Um estudo realizado pela Universidade de Exeter fornece a primeira evidência de que os recifes de coral podem se recuperar dos efeitos devastadores das mudanças climáticas. O estudo Marine Reserves Enhance the Recovery of Corals on Caribbean Reefs, publicado na revista PLoS ONE, mostra, pela primeira vez, que os recifes de coral localizados em reservas marinhas podem se recuperar dos impactos do aquecimento global.
Cientistas e ambientalistas têm alertado que os recifes de coral podem ser capazes de se recuperar dos danos causados pelas mudanças climáticas e que esses ambientes únicos poderão, em breve, ser ‘perdidos’ para sempre.
Agora, esta pesquisa acrescenta peso ao argumento de que os níveis de redução da pesca é a maneira mais viável e efetiva de proteger o mais delicado dos ecossistemas aquáticos.
Pesquisas anteriores documentaram que o aumento nas temperaturas de superfície do oceano colocam os recifes de coral sob estresse ambiental que rapidamente os levam ao branqueamento em massa.
O problema é intensificado pela acidificação do oceano, que também é causada pelo aumento de CO2. Isso diminui a capacidade dos corais de produção de carbonato de cálcio, que é o material que os recifes são feitos.
Aproximadamente 2% dos recifes de corais do mundo estão localizados dentro de reservas marinhas, em tese protegidos contra atividades humanas potencialmente prejudiciais, como dragagem e pesca.
Os pesquisadores realizaram exames de dez locais dentro e fora de reservas marinhas das Bahamas, ao longo de mais de 2,5 anos. Estes recifes foram severamente danificadas pelo branqueamento e depois pelo furacão Frances, no verão de 2004.
No início do estudo, os recifes tinham uma média de 7% de cobertura de coral. Ao final do projeto, a cobertura de coral, em áreas marinhas protegidas, tinha aumentado a uma média de 19%, enquanto que os corais fora das áreas protegidas não mostraram qualquer recuperação.
A pesquisa indica que, a fim de proteger os recifes no longo prazo, precisamos de medidas radicais para reduzir as emissões de CO2. No entanto, a pesquisa mostra que as medidas locais, para reduzir os efeitos da pesca, podem contribuir significativamente para o destino dos recifes, ajudando-os a lidar com as ameaças causadas pelas mudanças climáticas.
O estudo “Marine Reserves Enhance the Recovery of Corals on Caribbean Reefs“, publicado pela PLos ONE está disponível para acesso integral, no original em inglês e no formato HTML. Para acessar o estudo clique aqui.
Para maiores informações transcrevemos, abaixo, o abstract:
Marine Reserves Enhance the Recovery of Corals on Caribbean Reefs
Peter J. Mumby¹, Alastair R. Harborne²
Marine Spatial Ecology Lab, School of BioSciences, Hatherly Laboratory, University of Exeter, Exeter, United Kingdom
Abstract
The fisheries and biodiversity benefits of marine reserves are widely recognised but there is mounting interest in exploiting the importance of herbivorous fishes as a tool to help ecosystems recover from climate change impacts. This approach might be particularly suitable for coral reefs, which are acutely threatened by climate change, yet the trophic cascades generated by reserves are strong enough that they might theoretically enhance the rate of coral recovery after disturbance. However, evidence for reserves facilitating coral recovery has been lacking. Here we investigate whether reductions in macroalgal cover, caused by recovery of herbivorous parrotfishes within a reserve, have resulted in a faster rate of coral recovery than in areas subject to fishing. Surveys of ten sites inside and outside a Bahamian marine reserve over a 2.5-year period demonstrated that increases in coral cover, including adjustments for the initial size-distribution of corals, were significantly higher at reserve sites than those in non-reserve sites. Furthermore, macroalgal cover was significantly negatively correlated with the change in total coral cover over time. Recovery rates of individual species were generally consistent with small-scale manipulations on coral-macroalgal interactions, but also revealed differences that demonstrate the difficulties of translating experiments across spatial scales. Size-frequency data indicated that species which were particularly affected by high abundances of macroalgae outside the reserve had a population bottleneck restricting the supply of smaller corals to larger size classes. Importantly, because coral cover increased from a heavily degraded state, and recovery from such states has not previously been described, similar or better outcomes should be expected for many reefs in the region. Reducing herbivore exploitation as part of an ecosystem-based management strategy for coral reefs appears to be justified.
Citation: Mumby PJ, Harborne AR (2010) Marine Reserves Enhance the Recovery of Corals on Caribbean Reefs. PLoS ONE 5(1): e8657. doi:10.1371/journal.pone.0008657
Editor: Brian Gratwicke, Smithsonian’s National Zoological Park, United States of America
Received: October 23, 2009; Accepted: December 15, 2009; Published: January 11, 2010
Copyright: © 2010 Mumby, Harborne. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Funding: Funding for this study was provided by the Khalid bin Sultan Living Oceans Foundation (http://www.livingoceansfoundation.org/); the National Science Foundation (NSF – http://www.nsf.gov/); the Environmental Protection Agency (EPA – http://www.epa.gov/); the Natural Environment Research Council (NERC – http://www.nerc.ac.uk/); the Undersea Research Program of the National Oceanic and Atmospheric Administration (NURP – http://www.nurp.noaa.gov/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
¹ E-mail: P.J.Mumby{at}ex.ac.uk
² These authors contributed equally to this work.