Meeting Abstract
Intertidal organisms live in one of the most physiologically stressful habitats on the planet. Daily tidal cycles result in predictable, often severe fluctuations in abiotic factors (e.g., temperature, oxygen, salinity, pH). The relative magnitude and degree of variability of environmental stress, however, differs between intertidal zones, with the most extreme physiological stress likely experienced by high intertidal organisms. We therefore hypothesize that sessile conspecifics from different intertidal positions (i.e., low, mid, high) will have distinct ‘metabolic phenotypes’ (i.e., baseline metabolic capacity and performance). To investigate this hypothesis, we collected common acorn barnacles, Balanus glandula, from low, mid and high intertidal zones in San Luis Obispo Bay, CA and measured a suite of biochemical (lactate dehydrogenase and citrate synthase activity), physiological (O2 consumption rates, body size), and behavioral (cirri beat frequency, time operculum open) measurements at a common seawater temperature; 13°C in an attempt to characterize distinct intertidal position-driven metabolic phenotypes. Preliminary data revealed that high intertidal barnacles reach larger body sizes and have greater size-corrected oxygen consumption rates than those in the mid or low intertidal. Further, high intertidal barnacles have lower cirri beat frequencies and tend to remain open longer than barnacles in the mid and low zones. (Biochemical enzyme assays are currently underway.) These initial data support the idea of distinct metabolic phenotypes across the intertidal, and may suggest that B. glandula from different tidal positions have variable capacities to accommodate environmental change.
