All ETDs from UAB

Advisory Committee Chair

Thane Wibbels

Advisory Committee Members

Ken Marion

David Owens

Document Type

Thesis

Date of Award

2013

Degree Name by School

Master of Science (MS) College of Arts and Sciences

Abstract

The Kemp’s ridley (Lepidochelys kempii) sea turtle neared extinction during the mid-1980s, but due to intense conservation efforts its population is now gradually recovering. Hatchling sex ratios and natural predation on nests and hatchlings have been monitored at Rancho Nuevo, Mexico to optimize this species’ recovery. Sand and nest temperatures were evaluated for the 2009 - 2012 nesting seasons in the egg corrals and on the nesting beach. Temperatures were cool during the start of the nesting seasons (i.e. below pivotal temperature), and gradually rose and were at or above pivotal temperatures by mid–May. Temperatures remained warm for the remainder of the nesting seasons, except when tropical weather systems impacted the area and lowered incubation temperatures. Thus, a female bias was predicted from 2009–2012, but some nests early in the nesting season or those subjected to tropical weather systems during the middle third of incubation were predicted to produce males. The nesting beach was also warm (suggesting a female bias) but it was cooler than the egg corrals. Sex ratios for the egg corrals and nesting beach were recalculated using incubation temperatures that were raised by 1°C to hypothetically simulate the effects of increasing global temperatures on hatchling sex ratios. Increases in sand temperatures due to global climate change could result in extreme female biases for the egg corrals and the nesting beach. Subsets of in situ nests from arribadas in 2011 and 2012 were monitored for predation throughout incubation and hatching success was determined following emergence. Predation on in situ nests was low and hatching success relatively high. Additionally, survival of hatchlings during seafinding was evaluated for in situ nests in 2012 and results suggest relatively high survival rates. Evaluation of predation data supports the concept that arribadas may achieve predator satiation, thus enhancing nest and hatchling survival. Leaving arribada nests in situ may be an effective conservation strategy. These sex ratio and predation studies provide data to facilitate an effective transition from the use of egg corrals back to the use of the natural nesting beach as the Kemp’s ridley recovers.

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