Deepwater Horizon Oil Spill: 2010-2011 Biopsy sampling of estuarine dolphins in the western Florida Panhandle potentially exposed to contaminants from the spill

Fig. 1: Map of biopsy sampling locations
Fig. 1: Map of biopsy sampling locations in the western Florida Panhandle in 2010 and 2011.

The 2010 MC-252 disaster (Deepwater Horizon spill) caused weathered oil to wash ashore along the north central Gulf coast and impacted estuarine communities of plants and animals.

We assembled a collaborative team from three Florida Institute of Oceanography (FIO) institutions (faculty and graduate students from the University of Central Florida, researchers from the Sarasota Dolphin Research Program based at Mote Marine Laboratory, and scientists from the Florida Fish and Wildlife Research Institute) to study the ecological impacts in two connected estuaries in the Florida Panhandle. Our project encompasses Choctawhatchee Bay, Santa Rosa Sound and Pensacola Bay. The two inlets at Destin and Pensacola were impacted by oil slicks, and significant amounts of oil product were drawn into Pensacola Bay during incoming tides throughout the height of the spill. There is still residual oil and tar being found on local beaches and submerged in the bottom sediments, resulting in a lingering exposure to the ecosystem.

The primary goals of this ongoing project are to assess population size and genetic discreteness of oil spill impacted bottlenose dolphin communities in these bays, determine stable isotope and fatty acid signatures to define their feeding habits, and examine the relationship between feeding and trophic interactions in these apex predators as a means to assess the potential impacts of oil and residual contaminants throughout the region. The principal mechanism for assessing contaminant exposure is the collection of tissue samples from wild dolphins using remote biopsy darting. Samples acquired from resident dolphins are used in standard toxicological and enzyme marker assays from the blubber, genetic analysis, stable isotope analysis of skin (to assess feeding ecology and habitat utilization), and fatty acid signature analysis of blubber (feeding ecology). This project also incorporates samples collected from stranded animals by the Emerald Coast Wildlife Refuge, and the ongoing photo-ID work conducted by UCF grad students to identify

Fig 2: Seasonal and habitat based differences in stable isotope
Fig 2: Seasonal and habitat based differences in stable isotope values from biopsy samples.

habitat use and movement patterns of dolphins in this region.

Our small expert team (Allen, Barleycorn, and Shippee) ventured out in a 5.5 m boat during November 2010 and April 2011 to locate and sample select dolphins across the study area. In total, 66 samples were collected (34 in Nov, 32 in Apr) from a variety of sites in each of the estuarine regions on both occasions (Fig. 1). The resulting samples were processed and express shipped overnight for analysis at several laboratories.

To date, we have compiled the stable isotope results and compared them to the movement and habitat use patterns of the subject dolphins determined through photo-ID (Fig. 2). We are finding significant differences between dolphins that inhabit the inner bays and those found primarily around the inlets at Destin and Pensacola, as well as seasonal differences. Further exploration of these patterns will help determine correlates between movement patterns and dietary compositions, which will be facilitated through comparison to samples of putative prey fish species collected during this period by our colleagues at Florida FWRI. Other sample components (genetics, fatty acid signature, and contaminants) will eventually be analyzed and available for comparison to the stable isotope and habitat use data. Ultimately, pre- and post-spill knowledge of the spatial and temporal scales of these animals’ movements, population structure, specific habitat utilization and feeding preferences will allow interpretation of the toxicological and medical data. Our findings will assist resource managers with understanding the impacts of stressors at all levels of the ecosystem, which can be used to improve response strategies in future environmental disaster events.

This project is funded by grant number 4710-1101-00-D from the Florida Institute of Oceanography to GAJW.

 

Deepwater Horizon Oil Spill: 2010-2011 Natural Resource Damage Assessment (NRDA) of the St. Joseph Bay bottlenose dolphin community

In response to the Deepwater Horizon oil spill, a Natural Resource Damage Assessment (NRDA) was performed on the St. Joseph Bay bottlenose dolphin community. The overall goals of the NRDA process, which is part of NOAA’s Damage Assessment, Remediation, and Restoration Program (DARRP), are to:

1) Identify the extent of resources that were damaged

2) Determine methods for resource restoration

3) Assess the amount of restoration required to bring the resources back to levels pre-oil spill

X25 and Calf in St. Joseph Bay, Florida
Dolphin X25 with new calf in St. Joseph Bay, Florida during August 2010 photo-identification surveys. X25’s previous calf, X27, is now on her own and has been observed during the 2010 and 2011 surveys socializing with other sub-adults.

The goals for this particular NRDA assessment were to monitor the St. Joseph Bay bottlenose dolphins before, during, and after the oil spill. Although the oil spill never reached St. Joseph Bay, the bottlenose dolphins in this region are one of the best-studied communities along the northern Gulf of Mexico coast. Following an Unusual Mortality Event in 2004, health assessments and follow-up radio tracking were performed during 2005 and 2006 on 29 individuals. In addition, 103 remote biopsy samples were collected, and 165 photo-identification surveys were performed on the St. Joseph Bay bottlenose dolphin community, resulting in a catalog of over 350 individuals. Thus, the bottlenose dolphins in St. Joseph Bay could be considered a reference group to other coastal bottlenose dolphin communities that were directly affected by the Deepwater Horizon oil spill.

Photo-identification surveys with capture-recapture techniques were utilized to estimate seasonal abundance during June and August 2010, and February 2011. In addition, 38 remote biopsy samples were collected for genetic and contaminant analyses. Photo analysis on these surveys is nearly complete. Eighteen of the 29 tagged individuals from the 2005 and 2006 health assessments were sighted during the 2010 and 2011 survey effort. In addition, 6 females from these health assessments were also sighted with new calves.

As part of the Gulf-wide photo-identification catalog (see article in this newsletter), the entire St. Joseph Bay database is currently being converted to Finbase, a Microsoft Access database developed and maintained by NOAA that standardizes all photo-identification records and associated field data for each identified dolphin. The goal of Finbase is to enable photo-identification searches across catalogs and promote collaborations between various research groups in the Gulf of Mexico.

This material is based upon work supported by BP and NOAA. Any opinions, findings, and conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the views of BP and/or state or federal natural resources trustees. Additional support has been provided by the Disney Worldwide Conservation Fund.

 

 

Deepwater Horizon Oil Spill: 2010-2011 Efforts to respond to threats to dolphins along the central west coast of Florida

Much concern surrounded the potential catastrophic impacts of the April 2010 Deepwater Horizon (DWH) oil spill on wildlife and habitats in the Gulf of Mexico.

Long-term Gulf resident “Bracket” and her most recent calf,
Long-term Gulf resident “Bracket” and her most recent calf, seen here in September 2010.

The most common cetaceans in inshore waters of the Gulf, bottlenose dolphins, reside in coastal waters and bays, sounds, and estuaries where exposure to oil from the DWH incident was likely to occur. Prior to the DWH spill, little was known about the effects of oil spills on dolphins. There are a number of potential routes by which dolphins may be exposed to oil or associated chemicals such as inhalation, ingestion, and direct contact. Without the ability to predict the extent to which the spill would impact the Gulf coast and associated marine mammals, there was a strong need to collect baseline and control data for dolphin populations that might have been impacted directly or that might serve as comparative populations for those that are directly impacted, so that we can better understand the impacts of oil spills on cetaceans.

With the help of the Morris Animal Foundation’s Betty White Wildlife Rapid Response Fund, we initiated a project to address potential impacts on Gulf of Mexico bottlenose dolphins, specifically targeting stocks off the central west coast of Florida. The targeted stocks included the resident Sarasota Bay dolphin community, for which long-term health and population data were available, and the dolphins inhabiting the coastal waters of the Gulf of Mexico immediately offshore of Sarasota Bay, which likely would be exposed to oil before Sarasota Bay. Baseline data were collected on contaminant exposure, reproductive status, abundance, and distribution patterns of dolphins in these regions. We could not assign a probability to the oil spill spreading to Sarasota. If oil had arrived, then we would have collected exposure-response information that may be applicable for estimation of risks to other Gulf of Mexico cetacean populations. However, since the oil did not reach Sarasota Bay and the surrounding Gulf waters, the results of this study are being used by NOAA as control data for interpretation of data arising from potentially impacted populations elsewhere in the Gulf, such as Barataria Bay, Louisiana.

Sighting map of Bracket
Sighting locations for “Bracket,” one of several potential long-term resident Gulf animals identified during this project.

Two well-tested approaches were used to obtain information on contaminant exposure, abundance, distribution, and residency patterns of bottlenose dolphins in Gulf of Mexico and Sarasota Bay waters: 1) biopsy sampling, and 2) photo-identification. A total of 61 tissue samples for contaminant exposure assessment were obtained from Gulf dolphins through remote biopsy sampling and from Sarasota Bay resident dolphins through capture-sample-release techniques. Currently, all biopsy samples are being analyzed by NOAA and other collaborators.

Photo-identification surveys were conducted in the Gulf study area during June/July 2010 and August/September 2010, and in Sarasota Bay surveys were ongoing, 10 days each month. Data obtained from the photo-identification surveys were utilized to estimate abundance, and identify distribution and residency patterns. There were no significant changes in overall dolphin abundance between survey periods, or as compared to normal, pre-spill patterns. However, dolphin distribution seemed to vary somewhat from one survey period to the next, with more individuals being sighted closer to the coast during June/July and a higher number of individuals offshore during August/September.

These results suggest that there may be differences in the distribution of Gulf dolphins through the year. Project findings also support the concept of long-term residency for Gulf dolphins in addition to those in Sarasota Bay. Over the past three decades, about 900 individuals have been identified at one time or another in the study area for this project. Of these, 218 were identified from our 2010 photographs, including four individuals first identified as far back as 1980, when the Sarasota Dolphin Research Program initiated systematic photographic identification surveys.

It will be important to monitor the dolphins in oil-impacted bays and elsewhere in the Gulf of Mexico over time (years) to see if health or reproductive problems develop as a result of their exposure to oil and dispersants, either from direct contact or from transfer through the ecosystem. To facilitate accurate interpretation of subsequent data from the oil-impacted areas, it is necessary to have control data from sites that were in the same general region but were spared from the original spill.

The samples collected from Sarasota Bay and associated Gulf of Mexico waters in 2010 are serving as important controls for such comparisons.

 

 

Deep Water Horizon Oil Spill: Impacts on estuarine bottlenose dolphins in the West Florida Panhandle

By Graham A.J. Worthy, PhD (UCF), Steve Shippee (UCF), Randall S. Wells, PhD (CZS/Mote Marine Laboratory), Martin Shannon (FFWRI), and Peggy Ostrom, PhD (MSU)

We have assembled a collaborative team of researchers from the University of Central Florida, the Sarasota Dolphin

Study area map
Study area for joint University of Central Florida/Mote Marine Laboratory/ Chicago Zoological Society study of oil impacts near Destin, Florida, sponsored by the Florida Institute of Oceanography.

Research Program, and the Florida Fish and Wildlife Research Institute to study the potential impacts of the DWH oil spill in two connected estuaries in the Florida Panhandle. Our team is coordinating efforts to: assess population size and genetic discreteness of oil spill impacted bottlenose dolphin communities in these bays; determine their feeding habits; and examine the relationship between feeding habits and trophic interactions as a diagnostic tool in assessing the potential impacts of oil/dispersants throughout the region.

As apex predators, dolphins serve as key sentinel species for monitoring ocean and human health. Their roles as travelers between oceanic and coastal ecosystems emphasize their relevance for monitoring the potential impacts of oil and dispersants on fragile estuarine systems over both the short and long-term. We have begun a comprehensive assessment of the current status of bottlenose dolphin stocks in Pensacola Bay, Santa Rosa Sound and Choctawhatchee Bay and will assess the immediate impact of oil and residual contaminants on their distribution, habitat use, and feeding habits. Ultimately, these baseline data will be critical in the long-term assessment of their health and survival. Specifically we are conducting photo-ID surveys to determine their population size and distribution as well as collecting biopsy samples

Choctawhatchee Bay field team
The Choctawhatchee Bay field team, including SDRP staff member Aaron Barleycorn (left), UCF graduate student Steve Shippee (right), and a local volunteer, sets out for biopsy darting on a beautiful day in November.

for direct assessments of genetic relatedness and feeding ecology. In addition, we are collecting possible prey species from these same bay systems for nutritional/chemical analysis. The dart biopsy samples from select dolphins will allow us to combine standard toxicological and enzyme marker assays of blubber, with genetic analysis, stable isotope analysis of skin (to assess feeding ecology and habitat utilization), and fatty acid signature analysis of blubber (feeding ecology) to better understand oil exposure both from direct contact as well as through their food chain. Pre- and post-spill knowledge of the spatial and temporal scales of the movements of these animals, population structure, specific habitat utilization and feeding preferences is critical to the proper interpretation of toxicological and medical data. Data from these multiple approaches will enable resource managers to develop predictive models that evaluate response strategies and to integrate the impacts of stressors at all levels of the ecosystem.

This project is funded by grant number 4710-1101-00-D from the Florida Institute of Oceanography.

Deepwater Horizon Oil Spill: Natural Resource Damage Assessment (NRDA) of the St. Joseph Bay bottlenose dolphin community

By Brian Balmer, MS, PhD Student, Chicago Zoological Society and University of North Carolina Wilmington

In response to the Deepwater Horizon oil spill, we were contracted to perform a Natural Resource Damage Assessment (NRDA) on the St. Joseph Bay bottlenose dolphin community. The overall goals of the NRDA process, which is part of NOAA’s Damage Assessment, Remediation, and Restoration Program (DARRP), are to:

1) Identify the extent of resources that were damaged

2) Determine methods for resource restoration

3) Assess the amount of restoration required to bring the

resources back to levels pre-oil spill

Although it was uncertain if the Deepwater Horizon oil spill would reach St. Joseph Bay, the bottlenose dolphins in this region are one of the best-studied communities along the northern Gulf of Mexico coast. Since 2004, there have been two health assessments and follow-up radio tracking on 29 individuals, 103 remote biopsy samples collected, and 165 photo-identification surveys performed on the St. Joseph Bay bottlenose dolphin community, with a catalog of over 350 individuals. Thus, the bottlenose dolphins in St. Joseph Bay could provide insight into possible effects that the oil spill might have on other coastal bottlenose dolphin communities in the more affected regions of the northern Gulf coast.

“X23” with “X29” and calf
“X23” with “X29” and calf travelling past oil containment booms in Crooked Island Sound, along the northern Gulf coast of Florida.

The goals for this particular NRDA assessment were to monitor the St. Joseph Bay (and vicinity) bottlenose dolphins before, during, and after the oil spill. Specifically, remote biopsy samples from individual dolphins were to be collected and analyzed for contaminants before oil reached the region as well as if/when oil actually entered St. Joseph Bay. Seasonal abundance estimates utilizing mark-recapture, photo-identification surveys were to be performed during the same time periods as the above mentioned biopsy sampling, as well as an additional set of surveys planned for February 2011. The St. Joseph Bay research is part of a larger study by NOAA that includes similar efforts in Barataria Bay and Chandeluer Sound in Louisiana, and Mississippi Sound.

The “pre-oil” surveys for this assessment were conducted during 17 – 30 June 2010. During this survey effort, 21 remote biopsy samples were collected, and 123 distinctive dolphins were identified. In addition, 14 of the 29 individuals that were captured during health assessments in 2005 and 2006 were re-sighted, of which 6 females had new calves that had not been sighted until these surveys. No oil was observed in the region, but remediation efforts were apparent, with oil containment booms positioned along much of the coastline surrounding St. Joseph Bay. Abundance estimates are typically low during the summer and winter, with year-round residents (approximately 120 individuals) inhabiting the St. Joseph Bay region. During spring and fall, a two to three fold increase of animals is observed in which the majority of individuals are suspected to be seasonal residents or transients to St. Joseph Bay. Interestingly, the abundance estimates generated from these June 2010 surveys were much higher than expected and more similar to the spring and fall time periods when an influx of animals is observed in the region.

At the beginning of August 2010, when it was evident that the oil spill was not going to come into direct contact with the St. Joseph Bay region, the second round of remote biopsying and photo-identification surveys for NRDA was performed. During this survey effort, an additional 17 biopsy samples were obtained and 18 of the 29 individuals that were captured during previous health assessments were sighted. Although photo analysis is not complete for this portion of the project, preliminary data suggest that the abundance estimates for August 2010 will be similar to “typical” summer estimates in St. Joseph Bay, with a lower number of individuals sighted, primarily those with long-term residency patterns to the region. No oil was observed during this survey period and our field crew was able to observe the oil containment booms along the St. Joseph Bay coastline being removed by the hard working remediation crews; an encouraging sight to witness when just a few months earlier the ecosystem of St. Joseph Bay was under threat from the worst marine oil spill in history.

Funding for this research was provided by NOAA’s Damage Assessment, Remediation, and Restoration Program.