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Suspension feeders ecosystem role and services are mainly driven by their efficiency in clearing particles from the water column. As such there is an interest on suspension feeders feeding activity and how they interact with the ecosystem. Advancing research on feeding response requires experimental designs where individuals can be exposed to continuously changing environments and where feeding activity can be monitored at a high frequency and at different time scales. There are several methods to monitor feeding activity (as clearance rate (CR) and particle capture efficiency (CE)) of suspension feeders. Among them, the flow-through method is most often used and it allows individuals to be exposed to changing conditions. However, as with the other existing methods, the flow-through method is labor intensive and time consuming limiting both the number of individuals that could be observed simultaneously and the resolution at which measurements can be taken. The flow-through method is constrained by the need to measure the flow rate through the chambers and to take samples to determine particle concentration in the water. In this work we automated the standard flow-through method using micro-controller based prototyping. The result is a methodological approach that continuously monitor feeding at high frequency and on a larger number of individuals while reducing handling and measurement errors. This work provides the description and assessment of the automated set-up, which is an end to end solution that can readily assembled and configured.

Background: Blue mussels (Mytilus edulis L.) can accumulate undesirable substances, including the potentially toxic elements (PTEs) cadmium (Cd), mercury, (Hg), lead (Pb), arsenic (As) and As species. In this study, the levels of PTEs and As species were determined in samples of blue mussels to assess the influence of environmental and biological factors, and evaluate the potential risk associated with blue mussels in terms of food and feed safety.Methodology: Blue mussels were collected monthly in Western Norway from February 2018 to December 2018, and from April 2019 to April 2020. Samples were analyzed for PTEs using inductively coupled plasma mass spectrometry (ICP-MS) and high-performance liquid chromatography (HPLC) coupled to ICP-MS. Temperature, salinity and fluorescence (chlorophyll a) were monitored in the seawater column by STD/CTD, to assess the potential influence of these environmental factors on the PTE levels in the mussels.Results: The results showed seasonal variations in the PTEs, with somewhat higher concentrations in spring and winter months. Unusually high levels of total As (101.2 mg kg-1 dw) and inorganic As (53.6 mg kg-1 dw) were observed for some of the time points. The organic As species arsenobetaine was generally the major As species (17- 82% of total As) in the mussels, but also simple methylated As species and arsenosugars were detected. Principal components analysis (PCA) did not show a consistent relationship between the environmental factors and the PTE concentrations, showing contrary results for some elements for the periods studied. The condition index could explain variations in element concentration with significant correlations for Cd (r = -0.67, p = 0.009) and Pb (r = -0.62, p = 0.02 in 2019/20 and r = -0.52, p = 0.02 in 2018), whereas the correlation between As and CI was not significant (r = 0.12 in 2018, and r = -0.06 in 2019/20). Higher concentrations of iAs and arsenosugars coincided with increased signals of chlorophyll a, suggesting that phytoplankton blooms could be a source of As in the blue mussels.Conclusion: To our knowledge, this is the first study of As species in blue mussels collected over a time period of two years, providing an insight into the natural variations of these chemical forms in mussels. In terms of mussel as food and future feed material, concentrations of Cd, Hg and Pb were below the maximum levels (MLs) established in the EU food and feed legislation. However, levels of As and iAs in mussels at some time points exceeded the MLs for As in the feed legislation, and the margin of exposure (MOE) was low if these mussels were for human consumption, highlighting the importance of determining the chemical forms of As in feed and food.

23 pages; International audience; The Southern Ocean is undergoing rapid environmental changes that are likely to have a profound impact on marine life, as organisms are adapted to sub-zero temperatures and display specific adaptations to polar conditions. However, species ecological and physiological responses to environmental changes remain poorly understood at large spatial scale owing to sparse observation data. In this context, correlative ecological niche modeling (ENMc) can prove useful. This approach is based on the correlation between species occurrences and environmental parameters to predict the potential species occupied space. However, this approach suffers from a series of limitations amongst which extrapolation and poor transferability performances in space and time. Mechanistic ecological niche modeling (ENMm) is a process-based approach that describes species functional traits in a dynamic environmental context and can therefore represent a complementary tool to understand processes that shape species distribution in a changing environment. In this study, we used both ENMc and ENMm projections to model the distribution of the Antarctic echinoid Sterechinus neumayeri. Both models were projected according to present (2005–2012) and future IPCC scenarios RCP 4.5 and 8.5 for (2050–2099). ENMc and ENMm projections are congruent and predict suitable current conditions for the species on the Antarctic shelf, in the Ross Sea and Prydz Bay areas. Unsuitable conditions are predicted in the northern Kerguelen Plateau and South Campbell Plateau due to observed lower food availability and higher sea water temperatures compared to other areas. In contrast, the two models diverge under future RCP 4.5 and 8.5 scenarios. According to ENMm projections, the species would not be able to grow nor reach sexual maturity over the entire ocean, whereas the Antarctic shelf is still projected as suitable by the ENMc. This study highlights the complementarity and relevance of EMN approaches to model large scale distribution patterns and assess species sensitivity and potential response to future environmental conditions.

Losses due to predation are recognized as an important factor affecting shellfish stocks, restoration efforts and aquaculture production. Managing and mitigating the impact of predators require information on the population dynamics and functional responses to prey availability under varying environmental conditions.Asteriasspp. are well-known keystone predators with the capacity to exert a top down control on shellfish populations.Asteriasspp.populations are extremely plastic, booming fast when prey is abundant and exhibiting a remarkable individual resilience to starvation and adverse environmental conditions. These aspects have ledAsteriasspp.to be considered pests by shellfish producers and fishers and to be catalogued among the most devastating invasive species. Assessment and mitigation of the impact ofAsterias rubensin northern Europe have been the objective of several projects. However, there is still a limited understanding of the processes behindA. rubenspopulation plasticity and how environmental conditions affect individual growth and predation. Under these circumstances a comprehensive eco-physiological model becomes necessary. These models can integrate available information on biology and eco-physiology to gain understanding of the effect of the environmental conditions on the impact ofA. rubens.In this work, we performed a number of eco-physiological experiments and combined them with field data from a Danish estuary to estimate and validate the parameters of a dynamic energy budget (DEB) model for the whole life cycle ofA. rubens. DEB models can be used to assess the effects of environmental variability on the life cycle and key population traits allowing the prediction of the performance, abundance, resource requirements and potential distribution of individuals and populations under dynamic environments. As such the DEB model presented in this study aims to become a tool to be used to assess and manage the impact ofA. rubensin cultured and natural shellfish populations. The successfully parameterised DEB model describesA. rubensas a plastic species, an efficient predator with low maintenance costs and, at least while feeding on mussels, a high energy yield from its prey. The model validation against independent data resulted in the model being capable to assess growth, food demand, reproductive output and reserves dynamics ofA. rubensunder experimental and natural conditions. Moreover, application of the model to the Limfjorden seastar fishery is used to further discuss the use of the model to understand biology and ecology of this pest species in the context with the management of shellfish stocks and impact mitigation.

M.L. is supported by CARIM (Coastal Acidification: Rate, Impacts & Management), funded by the New Zealand Government through the Ministry of Business Innovation and Employment. This is contribution no. 236 of the Sydney Institute of Marine Science.

Water motion, because of its potential to dislodge intertidal organisms, plays a crucial role in shaping marine communities as it creates available spaces suitable for interactions, settlement and colonization. To understand how water flow influences the behavioural ecology of benthic species such as echinoids, we investigated how the sea urchin Paracentrotus lividus (Lamark, 1816) can cope with increasing flow velocities through a biomechanical and behavioural approach. Whereas sea urchins maintained in static conditions for several weeks showed weak adhesive properties, they immediately reacted to increasing hydrodynamic forces. Sea urchins were dislodged at a flow velocity of about 70 cm s−1, with a few individuals enduring up to 90 cm s−1. This response was modulated by two behavioural strategies: (1) at low flow velocities, an escaping strategy characterized by fast upstream locomotion relying on tube feet; and (2) above a threshold flow, a streamlining strategy characterized by changes in overall shape and spines orientation, accompanied by a fast decrease of the animal's movement until complete immobility. Although the threshold at which the switch in behaviour occurs and the detachment velocities were both probably underestimated because individuals were aquarium-acclimatized, the behavioural sequence reported reveals how P. lividus can avoid or withstand rough weather conditions. From an ecological perspective, the occurrence of a range of water velocities too slow to dislodge sea urchins but sufficient to inhibit their active movement is relevant to understand how echinoids can structure benthic communities by controlling macroalgae development through their grazing activity., SCOPUS: ar.j, info:eu-repo/semantics/published

The authors thank the Sydney Institute of Marine Science (SIMS) for assistance and access to the experimental facility. This research was supported by a NSW Environmental Trust grant (M.B.). This is SIMS contribution number 225.

The introduction of alien species is a global phenomenon that alters ecosystems structure and functioning. Invasive species are responsible for substantial economic and ecological losses. Invasive species impact resource availability, outcompeting and even causing extinction of native species. The management of invasive species requires knowledge on the ecology, physiology and population dynamics of these species. In a world where environmental conditions are changing fast due to global climate change and other anthropogenic stressors, a more comprehensive knowledge of the life history and physiology of these species is urgently needed. The DEB theory is unique in capturing the metabolic processes of an organism through its entire life cycle, and thus, is a useful tool to model lifetime feeding, growth, reproduction, and responses to changes in biotic and abiotic conditions. In this work, we estimated the parameters of a DEB model for Asterias amurensis. This starfish was introduced in Tasmania and is considered the most serious marine pest in Australia where it has caused local extinctions of several species. Asterias amurensis is a major predator and is a keystone species exerting top-down control of its prey populations by achieving large densities. We determined the influence of biotic and abiotic factors on the performance of A. amurensis. The DEB model presented here includes energy handling rules to describe gonad and pyloric caeca cycles. Model parameters were used to explore population dynamics of populations of A. amurensis in Australia. The DEB model allowed us to characterise the ecophysiology of A. amurensis, providing new insights on the role of food availability and temperature on its life cycle and reproduction strategy. Moreover it is a powerful tool for risk management of already established invasive populations and of regions with a high invasion risk.

Extensive research has shown that the early life stages of marine organisms are sensitive to ocean acidification (OA). Less is known, however, on whether larval settlement and metamorphosis may be affected, or by which mechanisms. These are key processes in the life cycle of most marine benthic organisms, since they mark the transition between the free swimming larval stage to benthic life. We investigated whether OA could affect the larval settlement success of the sea urchin Evechinus chloroticus, a key coastal species with ecological, economic and cultural importance in New Zealand. We performed four settlement experiments to test whether reduced seawater pH (ranging from 8.1 to 7.0, at an interval of ~0.2 pH units) alters larval settlement and metamorphosis success. Our results show that settlement success was not significantly reduced when the larvae were exposed to a range of reduced seawater pH treatments (8.1-7.0) at time of settlement (on direct effects). Similarly, when presented with crustose coralline algae (CCA) pre-conditioned in seawater pH of either pH 8.1 or 7.7 for 28 days, larval settlement success remained unaltered (on indirect effects). We conclude that competent larvae in this species are resilient to OA at time of settlement. Further research on a range of taxa that vary in settlement selectivity and behaviour is needed in order to fully understand the effects of OA on the life cycle of marine invertebrates and the consequences it might have for future coastal marine ecosystems.

Life traits such as reproductive strategy can be determining factors of species evolutionary history and explain the resulting diversity patterns. This can be investigated using phylogeographic analyses of genetic units. In this work, the genetic structure of five asteroid genera with contrasting reproductive strategies (brooding: Diplasterias, Notasterias and Lysasterias versus broadcasting: Psilaster and Bathybiaster) was investigated in the Southern Ocean. Over 1,400 mtDNA cytochrome C oxidase subunit I (COI) sequences were analysed using five species delineation methods (ABGD, ASAP, mPTP, sGMYC and mGMYC), two phylogenetic reconstructions (ML and BA), and molecular clock calibrations, in order to examine the weight of reproductive strategy in the observed differences among phylogeographic patterns. We hypothesised that brooding species would show higher levels of genetic diversity and species richness along with a clearer geographic structuring than broadcasting species. In contrast, genetic diversity and species richness were not found to be significantly different between brooders and broadcasters, but broadcasters are less spatially structured than brooders supporting our initial hypothesis and suggesting more complex evolutionary histories associated to this reproductive strategy. Broadcasters' phylogeography can be explained by different scenarios including deep-sea colonisation routes, bipolarity or cosmopolitanism, and sub-Antarctic emergence for the genus Bathybiaster; Antarctic- New Zealand faunal exchanges across the Polar Front for the genus Psilaster. Brooders' phylogeography could support the previously formulated hypothesis of a past trans-Antarctic seaway established between the Ross and the Weddell seas during the Plio-Pleistocene. Our results also show, for the first time, that the Weddell Sea is populated by a mixed asteroid fauna originating from both the East and West Antarctic., SCOPUS: ar.j, info:eu-repo/semantics/published

Antarctic surface waters are expected to be the first to experience severe ocean acidification (OA) with carbonate undersaturation and large decreases in pH forecasted before the end of this century. Due to the long stability in environmental conditions and the relatively low daily and seasonal variations to which they are exposed, Antarctic marine organisms, especially those with a supposedly poor machinery to eliminate CO2 and protons and with a heavily calcified skeleton like echinoderms, are hypothesized as highly vulnerable to these environmental shifts. The opportunities offered by the natural pH gradient generated by vent activities in Deception Island caldera, Western Antarctic Peninsula, were used to investigate for the first time the acid-base physiologies, the impact of OA on the skeleton and the impact of pH on metal accumulation in the Antarctic sea star Odontaster validus and sea urchin Sterechinus neumayeri. The two species were sampled in four stations within the caldera, two at pH (total scale) 8.0–8.1 and two at reduced pH 7.8. Measured variables were pH, alkalinity, and dissolved inorganic carbon of the coelomic fluid; characteristic fracture force, stress and Young's modulus using Weibull statistics and Cd, Cu, Fe, Pb and Zn concentrations in the integument, gonads and digestive system. Recorded acid-base characteristics of both studied species fit in the general picture deduced from temperate and tropical sea stars and sea urchins but conditions and possibly confounding factors, principally food availability and quality, in the studied stations prevented definitive conclusions. Reduced seawater pH 7.8 and metals had almost no impact on the skeleton mechanical properties of the two investigated species despite very high Cd concentrations in O. validus integument. Reduced pH was correlated to increased contamination by most metals but this relation was weak. Translocation and caging experiments taking into account food parameters are proposed to better understand future processes linked to ocean acidification and metal contamination in Antarctic echinoderms., SCOPUS: ar.j, info:eu-repo/semantics/published

Due to climatic warming, Asterias amurensis, a keystone boreal predatory seastar that has established extensive invasive populations in southern Australia, is a potential high-risk invader of the sub-Antarctic and Antarctic. To assess the potential range expansion of A. amurensis to the Southern Ocean as it warms, we investigated the bioclimatic envelope of the adult and larval life stages. We analysed the distribution of adult A. amurensis with respect to present-day and future climate scenarios using habitat temperature data to construct species distribution models (SDMs). To integrate the physiological response of the dispersive phase, we determined the thermal envelope of larval development to assess their performance in present-day and future thermal regimes and the potential for success of A. amurensis in poleward latitudes. The SDM indicated that the thermal 'niche' of the adult stage correlates with a 0-17 °C and 1-22.5 °C range, in winter and summer, respectively. As the ocean warms, the range of A. amurensis in Australia will contract, while more southern latitudes will have conditions favourable for range expansion. Successful fertilization occurred from 3 to 23.8 °C. By day 12, development to the early larval stage was successful from 5.5 to 18 °C. Although embryos were able to reach the blastula stage at 2 °C, they had arrested development and high mortality. The optimal thermal range for survival of pelagic stages was 3.5-19.2 °C with a lower and upper critical limit of 2.6 and 20.3 °C, respectively. Our data predict that A. amurensis faces demise in its current invasive range while more favourable conditions at higher latitudes would facilitate invasion of both larval and adult stages to the Southern Ocean. Our results show that vigilance is needed to reduce the risk that this ecologically important Arctic carnivore may invade the Southern Ocean and Antarctica.

Prey selection by predators is of interest to community ecologists. By choosing some prey over others, predators affect prey population dynamics and the strength of food webs. According to Optimal Diet Theory (ODT), as prey density increases predators will select more profitable prey. Thereby, prey population dynamics can also affect predator behaviour. Prey profitability involves the prey energetic value, energetic costs associated to predation (time spent searching, capturing and handling prey) and certain characteristics such as body size, abundance and behaviour. We examined the effect of the blue mussel (Mytilus edulis) association with conspecifics at different densities on prey selection and behaviour by the seastar Asterias rubens. Contrary to ODT prediction, when mussels were tightly clumped in high densities, the size range of the mussels consumed by A. rubens did not differ of the size range of the mussel population. Mussel association at high density caused seastars to feed locally, reducing their exposition to risks. Moreover, preying without selecting for a specific mussel size did not result in a decrease of net profit, rather it was increased. We concluded that under certain circumstances, not selecting prey results in an increase of net profit at prey size. We discuss our results in the context of the mussel industry where the effect of prey selection on the prey population dynamics is of importance. Mussel size selection by seastars, as described in previous works, will impact the size distribution of mussels within cultured populations affecting growth of the population and reproductive output among others, thus increasing the impact of seastar predation beyond that of just removing mussels from the population. However, this study shows that seastars prey upon availability at high densities, typically encountered in cultivated populations, and therefore their effect on mussel population is restricted to removal of mussels without affecting the size distribution of the population.

Species distribution models (SDMs) have been increasingly used over the past decades to characterise the spatial distribution and the ecological niche of various taxa. Validating predicted species distribution is important, especially when producing broad-scale models (i.e. at continental or oceanic scale) based on limited and spatially aggregated presence-only records. In the present study, several model calibration methods are compared and guidelines are provided to perform relevant SDMs using a Southern Ocean marine species, the starfish Odontaster validus Koehler, 1906, as a case study. The effect of the spatial aggregation of presence-only records on modelling performance is evaluated and the relevance of a target-background sampling procedure to correct for this effect is assessed. The accuracy of model validation is estimated using k-fold random and spatial cross-validation procedures. Finally, we evaluate the relevance of the Multivariate Environmental Similarity Surface (MESS) index to identify areas in which SDMs accurately interpolate and conversely, areas in which models extrapolate outside the environmental range of occurrence records. Results show that the random cross-validation procedure (i.e. a widely applied method, for which training and test records are randomly selected in space) tends to over-estimate model performance when applied to spatially aggregated datasets. Spatial cross-validation procedures can compensate for this over-estimation effect but different spatial cross-validation procedures must be tested for their ability to reduce over-fitting while providing relevant validation scores. Model predictions show that SDM generalisation is limited when working with aggregated datasets at broad spatial scale. The MESS index calculated in our case study show that over half of the predicted area is highly uncertain due to extrapolation. Our work provides methodological guidelines to generate accurate model assessments at broad spatial scale when using limited and aggregated presence-only datasets. We highlight the importance of taking into account the presence of spatial aggregation in species records and using non-random cross-validation procedures. Evaluating the best calibration procedures and correcting for spatial biases should be considered ahead the modelling exercise to improve modelling relevance., SCOPUS: ar.j, info:eu-repo/semantics/published

Crown-of-thorns seastar (COTS) outbreaks are a major threat to coral reefs. Although the herbivorous juveniles and their switch to corallivory are key to seeding outbreaks, they remain a black box in our understanding of COTS. We investigated the impact of a delay in diet transition due to coral scarcity in cohorts reared on crustose coralline algae for 10 months and 6.5 years before being offered coral. Both cohorts achieved an asymptotic size (16–18 mm diameter) on algae and had similar exponential growth on coral. After 6.5 years of herbivory, COTS were competent coral predators. This trophic and growth plasticity results in a marked age–size disconnect adding unappreciated complexity to COTS boom–bust dynamics. The potential that herbivorous juveniles accumulate in the reef infrastructure to seed outbreaks when favourable conditions arise has implications for management of COTS populations.

13 pages; International audience; AimTo describe and analyse asteroid biogeographic patterns in the Southern Ocean (SO) and test whether reproductive strategy (brooder versus broadcaster) can explain distribution patterns at the scale of the entire class. We hypothesize that brooding and broadcasting species display different biogeographic patterns.LocationSouthern Ocean, south of 45 °S.MethodsOver 14,000 asteroid occurrences are analysed using bootstrapped spanning network (BSN), non-metrical multidimensional scaling (nMDS) and clustering to uncover the spatial structure of faunal similarities among 25 bioregions.ResultsMain biogeographic patterns are congruent with previous works based on other taxa and highlight the isolation of New Zealand, the high richness in the Scotia Arc area particularly of brooding species, an East/West Antarctic differentiation, and the faunal affinities between South America and sub-Antarctic Islands. Asteroids show lower endemism levels than previously reported with 29% of species occurring in Antarctica only. In particular, asteroids from Tierra del Fuego showed affinities with those of West Antarctica at the species level, suggesting a recent mixing of assemblages. Biogeographic patterns are highly linked to reproductive strategy. Patterns also differ according to the taxonomic level, revealing the underlying role of historical factors.Main conclusionsPatterns of sea star biogeography are consistent with results obtained for other marine groups and are strongly linked to reproductive strategy.

The Atlantic saury Scomberesox saurus saurus (Walbaum) is a widely distributed epipelagic nekton species in the north Atlantic. It is considered one of the most abundant small pelagic species in the north Atlantic and is of increasing interest to commercial fisheries in American and European countries. Ageing of Atlantic saury is difficult, annual marks in otoliths, scales and other structures are often not present or are difficult to interpret, resulting in non-robust estimations. Growth of the Atlantic saury, from the northeastern Atlantic Ocean was studied by examining otoliths and scales for the presence of putative annual and daily growth marks. A description of Atlantic saury saggital otolith microstructure is given. No annual structures were observed on scales or otoliths. Counts of otolith micro-increments suggest that Atlantic saury exhibit a much faster growth rate than previously reported. Micro-increment counts ranged from 113 to 258 in fish from 110 mm to 288 mm of body size, suggesting that Atlantic saury is a short lived species. Assuming that otolith growth increments are deposited at a rate of one per day, average growth rates from hatching up to eight months old exceeded 1 mm/day. The saury population available for exploitation in the northeast Atlantic is dominated by fish that are most likely less than one year old. Management of short-lived, forage species require special considerations and represents a challenge to fishery science.

The aim of this study was to test the hypothesis that Atlantic saury stocks from the Mediterranean Sea and northeastern Atlantic could be identified by means of saggital otolith shape. Saury is a pelagic fish inhabiting the north Atlantic that undertakes long migrations for feeding and reproduction. A combination of otolith shape indices and elliptic Fourier descriptors are analysed by multivariate statistical procedures. The results obtained show that saury from the Mediterranean Sea and northeastern Atlantic can be distinguished using otolith shape analysis. Whether or not those differences are due to genetic isolation is not tested here but possible drivers of the observed shape variation are explored.

BackgroundThe Register of Antarctic Marine Species (RAMS, De Broyer et al. 2015) is the regional component of the World Register of Marine Species (WoRMS Editorial Board 2015) in the Southern Ocean. It has been operating for the last ten years, with a special effort devoted towards its completion after the International Polar Year (IPY) in 2007-2008, in the framework of the Census of Antarctic Marine Life (CAML, 2005 - 2010). Its objective is to offer free and open access to a complete register of all known species living in the Southern Ocean, building a workbench of the present taxonomic knowledge for that region. The Antarctic zone defined by this dynamic and community-based tool has been investigated with a particular interest. The Sub-Antarctic zone was a secondary objective during the establishment of the RAMS and is still lacking the impulse of the scientific community for some taxa.New informationIn the present study, more than 13,000 occurrences records of Asteroidea (Echinodermata) have been compiled within the RAMS area of interest and checked against the RAMS species list of sea stars, using WoRMS Taxon Match tool. Few mismatches (basionym mistakes :i.e. original name misspelled or incorrect) were found within the existing list and 97 unregistered species are actually occurring within the RAMS boundaries. After this update, the number of Asteroidea species was increased by around 50%, now reaching 295 accepted species., SCOPUS: ar.j, info:eu-repo/semantics/published

Marine organisms in Antarctica are adapted to an extreme ecosystem including extremely stable temperatures and strong seasonality due to changes in day length. It is now largely accepted that Southern Ocean organisms are particularly vulnerable to global warming with some regions already being challenged by a rapid increase of temperature. Climate change affects both the physical and biotic components of marine ecosystems and will have an impact on the distribution and population dynamics of Antarctic marine organisms. To pre- dict and assess the effect of climate change on marine ecosystems a more comprehensive knowledge of the life history and physiology of key species is urgently needed. In this study we estimate the Dynamic Energy Budget (DEB) model parameters for key benthic Antarctic species the sea star Odontaster validus using available information from literature and experiments. The DEB theory is unique in capturing the metabolic processes of an organ- ism through its entire life cycle as a function of temperature and food availability. The DEB model allows for the inclusion of the different life history stages, and thus, becomes a tool that can be used to model lifetime feeding, growth, reproduction, and their responses to changes in biotic and abiotic conditions. The DEB model presented here includes the esti- mation of reproduction handling rules for the development of simultaneous oocyte cohorts within the gonad. Additionally it links the DEB model reserves to the pyloric caeca an organ whose function has long been ascribed to energy storage. Model parameters described a slowed down metabolism of long living animals that mature slowly. O. validus has a large reserve that—matching low maintenance costs- allow withstanding long periods of starva- tion. Gonad development is continuous and individual cohorts developed within the gonads grow in biomass following a power function of the age of the cohort. The DEB model devel- oped here for O. validus allowed us to increase our knowledge on the ecophysiology of this species, providing new insights on the role of food availability and temperature on its life cycle and reproduction strategy., SCOPUS: ar.j, info:eu-repo/semantics/published

The Register of Antarctic Marine Species (RAMS) is a marine species database that manages an authorita- tive taxonomic list of species occurring in the Southern Ocean. RAMS links with several other initiatives managing biogeographic or genomics information. The current paper aims to briefly present RAMS and provides an updated snapshot of its contents, in the form of a DarwinCore checklist (available through http://ipt.biodiversity.aq/resource.do?r=rams) and illustrative barplots. Moreover, this article presents a ten year appraisal (since the creation of RAMS). This appraisal first focuses on RAMS bibliometrics. We observed that RAMS was cited (Google Scholar) in 50 distinct publications among which 32 were peer- reviewed in 18 different journals. Three journals (Antarctic Science, Polar Biology, ZooKeys) represent al- most 40% of these peer-review publications. The second appraisal focuses on the evolution of new RAMS records. We observed an important decrease in data additions since 2011. As a case study, we focused on an original dataset for a specific group (Asteroidea, Echinodermata). It appears that around one hundred species of asteroids are lacking in RAMS despite the relatively high availability of these data. This suggests that the users’ community (or collaborative projects such as AquaRES) could be helpful in order to main- tain the RAMS database over the long term., SCOPUS: ar.j, info:eu-repo/semantics/published

Reefs play an important role in the distribution of species associated with hard substrates and are of value for biodiversity conservation. High densities of the habitat building annelid Lanice conchilega also increase local biodiversity. This study describes the benthic biodiversity of a rocky reef and its surrounding sand bottom with dense L. conchilega beds in the Borkum Reef Grounds, north of the island of Schiermonnikoog in the Dutch North Sea. A side-scan sonar survey revealed distinct seabed areas with high acoustic reflections, indicating the presence of hard substrate on the sandy seafloor. To ground truth the side-scan sonar data and make an inventory of the biodiversity of the observed habitats, a multi-method sampling approach (box corer, SCUBA airlift sampler and visual transects, drop-down camera) was used. This revealed (1) rocky reefs: a combination of gravel, stones and rocks; (2) individual rocks in a sandy environment; (3) sand with dense L. conchilega beds (> 1500 ind·m − 2 ) and (4) sand bottom habitat. A total of 193 taxa were found with many unique species per habitat. Species richness was significantly higher on sand when compared to the rocky reef (NB-GLM; p = 0.006), caused by the presence of dense L. conchilega beds (Poisson GLM; p L. conchilega beds as an additional habitat showed that these held a higher species richness than the rocky reefs (NB-GLM; p = 0.002), while sand without dense L. conchilega beds did not (NB-GLM; p = 0.14). Since the rocky reefs were present on a sandy bottom, the local biodiversity more than doubled with the presence of rocky reefs. The nMDS plot clearly separated the sand and rocky reef communities and also showed a clustering of dense L. conchilega beds within the sand samples. Each method detected unique species, demonstrating the value of a multi-method approach compared to e.g. box coring alone. This study identified several species previously unknown to the Borkum Reefs Grounds area. The total area of rocky reefs in the southern part of the Dutch Borkum Reef area is estimated to be 9.8 km 2 and of L. conchilega beds with densities > 1500 ind·m − 2 to be 74 km 2 . Further research should focus on the possible function of L. conchilega as an ecosystem engineer creating intermediate sand-reef systems. For mapping these L. conchilega beds, we advise using side-scan sonar imaging combined with ground truthing by drop-down cameras.

Environmental stress plays an important role in determining ecosystem functioning and structure. In estuarine areas both tidal and seasonal salinity changes may cause osmotic stress on predators, affecting their behaviour and survival. The interaction between these predators and their prey may affect performance, thus influencing predator impact on prey populations. The common starfish, Asterias rubens, inhabits estuarine areas, such as the Dutch Wadden Sea, that exhibit large seasonal variation in salinity (10-32 PSU). In those areas A. rubens exerts top down control on its prey, thus representing an important shellfish predator. This predation may impact on cultured and natural shellfish populations. However, the effects of osmotic stress on A. rubens performance may influence its effect on prey. Although the effect of salinity in A. rubens survival has been extensively studied, the impact on its predation behaviour and acclimation capacity remains unclear. In this study, we analyse the performance of A. rubens preying on mussels (Mytilus edulis) after a salinity decrease and monitor its acclimation capacity over a period of 22. days. Our experiments demonstrated that salinity affected performance by reducing feeding activity and altering size prey selection. Moreover, as acclimation occurred, A. rubens predation performance improved in all sub-lethal treatments. We conclude that osmotic stress caused by decreasing salinity potentially influences A. rubens distribution, abundance, and potential impact on prey populations. However the magnitude of the change in salinity (from 31 to a minimum of 10. PSU) and its timescale (3. weeks) mediate this effect. However acclimation occurred.