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Census of Marine Life, Census of Coral Reefs Expedition to French Frigate Shoals (October 2006)

Light Traps

Lead Scientist: Russel Brainard
Target Habitats: Water column
Target Organisms: Planktonic larvae and adults

Description:
"Light traps" of various designs have been used for years to collect marine fishes and invertebrates, especially their larvae and other zooplankton at night.

Target taxa will include various planktonic crustaceans such as mysids, cumaceans, isopods, as well as marine worms (should small fish get caught, there will be little chance of mortality and they will be released). Many planktonic organisms navigate by and are attracted to light, and this method takes advantage of that fact. Light traps can be deployed by tying them to any other structure that is going to be in the water at night or they can have their own bottom weight. The light traps will either be attached to the ship or deployed by divers for careful placement of the light trap anchors. The traps themselves will not be on the bottom. It is best that they hang in the water column just below the surface. They will need to be deployed for only a couple of hours at a time after sunset. The organisms they are intended to catch will be in the upper meter or so of the water after dark, and usually for only a few hours. Although a large variety of designs have been used successfully over the years, we will use a simple and commercially available design that consists of a black PVC body with four openings lined by plastic funnels. Plankton enter via the wide end of the funnel and become trapped within the PVC body. Lighting is achieved by inserting either disposable cyalume "light sticks" or a small underwater flashlight into the trap. "Aquatic Light Trap" have been used successfully in the Caribbean. (Doherty 1987; Holmes & O’Connor 1988; Watson, et. al 2002)

Zooplankton illustrations above by Mark J. Rauzon

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Additional resources

• Plankton

Ship Logs:
Day-by-day activities of the expedition.

Journals:
Daily or semi-daily personal journal entries by the particpants in the expedition. These journals do not necessarily reflect the positions of any of the agencies connected with this project.

Interviews:
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