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Images: Barnacles and Biofilms

WHOI biochemist Ben Van Mooy is applying his interest in biofilms to the problem of biofouling, the accumulation of barnacles, algae, and other organisms on ship hulls. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)
Within a day of entering seawater, a ship hull acquires a thin coating of bacteria—the beginnings of a slimy biofilm that larger organisms such as algae and barnacles can attach to. The biofilm along the waterline of this boat is probably several weeks old. (Photo by Jim Canavan, Woods Hole Oceanographic Institution)
Fouling organisms drive up operating expenses by increasing frictional drag on the hull and propellers. Fouling of the rudder can also interfere with the ship's ability to maneuver. This ship, photographed in 1943, was overdue for a session in drydock. (Robert H. Cole, Woods Hole Oceanographic Institution Archives)
As seen during its 2012 visit to drydock, the hull of R/V Atlantis carried patchy accumulations of barnacles and algae. WHOI ships are put into drydock twice in every five-year period for routine maintenance, including removal of fouling organisms. (Photo by Dutch Wegman, Woods Hole Oceanographic Institution)
A worker uses a high-pressure jet of water to clean organisms from the propeller of R/V Atlantis during the ship's period of drydocking in 2012. Removal of biofouling organisms can also occur while the ship is in the water, although access is more difficult. "Almost annually, the Knorr crew requests that we bring in divers and polish the propellers again," said WHOI Marine Engineer Theo Moniz. "They actually gain speed by that." (Photo by Dutch Wegman, Woods Hole Oceanographic Institution)
Even internal parts of a ship suffer from biofouling. This grate on R/V Atlantis covers the inlet where seawater is drawn into pipes to cool the ship's mechanical systems. The grate keeps large organisms from entering the pipes, but small ones, including larval barnacles, can still enter, and the grate itself can develop a heavy encrustation of fouling organisms. This photo was taken while the ship was in drydock in November, 2012. The grate is low on the starboard bow; another one is on the port bow. (Photo by Dutch Wegman, Woods Hole Oceanographic Institution)
Oceanographers fight a never-ending battle against fouling organisms that attach to their instruments, moorings, and buoys, as well as to ships. This Nootka buoy, which is designed to receive acoustic data signals from instruments on the seafloor, had just been recovered after being in the cool waters off Vancouver Island for about 13 months. (Photo by Norman Farr, Woods Hole Oceanographic Institution)
This piece of wood is riddled with holes made by soft-bodied clams known as shipworms. Steel, the material of choice for ship hulls since the mid- to late 1800s, is worm-proof but vulnerable to fouling by algae, barnacles, and other organisms that attach to hard surfaces. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)
In an earlier experiment by Van Mooy's lab, WHOI research associate Byron Pedler prepared to suspend a biofilm test plate just below the surface of the water in Vineyard Sound. Each test plate bore strips of hull material coated with an antifouling paint or a fouling-release paint, or left uncoated. Here, at the beginning of the experiment, all the strips were clean and free of biofilm. (Photo by Ben Van Mooy, Woods Hole Oceanographic Institution)
After a short time in the water—a few weeks in winter, several days in summer—a test plate becomes covered with a biofilm, a slimy coating of bacteria and compounds they exude. Small algae (green strands) have attached to the biofilm on this plate. Note that the red strips, which were coated with a copper-based antifouling paint, are mostly free of biofilm. Both the green strips, which had no special coating, and the gray strips, which were coated with a fouling-release paint, are covered with biofilm. (Photo by Ben Van Mooy, Woods Hole Oceanographic Institution)
Photomicrographs of ship hull biofilms from one of Van Mooy's tests. The yellow and red spots are microbial cells; the red spots indicate cells that contain chlorophyll, such as algae. The left panel shows a copper-based anti-fouling coating with just a few cells adhering to it. The right panel shows a fouling-release coating with abundant cells and the mucilaginous slime that they secreted. The difference in color between the two panels is due to the way light from the microscope interacted with the two coatings. (Photomicrographs by Ben Van Mooy, Woods Hole Oceanographic Institution)
WHOI research associate Justin Ossolinski built narrow tanks that allowed scientist Ben Van Mooy to bathe bacteria-covered plates in a small volume of continuously flowing seawater. The plates had been placed in Vineyard Sound until a robust biofilm of microbes developed. Then they were brought into the lab and placed in the tanks. By selectively filtering out specific kinds of cells, Van Mooy was able to determine the rates of cell settling, proliferation, detachment, and predation on the biofilm. (Photo by Tom Kleindinst, Woods Hole Oceanographic Institution)
Biofilms form when bacteria settle onto a hard surface (1), where they proliferate and produce slime (2). Most efforts to fight biofouling have targeted these steps. WHOI biochemist Ben Van Mooy thinks a better approach might be to enhance the processes that naturally reduce the size of biofilms: detachment of some of the bacteria (3) and predation by protists (4). (Illustration by Jack Cook, Wood Hole Oceanographic Institution)
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