Gulf Of Mexico Beaches Research Articles

Evaluation of Gonadal Tissue to Validate Size at Reproductive Maturity in Kemp’s Ridley Sea Turtles Found Stranded in Texas, USA

The Kemp’s ridley, Lepidochelys kempii, is the most endangered sea turtle in the world. Anthropogenic mortality of Kemp’s ridleys has been well documented in the Gulf of Mexico (GOM), USA. We evaluated the reproductive maturity of 75 Kemp’s ridley sea turtles found dead on GOM beaches on Mustang Island and North Padre Island, Texas, USA, 1994–1999. Straight carapace length (SCL) ranged from 40.8 to 68.7 cm. Preserved gonads and associated tissues were examined and measured. Gonadal measurements were then compared with SCL. Adults and juveniles shared a larger range of carapace measurements than expected, supporting the idea that juveniles spend several years in a pubertal state. Our results suggest caution when using SCL, tail length, or curved front claws alone as indicators of sexual maturity. In fact, SCL can be used to discern adults from juveniles with more predictive power when coupled with testis length or oviduct length measurements, thus allowing endangered species managers to more clearly identify demographic shifts in the number of mature animals, which can precede population changes. This study shows that information gained from the examination of stranded sea turtles allows wildlife managers to make more informed decisions regarding conservation priorities.

Development of a field testing protocol for identifying Deepwater Horizon oil spill residues trapped near Gulf of Mexico beaches.

The Deepwater Horizon (DWH) accident, one of the largest oil spills in U.S. history, contaminated several beaches located along the Gulf of Mexico (GOM) shoreline. The residues from the spill still continue to be deposited on some of these beaches. Methods to track and monitor the fate of these residues require approaches that can differentiate the DWH residues from other types of petroleum residues. This is because, historically, the crude oil released from sources such as natural seeps and anthropogenic discharges have also deposited other types of petroleum residues on GOM beaches. Therefore, identifying the origin of these residues is critical for developing effective management strategies for monitoring the long-term environmental impacts of the DWH oil spill. Advanced fingerprinting methods that are currently used for identifying the source of oil spill residues require detailed laboratory studies, which can be cost-prohibitive. Also, most agencies typically use untrained workers or volunteers to conduct shoreline monitoring surveys and these worker will not have access to advanced laboratory facilities. Furthermore, it is impractical to routinely fingerprint large volumes of samples that are collected after a major oil spill event, such as the DWH spill. In this study, we propose a simple field testing protocol that can identify DWH oil spill residues based on their unique physical characteristics. The robustness of the method is demonstrated by testing a variety of oil spill samples, and the results are verified by characterizing the samples using advanced chemical fingerprinting methods. The verification data show that the method yields results that are consistent with the results derived from advanced fingerprinting methods. The proposed protocol is a reliable, cost-effective, practical field approach for differentiating DWH residues from other types of petroleum residues.

Impact of Photooxidation and Biodegradation on the Fate of Oil Spilled During the Deepwater Horizon Incident: Advanced Stages of Weathering.

While the biogeochemical forces influencing the weathering of spilled oil have been investigated for decades, the environmental fate and effects of "oxyhydrocarbons" in sand patties deposited on beaches are not well-known. We collected sand patties deposited in the swash zone on Gulf of Mexico beaches following the Deepwater Horizon oil spill. When sand patties were exposed to simulated sunlight, a larger concentration of dissolved organic carbon was leached into seawater than the corresponding dark controls. This result was consistent with the general ease of movement of seawater through the sand patties as shown with a 35SO42- radiotracer. Ultrahigh-resolution mass spectrometry, as well as optical measurements revealed that the chemical composition of dissolved organic matter (DOM) leached from the sand patties under dark and irradiated conditions were substantially different, but neither had a significant inhibitory influence on the endogenous rate of aerobic or anaerobic microbial respiratory activity. Rather, the dissolved organic photooxidation products stimulated significantly more microbial O2 consumption (113 ± 4 μM) than either the dark (78 ± 2 μM) controls or the endogenous (38 μM ± 4) forms of DOM. The changes in the DOM quality and quantity were consistent with biodegradation as an explanation for the differences. These results confirm that sand patties undergo a gradual dissolution of DOM in both the dark and in the light, but photooxidation accelerates the production of water-soluble polar organic compounds that are relatively more amenable to aerobic biodegradation. As such, these processes represent previously unrecognized advanced weathering stages that are important in the ultimate transformation of spilled crude oil.

Long-term weathering and continued oxidation of oil residues from the Deepwater Horizon spill

To investigate the long-term weathering of oil from the Deepwater Horizon (DWH) incident, oil-soaked sand patties were collected from Gulf of Mexico beaches from Florida to Alabama over a three-year period from 2012 to 2014. Analysis of oil residues by gas chromatography with flame ionization detection (GC-FID), thin-layer chromatography with flame ionization detection (TLC-FID), and Fourier transform infrared spectroscopy (FT-IR) indicated uniformity in their chemical composition. Some variability within and between samples was observed, arising from differences in exposure to light and water, which increase the amount of weathering. Oxygenated hydrocarbons (OxHC) produced by weathering processes dominate the majority of oil residues. These OxHC have continued recalcitrance in the environment, and increase in relative abundance over time. Analyses of the bulk characteristics of oil residues via TLC-FID and FT-IR should be continued as these techniques provide important insight into the weathering state of oil residues.

Degradation of oil by fungi isolated from Gulf of Mexico beaches

Fungi of the Ascomycota phylum were isolated from oil-soaked sand patties collected from beaches following the Deepwater Horizon oil spill. To examine their ability to degrade oil, fungal isolates were grown on oiled quartz at 20°C, 30°C and 40°C. Consistent trends in oil degradation were not related to fungal species or temperature and all isolates degraded variable quantities of oil (32–65%). Fungal isolates preferentially degraded short (<C18; 90–99%) as opposed to long (C19–C36; 7–87%) chain n-alkanes and straight chain C17- and C18-n-alkanes (91–99%) compared to their branched counterparts, pristane and phytane (70–98%). Polycyclic aromatic hydrocarbon (PAH) compounds were also degraded by the fungal isolates (42–84% total degraded), with a preference for low molecular weight over high molecular weight PAHs. Overall, these findings contribute to our understanding of the capacity of fungi to degrade oil in the coastal marine environment.

Long-Term Persistence of Dispersants following the Deepwater Horizon Oil Spill

During the 2010 Deepwater Horizon (DWH) oil spill, 1.84 M gallons of chemical dispersant was applied to oil released in the subsurface and to oil slicks at the surface. We used liquid chromatography with tandem mass spectrometry to quantify the anionic surfactant DOSS (dioctyl sodium sulfosuccinate) in samples collected from environments known to contain oil persisting from the DWH oil spill. DOSS was found to persist in variable quantities in deep-sea coral communities (6–9000 ng/g) 6 months after the spill and on Gulf of Mexico beaches (1–260 ng/g) 26–45 months after the spill. These results indicate that the applied dispersant, which was thought to undergo rapid degradation in the water column, remains associated with oil in the environment and can persist for ∼4 years.

Concentrations of the Genotoxic Metals, Chromium and Nickel, in Whales, Tar Balls, Oil Slicks, and Released Oil from the Gulf of Mexico in the Immediate Aftermath of the Deepwater Horizon Oil Crisis: Is Genotoxic Metal Exposure Part of the Deepwater Horizon Legacy?

Concern regarding the Deepwater Horizon oil crisis has largely focused on oil and dispersants while the threat of genotoxic metals in the oil has gone largely overlooked. Genotoxic metals, such as chromium and nickel, damage DNA and bioaccumulate in organisms, resulting in persistent exposures. We found chromium and nickel concentrations ranged from 0.24 to 8.46 ppm in crude oil from the riser, oil from slicks on surface waters and tar balls from Gulf of Mexico beaches. We found nickel concentrations ranged from 1.7 to 94.6 ppm wet weight with a mean of 15.9 ± 3.5 ppm and chromium concentrations ranged from 2.0 to 73.6 ppm wet weight with a mean of 12.8 ± 2.6 ppm in tissue collected from Gulf of Mexico whales in the wake of the crisis. Mean tissue concentrations were significantly higher than those found in whales collected around the world prior to the spill. Given the capacity of these metals to damage DNA, their presence in the oil, and their elevated concentrations in whales, we suggest that metal exposure is an important understudied concern for the Deepwater Horizon oil disaster.

Selection of genetically diverse sea oats lines with improved performance for coastal restoration in the northern Gulf of Mexico

Numerous sea oats (Uniola paniculata L.) plants are transplanted to Northern Gulf of Mexico beaches each year to reduce coastal erosion. To adapt to environmental changes and effectively reduce coastal erosion, genetically diverse sea oats plants with demonstrated plant performance must be used. The objectives of this study were to: (i) identify improved sea oats lines; and (ii) determine the genetic diversity of improved sea oats lines. From 2003 to 2005, 2,000 sea oats lines were evaluated in unreplicated field trials at natural beach sites. In 2005, 75 sea oats lines were selected based upon phenotypic performance. The 75 selected lines and 3 plants of ‘Caminada’, the only commercially available sea oats line, were evaluated in replicated field trials in 2008 and 2010. In 2008, UP01LA-15 K-HB-3092, UP01LA-16S-GP-3138, UP01LA-31-GP-3103, UP01LA-33-GP-1303, and UP01NC-04-HB-3374 had higher (p < 0.05) stem densities than Caminada. In 2010, variation was not detected for any trait measured; lack of significant differences was most likely due to plant stress caused by storm surge one week after transplant. Amplified Fragment Length Polymorphism detected 534 loci for the 75 selected lines and 3 Caminada plants. One hundred eighty one loci were polymorphic; the average polymorphism rate was 34% (range = 25–43%). Polymorphic information content values ranged from 0.15 to 0.41 and averaged 0.29 while Jaccard similarity coefficients ranged from 0.8243 to 0.9794. These findings demonstrate the application of plant breeding techniques to develop genetically different sea oats lines with improved performance for coastal restoration projects in the northern Gulf of Mexico.

No 'Smoking Gun' for Killer Oil

As turtle and dolphin corpses wash up on Gulf of Mexico beaches, scientists face a sleuthing challenge worthy of CSI : determining whether oil had a hand in the deaths.

Late Holocene sea-level changes from grain-size data: evidence from the Gulf of Mexico

Grain-size kurtosis of sand in the beach ridge plain of St. Vincent Island, Florida, is numerically reasonably uniform within any one ridge set, but changes at important set boundaries. Where these changes are found, there are also differences in air photo and field appearance and in measured ridge-set heights. Sets with low kurtosis (∼3.0) stand topographically high, and sets with higher values (∼3.6) stand low. Study of wave energy levels and beach sand grain-size kurtosis along modem Gulf of Mexico beaches shows that kurtosis is an inverse function of surf-zone energy density. Storms and storminess (for the study area) can be evaluated in the framework of the selective- transport model of May (1973); the actual data sequence is greatly different from what is required by the model, and therefore storms and storminess cannot be invoked to explain the history of the area. Instead, the data sequence matches results predicted by the model for small sea-level changes. Storms and tectonism do not have appropriate durations and rates of operation, hence did not cause changes in kurtosis across St. Vincent Island. Slow land elevation changes (warping, isostatic adjustment) do not take place repeatedly up and down like the granulometric parameters. Tidal effects, in the study area, are both much too small and too frequent to have been important. The changes in kurtosis therefore indicate water level changes, and provide a sea-level history, including three sea level drops and four rises, of 1-3 m each, since about 3000 BP. Similar results have been obtained elsewhere, so these results are not local.