Date of Award
Doctor of Philosophy (PhD)
Ocean Engineering and Marine Sciences
Ralph G. Turingan
Kenyon C. Lindeman
Reef fishes are an integral part of life in the Caribbean, fulfilling essential roles in their native marine ecosystems and the many human communities that neighbor them. Perhaps most directly to humans, reef fishes and their fisheries are an essential source of dietary protein, and further support local human communities through employment opportunities. More indirectly, reef fishes fulfill numerous ecological roles that help maintain their native reef ecosystems, which, in turn, confer benefits to humans. For example, a recent analysis estimated that every square kilometer of coral reef generates an average annual income of $473,000 (USD), which would represent 23 percent of the Caribbean’s revenue from tourism and approximately 10 percent of the region’s gross domestic product.
Unfortunately, the Caribbean Sea has undergone significant ecological degradation since the mid-1970s, with increased disease outbreaks, coral bleaching, and intense tropical storms, exacerbated by direct human pressures such as overfishing, pollution, and sedimentation. In response to this widespread degradation and the limitations of traditional management approaches, marine protected areas (MPAs) have been advocated as a holistic ecosystem-wide management tool. MPAs, defined as marine areas in which human activity is restricted to protect natural or cultural resources, have the potential to protect entire ecosystems and their processes.
To advance our understanding of the status of MPAs in the Caribbean Sea, and their theoretical capacity to address conservation goals, Chapter 2 used the World Database on Protected Areas (WDPA) in attempt to identify all MPAs in the Caribbean Sea and to characterize them using a suite of placement, design, and management characteristics. The following were among the key findings. In total, 572 MPAs were identified, covering a total marine area of 543,372.10km2. The distribution and marine area coverage of MPAs varied across different sub-regions, countries, and territories. The majority (56.99%) of MPAs were small (<10km2), and relatively few (22.55%) were large (>100km2). Of the MPAs that reported protection status, most (53.79%) were limited-take, which allow some extractive activities within their borders, while no-take MPAs, which prohibit all extractive activities within their borders, were relatively few (23.48%). There were also significant variations in marine area coverage between different MPA protection classes, but, once again, no-take MPAs reported the least. Data on the community and institutional capacities of MPAs were obtained for 36 MPAs, which reported suboptimal scores.
Altogether, this investigation revealed positives and negatives in the Caribbean region’s pursuit of effective marine conservation. With 572 MPAs distributed across many countries and territories, there is clear regional recognition of the importance of MPAs and progress toward international conservation goals. However, there are also prevalent design shortcomings, such as the small size of most MPAs, which highlight the need for greater emphasis on fundamental MPA design principles. In addition, limited data on the community and institutional capacities of MPAs underscores the need for improved data collection and reporting, specifically for governance information.
Next, to better understand the performance of MPAs in the Caribbean Sea at protecting reef fish assemblages and to discern the potential impacts of MPA age and MPA size, Chapter 3 investigated how the abundances and biodiversities of reef fishes compared between no-take MPAs and unprotected sites, as well as between no-take MPAs of different age and size classes. Generally, there were no statistically significant differences, which were discussed as being potentially attributable to (1) limitations in MPA placement, (2) limitations in MPA design, (3) limitations in MPA management, and (4) exposure of the MPAs to overpowering threats (e.g., climate change).
These findings suggest that MPAs in the Caribbean Sea are struggling to protect reef fishes but, by highlighting potential factors limiting MPA performance, the results provide a foundation for targeted improvements. The lack of statistically significant differences is concerning, but underscores the need for further investigation and a nuanced understanding of the complexities involved. By addressing these challenges head-on, and by implementing adaptive management strategies, there remains potential for improving the effectiveness of Caribbean MPAs and ensuring the long-term conservation of reef fishes in the region.
Lastly, while broader geographical analyses can provide valuable insights, on-the-ground management primarily occurs at the local level, where local management authorities require in-depth knowledge of their MPAs and the stressors they face. Chapter 4 pursued such a local investigation, assessing the abundances and biodiversities of reef fishes within and between three no-take MPAs in Puerto Rico: (1) Tres Palmas de Rincon, (2) Tourmaline Bank, and (3) Isla de Desecheo. The results were dominated by significant declines in abundances and richnesses, which were attributed to multiple threats such as overfishing, coastal development, waste pollution, coral bleaching, invasive species, and storm events.
However, the between-MPA comparisons revealed differences in conservation outcome, potentially suggesting that MPA benefits are developing. By acknowledging differences in the placement, design, and management of these MPAs, and identifying differences in their conservation performance, we can better understand the specific features contributing to successful conservation. This knowledge can then be used to inform and develop targeted management strategies and interventions to enhance MPA effectiveness. While the results and discussions highlight the many challenges that MPAs face in Puerto Rico, they also underscore the importance of continued research, adaptive management, and collaborative efforts in ensuring the long-term resilience of Puerto Rican reef fishes.
In conclusion, this dissertation presents a unique and novel contribution to the study of MPAs in the Caribbean Sea, evaluating current and historical trends in their establishment, placement, design, management and capacity to conserve reef fishes. By identifying major shortcomings in the conservation performance of MPAs, this research highlights important areas for improvement. The call for better data collection, reporting, and management practices presents an opportunity for positive change. With continued dedication and a focus on addressing these issues, there remains a positive outlook for improving the effectiveness of MPAs in the Caribbean Sea and striving toward successful conservation.
Cramer, Mathias Tjarko, "Evaluating the Use and Performance of Marine Protected Areas to Conserve Reef Fish Biodiversity in the Caribbean" (2023). Theses and Dissertations. 1310.
Available for download on Monday, July 29, 2024