Effects of ocean-acidification-induced morphological changes on larval swimming and feeding

• Published in: Journal of Experimental Biology
• Main Authors: Chan, Kit Yu Karen, Grünbaum, Daniel, O'Donnell, Michael J.
• Format: Text
• Language: English
• Published: Company of Biologists 2011
• Subjects: Research Articles; Ocean acidification
• Online Access: http://jeb.biologists.org/cgi/content/short/214/22/3857; https://doi.org/10.1242/jeb.054809

Reduction in global ocean pH due to the uptake of increased atmospheric CO 2 is expected to negatively affect calcifying organisms, including the planktonic larval stages of many marine invertebrates. Planktonic larvae play crucial roles in the benthic–pelagic life cycle of marine organisms by connecting and sustaining existing populations and colonizing new habitats. Calcified larvae are typically denser than seawater and rely on swimming to navigate vertically structured water columns. Larval sand dollars Dendraster excentricus have calcified skeletal rods supporting their bodies, and propel themselves with ciliated bands looped around projections called arms. Ciliated bands are also used in food capture, and filtration rate is correlated with band length. As a result, swimming and feeding performance are highly sensitive to morphological changes. When reared at an elevated P CO2 level (1000 ppm), larval sand dollars developed significantly narrower bodies at fourand six-arm stages. Morphological changes also varied between four observed maternal lineages, suggesting within-population variation in sensitivity to changes in P CO2 level. Despite these morphological changes, P CO2 concentration alone had no significant effect on swimming speeds. However, acidified larvae had significantly smaller larval stomachs and bodies, suggesting reduced feeding performance. Adjustments to larval morphologies in response to ocean acidification may prioritize swimming over feeding, implying that negative consequences of ocean acidification are carried over to later developmental stages.