Research

Biological Oceanography

Algal blooms, Anti-fouling treatments, Biofouling, Biology, Ecosystem dynamics, Fouling Dynamics, Microbial ecology, Oxygen minimum zones, Phytoplankton ecology, Suboxic ecology. 

In the marine environment, biofouling is the natural settlement of live organisms on solid structures in seawater. Although the process contributes to the productivity of coastal waters, it also leads to the unwanted accumulation of organic material on submerged surfaces that perform better or last longer when kept clean. Every sailor is familiar with the recurrent cleaning of barnacles from the hull of a vessel, whether an 8-foot skiff or 1000-foot car carrier. Various underwater instruments, cameras and sensors require frequent cleaning as well to maintain proper functioning and prevent corrosion. In the past, toxic coatings were applied, but their potent indiscriminate attack on live organisms meant that many bystanders were adversely affected, mostly plant and animals living in the water column or on the seafloor in harbors. The development of efficacious but environmentally friendly coatings requires a strong understanding of the biofouling process at different time scales, and adequate testing of experimental surfaces that takes into account the targeted organisms, the structures to be outfitted, and exposure to relevant environmental conditions.
The marine biofouling program at GSO aims to document the adhesion steps of micro- and macro-fouling communities. One of the goals of the program relates to the adequate testing of environmentally friendly coatings or surface treatments. A special emphasis is currently placed on the evaluation of the anti-fouling performance of experimental surfaces requiring maintenance of particular functions, such as optical clarity or material flexibility. The program not only addresses the identification of organisms with traditional microscopes, it also includes the use of a molecular fingerprinting technique to differentiate microbial communities very early in the biofilm formation. This allows for the rapid screening of coatings or materials for their potential anti-fouling properties by comparison with untreated surfaces. Test structures are either directly immersed in Narragansett Bay water for short or long-term exposures in all seasons, or maintained in continuous-flow systems permitting temperature and light manipulations. Evaluation of anti-fouling properties is also accomplished by exposure of test materials to a standard seaweed assay using sea lettuce spores. The spores are produced in spring and summer by local populations around Narragansett Bay. Once released into the water, the spores quickly seek favorable surfaces to adhere to. Thus, low concentrations of settled spores on test materials indicate excellent anti-fouling properties, at least against this notorious fouling seaweed. We collaborated with engineers to develop an assay particularly relevant for testing the efficacy of a type of slippery coating called ‘foul-release’ that is used on moving structures. This assay, named calibrated water-jet system assay (patent application pending), quantitatively evaluates biofilm removal by relating water pressure at the point of impact with vessel speed. Thus one would know how fast a vessel, or underwater instrument, or a glider needs to travel to maintain a clean surface.