In today’s Academic Minute, Dr. Quincy Gibson of the University of North Florida reveals the connection between manmade noises and aggressive behavior in dolphins.
Quincy Gibson is a research scientist at the University of North Florida where her primary research interests are behavioral development, maternal care strategies, individual variation, and social complexity of marine mammals. She is currently conducting boat-based photo-identification and behavioral surveys of bottlenose dolphins in the Jacksonville area. She holds a Ph. D. from Georgetown University.
Dr. Quincy Gibson – Noise Pollution and Dolphin Behavior
Although aggressive encounters among dolphins are rarely observed, the tooth rake marks that often result from such interactions serve as a useful tool for evaluating aggression levels in a population. However, no prior studies have quantified and compared tooth rake marks in neighboring populations. This study examined both the recency and body coverage of tooth rake marks on bottlenose dolphins from two Northeast Florida locations: the St. Johns River, which is an international shipping port with high levels of commercial, military and recreational vessel traffic, and the St. Augustine inlet, which has predominantly recreational vessel traffic.
Through weekly boat-based photo-identification and behavioral surveys, our research team has identified over 300 individual dolphins. Photographs from a 2-month period were examined for rake marks. At both sites, the majority of dolphins had tooth rake marks from aggressive interactions. The extent of rake mark coverage across body sections did not differ by study site, which suggests that the severity of aggressive encounters was similar in both populations. However, on average, rake marks were more recently inflicted on dolphins in the St. Johns River than in St. Augustine, suggesting that aggression may occur more frequently among St. John’s River dolphins.
These preliminary data suggest that the St. John’s River dolphins may be experiencing stress, as indicated by increased aggression compared to other populations. Altered resting patterns may be a further indication of stress in this population. Dolphins are rarely observed resting in the river, which may be a consequence of the increased vigilance necessary around high levels of vessel traffic. Future studies quantifying dolphin and vessel interactions at each site will help establish if there is a link between the frequency of dolphin aggression and vessel traffic.