EFFECTS OF SEDIMENT-BOUND POLYCYCLIC AROMATIC-HYDROCARBONS ON FEEDING-BEHAVIOR IN JUVENILE SPOT (LEIOSTOMUS-XANTHURUS LACEPEDE, PISCES)

Juvenile spot (Leiostomus xanthurus Lacepede) feed by obtaining sedime nt and manipulating it in its buccal cavity to remove meiobenthic prey . As meiofaunal densities increase, spot increase their number of feed ing strikes and manipulation (processing) time. We used these behavior s to determine the effects of sediment contaminated with polycyclic ar omatic hydrocarbons (PAH) on the ability of spot to use meiofauna as p rey. Laboratory experiments were conducted with produced-water (at 22 mg PAH kg(-1) dry sediment) and diesel-contaminated (at 122 mg PAH kg( -1) dry sediment) sediments. In an avoidance experiment (at 22 ppm PAH ), spot were allowed to choose between contaminated and uncontaminated sediment in the same aquarium to determine if they were capable of de tecting and avoiding PAH. Based on the location and pattern of feeding strikes, spot did not avoid contaminated sediments. Two selectivity e xperiments were conducted to determine whether sediment-bound PAH inte rfere with spot's ability to locate and utilize high-density patches o f meiofauna. In sediments contaminated at 22 ppm PAH, significant diff erences were found among meiofauna densities in mean per-strike proces sing times. Cumulative processing time (a function of per-strike proce ssing time and the number of strikes) was not affected by 22 ppm PAH. Burrowing avoidance by meiofauna may have contributed to a non-signifi cant increase in feeding strikes in contaminated sediment. At 122 ppm PAH, cumulative processing time significantly decreased in contaminate d sediments due to decreased feeding strikes. Seven out of ten fish st opped feeding before the end of 30 min feeding trials, probably due to a narcotic effect of PAH released into the water column as sediments were resuspended during feeding. Spot did not alter feeding behavior a t moderate-high PAH concentrations, which puts them at risk for both s ublethal and lethal effects - immune-system suppression, reduced growt h, endocrine disorders, fin erosion, skin lesions, cataracts, and ulti mately death. (C) 1998 Elsevier Science B.V.