They have merely focused on juvenile and adult fishes due to the difficulty of obtaining accurate species richness estimates for post-larvae. The present work predicted post-larval species richness (identified using DNA barcoding) and abundance at two coastal sites in SW Madagascar using random forests (RF). RF models were fitted using combinations of local variables with RSOCs at a small-scale (eight days preceding fish sampling in a 50x120 km2\ area), mesoscale (sixteen past-days in 100x200 km2), and large-scale (twenty-four past-days in 200x300 km2). RF models combining local and small-scale RSOC variables predicted more accurately the species richness and abundance with around 70\% and 60\% accuracy, respectively. We observed a small variation of RF model performance in predicting species richness and abundance among all sites, highlighting the predictive RF model consistency. Moreover, partial dependence plots showed that high species richness and abundance were predicted for sea surface temperatures \<27.0{\textdegree}C and chlorophyll\ a\ concentrations \<0.22 mg m-3. Referring to temporal changes of these variables, these thresholds were solely observed from November to December. These results suggest that, in SW Madagascar, species richness and abundance of post-larval fish may only be predicted prior to the ecological impacts of tropical storms on larval settlement success.}, issn = {0171-8630}, doi = {10.3354/meps13385}, url = {https://www.int-res.com/abstracts/meps/v645/p125-139/}, author = {Jaonalison, H and Durand, JD and Mahafina, J and Demarcq, H and Teichert, Nils and Ponton, D} } @article {7777, title = {Resolving the trade-off between silver eel escapement and hydropower generation with simple decision rules for turbine shutdown}, journal = {Journal of Environmental Management}, volume = {261}, year = {2020}, month = {Jan-05-2020}, pages = {110212}, issn = {03014797}, doi = {10.1016/j.jenvman.2020.110212}, url = {https://linkinghub.elsevier.com/retrieve/pii/S030147972030147X}, author = {Teichert, Nils and T{\'e}tard, St{\'e}phane and Thomas Trancart and Eric Feunteun and Anthony Acou and de Oliveira, Eric} } @article {6736, title = {Resolving the trade-off between silver eel escapement and hydropower generation with simple decision rules for turbine shutdown}, journal = {Journal of Environmental Management}, volume = {261}, year = {2020}, pages = {110212}, abstract = {Hydropower plants are commonly reported as a major cause of the worldwide decline of freshwater eels (Anguillidae), so that management solutions are urgently needed to mitigate their impacts. Where downstream passage solutions are complex to develop, turbine shutdown appears as an effective management solution to protect silver eels during their river migration toward spawning areas. However, the definition of operational decision rules for turbine shutdown is challenging due to the duality between the benefit for eel conservation and the concomitant cost in term of hydropower production. Here, we proposed a decision framework for turbine shutdown based on simple hydrological criteria to guide negotiations between stakeholders toward a trade-off between silver eel escapement and hydropower generation. Eel migration was assumed to be triggered by a minimum river flow associated with a minimum discharge pulse, so that threshold values can be directly implemented as decision rules for turbine shutdown. To estimate relevant thresholds, a generic methodological framework was developed to generate alternative decision rules from data collected at hydropower plants, which can include telemetry surveys and estimates of eel abundance. A multiple-criteria decision analysis was then conducted to rank alternatives and to determine the best compromise between promoting silver eel escapement and limiting turbine shutdown duration. Graphic outputs can help stakeholders to understand the competitive interests between eel conservation and hydropower production, while visually identifying a range of consensual alternatives to support negotiations in the choice of operational thresholds. The method was illustrated for three river systems in Europe featured by distinct hydrological conditions and can be applied in other areas, providing that eel monitoring surveys and flow data are available.}, keywords = {Conservation policy, Decision rules, Multiple-criteria decision, Turbine shutdown}, issn = {0301-4797}, doi = {https://doi.org/10.1016/j.jenvman.2020.110212}, url = {http://www.sciencedirect.com/science/article/pii/S030147972030147X}, author = {Teichert, Nils and St{\'e}phane T{\'e}tard and Thomas Trancart and Eric Feunteun and Anthony Acou and Eric de Oliveira} } @article {6959, title = {Response of phytoplankton traits to environmental variables in French lakes: New perspectives for bioindication}, journal = {Ecological Indicators}, volume = {108}, year = {2020}, month = {Jan-01-2020}, pages = {105659}, abstract = {The restoration and the preservation of aquatics ecosystems is a critical issue in our contemporary society. In lake ecosystems, phytoplankton taxonomic-based indicators have been developed to evaluate water quality, but suffer of limited ecosystem ecological value. The recent development of functional approaches may allow to evaluate other aspects of ecosystem quality, and to develop new trait-based indicators responding to different environmental conditions. Here, our aim was to analyze the response of phytoplankton traits to numerous environmental variables and to identify relevant traits for the development of future indicator metrics. We used a French national database of 469 lakes, consisting in phytoplankton biovolumes and physicochemical values. The response of 84 morpho-functional traits towards environmental variables was tested with Machine Learning models, taking into account lake typology.
We identified 21 traits significantly related to environmental variables. Dissolved Organic Carbon, Nitrates and Total Suspend Solids were the physiochemical parameters which had the higher influence on our traits selection. However the response of phytoplanktonic traits to environmental variables did not change according to lake typology, advocating for a consistent response at the whole national scale contrary to the classical taxonomic approach. We finally identified several candidate traits that could be used for the development of new metrics for French lakes in a context of bio-assessment programs.}, issn = {1470160X}, doi = {10.1016/j.ecolind.2019.105659}, url = {https://linkinghub.elsevier.com/retrieve/pii/S1470160X19306521}, author = {Derot, J. and Jamoneau, A. and Teichert, Nils and Rosebery, J. and Morin, S. and Laplace-Treyture, C.} } @article {7397, title = {Structure of small tropical island freshwater fish and crustacean communities: A niche-or dispersal-based process?}, journal = {Biotropica}, year = {2020}, month = {Jan-10-2021}, abstract = {Determining the relative importance of niche- and dispersal-based processes in the structuring of animal communities is central in ecology. Freshwater fish and crustacean communities of small tropical islands can bring new insights for understanding these processes as all their species present a pelagic larval stage which gives them important dispersal capacities. Consequently, we hypothesized that dispersal-based process may be preponderant for structuring these communities from the regional to the local, that is, survey site, scales. Gradient forest analyses allowed us to model the effect of 12 environmental variables on freshwater taxa abundances in two southwestern Indian Ocean islands: Mayotte (26 taxa) and Reunion (21). A total of 153 surveys in Mayotte and 266 in Reunion were used for building the models. Despite the strong heterogeneity of environmental conditions between the two islands, the main factors structuring freshwater fish and crustacean communities in both islands were the elevation and the slope of the sites. The observed structure appeared more pronounced for predatory species than for primary consumers and omnivores. As predators generally have limited locomotor capacities, it is concluded that dispersal-based process structures these communities not only at large geographical scales but also at the intra-watershed scale, by limiting the inland penetration (or dispersion) of species in relation to their locomotor capacities. However, more knowledge concerning ecological traits and taxonomic status of many species is needed to confirm this assumption.
}, keywords = {abundances, diadromy, environmental gradients, Migration, taxonomic richness, western Indian Ocean}, issn = {0006-3606}, doi = {10.1111/btp.12865}, url = {https://onlinelibrary.wiley.com/doi/10.1111/btp.12865}, author = {Lagarde, Rapha{\"e}l and Teichert, Nils and Valade, Pierre and Ponton, Dominique} } @article {7026, title = {Towards transferability in fish migration models: A generic operational tool for predicting silver eel migration in rivers}, journal = {Science of The Total Environment}, volume = {739}, year = {2020}, month = {Jan-10-2020}, pages = {140069}, abstract = {In the global context of river fragmentation, predicting fish migration is urgent to implement management actions aimed at protecting and promoting the free movement of diadromous fish. However, large-scale applicability of conservation measures requires transferable models that enable prediction of migration even in data-poor regions. Here, we surveyed 12 contrasted European river sites to predict the activity peaks of silver eels (Anguilla anguilla) during river migration towards spawning areas through an ensemble modelling approach. Site-specific Boosted Regression Tree (BRT) models were adjusted using standardized hydrological variables to predict migration probability, which were aggregated in consensus predictions. Results of independent cross-validations demonstrated that silver eel migration runs were accurately predicted in response to changes in river discharge. Transferability and predictive performance were improved by considering catchment-size dissimilarity between river sites (85 to 109 930 km{\texttwosuperior}) when combining the site-specific predictions. Nevertheless, we provided two examples for which the effects of human actions on flow conditions were so high that they prevented reliable predictions of migration runs. Further contributions should thus take advantage of the flexibility of our approach for updating model collection with new sites to extend the predictive performance under a larger range of ecological conditions. Our transferable hydrological-based modelling framework offers an opportunity to implement large-scale management strategies for eel conservation, even in rivers where eel monitoring data lack. The BRT models and prediction functions were compiled in an R package named {\textquoteleft}silvRpeak{\textquoteright} to facilitate operational implementation by end-user managers, which can determine when mitigation measures should be implemented to improve river continuity (e.g. turbine shutdown and sluice gate opening) and balance their economic activity towards eel conservation. The only input required is discharge records that are widely available across European hydrological stations.}, keywords = {eel runs prediction, ensemble modelling, European eel management, fish migration, model transferability, river obstacle}, issn = {00489697}, doi = {10.1016/j.scitotenv.2020.140069}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0048969720335890}, author = {Teichert, Nils and T{\'e}tard, St{\'e}phane and Thomas Trancart and de Oliveira, Eric and Anthony Acou and Alexandre Carpentier and Bourillon, Bastien and Eric Feunteun} } @article {6960, title = {Reproductive biology of a small amphidromous shrimp Atyoida serrata on Reunion Island, south-west Indian Ocean}, journal = {Limnologica}, volume = {76}, year = {2019}, month = {Jan-05-2019}, pages = {41 - 47}, issn = {00759511}, doi = {10.1016/j.limno.2019.03.005}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0075951118301579}, author = {Hoarau, Pierre E and Courtecuisse, Emilie and Treilhes, Camille RM and Lagarde, Rapha{\"e}l and Teichert, Nils and Valade, Pierre B} }