Effect of increased pCO2 level on early shell development in great scallop (Pecten maximus Lamarck) larvae

[摘要] As a result of high anthropogenic CO₂ emissions, the concentration ofCO₂ in the oceans has increased, causing a decrease in pH, known asocean acidification (OA). Numerous studies have shown negative effects onmarine invertebrates, and also that the early life stages are the most sensitiveto OA. We studied the effects of OA on embryos and unfed larvae of the greatscallop (Pecten maximus Lamarck), at pCO₂ levels of 469 (ambient), 807, 1164, and 1599 μatmuntil seven days after fertilization. To our knowledge, this isthe first study on OA effects on larvae of this species. A drop inpCO₂ level the first 12 h was observed in the elevatedpCO₂ groups due to a discontinuation in water flow to avoid escape ofembryos. When the flow was restarted, pCO₂ level stabilized and wassignificantly different between all groups. OA affected both survival andshell growth negatively after seven days. Survival was reduced from 45%in the ambient group to 12% in the highest pCO₂ group. Shell lengthand height were reduced by 8 and 15%, respectively, when pCO₂increased from ambient to 1599 μatm. Development of normal hinges wasnegatively affected by elevated pCO₂ levels in both trochophore larvaeafter two days and veliger larvae after seven days. After seven days,deformities in the shell hinge were more connected to elevatedpCO₂ levels than deformities in the shell edge. Embryos stained withcalcein showed fluorescence in the newly formed shell area, indicatingcalcification of the shell at the early trochophore stage between one andtwo days after fertilization. Our results show that P. maximus embryos and earlylarvae may be negatively affected by elevated pCO₂ levels within therange of what is projected towards year 2250, although the initial drop inpCO₂ level may have overestimated the effect of the highestpCO₂ levels. Future work should focus on long-term effects on thisspecies from hatching, throughout the larval stages, and further into thejuvenile and adult stages.

[学科分类] 地球化学与岩石