Learning from small islands in the Western Indian Ocean (WIO): A systematic review of responses to environmental change

Tropical small islands are particularly vulnerable to environmental impacts. In the small islands of the Western Indian Ocean (WIO), multiple stressors of environmental and socio-economic change interact and intensify at reduced spatial scales. Actors and institutions need to respond to these changes through responses – reactive or proactive actions planned or implemented by individuals, groups or organisations; aimed at responding to changing contexts and scenarios, by reducing, preventing and/or reverting the risks and impacts of environmental change. Through a mixed-method systematic review of academic literature from 2010 to 2020 using the Web of Science literature database, we document the types of responses, actors involved and elements of effective responses. We analysed 329 studies focusing on nine WIO small island states and territories (SISTs) – Zanzibar, Mafia, Seychelles, Comoros, Mayotte, La Réunion, Mauritius, Maldives and Lakshadweep. Using quantitative content analysis, we organised information into categories ranging from institutional (economic instruments, laws, policies and community based), social (educational and informational), infrastructural (engineered and technological) and ecological restoration-based responses. The articles varied in their geographical distribution, focus and depth with regard to the responses studied. Diverse responses are documented, that often overlap across categories and may be combined and pursued simultaneously. For example, responses range from coastal protection structures, land reclamation, land elevation and artificial islands to mangrove restoration, awareness raising programs, coastal zone regulations and climate induced migration and relocation policies. Responses were predominantly institutional (85% of 329 articles, n = 281) – mainly driven by governments. The most common social responses (53%, n = 183) were linked to environmental education programs and knowledge sharing platforms. Although the responses indicated an increasing interest in ecological restoration (27%, n = 91) and community-based initiatives (36%, n = 120), they were largely underrepresented in research. Cataloguing the different responses may help incorporate the diversity into well-informed decisions, offer alternative ways of thinking and highlight specific areas and response types that should be the focus of future research and practice. The elements influencing the effectiveness of responses were identified through thematic synthesis – relevance to the local social-ecological context, resources available (time and funding), knowledge (access, diversity, integration, transfer, innovative and anticipatory), governance of responses (coordinated, transparent, adaptive, equitable, participatory and polycentric) and iterative monitoring. These elements of effectiveness tend to be synergistic and no single element is effective in isolation. When these elements are not considered, the response intervention could be maladaptive or counterproductive. Poorly designed responses result in perverse social and ecological outcomes, further increasing the exposure and vulnerability to the environmental stressors and decreasing public confidence and support. This review documents current literature, points to knowledge gaps and highlights the potential for islands to learn from each other and to further apply these lessons to non-island settings, critically considering the local context.