A disaster for the ​Pisaster​? Temperature effects on Ochre sea star larval development

Abstract

Marine ecosystems are threatened by climate change. Sea surface temperatures are rising as a result of global warming, which may influence the larval development and survival rates of many species. Decreasing the quantity of successful larvae, especially for keystone species such as ​Pisaster ochraceus ​(Ochre sea star)​, ​has the potential to disrupt the predator-prey balance in a variety of habitats. The sea star wasting disease that passed through the west coast of the United States in 2013 greatly impacted populations of a variety of sea stars, notably that of the Ochre sea star, and emphasized the importance of sea star presence in intertidal ecosystems. By rearing ten day old ​P. ochraceus ​larvae in three different temperatures for a week, this study examines the growth, survival, and cloning rate of Echinoderm larvae in response to elevated sea surface temperatures. Larvae residing in temperatures of 20.15°C +/- 2.65°C experienced the highest mortality rates and fastest growth, while larvae in local San Juan Island, WA, temperatures (9.13°C +/- 0.47°C) exhibited the lowest mortality rates and slowest growth. A temperature range of 15.58°C +/- 1.48°C produced intermediary growth and mortality rates, although the success of the latter is comparable to that of local temperatures. Medium temperatures induced the highest frequency of asexual reproduction. There was no difference between the cloning rate of high temperature and low temperature larval cultures. This study concludes that due to the exhibited larval sensitivity to temperature changes, it is possible ​P. ochraceus ​may experience population shifts or geographic redistribution as a result of sea surface temperature rise.