Effects of Seagrass on the Benthic Distribution of Copepod Resting Eggs

To avoid unfavorable seasonal conditions, some species of calanoid copepods produce resting eggs that do not immediately hatch. When buried in the sediment, these eggs can remain viable from weeks to years, and therefore can represent a potentially important source of recruits to the pelagic population over various time scales. Copepod resting eggs tend to behave similarly to other fine particles in the water column and will accumulate in areas of high deposition and low resuspension. Seagrass beds are known to be environments that promote the accumulation of fine sestonic particles by inhibiting resuspension but have not been previously investigated as possible reservoirs for copepod resting eggs. Three years of field sampling on a shallow reef in the northern Gulf of Mexico has revealed that viable resting eggs of the copepod Acartia tonsa are significantly more abundant in seagrass-colonized sediment than in adjacent unvegetated sediment, even during times of the year when the seagrass canopy is low. Enhanced egg accumulation in seagrass sediment appears to be the result of unique biological, physical, and chemical characteristics within that environment. Seagrass beds may therefore be important accumulation sites for resting copepod eggs in shallow areas subjected to frequent disturbance, and seagrass loss could have significant impacts on local populations reliant on recruitment from resting eggs.