@article {6578, title = {Influence of the physiological condition of bivalve recruits on their post-settlement dispersal potential}, journal = {Marine Ecology Progress Series}, volume = {636}, year = {2020}, pages = {77 - 89}, abstract = {Secondary dispersal (= migration) of bivalves occurs after metamorphosis and is a key recruitment process that can radically change patterns of primary settlement. An example of secondary dispersal is active migration behavior of bivalve recruits such as in bysso-pelagic drift. We hypothesize that these active migrations represent an energy cost for recruits and that the ability to actively migrate will depend upon the recruit{\textlnot}{\'\i}s physiological profile (quantity and quality of energy reserves). In lab experiments, we hatched 4 batches of recruits of\ Venus verrucosa\ with different physiological profiles by varying rearing temperature and diet composition. We then introduced these recruits into a fall velocity tube (5 m height) to estimate their vertical fall velocity as a proxy of their dispersal potential: slower fall velocity implies enhanced dispersal potential. We also compared alive vs. passive (dead) recruits to assess behavioral differences. Fall velocity increased logarithmically with recruit volume for each treatment, and no differences between active and passive individuals were observed for batches reared at 20{\textdegree}C with a mixture of\ Tisochrysis lutea\ and\ Chaetoceros gracilis. By contrast, active recruits in 2 other treatments (T. lutea\ at 20{\textdegree}C and a mix of\ C. gracilis\ and\ T. lutea\ at 15{\textdegree}C) significantly decreased their fall velocity regardless of their volume. Moreover, the ability of recruits to control their fall velocity by their behavior was correlated with triglyceride content. Recruits with the highest energy reserves had the greatest capacity to decrease their fall velocity, which suggests a major role of physiological conditions on potential secondary dispersal. We also used a benthic flume to test the substrate selection ability of recruits depending on their physiological profile and found no differences between physiologically different batches. However,\ V. verrucosa\ recruits preferred fine sediments, unlike adults, which live mainly in coarse sediment habitats; such difference in substrate preference suggests potential secondary migrations between nursery and adult areas.}, keywords = {Behavior, Bivalves recruits, Energetic reserves, Physiology, secondary migrations, Venus verrucosa}, issn = {0171-8630}, doi = {10.3354/meps13223}, url = {https://www.int-res.com/abstracts/meps/v636/p77-89}, author = {Martin For{\^e}t and Fr{\'e}d{\'e}ric Olivier and Miner, P and Gesche Winkler and Nadalini, J-B and R{\'e}jean Tremblay} } @article {6916, title = {An integrated investigation of the effects of ocean acidification on adult abalone (Haliotis tuberculata)}, journal = {ICES Journal of Marine Science}, volume = {77}, year = {2020}, month = {Sep-01-2020}, pages = {757 - 772}, type = {research article}, abstract = {Ocean acidification (OA) and its subsequent changes in seawater carbonate chemistry are threatening the survival of calcifying organisms.Due to their use of calcium carbonate to build their shells, marine molluscs are particularly vulnerable. This study investigated the effect of CO2-induced OA on adult European abalone (Haliotis tuberculata) using a multi-parameter approach. Biological (survival, growth), physiological (pHT of haemolymph, phagocytosis, metabolism, gene expression), and structural responses (shell strength, nano-indentation measurements,Scanning electron microscopy imaging of microstructure) were evaluated throughout a 5-month exposure to ambient (8.0) and low (7.7) pH conditions. During the first 2 months, the haemolymph pH was reduced, indicating that abalone do not compensate for the pH decrease of their internal fluid. Overall metabolism and immune status were not affected, suggesting that abalone maintain their vital functions when facing OA. However, after 4 months of exposure, adverse effects on shell growth, calcification, microstructure, and resistance were highlighted, whereas the haemolymph pH was compensated. Significant reduction in shell mechanical properties was revealed at pH 7.7, suggesting that OA altered the biomineral architecture leading to a more fragile shell. It is concluded that under lower pH, abalone metabolism is maintained at a cost to growth and shell integrity. This may impact both abalone ecology and aquaculture.}, keywords = {Abalone, calcification, Gene Expression, Growth, mechanical properties, Ocean acidification, Physiology, shell microstructure}, issn = {1054-3139}, doi = {10.1093/icesjms/fsz257}, url = {https://academic.oup.com/icesjms/article/77/2/757/5699268}, author = {Avignon, Sol{\`e}ne and St{\'e}phanie Auzoux-Bordenave and Martin, Sophie and Dubois, Philippe and Badou, Aicha and Coheleach, Manon and Richard, Nicolas and Di Giglio, Sarah and Malet, Lo{\"\i}c and Servili, Arianna and Gaillard, Fanny and Huchette, Sylvain and Roussel, Sabine} } @article {6665, title = {Digestive enzyme ratios are good indicators of hatchling yolk reserve and digestive gland maturation in early life stages of cuttlefish Sepia officinalis L.: application of these new tools in ecology and aquaculture}, journal = {Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology}, volume = {188}, year = {2018}, pages = {57-76}, abstract = {In Sepia officinalis (Linnaeus, 1758), the digestive gland matures during the first month post-hatching, while a shift from intracellular acid to extracellular alkaline digestion occurs. The purpose of this study was to investigate the possibility of using enzymatic ratios for the description of digestive system maturation in early life stages of S. officinalis. Second, it is intended to apply these new tools as eco-physiological indicators for understanding the impact of cuttlefish eggs{\textquoteright} life history from different spawning sites of the English Channel on digestive performance of juveniles. An experimental rearing was performed over 35\ days after hatching (DAH) on juveniles from wild collected eggs in 2010 and 2011. Four digestive enzyme activities and their ratios [i.e., trypsin, cathepsin, acid (ACP), and alkaline (ALP) phosphatase, ALP/ACP, and trypsin/cathepsin] were studied along with histological features (e.g., internal yolk surface and digestive gland development). The two enzyme ratios were good indicators of digestive system maturation allowing the study of the digestive gland{\textquoteright}s development. They were highly correlated to juveniles{\textquoteright} weight increase and histological features of the gland in early DAH. These ratios described more accurately the shift occurring between the intracellular acid and the extracellular alkaline modes of digestion in S. officinalis and were more specific than separated enzyme activities. Their application as eco-physiological tools revealed that enzyme ratios reflected yolk content and digestive gland development in new hatching juveniles. Finally, ALP/ACP ratio was shown to be a powerful tool to describe growth performance of S. officinalis which is useful for aquaculture optimization. {\textcopyright} 2017, Springer-Verlag GmbH Germany.}, keywords = {Acid Phosphatase, alkaline phosphatase, anatomy and histology, animal, Animals, Aquaculture, cathepsin, Cathepsins, cuttlefish, Gastrointestinal Tract, Physiology, Sepia, Trypsin}, issn = {01741578}, doi = {10.1007/s00360-017-1115-4}, url = {https://link.springer.com/article/10.1007\%2Fs00360-017-1115-4}, author = {Safi, Georges and Anne-Sophie Martinez and Le Pabic, Charles and Le Bihan, E and Jean-Paul Robin and Koueta, Noussith{\'e}} }