Phase III – Preparing for Climate Change through the Assessment of Biodiversity and Management

A key concern of modern marine management and conservation is to determine the interactions between climate change and human resource use, and to identify their potential outcomes. The project aimed at investigating environmental and biodiversity gradients created as a basis for understanding climate change effects, adaptation, and its consequences for biodiversity. The study had three major foci, one on the ecology of coral reefs, a second on the ecology of algal symbionts in corals, and finally an evaluation of the types of management restrictions that coral reef stakeholders in the region prefer and are likely to support. This project was implemented in Kenya, Tanzania, Mozambique, Madagascar, Mayotte, Maldives, Mauritius, Seychelles, and South Africa. Targeted beneficiaries of this project included local communities, the scientific community, MPA managers, Conservationists, the international community including donors, decision and policy makers.

Methodologies for this project, included belt transects (for fish surveys), line-intercept transects method (for benthic substratum functional groups and hard coral community structure), search-sampling procedure (for relative abundance of the different coral genera and their health), and interviews (for management preferences and socio-economic studies). Coral tissue samples for symbiotic algae studies were sent to the Baker lab at the University of Miami, USA for DNA analysis.

The ecological studies indicate that climate disturbances are not uniform at regional, habitat, or management scales. Patterns of coral and benthic composition in the region reflected the strong impact of the 1998-bleaching disturbance in the central northwestern Indian Ocean. Coral cover was lowest in the period immediately after 1998 and decreased with latitude going northward. Fisheries closures had lower coral cover than fished reefs during this period. Exposed reefs suffered the highest declines in cover in 1998, which is contrary to assumptions that exposure mitigates the impact of coral bleaching. Coral taxonomic richness was higher in sheltered closures, and richness and diversity increased northward. Acroporid and pocilloporid corals showed changes in cover that were opposite to those in Poritiids and were more abundant on exposed reefs in the south, reflecting weaker patterns in bleaching in the south and, therefore, higher coral community susceptibility in the south. Pocilloporids, despite their high bleaching susceptibility, showed fast recovery in the old parks of Kenya. Recovery of other coral species in these old parks has been slow. The study suggests a strong positive relationship between total coral cover, and cover of bleaching susceptible taxa, such Acropora and Montipora.

Results further indicate that Symbiodinium occur in two clades, C and D. Large-scale regional studies of algal symbiont distribution indicate that Symbiodinium in clade C is the most common and is a broad tropical generalist. Clade D on the other hand is less common and found in more specific environments where temperatures are high and often variable. There was some evidence that strong thermal anomalies can promote changes in symbionts from C to D in some coral taxa but this change may not persist beyond five years after the disturbance unless background temperature anomalies, or continued warming, continue to promote clade D. Results further indicate that sheltered reefs such as reefs behind islands, in enclosed bays, and back reefs are the most likely to persist under climate change due to associations with acclimatization and community changes in the symbionts. In order that corals are secured against future impacts of climate change and fishing, such reefs should be considered as high priority areas and consequently their management should be enhanced.

The regional evaluation of management preferences indicated that there is generally broad-scale support for management restrictions, particularly gear and minimum size restrictions. There was support for restrictions on space, such as no-fishing closures, species and temporal closures, but there were also a number of communities (in all countries) that did not support these restrictions. Communities with a long history of marine protected areas tend to support closures, especially those that are less reliant on marine resources, supporting the need for diversified and profitable alternative livelihoods.

The fact that some taxa at these sites, such as Pavona and Pocillopora, do have high dominance of clade D, but they also may not survive well at all sites due to strong biological interactions on some reefs, not only complicates the prioritization of conservation actions, but also emphasizes the need for managing shallow reefs as well as reefs in warm environments as a new conservation priority. Furthermore, the different views and attitudes toward management portrayed by stakeholders is a valuable input towards resolving conflicts, higher levels of adoption and compliance, and should be regarded as an important consideration towards effective coral reef management.