Marine Threats Overlap Key Foraging Habitat for Two Imperiled Sea Turtle Species in the Gulf of Mexico

Hart, Kristen M.; Iverson, Autumn R.; Fujisaki, Ikuko; Lamont, Margaret M.; Bucklin, David N.; Shaver, Donna J.

doi:10.3389/fmars.2018.00336

Cited by 43 publications

(49 citation statements)

References 45 publications

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“…In the absence or in the case of poor quantitative and geographic data, which is common in lesser developed countries, our method has the advantage of allowing manually curated and expert knowledge to be used in the model. Love et al (2017) and Hart et al (2018) assessed a spatially explicit impact score for Kemp's ridley Lepidochelys kempii and loggerhead turtles Caretta caretta after combining different in-water and terres- trial threats in the northern Gulf of Mexico. While this assessment is comparable to the potential impact maps that we obtained, the numerical and conceptual approach differs in that it considers only one species at a time and does not include all the terms specified by the ecological vulnerability formula.…”

Section: Methodological Approachmentioning

confidence: 99%

Ecological vulnerability of two sea turtle species in the Gulf of Mexico: an integrated spatial approach

Cuevas¹,

Liceaga-Correa²,

Uribe-Martínez³

2019

Endang. Species. Res.

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Changes in ecological attributes as a result of anthropogenic activities and climatic forces can jeopardize biodiversity, so these potential impacts must be evaluated for conservation. Integrating the different components of a large ecosystem can, however, pose a methodological challenge. When evaluating the sensitivity of a system, the level of stress imposed by a threat and the system's ability to deal with pressures ultimately define its actual condition. The objective of this study was to assemble a spatially explicit quantitative approach for evaluating the ecological vulnerability of 2 sea turtle species (Eretmochelys imbricata and Chelonia mydas). We used a method that combined the use of an open source planning tool (Conservation Action Planning) and spatial multicriteria analysis to determine the total cumulative ecological vulnerability to multiple threats for each species individually and for both species combined. The spatially explicit outputs were supported by hard data and expert knowledge, including the cumulative ecological vulnerability of each species to multiple threats. For each species, we identified areas in the Gulf of Mexico where individual threats have a potential impact and also determined high vulnerability locations. This spatially explicit approach is important when assessing ecological vulnerability and risk, it is versatile and easily reproducible for other organisms, and can be an important tool in supporting the conservation and management of endangered species.

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Section: Methodological Approachmentioning

confidence: 99%

Ecological vulnerability of two sea turtle species in the Gulf of Mexico: an integrated spatial approach

Cuevas¹,

Liceaga-Correa²,

Uribe-Martínez³

2019

Endang. Species. Res.

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“…However, it was not possible to overcome spatial biases in sample collection and as a result this may represent the greatest source of bias in our analysis. Kemp's ridley sea turtles forage in a wide range of shallow, benthic marine habitats, including a substantial part of the continental shelf (Shaver et al, 2013;Hart et al, 2018). Unfortunately, few studies have characterized invertebrate stable isotope values for continental shelf habitats resulting in greater prevalence of estuarine and coastal organisms in our prey isotopic dataset.…”

Section: Regional Diet Variationmentioning

confidence: 99%

Regional Variation in Kemp’s Ridley Sea Turtle Diet Composition and Its Potential Relationship With Somatic Growth

et al. 2020

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Reptile growth is influenced by many ecological processes that can cumulatively give rise to divergent somatic growth rates within spatially structured populations. As somatic growth variation can strongly influence a species' population dynamics, identifying proximate drivers can be critical to the conservation and management of protected species. Kemp's ridley sea turtles (Lepidochelys kempii) exhibit spatial variation in both diet composition and growth, but whether components of this variation are linked has not been evaluated. Through an integration of skeletochronological and stable isotope analyses of stranded turtle humerus bones we characterized regional variation in Kemp's ridley diet composition and potential relationships with somatic growth rates. Turtles were divided among five regions within the United States Gulf of Mexico (GoM) and Atlantic Coast based on location of stranding, and humerus bones were sampled for stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope ratios. These data were combined with region-specific prey stable isotope data sourced from the primary literature into Bayesian stable isotope mixing models (MixSIAR) to estimate the proportional contribution of five prey groups (crustaceans, bivalves, gastropods, fish, and macroalgae/seagrass) to Kemp's ridley diets. Our analysis revealed strong regional differences in mixing model-derived diet composition estimates that closely tracked published records of Kemp's ridley diet. Invertebrates generally comprised the largest proportion (43.5-97.7%) of turtle diets. However, we also observed high proportional contributions of fish (42.6-43.1%) to western GoM turtle diets and macroalgae/seagrass (42.4-47.8%), or isotopically similar prey resources (e.g., tunicates), to eastern GoM turtle diets. Growth rates were poorly correlated with δ 15 N values-a proxy for trophic level-and diet composition estimates, suggesting that diet composition alone may not explain the regional differences in somatic growth observed in this species. This study highlights the value of complementary skeletal and isotopic analyses to understanding regional

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“…Satellite data were available for download on the Wildlife Computers Portal. 1 We used a hierarchical SSM (Jonsen et al, 2003;Patterson et al, 2008) to characterize the movements of all turtles, following our previous studies where we determined foraging and inter-nesting periods for some of these same turtles (Hart et al, 2012(Hart et al, , 2013(Hart et al, , 2014(Hart et al, , 2015(Hart et al, , 2018a. Specifically, we applied a model used by Breed et al (2009) that estimates model parameters by Markov Chain Monte Carlo (MCMC) using WinBUGS via the software program R. As input into the model, we used all tracking data except for locations defined as Location Class Z, which are considered invalid locations (CLS, 2011).…”

Section: Turtle Capture and Ssmmentioning

confidence: 99%

“…Previous work identified where foraging grounds for loggerheads and Kemp's ridleys (Lepidochelys kempii) in the GoM overlapped with eight spatially explicit anthropogenic threats and found that threats for turtles using the southwest coast of Florida included commercial line fishing and harmful algal blooms (HABs; Hart et al, 2018a). However, when we included only threats during the peak migration time of July and August, HABs -which occur usually between August and February 2were only present in a single year and in a relatively small spatial location and so we did not include HABs in our analysis.…”

Section: Anthropogenic Threatsmentioning

confidence: 99%

Migration Corridors and Threats in the Gulf of Mexico and Florida Straits for Loggerhead Sea Turtles

et al. 2020

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Along migration corridors, animals can face natural and anthropogenic threats that differ from those in breeding and non-breeding residence areas. Satellite telemetry can aid in describing the timing and location of these migrations. We use this tool with switching state-space modeling and line kernel density estimates to identify migration corridors of post-nesting adult female loggerhead sea turtles (Caretta caretta, n = 89 tracks) that nested at five beaches in the Gulf of Mexico. Turtles migrated in both neritic and oceanic areas of the Gulf of Mexico with some exiting the Gulf. High-use migration corridors were found in neritic areas to the west of Florida and also in the Florida Straits. Repeat tracking of post-nesting migrations for eight turtles showed variability in track overlap, ranging from ∼13 to 82% of tracks within 10 km of each other. Migration primarily occurred in July and August. We document the longest known post-nesting migration to-date of a wild adult female loggerhead of >4,300 km, along with an apparent stopover of about 1 month. Migration corridors overlaid on three spatially explicit anthropogenic threats (shipping density, commercial line fishing, and shrimp trawling) showed hotspots in the Florida Straits, off the northwest Florida coast and off the coast of Tampa Bay. Identifying where and at what intensity multiple human activities and natural processes most likely occur is a key goal of Cumulative Effects Assessments. Our results provide the scientific information needed for designing management strategies for this threatened species. Information about this loggerhead migration corridor can also be used to inform adaptive management as threats shift over time.

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Marine Threats Overlap Key Foraging Habitat for Two Imperiled Sea Turtle Species in the Gulf of Mexico

Cited by 43 publications

References 45 publications

Ecological vulnerability of two sea turtle species in the Gulf of Mexico: an integrated spatial approach

Ecological vulnerability of two sea turtle species in the Gulf of Mexico: an integrated spatial approach

Regional Variation in Kemp’s Ridley Sea Turtle Diet Composition and Its Potential Relationship With Somatic Growth

Migration Corridors and Threats in the Gulf of Mexico and Florida Straits for Loggerhead Sea Turtles

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