Assessing the vulnerability of endangered and endemic brooding sea urchin Cassidulus mitis in response to climate change: Impacts on larvae and settlers in the southwestern Atlantic

Abstract

Echinoderms play important roles in marine ecosystems and exhibit high sensitivity to environmental changes. The echinoid Cassidulus mitis has been considered an endangered species due to its restricted geographic distribution and unique reproductive behavior, with an epibenthic lecithotrophic larva and offspring brooded among the female spines during initial development until the settler stage. We studied the effects of low salinities (30 and 26) and high temperatures (27 and 31 °C) on the early development of C. mitis in a predicted scenario of global climate change through four parameters: 1. survival and 2. chronology of larval development, and 3. survival and 4. growth of settlers. Both larvae and settlers of C. mitis can survive under these scenarios, probably due to the lecithotrophic and epibenthic larval characteristics and developmental strategies of this species. However, all experimental conditions affected at least one of the initial developmental studied parameters of C. mitis, potentially compromising the species' viability in a scenario of climate change.