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Brunswick, GA, United States

Hawkes L.A.,University of Exeter | Hawkes L.A.,Bangor University | Witt M.J.,University of Exeter | Broderick A.C.,University of Exeter | And 10 more authors.
Diversity and Distributions | Year: 2011

Aim Although satellite tracking has yielded much information regarding the migrations and habitat use of threatened marine species, relatively little has been published about the environmental niche for loggerhead sea turtles Caretta caretta in north-west Atlantic waters. Location North Carolina, South Carolina and Georgia, USA. Methods We tracked 68 adult female turtles between 1998 and 2008, one of the largest sample sizes to date, for 372.2±210.4days (mean±SD). Results We identified two strategies: (1) 'seasonal' migrations between summer and winter coastal areas (n=47), although some turtles made oceanic excursions (n=4) and (2) occupation of more southerly 'year-round' ranges (n=18). Seasonal turtles occupied summer home ranges of 645.1km2 (median, n = 42; using α-hulls) predominantly north of 35° latitude and winter home ranges of 339.0km2 (n=24) in a relatively small area on the narrow shelf off North Carolina. We tracked some of these turtles through successive summer (n=8) and winter (n=3) seasons, showing inter-annual home range repeatability to within 14.5km of summer areas and 10.3km of winter areas. For year-round turtles, home ranges were 1889.9km2. Turtles should be tracked for at least 80days to reliably estimate the home range size in seasonal habitats. The equivalent minimum duration for 'year-round' turtles is more complex to derive. We define an environmental envelope of the distribution of North American loggerhead turtles: warm waters (between 18.2 and 29.2°C) on the coastal shelf (in depths of 3.0-89.0m). Main conclusions Our findings show that adult female loggerhead turtles show predictable, repeatable home range behaviour and do not generally leave waters of the USA, nor the continental shelf (<200m depth). These data offer insights for future marine management, particularly if they were combined with those from the other management units in the USA. © 2011 Blackwell Publishing Ltd.

van der Hoop J.,Woods Hole Oceanographic Institution | Moore M.,Woods Hole Oceanographic Institution | Fahlman A.,Woods Hole Oceanographic Institution | Fahlman A.,Texas A&M University | And 9 more authors.
Marine Mammal Science | Year: 2014

Protracted entanglement in fishing gear often leads to emaciation through reduced mobility and foraging ability, and energy budget depletion from the added drag of towing gear for months or years. We examined changes in kinematics of a tagged entangled North Atlantic right whale (Eg 3911), before, during, and after disentanglement on 15 January 2011. To calculate the additional drag forces and energetic demand associated with various gear configurations, we towed three sets of gear attached to a load-cell tensiometer at multiple speeds. Tag analyses revealed significant increases in dive depth and duration; ascent, descent and fluke stroke rates; and decreases in root mean square fluke amplitude (a proxy for thrust) following disentanglement. Conservative drag coefficients while entangled in all gear configurations (mean ± SD Cd,e,go = 3.4 × 10-3 ± 0.0003, Cd,e,gb = 3.7 × 10-3 ± 0.0003, Cd,e,sl = 3.8 × 10-3 ± 0.0004) were significantly greater than in the nonentangled case (Cd,n = 3.2 × 10-3 ± 0.0003; P = 0.0156, 0.0312, 0.0078, respectively). Increases in total power input (including standard metabolism) over the nonentangled condition ranged from 1.6% to 120.9% for all gear configurations tested; locomotory power requirements increased 60.0%-164.6%. These results highlight significant alteration to swimming patterns, and the magnitude of energy depletion in a chronically entangled whale. © 2013 Society for Marine Mammalogy.

Ricks W.E.,One Conservation Way | Cooper R.J.,University of Georgia | Gulsby W.D.,Auburn University | Miller K.V.,University of Georgia
Southeastern Naturalist | Year: 2016

Food plots are commonly planted for Odocoileus virginianus (White-tailed Deer) in the eastern US, because they are known to benefit this species. We hypothesized that food plots may also provide early-successional habitat for nongame species, such as songbirds, in areas where it is normally lacking. Thus, we evaluated songbird use of food plots planted with Trifolium spp. (perennial clovers) in the northern and southern Appalachian Mountains by comparing avian species richness and abundance within plots, along their edges, and in the adjacent forest. During the breeding season on northern sites, there was no difference in avian richness or abundance among the plots, their edges, or adjacent forest. However, both species richness and abundance were greater along plot edges during breeding season on southern sites. Species richness was also greater along plot edges for a subset of southern sites sampled during winter. Thus, food plots within southern Appalachian hardwood forests enhanced habitat conditions (as indexed by use) for songbirds, including several species that are classified as declining. Population losses of those species may be due to otherwise limited availability of early successional habitat within these systems.

Carlson-Bremer D.,University of California at Davis | Norton T.M.,St. Catherines Island Foundation | Norton T.M.,Georgia Sea Turtle Center | Gilardi K.V.,University of California at Davis | And 10 more authors.
Journal of Wildlife Diseases | Year: 2010

The American Oystercatcher (Haematopus palliatus palliatus) is the only species of oystercatcher native to the Atlantic coast of North America and is restricted in distribution to intertidal shellfish beds in coastal areas. Currently, the American Oystercatcher population in South Carolina and Georgia is threatened by widespread habitat loss, resulting in low reproductive success and small population size. Oystercatchers could be an important indicator of ecosystem health because they depend on quality coastal breeding habitat and prey on bivalves, which can accumulate toxins and pathogens from the local environment. Data were collected from American Oystercatchers (n = 171) captured at five sites in South Carolina and Georgia between 2001 and 2006. Iridial depigmentation was frequently noted during physical examination and was more prevalent in female birds. Female birds were larger than males on average, but ranges for weight and morphometry measurements had considerable overlap. Mean values were calculated for hematology, plasma biochemistry, and hormone levels, and prevalence of exposure to select pathogens was determined. Mercury was the only trace metal detected in blood samples. These data provide baseline health information needed for longitudinal monitoring and conservation efforts for American Oystercatchers. In addition, this study illustrates the potential use of this species as an indicator for the health of the southeastern US coastal nearshore ecosystem. © Wildlife Disease Association 2010.

Portnoy D.S.,Texas A&M University-Corpus Christi | Hollenbeck C.M.,Texas A&M University-Corpus Christi | Belcher C.N.,One Conservation Way | Driggers W.B.,National Oceanic and Atmospheric Administration | And 4 more authors.
Molecular Ecology | Year: 2014

Patterns of population structure and historical genetic demography of blacknose sharks in the western North Atlantic Ocean were assessed using variation in nuclear-encoded microsatellites and sequences of mitochondrial (mt)DNA. Significant heterogeneity and/or inferred barriers to gene flow, based on microsatellites and/or mtDNA, revealed the occurrence of five genetic populations localized to five geographic regions: the southeastern U.S Atlantic coast, the eastern Gulf of Mexico, the western Gulf of Mexico, Bay of Campeche in the southern Gulf of Mexico and the Bahamas. Pairwise estimates of genetic divergence between sharks in the Bahamas and those in all other localities were more than an order of magnitude higher than between pairwise comparisons involving the other localities. Demographic modelling indicated that sharks in all five regions diverged after the last glacial maximum and, except for the Bahamas, experienced post-glacial, population expansion. The patterns of genetic variation also suggest that the southern Gulf of Mexico may have served as a glacial refuge and source for the expansion. Results of the study demonstrate that barriers to gene flow and historical genetic demography contributed to contemporary patterns of population structure in a coastal migratory species living in an otherwise continuous marine habitat. The results also indicate that for many marine species, failure to properly characterize barriers in terms of levels of contemporary gene flow could in part be due to inferences based solely on equilibrium assumptions. This could lead to erroneous conclusions regarding levels of connectivity in species of conservation concern. © 2014 John Wiley & Sons Ltd.

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