Effects of oil pollution on hydroid behavior and neurophysiology

The hydroids, Tubularia crocea and Myrionema hargitti are sensitive organisms for assessing the effects of oil pollution. The abilities of these hydroids to capture Artemia nauplii were reduced after 1 hr exposure to a water-soluble fraction (WSF) of Monterey Formation crude oil. Algal symbionts within Myrionema contribute photosynthetically-fixed carbon to the host hydroid. No significant effects upon these symbionts were noted after 1 or 3 h but significant reductions in the mitotic index, photosynthesis and carbon translocation rates were observed after a 24-48 h exposure to 100% WSF. Myrionema hargitti was less responsive to mechanical stimuli after a brief 100% WSF exposure. The responsiveness to a feeding stimulant (proline) and concert frequency of 100% WSF-treated Tubularia crocea were lower than controls. Significant increases in epithelial activity were also recorded at 1% WSF and the increased firing frequency did not persist beyond the duration of the exposure. Bioaccumulation of 3H-toluene (20 ppm) from 100% WSF reached a maximum within 1 min but declined over the next hour. Higher concentrations of 3H-toluene evoked increased hydranth shedding with 1 h but these hydranths never accumulated as much 3H-toluene as hydranths exposed to lower concentrations