Why Did the Population of the Olive Ridley Turtle Lepidochelys olivacea (Eschscholtz, 1829) Increase in Alas Purwo Natio
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RIGINAL PAPERS
Why Did the Population of the Olive Ridley Turtle Lepidochelys olivacea (Eschscholtz, 1829) Increase in Alas Purwo National Park’s Beach, East Java, Indonesia?1 Nia Kurniawana, * and Awang Gitayanab, ** aDepartment
of Biology, Faculty of Mathematics and Natural Sciences, Brawijaya University, St. Veteran Malang, East Java, 65145 Indonesia b Alas Purwo National Park, St. Brawijaya Banyuwangi, East Java, 68416 Indonesia *e-mail: [email protected] **e-mail: [email protected] Received December 20, 2019; revised March 27, 2020; accepted April 10, 2020
Abstract—From 1983 to 2018, in the Alas Purwo National Park (APNP) beach, the olive ridley sea turtle (Lepidochelys olivacea) nested population showed a significantly increasing number compared to the other three species using the same beach. One of the reasons is believed to be the success of conservation efforts (nest relocation and protected egg incubation) to produce a balanced hatchling sex ratio. However, a balanced sex ratio is only the first step in maintaining a good number of individuals in the population. We reviewed several other factors that also influenced the increase in the olive ridley population. The Olive Ridley as the shortest sea turtle species reaches maturity faster, so the population can grow in a shorter time compared to other species. The shortage of males in the olive ridley sea turtle population might not have a dangerous effect because, owing to the ocean current, they can mate with males from other populations. They are also highly polygamous and polyandrous, and have a high degree of genetic variation that helps them to be more adaptable to the changing environment. Lastly, the low illegal hunt rate for this species can also help the population to thrive. Keywords: Olive Ridley Turtle, Alas Purwo National Park, population DOI: 10.1134/S1063074020050065
INTRODUCTION It was long predicted that global warming potentially causes sex ratio distortion in the sea turtle populations [44]. Previous studies revealed that raising temperatures in nesting beaches resulted in sex ratio distortion and possibly led to decreasing sea turtle populations [24, 29]. Mostly, sea turtles and other reptiles have a temperature-dependent trait for their sex determination. Eggs that were nested in cooler temperature result in more males, and eggs that were nested in warmer temperature result in more females [1]. As global warming exponentially continues, conservationists worry that the sea turtle population will be skewed to a female-biased population (feminization) that could lead to decreasing population fertility. Feminization threatened almost all of the sea turtle species, including endangered species, Eretmochelys imbricata (Hawksbill Sea Turtle) [10], Caretta caretta (Loggerhead Sea Turtle) [53], and even the species with the largest population, Chelonia mydas (Green Sea Turtle) [28]. Realizing this threat, many conservation attempts are focusing on the production of a bal1 The text was submitted by the authors in English.
anced sea turtle ha
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