Following the oil spill accident of the Solar I tanker in 2006 off the coast of Guimaras Island in the Philippines, polycyclic aromatic hydrocarbons (PAHs) and alkylated PAHs in some aquatic organisms were investigated at Luzaran in Guimaras and Taklong Islands, which were heavily polluted with spilled oil, immediately and 1 month after the accident. The concentrations of total PAHs were 11.9-52.3 ng/g dry weight in fish. Meanwhile, total PAH concentrations in shellfish were 38.0-3,102 ng/g dry weight in Luzaran and 128-236 ng/g dry weight in Taklong. Pyrene, phenanthrene, and fluoranthene were dominant in most fish and chrysene in all shellfish. Significantly higher concentrations of all alkylated homologs were detected in shellfish than in fish. These differences had two possible causes, that is, the differences between fish and shellfish could be attributed to the uptake routes and/or their metabolizing abilities.

SUMMARYAntennules have been reported to influence localization of distant food odors, sex discrimination, and agonistic and social behaviors of decapod crustaceans. Although olfaction by the antennules is largely recognized, information on the sensitivity of antennules to hydrodynamic stimuli has been scant. In red swamp crayfish Procambarus clarkii antennules, mechanosensory setae outnumber the chemosensory setae. We studied the mechanosensitivity of crayfish antennules by recording neural activities from isolated antennules in response to sinusoidal dipole stimuli. Both the lateral and the medial flagellum of the antennules responded to hydrodynamic stimuli, although the medial flagellum showed more sensitivity at frequencies higher than 60Hz. The most dominant setae present on the stimulated site were the simple setal type. Although both lateral and medial flagella are capable of detecting chemical and hydrodynamic cues, results from neural responses, morphological observations and antennular behavior observations indicate that the lateral flagellum of P. clarkii functions as an olfactory organ whereas the medial flagellum complements as a hydrodynamic receptor. It appears that in crayfish antennular sensory processing, crayfish simultaneously use chemical and hydrodynamic information. We have compared our data with the threshold of fish lateral line to the same stimuli and we discuss probable similarities in response properties.

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