Embryo deformities and nesting trends in Kemp’s ridley sea turtles Lepidochelys kempii before and after the Deepwater Horizon oil spill

Dj Shaver,Je Yacabucci,Caj Godard-Codding,Cj Schmitt,C Gredzens,Ph Dutton,A Frey,Js Walker

doi:10.3354/esr01107

Abstract

Kemp’s ridley sea turtles Lepidochelys kempii were disproportionately affected by the Deepwater Horizon (DWH) oil spill, which began on 20 April 2010. Embryo deformities were documented in inviable L. kempii eggs before (2008-2010) and after (2011-2013) the DWH spill in 2 Texas (USA) nesting areas (Upper Texas Coast and Padre Island National Seashore). Additional nesting trends, including clutch size and hatching success, were also investigated. Total and late-stage embryo deformity prevalence were 1.5 times greater after 2010 than before, but low in all nesting seasons (mean ± SD: 0.7 ± 8.5% total; 0.6 ± 8.0% late-stage) and did not differ between locations. Craniofacial and carapace deformities were the most frequently observed deformity types. Documented nests in both areas declined in 2010 relative to previous years, ending an exponential increase observed beginning in 1995. Clutch size remained consistent before and after the spill. Hatching success averaged 87.0 ± 33.3% in all years, but no effects from DWH were determined. Collectively, these data represent useful benchmarks against which to judge impacts of future crude oil spills and other catastrophic events.

Highlights

On 20 April 2010, the Deepwater Horizon/Mississippi Canyon 252 (DWH) explosion and subsequent 87 d oil leak released 3.19 × 106 barrels (5.07 × 108 l) of oil into the northern Gulf of Mexico (GOM), resulting in the largest marine oil spill in history (DWH NRDA Trustees 2016)
This study investigated potential spill effects on embryo deformities, clutch size, and nest success in L. kempii based on statistical comparisons and quantification of data from Texas nesting seasons before (2008−2010) and after (2011−2013) the DWH spill
The study area consisted of Kemp’s ridley Lepidochelys kempii nesting beaches along 2 portions of the Texas coast where long-term monitoring has been conducted: the 105 km length of Padre Island National Seashore (PAIS) and a 100 km section on the Upper Texas Coast (UTC) extending from the southern terminus of Surfside Beach at Brazos Inlet northeastward the length of Bolivar Peninsula to Shaver et al.: Kemp’s ridley embryo deformities and nesting trends

Summary

Introduction

On 20 April 2010, the Deepwater Horizon/Mississippi Canyon 252 (DWH) explosion and subsequent 87 d oil leak released 3.19 × 106 barrels (5.07 × 108 l) of oil into the northern Gulf of Mexico (GOM), resulting in the largest marine oil spill in history (DWH NRDA Trustees 2016). The northern GOM, which experienced the heaviest impacts, provides key foraging habitat for adult female Kemp’s ridley sea turtles Lepidochelys kempii that nest along the Texas and Mexico coasts (Seney & Landry 2008, Shaver et al 2013, Gredzens & Shaver 2020). L. kempii is predominantly a GOM species that is federally listed (endangered) in the USA (NMFS 2011), Critically Endangered globally (Wibbels & Bevan 2019), and has the smallest geographic nesting range of all marine turtles (Pritchard & MárquezMillán 1973). The majority of post-nesting L. kempii migrate northeastward along the GOM coast and forage in a shallow (< 37 m depth; Shaver & Rubio 2008, Shaver et al 2016a) coastal corridor from Texas to southwestern Florida, with strong foraging area fidelity (Seney & Landry 2008, Shaver et al 2013, 2016a, Gredzens & Shaver 2020)

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Conclusion