Densities and drivers of sea turtle populations across Pacific coral reef ecosystems

Sea turtle populations are often assessed at the regional to sub-basin scale from discrete indices of nesting abundance. While this may be practical and sometimes effective, widespread in-water surveys may enhance assessments by including additional demographics, locations, and revealing emerging po...

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Bibliographic Details
Published in:PloS one 2019-04, Vol.14 (4), p.e0214972-e0214972
Main Authors: Becker, Sarah L, Brainard, Russell E, Van Houtan, Kyle S
Format: Article
Language:English
Subjects:
American Samoa
Animals
Anthropogenic factors
Aquatic reptiles
Atolls
Basins
Behavior
Biology
Biology and Life Sciences
Budgets
Caretta caretta
Chelonia mydas
Climate change
Conservation
Coral reef ecosystems
Coral Reefs
Demographics
Demography
Deoxyribonucleic acid
DNA
Driverless cars
Earth Sciences
Ecology
Ecology and Environmental Sciences
Ecosystem biology
Ecosystems
Endangered & extinct species
Environmental aspects
Environmental DNA
Eretmochelys imbricata
Fisheries
Green turtle
Habitats
Hawaii
Human impact
Human influences
Islands
Marine ecosystems
Migration
Migratory animals
Motor vehicle drivers
Nesting
Overexploitation
Pacific Ocean
Polls & surveys
Population Dynamics
Population growth
Production management
Reefs
Regional analysis
Reptiles & amphibians
Scuba diving
Sea turtles
Social Sciences
Trends
Turtles
Turtles - classification
Turtles - physiology
Wildlife conservation
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Summary:Sea turtle populations are often assessed at the regional to sub-basin scale from discrete indices of nesting abundance. While this may be practical and sometimes effective, widespread in-water surveys may enhance assessments by including additional demographics, locations, and revealing emerging population trends. Here, we describe sea turtle observations from 13 years of towed-diver surveys across 53 coral islands, atolls, and reefs in the Central, West, and South Pacific. These surveys covered more than 7,300 linear km, and observed more than 3,400 green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles. From these data, we estimated sea turtle densities, described trends across space and time, and modelled the influence of environmental and anthropogenic drivers. Both species were patchily distributed across spatial scales, and green turtles were 11 times more abundant than hawksbills. The Pacific Remote Island Areas had the highest densities of greens (3.62 turtles km-1, Jarvis Island), while American Samoa had the most hawksbills (0.12 turtles km-1, Ta'u Island). The Hawaiian Islands had the lowest turtle densities (island ave = 0.07 turtles km-1) yet the highest annual population growth (μ = 0.08, σ = 0.22), suggesting extensive management protections can yield positive conservation results. Densities peaked at 27.5°C SST, in areas of high productivity and low human impact, and were consistent with patterns of historic overexploitation. Though such intensive surveys have great value, they are logistically demanding and therefore have an uncertain budget and programmatic future. We hope the methods we described here may be applied to future comparatively low-cost surveys either with autonomous vehicles or with environmental DNA.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0214972