The impacts of past, present and future ocean chemistry on predatory planktonic snails

Abstract

The atlantid heteropods represent the only predatory, aragonite shelled zooplankton. Atlantid shell production is likely to be sensitive to ocean acidification (OA), and yet we know little about their mechanisms of calcification, or their response to changing ocean chemistry. Here, we present the first study into calcification and gene expression effects of short-term OA exposure on juvenile atlantids across three pH scenarios: mid-1960s, ambient and 2050 conditions. Calcification and gene expression indicate a distinct response to each treatment. Shell extension and shell volume were reduced from the mid-1960s to ambient conditions, suggesting that calcification is already limited in today's South Atlantic. However, shell extension increased from ambient to 2050 conditions. Genes involved in protein synthesis were consistently upregulated, whereas genes involved in organismal development were downregulated with decreasing pH. Biomineralization genes were upregulated in the mid-1960s and 2050 conditions, suggesting that any deviation from ambient carbonate chemistry causes stress, resulting in rapid shell growth. We conclude that atlantid calcification is likely to be negatively affected by future OA. However, we also found that plentiful food increased shell extension and shell thickness, and so synergistic factors are likely to impact the resilience of atlantids in an acidifying ocean.

Diversity and genetic connectivity of heteropod (Pterotracheoidea) gastropods in the Tropical Eastern Pacific

“…Pelagic gastropods are an important and underappreciated component of marine zooplankton, which have garnered recent attention because of their importance in the ocean carbon cycle (Baumann et al, 2003;Bednaršek et al, 2012Bednaršek et al, , 2014Buitenhuis et al, 2019;Fabry, 1990;Fortier et al, 1994) and the vulnerability of their aragonitic shells to ocean acidification (Bednaršek et al, 2016;Manno et al, 2017;Wall-Palmer et al, 2021). Pelagic gastropods are ecologically important as herbivores and predators in the plankton (Bernard & Froneman, 2009;Hunt et al, 2008;Lalli & Gilmer, 1989;Sato-Okoshi et al, 2010;Wall-Palmer et al, 2016).…”