While they may not be instagramming their meals or following each other on Twitter, dolphins are still able to form highly complex social networks. According to researchers at the Harbor Branch Oceanographic Institute (HBOI) at Florida Atlantic University, bottlenose dolphins in the Indian River Lagoon (IRL) form ‘communities’ in discrete areas. Not only that, but they choose to hang out with the dolphins they like and avoid the ones they don’t.
The study, published in the journal Marine Mammal Science, involved observing dolphins in the IRL during a six-and-a-half year period using intensive photo-ID surveys. Through this non-invasive technique, researchers were able to recognize some 200 individual dolphins by the markings on their dorsal fins.
The IRL—a 156-mile-long (250-kilometer-long) estuary located on Florida’s east coast—is a unique habitat compared to those traditionally inhabited by other similar marine mammals due to its linear shape, which allows the dolphins to move along a north-south axis. The IRL is one of the most biodiverse estuaries in North America and was designated as an “Estuary of National Significance,” by the U.S. Environmental Protection Agency in 1990.
“One of the more unique aspects of our study was the discovery that the physical dimensions of the habitat, the long, narrow lagoon system itself, influenced the spatial and temporal dynamics of dolphin association patterns,” said Elizabeth Murdoch Titcomb, a research biologist at HBOI, in a statement.
Titcomb and her research team suggest the habitat shape may influence both association and ranging patterns in dolphins and thus their community structure.
“For example, communities that occupy the narrowest stretches of the Indian River Lagoon have the most compact social networks, similar to humans who live in small towns and have fewer people with whom to interact,” she continued. The dolphins also clustered into six distinct social communities in the IRL, with patterns of social organization and dynamics differing between the groups.
There are significant implications, according to the researchers, if the distinct substructure within a population is ignored and instead treated uniformly. The study concludes that an increased understanding of the dolphins’ social affiliations, in combination with their genetic structure, could be a useful tool when modeling the spread of disease and behavioral responses throughout a population.