S1-1.2 Jan. 4 A star on the rise: how temperature affects distribution and abundance of sea stars on the coast of Maine. PRATT, Marney C.; University of New England, Biddeford, ME firstname.lastname@example.org
There are two species of sea stars in the genus Asterias that are common on the east coast of North America. The northern species, A. rubens (=vulgaris), has historically dominated the intertidal in Maine, but recent observations suggest that the southern species, A. forbesi, is beginning to dominate some sites. I am investigating the effects of temperature on these two species of sea stars to determine whether climate change may be affecting their distributions. Specifically, I measured growth, respiration, and feeding rates in these two species at a warm (18°C) and cool (8°C) temperature. While there is no difference in respiration rates between species within a temperature treatment, respiration is higher for both species at 18°C than at 8°C. Growth and feeding rates were similar between species at the cooler temperature, but A. forbesi grew significantly faster and ate more at the warmer temperature. Not only did A. rubens grow much slower and eat less at 18°C, survival was also much lower at this temperature. While sea surface temperatures do not stay at 18°C for months at a time in the local waters of Casco Bay, it is not an uncommon temperature in the summer. Thus, growth and survival is likely to be lower for A. rubens in the intertidal in the summer and this may allow the A. forbesi population to expand more than it was able to in the past when summer water temperatures were cooler. In addition, since the feeding rate of A. forbesi is higher in warmer temperatures, this important predator may have a stronger impact than A. rubens in shaping the rocky intertidal community during the summer months.