Abstract

Anthropogenic underwater noise can have detrimental impacts on marine invertebrates; however, its effects on mating and metabolism are not fully understood. In the rock shrimp Rhynchocinetes typus two morphotypes of mature males, “typus” and “robustus”, compete for sexually receptive females. Robustus are the dominant, whereas typus utilize an “alternative mating tactic” (sneaking). The stress proxies, metabolic rate, and hemolymph protein and glucosa concentration, of males and females were measured in the presence and absence of recordings of outboard motor noise in laboratory settings. Mating experiments were simultaneously conducted. In the absence of noise, typus had a higher metabolic rate than robustus, however, when noise was applied, typus decreased their metabolic rate while robustus maintained theirs. Protein and glucose concentrations in individuals from the field were higher than in laboratory animals, but they were also higher in robustus under noise. In mating experiments, typus had more interactions with the female whilst exposed to noise because robustus became less active. These results suggest that males of the rock shrimp perceive and respond to outboard motor noise, and it may modify their individual fitness. Therefore, anthropogenic noise may be considered as a selective force for this and probably for other marine invertebrate.