Sea Star Wasting Disease in Pisaster Ochraceus on the Washington Coast and in Puget Sound

<em>Pisaster ochraceus </em>is a common west coast sea star whose predation of <em>Mytilus californianus </em>(the California mussel) increases the biodiversity of its intertidal community. Sea star wasting disease is an illness that causes sea star tissues to become necrotic until the creature wastes away and dies. In 2013, a coast wide outbreak of sea star wasting disease caused a mass mortality event in <em>P. ochraceus. </em>The goals of this study were to try to identify some of the possible causes for the outbreak, as well as analyze the impact that sea star wasting disease prevalence has on biodiversity. In this study, forty tide pools in four different regions of Washington State (northern coast, southern coast, northern Puget Sound, and southern Puget Sound) were surveyed for Shannon biodiversity, species richness, abundance of <em>P. ochraceus, </em>percentage of <em>P. ochraceus </em>infected with sea star wasting disease, total dissolved solids, pH, alkalinity, and salinity. Four separate statistical models were performed testing percentage of <em>P. ochraceus </em>with sea star wasting disease, presence of sea star wasting disease, Shannon biodiversity, and species richness as the response variable. Nothing was statistically significant for presence of sea star wasting disease, percentage of <em>P. ochraceus </em>with sea star wasting disease, and species richness. However, Shannon biodiversity had a positive correlation with abundance of <em>P. ochraceus </em>and a negative correlation with percentage of <em>P. ochraceus </em>with sea star wasting disease. This negative correlation suggests that the mere presence of sea star wasting disease is enough to negatively influence <em>P. ochraceus </em>populations by disabling their ability to eat, which drives down biodiversity. The data suggests that even before a sea star dies; it is not functioning as a predator. <em> </em>However, neither location nor water quality appeared to influence biodiversity or sea star wasting disease, which suggests that further research should be conducted on these variables and others to try to identify a causal agent for these outbreaks.

Name thesis:degree_name

Master of Science (MS)

Discipline thesis:degree_discipline

Biology

Year dc:date.available

2019

Author dc:creator

• Wilkes, Caitlin

Contributors dc:contributor

• Lixing Sun
• Paul W. James
• Clay Arango

• community ecology
• tide pool
• virology
• sea star
• biodiversity
• Life Sciences

Language dc:language

English

Repository record dc:identifier

https://digitalcommons.cwu.edu/etd/1189

OAI identifier oai:identifier

oai:digitalcommons.cwu.edu:etd-2235