Meeting Abstract

P3.62  Wednesday, Jan. 6  Broad physiological tolerances of the invasive clam, Nuttallia obscurata WITTES, J.S.*; DONOVAN, D.A.; Swarthmore College, Pennsylvania; Western Washington University jwittes@gmail.com

Nuttallia obscurata has spread rapidly through Puget Sound and the Strait of Georgia since it was introduced from Asia to the Eastern Pacific Ocean in the late 1980s. This species has been found living in regions of broadly varying salinity. We investigated how N. obscurata responds to hyposmotic, hyperosmotic, and thermal stress in order to determine whether broad physiological tolerances play a key role in its success as an invasive species, and also to make predictions about areas in the Eastern Pacific that may be at risk of being colonized. Clams were acutely exposed to salinities ranging from 1 – 60 ppt at 13°C and 20°C. Hemolymph osmolality and gill tissue hydration were monitored over two weeks. We found that N. obscurata tolerates an exceptionally broad range of salinities. It osmoconforms at salinities ranging from 10 – 50 ppt, and osmoregulates at 1 and 5 ppt. Patterns of osmoregulation and osmoconformity were the same at both temperatures. Gill tissue hydration ranged from 81 – 90 % water content and decreased significantly at higher salinities. Temperature did not significantly affect gill tissue hydration. Given the breadth of this species’ salinity tolerance and its distribution in more temperate waters in Asia, this clam may have the potential to extend its range south along the coasts of Oregon and California.