Marine Pollution Bulletin xxx (2015) xxx–xxx

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Marine Pollution Bulletin journal homepage: www.elsevier.com/locate/marpolbul

Baseline

Mercury concentrations in Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, Florida: Patterns of spatial and temporal distribution Adam M. Schaefer a,⇑, Elizabeth Murdoch Titcomb a, Patricia A. Fair b, Hui-Chen W. Stavros b,c, Marilyn Mazzoil a, Gregory D. Bossart d,e, John S. Reif f a

Harbor Branch Oceanographic Institute at Florida Atlantic University, 5600 U.S. 1 North, Fort Pierce, FL 34946, United States Center for Coastal Environmental Health and Biomolecular Research, NOS, NOAA, 219 Fort Johnson Road, Charleston, SC 29142, United States c O2Si Smart Solutions, 2030 Savage Road, Charleston, SC 29407, United States d Georgia Aquarium, 225 Baker Street, Atlanta, GA 30313, United States e University of Miami, Miller School of Medicine, 1600 10th Ave, Miami, FL 33136, United States f Department of Environmental and Radiological Health Sciences, Colorado State University, Fort Collins, CO 80523, United States b

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Article history: Received 15 December 2014 Revised 7 April 2015 Accepted 2 May 2015 Available online xxxx Keywords: Mercury Indian River Lagoon Florida Bottlenose dolphins

a b s t r a c t Bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, FL (IRL) have tissue mercury concentrations among the highest reported worldwide. Analysis of total mercury (THg) concentrations in blood collected between 2003 and 2012 showed a significant linear decrease over time (p = 0.04). Significant differences in the spatial distribution of THg in resident IRL dolphins were also observed with a general gradient in concentration from north to south. Evaluation of local biogeochemistry and accumulation of mercury in prey species is needed to better understand factors influencing the distribution of Hg in the apex predator. Analyses of temporal and spatial patterns of exposure to THg in this sentinel species may have implications for both ecosystem and public health in the region. Ó 2015 Elsevier Ltd. All rights reserved.

Mercury concentrations in skin and blood from free-ranging bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, Florida (IRL) have total mercury (THg) concentrations that are among the highest reported for the species (Stavros et al., 2007, 2008; Schaefer et al., 2011). This exposure has been associated with changes in multiple hepatic, renal, endocrine and hematological parameters suggestive of deleterious health effects (Schaefer et al., 2011). IRL bottlenose dolphins have a long life span, bioaccumulate contaminants and display defined home ranges with a high degree of site fidelity (Mazzoil et al., 2008; Bossart, 2011). Apex predators such as dolphins can serve as indicators of THg contamination (Bellante et al., 2011). As a result of biomagnification through the food chain, tissue concentrations reach the highest levels in species at the top of the food web (Kidd et al., 2011). The high THg concentrations observed in this dolphin population may reflect regional differences in deposition and accumulation. Therefore, longitudinal studies that document temporal and spatial variation of THg in may provide

⇑ Corresponding author. E-mail address: [email protected] (A.M. Schaefer).

insight regarding variation in factors which lead to deposition and uptake of Hg in the local environment. The IRL occupies approximately 40% of Florida’s Atlantic coast, a distance of more than 250 km. The estuary contains three major basins and can be divided into six segments based on unique hydrodynamic and geographic features that include low water turnover throughout (Fig. 1) (Smith, 1993; Woodward-Clyde, 1994). When compared to other cetacean study sites, this area is distinguished by its linear shape, allowing the animals to move essentially only along a north–south axis. The watershed is characterized by high variability in land use patterns, including wildlife preserves, agricultural activities and urban development. The northernmost areas of the IRL, which include the Merritt Island National Wildlife Refuge and the Canaveral National Seashore, are characterized by minimal coastal development. Increased coastal development, greater human population density and a higher concentration of drainage canals from inland areas are key features of the southern portion of the lagoon (Woodward-Clyde, 1994). The objectives of this study were to: (1) assess temporal changes in dolphin THg concentrations between 2003 and 2012; (2) determine whether there are differences in dolphin THg concentrations associated with sub regions of the IRL.

http://dx.doi.org/10.1016/j.marpolbul.2015.05.007 0025-326X/Ó 2015 Elsevier Ltd. All rights reserved.

Please cite this article in press as: Schaefer, A.M., et al. Mercury concentrations in Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, Florida: Patterns of spatial and temporal distribution. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.05.007

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A.M. Schaefer et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx

Fig. 1. Indian River Lagoon, Fl including surrounding lands and environmental segments.

Free-ranging bottlenose dolphins (T. truncatus) were captured, sampled and released in the IRL during the Bottlenose Dolphin Health and Environmental Risk Assessment Project (HERA) each June between 2003–2007 and 2010–2012 using previously described techniques (Fair et al., 2006). Samples from dolphins were collected under National Marine Fisheries Permit No. 998-1678-00 as approved by the Florida Atlantic University Animal Care and Use Committee. Blood samples were drawn from the periarterial venous rete in the flukes with a 19-gauge, 1.9-cm,

butterfly catheter (Becton Dickinson, Franklin Lakes, NJ, USA). Age was determined by counting postnatal dentine layers in an extracted tooth (Hohn et al., 1989). Adult males were defined as individuals 10 years of age or older and adult females were defined as individuals 7 years of age or older based on sexual maturity criteria (Mead and Potter, 1990). Total mercury concentration was determined in blood samples using combustion atomic absorption spectrometry (CAAS; U.S. EPA). Laboratory analyses were conducted by NOAA, Center for

Please cite this article in press as: Schaefer, A.M., et al. Mercury concentrations in Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, Florida: Patterns of spatial and temporal distribution. Mar. Pollut. Bull. (2015), http://dx.doi.org/10.1016/j.marpolbul.2015.05.007

A.M. Schaefer et al. / Marine Pollution Bulletin xxx (2015) xxx–xxx

Coastal Environmental Health and Biomolecular Research from 2003 to 2005 and by Florida Wildlife Commission, Fish and Wildlife Research Institute from 2006 to 2012. The CAAS analysis was conducted with a calibrated DMA-80 Direct Mercury Analyzer (Milestone Inc., Shelton, CT) in both laboratories using EPA Method 7473 (U.S. EPA, 2007). Quality control procedures included analysis of laboratory method blanks, duplicate or triplicate tissue samples and certified reference material (TORT-2 or DOLT-4 obtained from the National Research Council of Canada) for each group of 10 samples analyzed (U.S. EPA, 2007). All measurements were within recommended EPA limits for the analytical method (U.S. EPA, 2007). Mean mercury concentrations of certified reference materials (CRM) were accurate and within certified confidence intervals for both TORT-2 and DOLT-4. In addition, duplicate matrix spikes were completed for each group of 40 samples analyzed. Precision, estimated as the coefficient of variation, was

Mercury concentrations in Atlantic bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, Florida: Patterns of spatial and temporal distribution.

Bottlenose dolphins (Tursiops truncatus) inhabiting the Indian River Lagoon, FL (IRL) have tissue mercury concentrations among the highest reported wo...
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