2003, Karczmarski

et al. 2005). Bottlenose dolphins in the Bahamas lost 30% of their resident individuals, with an influx of almost the same number of immigrants after two major hurricanes impacted the area (Elliser and Herzing 2011). This resulted in a split of the community into two Idelalisib solubility dmso units, which were distinct and more homogenous in nature (Elliser and Herzing 2011). After the extreme environmental disturbance of the oil spill from the Exxon Valdez, killer whales suffered similar losses and a split in a matriline occurred (Matkin et al. 2008). It is evident that demographic and/or environmental factors can help shape the social structure of a given population. How individuals adjust

to these changes may depend on the species, habitat, and social structure of the population. This study reports on a large loss of individuals from a small stable, resident, community of Atlantic spotted dolphins and the subsequent effects on their social structure. This community has been studied since 1985 (Herzing 1997, Herzing and Brunnick 1997). Long-term association patterns reveal a society remarkably similar to well-studied coastal bottlenose dolphin societies, including female networks, male alliances, and no long-term associations between sexes (Elliser and Herzing, in press). This community is divided into three Copanlisib ic50 social Aprepitant clusters with overlapping ranges where mixed-cluster groups occur, but associations are stronger within clusters than between (Elliser and Herzing 2012). In 2004 this community was impacted by two major hurricanes within three weeks of each other. Following the hurricanes this community had a decrease in community size, either through mass mortality, displacement, or other correlated events. Due to the synchronous and sharp decline and lack of resightings of individuals that disappeared after 2004 (as of 2012 none have been

resighted), the reduction in community size was most likely due to the hurricanes. The goal of the present study was to quantitatively describe the differences in social structure of this community of spotted dolphins before and after the hurricanes in 2004. Little Bahama Bank (LBB) is about 64 km from the east coast of Florida, and just north of West End, Grand Bahama Island. The study area spans 60 km north to south and 8 km east to west and encompasses 480 km2. The sandbank is shallow, between 6 and 16 m deep, and is surrounded by deep water (steep drop off to over 500 m into the Gulf Stream). It has a mostly sandy bottom, scattered with areas of rock, reef, and patches of seagrass (Thalassia testudimum). The entire study area was divided into six sections, A–F (Fig. 1). Effort was not evenly distributed throughout every area (% of total effort: A = 3.5%, B = 10.2%, C = 31.8%, D = 51.4%, E&F = 3.