Meeting Abstract

48.5  Jan. 6  Timing of colonial ascidian life cycle offset by warmer winter water temperatures in the Gulf of Maine WESTERMAN, E.L.*; HARRIS, L.G. ; BOLKER, J.A.; DIJKSTRA, J; University of New Hampshire; University of New Hampshire; University of New Hampshire; University of New Hampshire erica.westerman@unh.edu

Temperature and its effects on life cycles in organisms�particularly those of invasive species� have received great attention in recent times due to heightened awareness of global warming. To compare effects of rising ocean temperatures on native vs. recently arrived species, we monitored the relative growth and reproductive development in two dominant species of ascidians from the Gulf of Maine: Botrylloides violaceus, a recent invader; and Botryllus schlosseri, an established non-native species. Panels deployed at three sites with different temperature regimes (Damariscotta, ME, Newcastle, NH, and Salem, MA) allowed us to monitor growth and reproductive development for two years. Settlement panels deployed at the same sites supported a recruitment study from May through December, 2006. Average water temperatures were highest in Salem, Mass and lowest in Newcastle, NH, with those of Damariscotta, ME lying in the middle. Winter water temperatures were warmer during 2005-2006 than 2004-2005; spring and early summer temperatures were comparable. Earlier growth and settlement was exhibited by both species at all sites during the spring of 2006, which may be a result of warmer winter water temperatures. Similar temporal patterns of growth were found for both species throughout the sites, however those of the northern, colder sites were offset from those at Salem. During 2006, both species recruited to panels in MA over a month earlier than those in ME and NH. These results suggest that though temperature may not shape ascidian life cycles, it may be a driving force behind their annual starting time.