Vessel noise is a worldwide concern because it is known to alter behavior in marine animals. While fishes show avoidance behavior to vessel noise, research is needed to determine how vessel noise impacts fish reproduction and larval development. In this study, the oyster toadfish (Opsanus tau) will be used as a model organism because males call to females using "boatwhistle" sounds and care for benthic, substrate-attached embryos at dens. Vessel noises can mask mating calls, which may lower female den visitation rates and alter larval development. If this study demonstrates that vessel noise alters reproduction and larval survival, then it is likely to encourage the development of noise-quieting technology for vessels, provide additional evidence to justify ocean soundscape monitoring and could impact policies that limit acoustic disturbance in protected habitats, e.g., marine protected areas, seagrass beds, and coral and oyster reefs. The investigators will continue to participate in community outreach through exhibitions and demonstrations that address the area of bioacoustics, and the findings will be used in undergraduate and graduate courses.
This study will determine if vessel noise alters adult and larval behavior and survival. Larval toadfish exposed to vessel noise experimentally will be examined for changes in sensory anatomy, sensitivity to sounds and noise, and preferred sound frequency of juvenile toadfish during settlement. Adult and larval toadfish will be exposed to two types of vessel noise (outboard motor and large vessel) and snapping shrimp sounds (natural sounds, control). Reproductive output will be monitored weekly and larvae will be collected for microscopic examination of neurological development of sound-producing (swimbladder musculature) and morphometric examination of sound-receiving (lateral line and inner ears) structures. Larvae in each treatment will be tested for sensitivity to particle motion and sound frequency preferences to determine if acoustic imprinting occurs during development in fishes. The researchers hypothesize that vessel noise will reduce male calling rates, lower reproductive output, and cause larvae to change their acoustic behavior during and/or after settlement, potentially altering survival.
