NSF-IOS-BSF: Mediation of biological filtration in marine suspension feeders: significance of intrinsic and extrinsic factors

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Filter-feeding marine animals such as bivalve molluscs (e.g., clams, oysters, scallops) and sea squirts are among the most important members of bottom-dwelling communities, both for their environmental impacts and commercial value. Their feeding processes strongly couple organisms in the water-column with those on the bottom, and can influence the general "health" of near-shore ecosystems. In this research, scientists from the University of Connecticut will collaborate with scientists in Israel and Canada to study filter feeding using a combination of field and laboratory experiments. Using their previously developed methods and innovative approaches, scientists will examine, with unprecedented accuracy and resolution, the full range of planktonic cells that filter feeders can capture, and address fundamental questions regarding physiological control (or lack thereof) of particle feeding. One of the novel aspects of the research is that scientist will determine if particle capture by the animal responds to changes in the types of planktonic cells available, or if capture is a consequence of the characteristics of the cells themselves (e.g., size, shape, surface properties). Results of this research will enable better predictions of the types of plankton that are and are not filtered efficiently, provide insight into the factors that influence particle capture, help define the food resources of bottom-dwelling filter feeders in different environments, and strengthen existing models regarding competition between different species of filter feeders and their influence on the community structure of plankton in near-shore ecosystems. The project will involve high-school, undergraduate and graduate students, and will develop educational packages for home-school and marine-science educators. This project will investigate the plasticity of particle capture in two groups of invertebrate suspension-feeders (bivalves, tunicates) and determine if the process can be mediated by intrinsic (behavioral, physiological) or extrinsic (particle properties) factors. The work focuses on feeding because of the primacy of this process in determining fitness. Specifically, researchers will determine if particle capture responds to changes in the number and types of planktonic cells available (i.e., plasticity), or if capture is a consequence of the physicochemical properties of the cells (e.g., size, shape, surface charge, wettability). They will employ their previously developed methods and innovative approaches to study suspension feeding using a combination of in situ techniques, controlled dock-side experiments, in vivo laboratory assays, flow cytometry, and DNA barcoding by means of Illumina sequencing. The combined application of these methods will allow researchers to examine, with unprecedented accuracy and resolution, the full range of planktonic cells that suspension-feeders capture, and address fundamental questions regarding physiological control of particle capture (or lack thereof) under different particle spectra and, thus, changing food supplies. In the process, they will re-examine the paradigm that biological filtration of plankton is mostly controlled by particle size. Results of the study will enable better predictions of the types of plankton that are and are not captured efficiently, provide insight into the factors influencing mechanisms of particle capture, help define the food resources of mesotrophic and oligotrophic suspension-feeders, and strengthen existing models regarding interspecific competition and impacts of suspension-feeders on microbial community structure of the seston.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.