SUBLETHAL PREDATION - FIELD-MEASUREMENTS OF ARM TISSUE LOSS FROM THE OPHIUROID MICROPHIOPHOLIS-GRACILLIMA AND IMMUNOCHEMICAL IDENTIFICATIONOF ITS PREDATORS IN NORTH INLET, SOUTH-CAROLINA, USA
Pa. Papelindstrom et al., SUBLETHAL PREDATION - FIELD-MEASUREMENTS OF ARM TISSUE LOSS FROM THE OPHIUROID MICROPHIOPHOLIS-GRACILLIMA AND IMMUNOCHEMICAL IDENTIFICATIONOF ITS PREDATORS IN NORTH INLET, SOUTH-CAROLINA, USA, Marine ecology. Progress series, 156, 1997, pp. 131-140
A daily rate of sublethal predation of arm tissue of the burrowing amp
hiurid brittlestar Microphiopholis gracillima (Stimpson) was determine
d by experimental field manipulation. A concurrent field predator surv
ey documented the ingestion of arm tissue by invertebrate and vertebra
te predators. Fish, shrimps and crabs were collected by seining and tr
awling in Debidue Creek, North Inlet, South Carolina, USA. Gut content
s of these predators were examined both visually and immunochemically
to determine presence or absence of arm tissue. Of white shrimp guts t
ested, 88% were positive for M. gracillima arm tissue, while 70 % of b
lue crab guts and 39 % of brown shrimp guts tested positive. Several f
ish species and hermit crab species were found to prey on the brittles
tar arm tissue less frequently or in lesser quantities. To determine t
he daily sublethal predation rate, individual brittlestars of known ar
m length were emplaced subtidally in Debidue Creek, retrieved after ei
ther 24 or 72 h, and then had their arm tissue remeasured. Loss of bri
ttlestar arm tissue was statistically measurable over a 24 h period re
lative to laboratory controls. Brittlestars held for 32 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 b
rittlestar(-1) was calculated for the late summer/early fall period. T
rophic 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 seconda
ry production in other systems.