MEPS 156:131-140 (1997)  -  doi:10.3354/meps156131

A daily rate of sublethal predation of arm tissue of the burrowing amphiurid brittlestar Microphiopholis gracillima (Stimpson) was determined by experimental field manipulation. A concurrent field predator survey documented the ingestion of arm tissue by invertebrate and vertebrate predators. Fish, shrimps and crabs were collected by seining and trawling in Debidue Creek, North Inlet, South Carolina, USA. Gut contents of these predators were examined both visually and immunochemically to determine presence or absence of arm tissue. Of white shrimp guts tested, 88% were positive for M. gracillima arm tissue, while 70% of blue crab guts and 39% of brown shrimp guts tested positive. Several fish species and hermit crab species were found to prey on the brittlestar arm tissue less frequently or in lesser quantities. To determine the daily sublethal predation rate, individual brittlestars of known arm length were emplaced subtidally in Debidue Creek, retrieved after either 24 or 72 h, and then had their arm tissue remeasured. Loss of brittlestar arm tissue was statistically measurable over a 24 h period relative to laboratory controls. Brittlestars held for 72 h in the field lost 3 to 4 times more arm tissue than those exposed to predation for only 24 h. An average daily sublethal loss rate of 20 mm arm tissue brittlestar^-1 was calculated for the late summer/early fall period. Trophic transfer due to sublethal predation on this individual species of brittlestar in Debidue Creek ranges between 3.3 and 9.7 g AFDW m^-2 yr^-1, an amount equivalent to total community macrobenthic secondary production in other systems.

Sublethal predation · Ophiuroid · Immunoassay · Secondary production