TP6 Effects of PAHs: Predicting Field Effects from Lab Studies
Room 18A/B, Level 4
2:10 PM - 5:30 PM, Tuesday, 11 November 2003
Chair: Hellou, Jocelyne ,
(293) Foraging behavior of Australian seastars (Echinodermata) exposed to oil-contaminated sediment.
Ryder, K1, Holdway, D1, Temara, A1, 1 RMIT University, Melbourne, Victoria, Australia
ABSTRACT- The present study exposed starved Asterias amurensis (introduced species) and Coscinasterias muricata (native species) to oiled-sediment, followed by testing of their foraging behavior when presented with either control or oiled mussels (Mytilus edulis) as a food source. During exposure to oiled sediment over 11 days, foraging behavior was tested on days 1 and 11 for A. amurensis, and days 1, 4, and 11 for C. muricata. The clean versus oiled mussels used as prey were placed at 0o in an 80cm-diameter circle (marked in 30o intervals on the bottom of a glass tank for behavioral observations). There were two replicate tanks (each containing 6 randomly selected seastars) for each of the three treatment levels (control, low oil, and high oil). All seastars were starved for 47 days before their use in experiments and were given a maximum of 12 minutes to either contact the mussels or for their disk′s to leave the circle. Sediment samples from each treatment were stored at −80oC and later analyzed for oil-content (
g/g oil equivalents) by UVF-spectrophotometry. Foraging behavior was quantified using circular statistics. Results differed between species. Exposure of A. amurensis to oiled-sediment and/or oiled-mussels diminished their foraging success relative to the control-seastars. Following oiled-sediment exposure, A. amurensis located more oiled-mussels than control-mussels. C. muricata′s exposure to oiled-sediment and/or oiled-mussels did not dramatically alter their foraging success. However, results indicated that oil interfered with C. muricata′s ability to locate prey and/or distinguish between oiled and unoiled prey. C. muricata′s avoidance of highly oiled-sediment decreased with the age of the sediment, whereas A. amurensis did not avoid the oiled-sediment. Observations support the theory that oil interferes with both species′ ability to locate prey and/or distinguish between oiled and unoiled prey.
Key words: oil, echinoderm, sediment, foraging behavior