Habitat collapse due to overgrazing threatens turtle conservation in marine protected areas

Marine protected areas (MPAs) are key tools for combatting the global overexploitation of endangered species. The prevailing paradigm is that MPAs are beneficial in helping to restore ecosystems to more ‘natural’ conditions. However, MPAs may have unintended negative effects when increasing densitie...

Full description

Saved in:
Bibliographic Details
Published in:Proceedings of the Royal Society. B, Biological sciences Biological sciences, 2014-02, Vol.281 (1777), p.20132890-20132890
Main Authors: Christianen, Marjolijn J. A., Herman, Peter M. J., Bouma, Tjeerd J., Lamers, Leon P. M., van Katwijk, Marieke M., van der Heide, Tjisse, Mumby, Peter J., Silliman, Brian R., Engelhard, Sarah L., van de Kerk, Madelon, Kiswara, Wawan, van de Koppel, Johan
Format: Article
Language:English
Subjects:
Alternate Stable States
Animals
Conservation of Natural Resources
Ecosystem
Feeding Behavior
Indonesia
Marine Reserves
Models, Biological
Plant–herbivore Interactions
Population Density
Turtles - physiology
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Marine protected areas (MPAs) are key tools for combatting the global overexploitation of endangered species. The prevailing paradigm is that MPAs are beneficial in helping to restore ecosystems to more ‘natural’ conditions. However, MPAs may have unintended negative effects when increasing densities of protected species exert destructive effects on their habitat. Here, we report on severe seagrass degradation in a decade-old MPA where hyper-abundant green turtles adopted a previously undescribed below-ground foraging strategy. By digging for and consuming rhizomes and roots, turtles create abundant bare gaps, thereby enhancing erosion and reducing seagrass regrowth. A fully parametrized model reveals that the ecosystem is approaching a tipping point, where consumption overwhelms regrowth, which could potentially lead to complete collapse of the seagrass habitat. Seagrass recovery will not ensue unless turtle density is reduced to nearly zero, eliminating the MPA's value as a turtle reserve. Our results reveal an unrecognized, yet imminent threat to MPAs, as sea turtle densities are increasing at major nesting sites and the decline of seagrass habitat forces turtles to concentrate on the remaining meadows inside reserves. This emphasizes the need for policy and management approaches that consider the interactions of protected species with their habitat.
ISSN:0962-8452
1471-2954
DOI:10.1098/rspb.2013.2890