Adaptation for coastal and marine ecosystems


Madagascar is globally recognized as an island of exceptional coastal and marine biodiversity. While knowledge on coastal and marine ecosystems is less than for terrestrial ecosystems, it is broadly recognized that there is extraordinary diversity within remaining coral, mangrove and inter-tidal ecosystems in Madagascar. However, human activities are threatening the ongoing survival of this natural legacy. Sedimentation caused by erosion of deforested land is polluting coastal waters and causing coral bleaching, unsustainable resource use is threatening the survival of mangrove ecosystems, and overfishing is depleting fish populations in some areas.

Climate change is compounding existing stresses on ecosystems and is considered by many researchers to be the future major threat to the survival of numerous unique species found here. Adaptation to climate change to protect coastal and marine ecosystems must therefore form an integral component of the national response to climate change.

Potential Impacts

Some coastal and marine species and ecosystems in Madagascar are already exhibiting responses to a changing climate; for example, coral bleaching and increased incidence of green algae, thought to be linked to rising ocean water temperatures has been observed on coral reefs near Toliara. Climate change impacts on coastal and marine ecosystems are likely to intensify in the future and occur as a result of both climate variability and extreme climate events.
Effects will be felt at the population, species and ecosystem level but the nature and scale of the impacts will not be equal. Potential impacts include:

• Changes in species range and distribution including expansion or contraction of range and range shifts for fish, mangrove, coral and inter-tidal species. While responses of species vary widely, species that are confined to narrow habitats are generally likely to be more severely impacted. Migration may be essential for some species where future predicted distributions have limited overlap with existing distributions. The ability of species to migrate is however threatened by the fragmented nature of remaining habitats, including mangroves and inter-tidal habitats.

• Genetic and evolutionary effects as animal and plan populations experience new selection pressures due to changing climate conditions or changing ecosystem composition. Climate change has been identified by some researchers to be the dominant influence on evolutionary processes in the coming centuries.

• Phenological effects such as changes in breeding seasons, flowering seasons, life cycles, migration patterns, emergence timing or metamorphic patterns are possible. Species that do not undergo direct phenological changes may be indirectly affected by changes in species upon which they rely; for example availability of food sources may change with change in budding and fruiting periods of plants.

• Ecosystem composition is likely to change as different species within existing ecosystems react differently to climate stressors. Extinction of some species within ecosystems is possible due to increased competition for available habitat niches. Invasive species with the ability to withstand a wide range of climate conditions may overwhelm ecosystems.

• Physical damage or harm to species and ecosystems can result directly from climate variability or climate extremes. For example, increased ocean water temperatures can affect the alkalinity of seawater and calcification rates of corals, while cyclones, sea level rise and freshwater flooding may damage coastal mangrove ecosystems and thus reduce their coastal protection function. Impacts can also be caused indirectly from the secondary effects of climate change. For example, erosion of already deforested lands is likely to be increased as a result of changing precipitation and the resulting increased sedimentation of coastal waters has the potential to cause coral bleaching events and effects on the viability of mangrove ecosystems.

• Increased pressure on natural resources resulting from changes in demand for ecosystem goods and services by local communities. Poor and vulnerable populations in Madagascar are highly reliant on natural resources provided by coastal and marine ecosystems (e.g. fuel wood, fish and other foodstuffs, medicinal plants etc.). Current levels of resource use are at, or are reaching, unsustainable levels in some areas and pressures could be exacerbated by increased demand resulting from climate-induced migration, or households being forced into poverty by climate change impacts.

• Impacts from changes in the hydrological cycle particularly on mangrove ecosystems which can be affected by flow rates, sea levels, salinity levels and groundwater recharge rates.

• Loss of habitat and loss of connectivity between habitats, particularly in relation to mangrove habitats, resulting from one or more of the potential impacts described above. Loss of connectivity between areas of suitable habitat through is particularly of concern as the main response of certain species to climate change may be migration, which will not be possible for most species without physical connections between habitat areas. Sea turtle nesting habitats are also at risk from sea level rise and erosion and breeding and hatching conditions are at risk from an increase in sand temperature.

Priority Actions

Climate change adaptation measures are required to increase the resilience of coastal and marine ecosystems, and the goods and services they provide, to future climate conditions. Examples of adaptation approaches that should be considered for implementation include:
• Further research into specific impacts on high priority species and ecosystems to better understand the characteristics and vulnerabilities
of coastal and marine ecosystems in the face of future climate change and the priorities in terms of populations, species and ecosystems.
Dissemination of results of research to a wide audience in order to raise awareness about the effects of climate change on biodiversity.

• Ongoing extension, reinforcement and improved management of the marine protected area network to improve representation and replication and facilitate conservation of priority population, species and ecosystems identified as being at risk of climate change effects; inclusion of corridors and connective habitat in the network where possible; improved focus of network management on ecosystem function; development of adaptive management frameworks to respond to the identified effects of climate change; and improved management and enforcement of the network to reduce the effects of non-climate stressors.

• Development of a comprehensive monitoring system within protected areas for climate change impacts to allow early warning of impacts and potential tipping points within ecosystems and facilitate adaptative management of protected areas.

• Development of species specific management strategies to focus resources on priority species with a high risk of extinction and including consideration of the feasibility of translocation of species or establishment of captive populations for species at risk of extinction.

• Enhancement of connectivity between fragmented mangrove habitats including identification of key corridors between areas of habitat and implementation of restoration or rehabilitation activities; improvement of institutional management and monitoring frameworks for corridors through development of landscape conservation plans; and involvement of local communities in restoration, rehabilitation and monitoring activities.

• Management of mangrove and coral reef areas outside the protected area network to allow for ongoing sustainable resource use by local communities thereby decreasing pressure on resources within the protected area network.

• Improved upstream land use planning and implementation of integrated coastal zone management approaches to minimize sedimentation and pollution of coastal waters and associated effects on mangroves, reefs, sea turtle nesting beaches and other important coastal and marine ecosystems. Examples include development of buffer zones allowing limited resource extraction upstream of sensitive coastal and marine ecosystems.

• Integration of adaptation strategies for biodiversity and socio-economic development to ensure that adaptation strategies developed to increase resilience of coastal and marine ecosystems take into account the social issues and include elements to minimize both existing human induced stressors and secondary social effects of climate change (e.g. climate migrants) on biodiversity. Examples include development of programs for sustainable alternative livelihoods for resource dependent communities, establishment of financial incentives for conservation, development of alternative sources of natural resources (e.g. aquaculture).