The Effects of Long-Term Exposure to Multiple Stressors on Biochemical Pathways of the Blue Mussel
Sessile marine invertebrates in the rocky intertidal zone are subject to a unique and dynamic environment, with both short term, daily tidal fluctuations, and longer term, seasonal changes. The mechanisms and strategies of biochemical adaptations of intertidal organisms, such as the blue mussel, Mytilus edulis, are not fully understood, especially when the environmental stressors are chronic, and a result of anthropogenic climate change’s impact on intertidal communities. Previous study of short-term (1 hour) exposure found the effect of temperature alone, which showed increased aerobic response (measured by Citrate Synthase (CS) activity), and a significant antagonistic relationship between anaerobic response (measured by cytosolic malate dehydrogenase (cMDH)) and combined predation risk and food availability effects. In this study, the impact on subcellular physiology of long-term exposure to biotic and abiotic stressors will be assessed in M. edulis, in order to understand physiological trends not manifesting in acute exposure. In a two-level factorial experiment, M. edulis collected off the coast of Nahant, MA (n = 240) were exposed to combinations of food availability (fed or starved), increased water temperature (16°C or 18.5°C) , and risk of predation (predator cue or lack thereof) resulting in eight treatment groups. Six mussels were exposed and sampled from treatment groups at time points of 1, 2, 6 and 12 weeks (T1, T2, T3, and T4 respectively, n = 48 for each). Physiological response will be measured by CS and cMDH activity, as well as glycogen abundance (to assess energy storage). This study aims to elucidate the mechanism of survival strategies over chronic exposure to stressors in Mytilus edulis, an important, economically valuable, ecosystem engineer.