Particle counter for ecophysiological studies of benthic filter-feeders

In this proposal, I request funds to purchase an instrument to count the number and size of particles that are suspended in seawater. This equipment will be used to study the feeding behaviour of organisms that live on the seafloor such as mussels, oysters and tunicates (sea squirts). These so-called filter-feeders feed by straining small food particles from water, typically by passing the water over a specialized filtering structure. Filter feeders play a critical role in coastal ecosystems, and can provide key ecosystem services. For example, mussels and oysters may be grown for food, and it is widely recognized that their filtration activity improves water quality. Other filter-feeders, such as some sea squirts, are invasive species that can rapidly proliferate and out-compete natural populations of filter-feeders, thus compromising the ability of native species to continue supporting coastal ecosystems. This is a well-known problem in mussel and oyster farming, where invasive sea squirts can rapidly enter and dominate the system, and negatively impact the economic viability of the aquaculture sector. Despite the importance of filter-feeders in coastal ecosystems, some critical aspects of their feeding behaviour are still not clear. The particle counting instrument that I propose to purchase will improve our understanding of the feeding behaviour of mussels, oysters and two species of invasive sea squirts. My research will determine (1) the size and type of particles that these species can effectively retain in their filtering structures, (2) their feeding rates and behaviour under different environmental conditions, and ultimately (3) their potential impact on the ecosystem. This will be achieved by performing experiments with the instrument in the field and under controlled conditions in the laboratory, for example, to explore the effect of the temperature on feeding rates. The information we collect will be used for multiple scientific and management purposes. For example, by comparing the number and size of particles in seawater directly before and after it passes through filter feeders, we will be able to determine what size of particles that they can effectively retain, a question that is still under discussion. The knowledge that my research team will generate with this instrument will improve our ability to manage Canadian coastal zones. For example, we will be able to (1) explore the impact of mussel and oyster aquaculture on the environment and consequently provide recommendations to guarantee the sustainability of this important economic activity; (2) simulate predicted climate change in the laboratory and explore the potential of invasive sea squirts. Ultimately, this work will contribute to improving effectiveness of coastal zone management in Atlantic Canada, and help to promote improved aquaculture practices worldwide.