Graduation date: 2008
Coastal and marine ecosystems in Latin America and the Caribbean are
undergoing a rapid and drastic transformation. Dense human populations are
concentrated in coastal areas, leading to increased coastal development, destruction of
near-shore habitats, pollution, and overexploitation of marine resources. For most
Latin American and Caribbean countries, the deterioration of coastal ecosystems is
particularly critical due to the strong dependency of their economies on the quality of
natural resources and ecosystems. Thus, the necessity of effectively conserving and
managing marine ecosystems with a more integrative, ecosystem–based approach is
urgent. Marine reserves constitute a powerful conservation tool for mitigating ocean
degradation. Because they provide spatial refuges for fished populations, and protect
important habitats and their associated ecological interactions, they are particularly
beneficial for counteracting the harmful effects of overfishing.
In Chapter 2 of this thesis, I present a comprehensive analysis of the status and
progress of marine protected areas (MPAs), particularly no-take marine reserves in
Latin America and the Caribbean. I also show that the number and area protected have
increased through time, particularly since the 1980s; but the system of MPAs is still
deficient in fully representing the whole array of marine biogeographic provinces. In
addition, I demonstrate that no-take marine reserves are poorly utilized for
conservation of marine biodiversity in this region. Finally, I highlight the need for
strengthening the marine conservation initiative in Latin America and the Caribbean
under a regional approach.
In Chapter 3 using meta-analytic methods, I quantitatively estimate the
magnitude of the conservation effects of marine reserves in Latin America and the
Caribbean. I examine the species and reserve characteristics that contribute to explain
the variation in responses to protection. These analyses demonstrate positive outcomes
of reserve protection at assemblage and species levels, and confirm the effectiveness
of marine reserves as a conservation tool to rebuild exploited populations. Less clear is
the relationship between density responses to protection and species-specific
characteristics. Species with different trophic levels, adult mobility, body size and
resilience can benefit from protection. Nevertheless, when I examine the effects of
protection on one habitat type (coral reefs) using biomass as the response variable
different trophic groups show differential responses. Predators demonstrated higher
positive responses compared to herbivores or producers. In addition some indirect
effects were disclosed.
Findings from this research have direct implications for the advancement of
marine conservation in Latin America and the Caribbean. Chapter 2 provides an
important tool for planning marine conservation strategies at a regional scale. Areas
that need more protection are highlighted, especially networks of no-take marine
reserves in the Eastern Pacific and Southern Atlantic. Additionally, this assessment
can be used as a baseline to make future comparisons of the progress of marine
biodiversity conservation in this region. Chapter 3 demonstrates the powerful effect of
no-take marine reserves in restoring depleted populations and in some cases
recovering ecological functions that have been lost due to overfishing in Latin
American and the Caribbean.