Dataset Information

Data on Sea turtle relative abundance in nearshore waters adjacent to the Mississippi River delta, Gulf of Mexico, United States.

ABSTRACT: We measured the relative abundance of sea turtles using standardized transect surveys conducted during the summer and fall of 2013 in neritic waters surrounding the Mississippi River delta in Louisiana, USA. Data comprise sea turtle locations, observation circumstances, and environmental covariates recorded at the beginning of each transect and at the time of each turtle observation. Turtles were recorded by species and size class, as well as location in the water column and the distance the turtle was from the transect line. Transects were performed on an 8.2 meter vessel with two observers atop a 4.5 meter elevated platform, with vessel speed standardized at ∼15 km/hr. These data are the first to describe relative abundance of sea turtles observed from small vessels in this region. Detection of turtles <45 cm SSCL and data detail are greater than aerial surveys. The data serve to inform resource managers and researchers regarding these protected marine species.

SUBMITTER: Welsh RC

PROVIDER: S-EPMC9969292 | biostudies-literature | 2023 Apr

REPOSITORIES: biostudies-literature

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Data on Sea turtle relative abundance in nearshore waters adjacent to the Mississippi River delta, Gulf of Mexico, United States.

Welsh Ryan C RC Witherington Blair E BE Guertin Jeffrey R JR Mott Cody R CR Bresette Michael J MJ

Data in brief 20230214

We measured the relative abundance of sea turtles using standardized transect surveys conducted during the summer and fall of 2013 in neritic waters surrounding the Mississippi River delta in Louisiana, USA. Data comprise sea turtle locations, observation circumstances, and environmental covariates recorded at the beginning of each transect and at the time of each turtle observation. Turtles were recorded by species and size class, as well as location in the water column and the distance the tur ...[more]

PMID: 36860409

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Project description:Animals co-occurring in a region (sympatry) may use the same habitat (syntopy) within that region. A central aim in ecology is determining what factors drive species distributions (i.e., abiotic conditions, dispersal limitations, and/or biotic interactions). Assessing the degree of biotic interactions can be difficult for species with wide ranges at sea. This study investigated the spatial ecology of two sea turtle species that forage on benthic invertebrates in neritic GoM waters: Kemp's ridleys (Lepidochelys kempii) and loggerheads (Caretta caretta). We used satellite tracking and modeled behavioral modes, then calculated individual home ranges, compared foraging areas, and determined extent of co-occurrence. Using six environmental variables and principal component analysis, we assessed similarity of chosen foraging sites. We predicted foraging location (eco-region) based on species, nesting site, and turtle size. For 127 turtles (64 Kemp's ridleys, 63 loggerheads) tracked from 1989 to 2013, foraging home ranges were nine to ten times larger for Kemp's ridleys than for loggerheads. Species intersected off all U.S. coasts and the Yucatán Peninsula, but co-occurrence areas were small compared to species' distributions. Kemp's ridley foraging home ranges were concentrated in the northern GoM, whereas those for loggerheads were concentrated in the eastern GoM. The two species were different in all habitat variables compared (latitude, longitude, distance to shore, net primary production, mean sea surface temperature, and bathymetry). Nesting site was the single dominant variable that dictated foraging ecoregion. Although Kemp's ridleys and loggerheads may compete for resources, the separation in foraging areas, significant differences in environmental conditions, and importance of nesting location on ecoregion selection (i.e., dispersal ability) indicate that adult females of these species do not interact greatly during foraging and that dispersal and environmental factors more strongly determine their distributions. These species show sympatry in this region but evidence for syntopy was rare.

Project description:Estuaries on wave-dominated coasts generally comprise three sedimentary environments: fluvial sands and gravels derived from the catchment; marine sands characteristic of the beaches and nearshore; and silts and clays that accumulate in the sheltered central basin. Estuarine transition to deltaic form occurs when geomorphological maturity is achieved during coastal evolution. Sedimentary plains become infilled and a narrow channel connects the catchment and facilitates the transport of fluvial sediments to the coast. Here, we present modern sedimentary data that supports the idea that the wave-dominated Shoalhaven system in southeastern Australia has transitioned from an estuary to delta, transporting fluvial sediments to the modern adjacent beach and contributing to coastal progradation. A total of 141 bed channel and swash zone samples were collected from the estuarine channel of the Shoalhaven River and the adjacent Comerong Island and Seven Mile Beach, respectively. Surficial sediments were subject to grain size analysis, whereas random quartz grains from selected samples were used to indicate a qualitative degree of weathering using a scan electron microscopy (SEM). Additionally, selected samples were examined for mineralogical composition using x-ray diffraction (XRD) to provide understanding of sediment transport and provenance. The dataset, one of the most comprehensive modern sedimentary coastal records in Australia, can be used to understand the sediment dynamics and support a diverse range of coastal management decisions. The experiment design and analyses also serve as a model that can be replicated elsewhere to better understand fluvial delivery of sediments to the coast. The dataset and analyses presented here support the research article entitled "Evolution from estuary to delta: alluvial plain morphology and sedimentary characteristics of the Shoalhaven River mouth, southeastern Australia" [1], to which readers should refer to for interpretation.

Dataset Information

Data on Sea turtle relative abundance in nearshore waters adjacent to the Mississippi River delta, Gulf of Mexico, United States.

Publications

Data on Sea turtle relative abundance in nearshore waters adjacent to the Mississippi River delta, Gulf of Mexico, United States.

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