Gene Expression Patterns of Red Sea Urchins (Mesocentrotus Franciscanus) Exposed to Different Combinations of Temperature and pCO2 During Early Development

Abstract

<jats:title>Abstract</jats:title> <jats:p><jats:bold>Background: </jats:bold>The red sea urchin <jats:italic>Mesocentrotus franciscanus</jats:italic> is an ecologically important kelp forest herbivore and an economically valuable wild fishery species. To examine of how <jats:italic>M. franciscanus</jats:italic> responds to its environment on a molecular level, differences in gene expression patterns were observed in embryos raised under combinations of two temperatures (13 °C and 17 °C) and two <jats:italic>p</jats:italic>CO<jats:sub>2</jats:sub> levels (475 matm and 1050 matm). The transcriptomic responses of the embryos were assessed at two developmental stages (gastrula and prism) in light of previously described plasticity in body size and thermotolerance under these temperature and <jats:italic>p</jats:italic>CO<jats:sub>2</jats:sub> treatments.<jats:bold>Results: </jats:bold>Although transcriptomic patterns primarily varied by developmental stage, there were pronounced differences in gene expression as a result of the treatment conditions. Temperature and <jats:italic>p</jats:italic>CO<jats:sub>2</jats:sub> treatments led to the differential expression of genes related to the cellular stress response, transmembrane transport, metabolic processes, and the regulation of gene expression. Temperature had a greater influence on gene expression than <jats:italic>p</jats:italic>CO<jats:sub>2</jats:sub>, and may have contributed to positive effects of temperature on body size and thermotolerance at the prism stage. On the other hand, a relatively muted transcriptomic response to <jats:italic>p</jats:italic>CO<jats:sub>2</jats:sub> may have permitted the stunting effect of elevated <jats:italic>p</jats:italic>CO<jats:sub>2</jats:sub> on embryo body size.<jats:bold>Conclusions: </jats:bold><jats:italic>M. franciscanus</jats:italic> exhibited both transcriptomic and phenotypic plasticity in response to temperature and <jats:italic>p</jats:italic>CO<jats:sub>2</jats:sub> stress during early development. As climate change continues, red sea urchins<jats:italic> </jats:italic>may benefit from moderate ocean warming, whereas they will be negatively affected by ocean acidification. Present-day <jats:italic>p</jats:italic>CO<jats:sub>2</jats:sub> conditions that occur due to coastal upwelling may already be detrimental to populations of <jats:italic>M. franciscanus</jats:italic>.</jats:p>