Naphthalene disrupts pheromone induced mate search in the amphipod Corophium volutator (Pallas).

Many crustaceans communicate with pheromones during mating. In the infaunal amphipod Corophium volutator (Pallas), females release gender-specific waterborne pheromones that guide males in their search for receptive burrowed females. Pollutants that affect the pheromone release or impair the ability of males to detect and respond to chemosensory cues, could profoundly affect mating. C. volutator is commonly found on shallow soft sediments in estuaries and coastal waters, and their reproductive season coincides with intense traffic of leisure boats, which discharge high concentrations of fuel into the water and sediment of these areas. This study shows that sublethal exposure to naphthalene, a polycyclic aromatic hydrocarbon abundant in motor fuel, disturbs chemical communication in C. volutator. This was demonstrated in Y-maze bioassays, where males were allowed to follow female pheromones after separately exposing the males or females to naphthalene spiked sediments (0, 0.5, 5 or 50 microg g(-1) dw, nominal concentrations) for 3 days. The results show that exposure to naphthalene at the two lower concentrations significantly affects the males' response to female pheromones (p<0.05 and p<0.01, respectively). Male search activity was reduced by 27-45% and males could no longer find females by the use of the olfactory sense. Analysed sediment samples, however, indicate that the naphthalene concentrations causing this effect were 2-20 times lower than nominal concentrations. At the highest naphthalene treatment, no significant difference from the controls was found, probably explained by a different exposure regime for these amphipods since they seemingly avoided burrowing in sediments. Female C. volutator produce and release pheromones, despite naphthalene exposure. Disrupted chemical communication in C. volutator may affect the reproductive fitness of males and females with possible consequences for populations in contaminated areas.