Ocean acidification reshapes the otolith-body allometry of growth in juvenile seabream

International audienceThe effects of elevated CO2 partial pressure (pCO2) on otolith calcification and on the coupling between the somatic and otolith growth were investigated in juvenile gilthead seabream Sparus aurata. Six-month old individuals were raised during seven weeks under four pCO2 conditions set according to projected future ocean acidification scenarios. Body and otolith biometric parameters were measured throughout the experiment along with the otolith biomineralization monitored using a radiotracer technique based on 45Ca incorporation. Seabream exhibited somatic growth resilience to all treatments. In contrast, increased growth rate and shape complexity of otoliths were observed with a pHT drop from 8.1 to 7.5. Hypercalcification was observed under lowered pH, with a rate of calcium incorporation increasing by up to 18% between pHT 8.1 and pHT 7.7. This work highlighted an uncoupling of otolith and body growth of juvenile seabream within 40 d at pHT 7.9 projected to be reached by the end of the century. As the otolith is an essential tool used in reconstructing fish life history, this work suggests that information resulting from otolith studies should be interpreted with caution with respect to the potential impacts that ocean acidification projected modifications could have on otolith biomineralization

Ocean acidification and temperature rise: effects on calcification during early development of the cuttlefish Sepia officinalis

This study investigated the effects of seawater pH (i.e., 8.10, 7.85 and 7.60) and temperature (16 and 19 °C) on (a) the abiotic conditions in the fluid surrounding the embryo (viz. the perivitelline fluid), (b) growth, development and (c) cuttlebone calcification of embryonic and juvenile stages of the cephalopod Sepia officinalis. Egg swelling increased in response to acidification or warming, leading to an increase in egg surface while the interactive effects suggested a limited plasticity of the swelling modulation. Embryos experienced elevated pCO2 conditions in the perivitelline fluid (>3-fold higher pCO2 than that of ambient seawater), rendering the medium under-saturated even under ambient conditions. The growth of both embryos and juveniles was unaffected by pH, whereas 45Ca incorporation in cuttlebone increased significantly with decreasing pH at both temperatures. This phenomenon of hypercalcification is limited to only a number of animals but does not guarantee functional performance and calls for better mechanistic understanding of calcification processes

Natural geochemical markers reveal environmental history and population connectivity of common cuttlefish in the Atlantic Ocean and Mediterranean Sea

Natural markers (delta C-13 and delta O-18 stable isotopes) in the cuttlebones of the European common cuttlefish (Sepia officinalis) were determined for individuals collected across a substantial portion of their range in the Northeast Atlantic Ocean (NEAO) and Mediterranean Sea. Cuttlebone delta C-13 and delta O-18 were quantified for core and edge material to characterize geochemical signatures associated with early (juvenile) and recent (sub-adult/adult) life-history periods, respectively. Regional shifts in cuttlebone delta C-13 and delta O-18 values were detected across the 12 sites investigated. Individuals collected from sites in the NEAO displayed more enriched delta C-13 and delta O-18 values relative to sites in the Mediterranean Sea, with the latter also showing salient differences in both markers among western, central and eastern collection areas. Classification success based on cuttlebone delta C-13 and delta O-18 values to four geographical regions (NEAO, western, central and eastern Mediterranean Sea) was relatively high, suggesting that environmental conditions in each region were distinct and produced area-specific geochemical signatures on the cuttlebones ofS. officinalis. A modified delta C-13 and delta O-18 baseline was developed from sites proximal to the Strait of Gibraltar in both the NEAO and Mediterranean Sea to assess potential mixing through this corridor. Nearly, all (95%) of delta C-13 and delta O-18 signatures ofS. officinaliscollected in the area of the NEAO closest to the Strait of Gibraltar (Gulf of Cadiz) matched the signatures of specimens collected in the western Mediterranean, signifying potential movement and mixing of individuals through this passageway. This study extends the current application of these geochemical markers for assessing the natal origin and population connectivity of this species and potentially other taxa that inhabit this geographical area.Portuguese Foundation for Science and Technology: IF/00576/2014info:eu-repo/semantics/publishedVersio

Cuttlefish conservation: a global review of methods to ameliorate unwanted fishing mortality and other anthropogenic threats to sustainability

Cuttlefish are an important global fisheries resource, and their demand is placing increasing pressure on populations in many areas, necessitating conservation measures. We reviewed evidence from case studies spanning Europe, Africa, Asia, and Australia encompassing diverse intervention methods (fisheries closures, protected areas, habitat restoration, fishing-gear modifications, promoting egg survival, and restocking), and we also discuss the effects of pollution on cuttlefish. We conclude: (1) spatio-temporal closures need to encompass substantial portions of a species’ range and protect at least one major part of their life cycle; (2) fishing-gear modifications have the potential to reduce unwanted cuttlefish capture, but more comprehensive trials are needed; (3) egg survival can be improved by diverting and salvaging from traps; (4) existing lab rearing and restocking may not produce financially viable results; and (5) fisheries management policies should be regularly reviewed in light of rapid changes in cuttlefish stock status. Further, citizen science can provide data to reduce uncertainty in empirical assessments. The information synthesized in this review will guide managers and stakeholders to implement regulations and conservation initiatives that increase the productivity and sustainability of fisheries interacting with cuttlefish, and highlights gaps in knowledge that need to be addressed

Incorporation des métaux dans les œufs de la seiche commune Sepia officinalis et effets potentiels sur les fonctions digestives et immunitaires

The common cuttlefish Sepia officinalis makes large reproductive migrations in spring to mate and spawn in coastal waters. The eggs are laid in shallow waters and are therefore likely subjected to the anthropogenic contaminations leading to potential toxicity effects of metals during the embryonic development. In this study, cuttlefish eggs revealed efficient accumulation capacities following exposure to 9 dissolved radiotracers (110mAg, 241Am, 109Cd, 57Co, 134Cs, 203Hg, 54Mn, 210Pb and 65Zn) all along the development time. In this context, the eggshell played a key role in the accumulation process, as the greatest fraction of most of these elements remained associated with its glycoproteic components. The radiotracers distribution showed that the eggshell acts as an efficient shield against trace element penetration during organogenesis, i.e. during the first month of development. A selective permeability of the eggshell appeared during the last stages of the development, i.e when the embryo growth began until hatching. The trace element capacities to diffuse through the eggshell seemed to be dependent of their chemical properties and of the biological processes of the embryogenesis. Thus, metals could be accumulated in the embryo with various affinities (i.e. Ag >> Zn > Hg > Mn > Co ≈ Cd > 134Cs ≠ 241Am, Pb).All along the development time, the exposure of the eggs to Ag, Cd and Cu (1, 0.5 and 250 µg.l-1, respectively) in experimental conditions showed no effect on the egg growth and did not induce abnormalities or mortality in embryos, confirming the protective role of the eggshell during organogenesis. However, during the last developmental stages, Ag and Cd reduced the acid phosphatase activities, which are involved in the digestive processes, whereas Cu acted as an activator. Moreover, phenoloxidase-like activity, which is here reported in the embryo for the first time, was modulated during the post-organogenesis phase, following exposure to dissolved Ag and Cu.Despite the protective role of the eggshell during the organogenesis, trace elements would be accumulated in the embryo during the first developmental stages following their maternal transfer in the egg. In this context, radiotracers technique highlighted that the maternal transfer was a selective way, 1) with only Ag, Se and Zn being transferred following a dietary exposure of the female to 110mAg, 241Am, 109Cd, 60Co, 134Cs, 54Mn, 75Se and 65Zn, and 2) Se and Zn being incorporated in the vitellus whereas Ag was found in similar proportions in the vitellus and in the eggshell.Au printemps, la seiche commune Sepia officinalis effectue des migrations du large vers la côte pour se reproduire et mourir. La ponte a lieu en zone côtière, sujette à la contamination métallique d'origine anthropique, ce qui pose la question de la toxicité des éléments traces sur le développement embryonnaire. Dans ce travail, l'exposition à neuf radiotraceurs (110mAg, 241Am, 109Cd, 57Co, 134Cs, 203Hg, 54Mn, 210Pb et 65Zn) durant toute la durée du développement révèle que l'œuf de seiche possède de grandes capacités de bioaccumulation des éléments traces. Dans ce contexte, la capsule glycoprotéique de l'œuf joue un rôle majeur en fixant la plus grande proportion de ces éléments. La distribution des radiotraceurs dans l'œuf montre que cette capsule constitue une barrière protectrice contre la pénétration des métaux depuis la ponte jusqu'à la fin de l'organogenèse. Cependant, lorsque la phase de croissance de l'embryon et de l'œuf commence, la capsule montre progressivement une perméabilité sélective aux éléments traces jusqu'à l'éclosion. La disposition des composants de la capsule à les laisser diffuser à travers les différentes enveloppes qui la composent semble dépendante des propriétés chimiques des éléments traces mais aussi des processus biologiques liés à l'embryogenèse. Ainsi, certains éléments pénètrent dans l'œuf et s'accumulent dans l'embryon avec une affinité variable (i.e. Ag >> Zn > Hg > Mn > Co ≈ Cd > 134Cs ≠ 241Am, Pb).Des expositions sur le long terme à l'Ag, au Cd et au Cu dissous (1, 0,5 et 250 µg.l-1, respectivement) en condition expérimentale, n'ont aucun effet sur la croissance de l'œuf et n'induisent ni malformation, ni mortalité des embryons, confirmant l'effet protecteur de la capsule pendant les stades sensibles de l'embryogenèse. Néanmoins, pendant la période de croissance de l'embryon, l'Ag et le Cd semblent ralentir l'augmentation de l'activité des phosphatases acides, impliquée dans les processus digestifs alors que le Cu révèle un effet stimulateur. De même, l'activité de type phénoloxydase, impliquée dans les fonctions immunitaires des Invertébrés, décrite pour la première fois dans l'embryon de seiche, est modulée par l'Ag et le Cu, lors de la phase post-organogenèse. Malgré le rôle protecteur de la capsule durant l'organogenèse, les éléments traces peuvent s'accumuler dans les embryons dès les premiers stades de développement du fait de leur apport par transfert maternel. Dans ce contexte, l'utilisation des radiotraceurs montre que le transfert de la mère à l'œuf est sélectif, 1) seuls l'Ag, le Se et le Zn étant transférés suite à une exposition de la mère par de la nourriture marquée au 110mAg, à l'241Am, au 109Cd, au 60Co, au 134Cs, au 54Mn, au 75Se et au 65Zn et 2) le Se et du Zn étant stockés dans le vitellus de l'œuf alors que l'Ag se retrouve à la fois dans le vitellus et la capsule

Ecotoxicology of early-life stages in the common cuttlefish Sepia officinalis: review and perspectives

International audienceCephalopods, and among them, the cuttlefish Sepia officinalis, are well-known to highly accumulate both organic and inorganic contaminants in their tissues. According to their ecology, embryonic and juvenile development occurs in coastal waters and is thus particularly subjected to anthropogenic contaminants. Considering that these early life stages are relatively long compared to the total life span of cuttlefish (i.e. 2 months of embryogenesis and 1 month of maturing juvenile life vs. 12 to 18 months of life span), the exposure of eggs and juveniles to contaminants may affect the ontogenesis and development of these earliest stages and impact their recruitment success. This paper reviews the sparse knowledge on the effects of contaminants on embryonic development and juvenile life. The embryos which are surrounded by an eggshell are partly protected against dissolved metal accumulation, but may be subjected to maternally transferred contaminants. Moreover, this bioaccumulation capacity could be affected by the physiological responses of embryos to the environmental variations such as seawater warming or hypercarbia. When hatched, juveniles can accumulate contaminants from waterborne, sediment and dietary pathways. Food appears to be the main source of contamination for most metallic contaminants. The digestive gland is known as being the main organ of detoxification and storage in adult cephalopods but in embryos and juveniles, the immaturity of the digestive system raises the question of its efficiency to cope with the toxic effects of contaminants during these early life stages. To date, a couple of studies have highlighted the sublethal effects of metals, e.g Ag, Cd, Zn, and pharmaceuticals, e.g. fluoxetine, on digestive, immune and neural systems, with consequences on growth and behaviour