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Responses of algae, corals and fish to the reduction of macroalgae in fished and unfished patch reefs of Glovers Reef Atoll, Belize
The Wildlife Conservation Society, P.O. Box 99470, Mombasa, Kenya.
Department of Marine Science, University of South Florida .
Stockholm University, Faculty of Science, Department of Systems Ecology.
Stockholm University, Faculty of Science, Department of Zoology.
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2001 (English)In: Coral Reefs, ISSN 0722-4028, Vol. 19, no 4, 367-379 p.Article in journal (Refereed) Published
Abstract [en]

Macroalgae were experimentally reduced by approximately 2.5 kg/m2 on eight similar-sized patch reefs of Glovers Reef Atoll, Belize, in September 1998. Four of these reefs were in a protected "no-take" zone and four were in a "general use" fishing zone. Eight adjacent reefs (four in each management zone) were also studied as unmanipulated controls to determine the interactive effect of algal reduction and fisheries management on algae, coral, fish, and rates of herbivory. The 16 reefs were sampled five times for 1 year after the manipulation. We found that the no-fishing zone had greater population densities for 13 of 30 species of fish, including four herbivorous species, but lower herbivory levels by sea urchins. However, there was lower stony coral cover and higher macroalgal cover in the "no-take" zone, both prior to and after the experiment. There were no significant effects of management on the percent cover of fleshy macroalgae. The algal reduction resulted in an increase in six fish species, including four herbivores and two which feed on invertebrates. One species, Lutjanus griseus, declined in experimental reefs. Macroalgal biomass quickly recovered from the reduction in both management areas within a few months, and by species-level community measures within 1 year, while stony coral was reduced in all treatments. Coral bleaching and Hurricane Mitch disturbed the site at the beginning of the study period and may explain the loss of stony coral and rapid increase in erect algae. We suggest that reducing macroalgae, as a technique to restore turf and encrusting coralline algae and stony corals, may work best after reefs have been fully protected from fishing for a period long enough to allow herbivorous fish to recover (i.e. >5 years). Further ecological studies on Glovers Reef are required to understand the shift from coral to algal dominance that has occurred on this reef in the last 25 years.

Place, publisher, year, edition, pages
Springer , 2001. Vol. 19, no 4, 367-379 p.
Keyword [en]
Algae - Coral reef fishes - Disturbance - Fishing - Herbivory - Marine protected areas
National Category
Biological Sciences
Research subject
Systems Ecology
URN: urn:nbn:se:su:diva-23180DOI: 10.1007/s003380000131OAI: diva2:190531
Part of urn:nbn:se:su:diva-176Available from: 2004-05-17 Created: 2004-05-17 Last updated: 2009-12-28Bibliographically approved
In thesis
1. Masking environmental feedback: Misfits between institutions and ecosystems in Belize and Thailand
Open this publication in new window or tab >>Masking environmental feedback: Misfits between institutions and ecosystems in Belize and Thailand
2004 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The thesis analyses relationships between ecological and social systems in the context of coastal ecosystems. It examines human impacts from resource extraction and addresses management and governance behind resource exploitation. The main premises are that a lack of ecological knowledge leads to poor ecosystem management and that the dichotomy between social and natural systems is an artificial one. The thesis illustrates the importance of basing resource management on the ecological conditions of the resource and its ecosystem. It also demonstrates the necessity of accounting for the human dimension in ecosystem management and the challenges of organising human actions for sustainable use of ecosystem services in the face of economic incentives that push users towards short-term extraction.

Many Caribbean coral reefs have undergone a shift from coral to macroalgal domination. An experiment on Glovers Reef Atoll in Belize manually cleared patch reefs in a no-take zone and a fished zone (Papers I and II). The study hypothesised that overfishing has reduced herbivorous fish populations that control macroalgae growth. Overall, management had no significant effect on fish abundance and the impacts of the algal reduction were short-lived. This illustrated that the benefits of setting aside marine reserves in impacted environments should not be taken for granted.

Papers III and IV studied the development of the lobster and conch fisheries in Belize, and the shrimp farming industry in Thailand respectively. These studies found that environmental feedback can be masked to give the impression of resource abundance through sequential exploitation. In both cases inadequate property rights contributed to this unsustainable resource use.

The final paper (V) compared the responses to changes in the resource by the lobster fisheries in Belize and Maine in terms of institutions, organisations and their role in management. In contrast to Maine’s, the Belize system seems to lack social mechanisms for responding effectively to environmental feedback. The results illustrate the importance of organisational and institutional diversity that incorporate ecological knowledge, respond to ecosystem feedback and provide a social context for learning from and adapting to change.

Place, publisher, year, edition, pages
Stockholm: Institutionen för systemekologi, 2004. 35 p.
Marine reserves, ecosystem change, sequential exploitation, pathology of resource use, institutions, driving forces, coral reefs, social-ecological systems, mangroves, aquaculture, Belize, Thailand, Maine
National Category
urn:nbn:se:su:diva-176 (URN)91-7265-881-9 (ISBN)
Public defence
2004-06-07, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 8 C, Stockholm, 10:00
Available from: 2004-05-17 Created: 2004-05-17Bibliographically approved

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