University of Connecticut
Department of Marine Sciences

Dr. J. Evan Ward, Professor

Related Links: University of Connecticut Department of Marine Sciences Marine Sciences Major

 

 

 

Research Initiatives

Sampling on LISResearch in my laboratory is directed towards an understanding of the dynamic interactions between marine animals and their environment. In particular, my work focuses on the endogenous and exogenous factors that mediate the behavior and physiology of benthic, particle-feeding invertebrates.

My students and I take an integrative approach in our research program by studying processes ranging from the organism to ecosystem level. Much of this research focuses on commercially important bivalves such as clams, oysters, mussels and scallops. These animals are key components of most coastal ecosystems, provide vital ecosystem services, and are an important link between the oceans and human health.

Our work is funded by grants from the National Science Foundation, National Oceanographic & Atmospheric Administration (Oceans and Human Health Initiative & CT Sea Grant), and US Department of Agriculture. For more information about my work with Oceans and Human Health (OHH), please see the I-RICH web site.

I. Interactions Between Marine Aggregates and Benthic Suspension Feeders: Living and non-living particulate matter is ubiquitous in aquatic systems. Through physical, chemical and biological interactions, this particulate matter aggregates into larger particle masses (marine snow, flocs). Aggregation of particles is an important mechanism for the transport of carbon, nutrients, and other materials to the benthos where large populations of suspension feeders often thrive. Our work on the interaction of aggregates and suspension feeders can be divided into three areas of focus.

Underwater Research in Bermudaa. Aggregates, TEP and benthic pelagic coupling - The traditional concept of benthic-pelagic coupling by suspension feeders involves the removal of phytoplankton and other particles from the water column, deposition of feces and pseudofeces to the bottom, and conversion of food material for animal production. Recently, we have described another possible mechanism by which coupling could occur. This mechanism involves production of transparent exopolymer particles (TEP) by suspension feeders, and enhanced aggregation and deposition of material to benthic populations. This process may represent an important but under-studied process that impacts water column processes and the fate of organic matter in near-shore waters.   [Give Me the Details]

b. The ecological role of marine aggregates in linking pathogens to molluscan shellfish (an OHH Linkage) - In this study we are focusing on the role of aggregates as a link between pathogens (e.g., protistan & prokaryote) and bivalve shelllfish. Because aggregates are ubiquitous in the marine environment, benthic organisms (e.g., bivalves) are exposed to a steady supply of aggregates and the various microorganisms contained within. Results from our studies over the past few years support the hypotheses that aggregates can serve as: 1) reservoirs when they serve to concentrate marine pathogens within their matrix; and 2) vectors when they serve to enhance the capture efficiency of smaller pathogens (e.g., bacteria, zoospores) by the gills, thus increasing exposure to the bivalve host. This research is being conducted in collaboration with scientists at Old Dominion University, University of Minnesota, and University of Georgia.   [Give Me the Details]

II. Exposure of Bivalve Molluscs to Nanomaterials and Microplastics - Uptake and Effects: Emerging contaminants such as manufactured nanomaterials and microplastics are of growing concern in the marine environment, not only because they can directly impact resident organisms, but also because they can potentially be transferred to humans via the food chain. Research in my laboratory is examining the ingestion and accumulation of these materials by bivalves, and their subsquent effects. Understanding uptake and depuration kinetics will allow us to begin assessing the risk such materials pose to humans who consume shellfish.     

Culturing Microalgae in the Laba. Uptake and impact of nanomaterials (an OHH Linkage) - Manufactured nanoparticles and nanotubes are at the forefront of nanotechnology and are being used in a variety of applications including cosmetics, electronics, drug delivery, molecular biology, and paints. Several types of nanoparticles have been shown to have harmful effects on some aquatic species, but the way in which nanoparticles are taken up by aquatic organisms has been little studied. In this project, we are considering how feeding limitations of several bivalve species affect their uptake of nanoparticles, and determining how the form of delivery (freely suspended or incorporated in aggregates) mediates bioavailability, retention, and thus internal exposure. This work is being conducted in collaboration with Rob Mason (Department of Marine Sciences) and Bryan Huey (Department of Chemical, Materials, & Biomolecular Engineering).   [Give Me the Details]

III. Feeding Behavior and Physiology of Bivalve Molluscs: In this line of research, my students and I are addressing fundamental questions regarding suspension feeding mechanisms. We are studying bivalve species that possess different gill architectures, which translate to differences in the way in which particles are handled by the pallial organs. This research direction can be divided into two areas of focus.

Examining scallop with endoscopea. Elucidating particle capture & selection mechanisms in bivalves - In this project, we are applying previously developed techniques of feeding physiology and biochemistry to examine the bases of particle capture and selection at the cell and organ level. Our work focuses on the most plausible mechanisms involved in the feeding process, and includes: a) manipulating particle surfaces to determine if selection is a function of surface properties (charge, wettability, stickiness); and b) investigating whether lectins in gill and labial-palp mucus bind to carbohydrate residues of the extracellular matrix of phytoplankton to mediate capture and selection. Results from this research are providing a better understanding of feeding processes in different species of bivalves and the potential impact of bivalves on coastal environments. This study is being conducted in collaboration with Sandra Shumway, another faculty member in the Department of Marine Sciences, and scientists at Stony Brook University.   [Give Me the Details]

Studying bivalve with PIVb. Functional mechanisms of control in the bivalve pump - Using our recently developed Pressure-Gape System, Video Endoscopy, and Particle Image Velocimetry (PIV) we are investigating the physiological bases of water pumping and particle feeding in bivalve molluscs. Experiments are designed to determine relationships between valve gape and pumping rate (volume flux), investigate mechanisms by which bivalves alter pumping activity, test the hypothesis that bivalve pumping activity is mediated by exogenous factors, and examine the variation in pumping behavior and performance among several bivalve species. Our research has the potential to resolve some of the long standing controversies regarding the physiological basis of water processing in bivalves. This study is being conducted in collaboration with Sandra Shumway, another faculty member in the Department of Marine Sciences, and scientists at the University of Louisiana.   [Give Me the Details]



Note: Research material is based upon work supported by the NSF, NIH, & NOAA. Any opinions, findings and conclusions, or recommendations expressed in this material are those of the author and do not necessarily reflect the views of these agencies.