Volume 7, Number 1, 1997

On Research

Positive role for sea slime

Beginning life as insect-like microscopic larvae, young crabs float in the water at the mercy of currents, winds and tides. Then suddenly, as if on cue, the larvae settle to the bottom of the bay and metamorphose into miniatures versions of the adult crab.

Marine biologist Charles Epifanio and an interdisciplinary team of scientists at the College of Marine Studies want to discover how the newly hatched crab larvae identify a suitable nursery habitat. Preliminary research on the mud crab (Panopeus herbstii) indicates that certain biological films, or slimes, may be the cue that convinces the larvae to settle to the bottom to begin their transformation.

Epifanio and fellow researchers Nancy Targett, David Kirchman and Ana Dittel hope to pinpoint the irresistible chemical attractant in the films and determine exactly how this signal reaches the crabs. First, they will determine if microorganisms in the films release a water-soluble cue that the larvae sense or if the crab larvae must actually touch the biofilm to receive the chemical cue.

Next, the group proposes to identify which component of the biofilm produces the cue and the exact chemical nature of the cue.

Abundant in estuaries from Cape Cod to Cape Hatteras, the common mud crab has been identified as a predator of young oysters and clams. Epifanio's team hopes to provide new information about the life history of mud crabs that may be applicable to other economically important species such as the blue crab, while also illuminating the powerful role that biofilms play in attracting such organisms as barnacles and tubeworms to settle.

-Tracey Bryant