Melita Samoilys

Transforming management of tropical coastal seas to cope with challenges of the 21st century

Over 1.3 billion people live on tropical coasts, primarily in developing countries. Many depend on adjacent coastal seas for food, and livelihoods. We show how trends in demography and in several local and global anthropogenic stressors are progressively degrading capacity of coastal waters to sustain these people. Far more effective approaches to environmental management are needed if the loss in provision of ecosystem goods and services is to be stemmed. We propose expanded use of marine spatial planning as a framework for more effective, pragmatic management based on ocean zones to accommodate conflicting uses. This would force the holistic, regional-scale reconciliation of food security, livelihoods, and conservation that is needed. Transforming how countries manage coastal resources will require major change in policy and politics, implemented with sufficient flexibility to accommodate societal variations. Achieving this change is a major challenge - one that affects the lives of one fifth of humanity.

Towards a network of locally managed marine areas (LMMAs) in the Western Indian Ocean.

In the Western Indian Ocean (WIO), local communities are increasingly assuming responsibility for inshore marine resources either on their own or through collaborative management arrangements with governments or non-state actors. In this paper, we trace the evolution and expansion of community management in the WIO and present the first ever inventory and assessment of the region’s locally managed marine areas (LMMAs). We compare the key attributes of these areas to those under government stewardship and assess their relative contributions to progress towards the Convention on Biodiversity (CBD) target of 10% of marine and coastal ecological regions to be effectively conserved by 2020. We also explore the legal frameworks that underpin locally managed marine initiatives in Kenya, Madagascar, Mozambique and Tanzania to assess the potential for future expansion. A principal finding is that whilst LMMAs protect more than 11,000 square kilometres of marine resource in the WIO, they are hampered by underdeveloped local and national legal structures and enforcement mechanisms. In our recommendations to improve local management, we suggest establishing a network of LMMA practitioners in the WIO region to share experiences and best practice.

Patterns in reef fish assemblages: Insights from the Chagos Archipelago

Understanding the drivers of variability in the composition of fish assemblages across the Indo-Pacific region is crucial to support coral reef ecosystem resilience. Whilst numerous relationships and feedback mechanisms between the functional roles of coral reef fishes and reef benthic composition have been investigated, certain key groups, such as the herbivores, are widely suggested to maintain reefs in a coral-dominated state. Examining links between fishes and reef benthos is complicated by the interactions between natural processes, disturbance events and anthropogenic impacts, particularly fishing pressure. This study examined fish assemblages and associated benthic variables across five atolls within the Chagos Archipelago, where fishing pressure is largely absent, to better understand these relationships. We found high variability in fish assemblages among atolls and sites across the archipelago, especially for key groups such as a suite of grazer-detritivore surgeonfish, and the parrotfishes which varied in density over 40-fold between sites. Differences in fish assemblages were significantly associated with variable levels of both live and recently dead coral cover and rugosity. We suggest these results reflect differing coral recovery trajectories following coral bleaching events and a strong influence of ‘bottom-up’ control mechanisms on fish assemblages. Species level analyses revealed that Scarus niger, Acanthurus nigrofuscus and Chlorurus strongylocephalos were key species driving differences in fish assemblage structure. Clarifying the trophic roles of herbivorous and detritivorous reef fishes will require species-level studies, which also examine feeding behaviour, to fully understand their contribution in maintaining reef resilience to climate change and fishing impacts.

The current status of coral reefs and their vulnerability to climate change and multiple human stresses in the Comoros Archipelago, Western Indian Ocean

Coral bleaching and various human stressors have degraded the coral reefs of the Comoros Archipelago in the past 40 years and rising atmospheric CO2 levels are predicted to further impact marine habitats. The condition of reefs in the Comoros is poorly known; using SCUBA based methods we surveyed reef condition and resilience to bleaching at sites in Grande Comore and Mohéli in 2010 and 2016. The condition of reefs was highly variable, with a range in live coral cover between 6% and 60% and target fishery species biomass between 20 and 500 kg per ha. The vulnerability assessment of reefs to future coral bleaching and their exposure to fishing, soil erosion and river pollution in Mohéli Marine Park found that offshore sites around the islets south of the island were least likely to be impacted by these negative pressures. The high variability in both reef condition and vulnerability across reefs in the Park lends itself to spatially explicit conservation actions. However, it is noteworthy that climate impacts to date appear moderate and that local human pressures are not having a major impact on components of reef health and recovery, suggesting these reefs are relatively resilient to the current anthropogenic stresses that they are experiencing.