Maps May Offer Dolphins Protection From Tourist Activities
Brett Smith for redOrbit.com – Your Universe Online
As we all know, starting your day without a good night’s rest can impact your performance and ability to think.
The same applies to spinner dolphins around Hawaii who may not be getting enough rest because of tourists cruising the waters in search of the famously sociable and acrobatic mammals. But a new plan published in PLoS ONE could give the dolphins their space without closing off the waters to tourists completely.
“Using the maps produced through this study we can identify the bays where the effects of human activities on spinner dolphins should be monitored most closely, and where immediate conservation actions are required,” said co-author David Johnston, research scientist at Duke University’s Nicholas School of the Environment.
Spinner dolphins that live around Hawaii have fairly predictable routines that involve resting in the island bays in the daytime and foraging in the open waters at night. Using this knowledge of the dolphins’ behavior along with Maximum Entropy modeling, the researchers, led by a team from Duke, described habitat relationships and calculated spatial predictions of the spinner dolphin resting habitat around the main Hawaiian Islands.
The results of the modeling indicated that 21 out of 99 inland bays were suitable habitats for resting dolphins.
“We may be able to minimize detrimental effects on dolphins by putting restrictions or preventative measures into place in a relatively small number of bays, rather than limiting access to dolphins along the entire coast,” said lead author, Lesley Thorne, a Duke graduate and current lecturer in marine science at Stony Brook University. “That benefits tourists and tourism operators as well as the dolphins.”
“Sleep is essential for most animals,” added Johnston. “When deprived of their necessary ‘zzzz’s,’ they gradually show a decreased ability to process information and remain attentive to environmental stimuli. In technical lingo, we call this a ‘vigilance decrement’.”
According to the scientists, Spinner dolphins that are regularly bothered by humans during their resting periods never fully recuperate their vigilance decrement. This condition makes it difficult for the animals to forage for food, lowers their responsiveness to potential threats, and degrades their communication abilities.
The tourism industry’s intrusiveness into Spinner dolphins’ natural habitat has long been a bugaboo for marine biologists. The creatures’ friendly nature and acrobatic skill makes them a natural tourist draw, however the sustainability of this ‘attraction’ may be at risk if the dolphins’ circadian rhythms are disturbed.
The research team noted that the Maximum Entropy modeling used in the study could have wider implications, because it reflected an efficient method for factoring the human-dolphin interactions in the hundreds of bays around the main Hawaiian islands.
“This type of modeling has only recently been applied to the study of marine mammals, but our work suggests it may be especially useful for studies (where data is) derived from opportunistic sightings and surveys using different types of research platforms,” Thorne said.
Thorne and Johnston said they plan to assess their models by conducting comparable studies of spinner dolphin distributions and habitat use in the areas around other Pacific islands.