Ecophysiology of Marine Bivalves : Physiological Rate Processes in Dynamic Environments

Graduation date: 2016Marine bivalves are globally recognized as ecologically and commercially valuable species and, for over a century, researchers have been studying their feeding, digestion and other related physiological processes. These studies have shown that marine bivalves have complex feeding and particle processing behaviors to maximize growth in dynamic environmental conditions. Additionally, these studies have provided insights into the ecological roles that these animals can play in coastal waters. Suspension-feeding bivalves are commonly regarded as providing key ecosystem services through their feeding activities that improve water quality and clarity. However, marine bivalves are currently under threat from a variety of anthropogenic effects and there is concern about their future health under these new stresses. Here I examined several unexplored aspects of adult and larval bivalve feeding physiology in an attempt to better understand environmental effects on their feeding activity and ecosystem services. In Chapter 2, my co-authors and I examined the ecological feeding physiology of native Olympia oysters Ostrea lurida by determining their feeding and particle processing behavior in response to the effects of temperature, salinity, and total particulate matter. We examined and compared these processes to those of the non-native yet dominant commercial oyster species, the Pacific oyster Crassostrea gigas. From these studies, we describe the first modern detailed feeding behavior of O. lurida. We found that, although markedly different in laboratory studies, in situ feeding rates were similar between these species seasonally. We concluded that bivalve filtration services are likely to be greater with the emergence of C. gigas as the now dominant species in many PNW estuaries and seasonally much greater than the services historically contributed by O. lurida. In Chapters 3, my co-authors and I examined the particle processing behavior of bivalve larvae. This study was novel in that it utilized methods of our own design to examine the rarely evaluated post-oral particle processing behavior of larvae that historically has been difficult to measure. Additionally, it represented the first attempt at modeling larval guts as chemical reactors to provide insights into their digestive strategies. In Chapter 4, we again applied these novel techniques to evaluate the effects of ocean acidification on ingestion rates and particle processing of larvae of the California mussel Mytilus californianus. These data were applied to a simple larval energy budget to understand how impacts of ocean acidification on initial larval development may affect their subsequent development rates. The outcomes of these experiments provide useful information on feeding and particle processing activities of the adult and larval life stages of marine bivalves and the effects of environmental factors, such as ocean acidification