Michael Thimgan Marine and Estuarine Science Program   Department of Biology MSc completed July 2005 BSc  University of California, San Diego, 1999.                        E-mail:     thimgam@cc.wwu.edu                        Phone:     360-650-7465                        Office:     BI 205                        Mail:        Biology Dept., MS 9160, WWU                                          516 High St.                                          Bellingham, WA 98225-9081

Thesis Project

Title: The effects of wave force and period on the energy expenditure of the intertidal marine gastropod Scutus antipodes.

Abstract: Intertidal organisms must contend with harsh conditions including fluctuating tide levels and changing temperatures, and they must maintain position despite hydrodynamic forces induced by waves.  However, the amount and type of energy needed to maintain position, from either aerobic or anaerobic pathways, is poorly understood.  Laboratory experiments were conducted to assess the use of aerobic and anaerobic metabolism in the marine gastropod Scutus antipodes while subjected to simulated wave forces (0.5 N and 5.0 N) and periods (8 sec and 12 sec).  Baseline resting and active oxygen consumption of S. antipodes were also assessed.  Finally, morphometric measurements were analyzed to determine whether variation in morphology might affect energy expenditure.  The was a significant difference in aerobic energy expenditure in S. antipodes as force increased form 0.5 N to 5.0 N.  There was also a significant difference in the accumulation of the anaerobic metabolite tauropine by S. antipodes as period decreased from 12 to 8 seconds, but not for depletion of arginine phosphate.  Oxygen consumption increased with increasing mass for both resting and active animals, but crawling animals had relatively higher metabolic rates.  Morphometric measurements revealed S. antipodes tends to get relatively lighter but with a larger foot compared to shell length as it grows.  These results indicate that S. antipodes uses both aerobic and anaerobic metabolism to maintain position during wave exposure, and aerobic energy expended to maintain position during low force is similar to that expended during crawling.  Allocation of energy to maintain position potentially limits energy to other important life processes.

This work was accomplished in Australia with the help of Dr. John Baldwin at Monash University and with a grant from the Bureau of Faculty Research at Western Washington University.