MARINE AND COASTAL ECOSYSTEMS GROUPS
MANGROVES
1 – Climate change risks to mangrove
a) Key climate change impacts that may affect mangroves
sedimentation  due to upstream erosion (as caused by deforestation, poor land use
practices) particles are washed to mangroves (mangrove stands becoming
smaller)
 due to wind erosion, to waves ; sédimentation in mangroves
Sea level rise : considered as of low impact on mangroves up to now but needs to be mitigated
Flooding permanently with sea water some part of the mangrove which will
die
Abnormal droughts : reduction in freshwater input, thus also nutrients. Affect performance
and reproductive potential, stand development, mangrove structure,
siltation at river mouth as this latter will no longer be able to flush away
the accumulated sediment
Abnormal precipitations : flooding leading to erosion upstream and sedimentation
downstream – mangrove stands die if their roots are exposed to
freshwater for few days ; change in chenal course if it encounters
blockage (from sediment and tree trunk carried by the river) ; thus,
the portion of mangrove affected will no more receive sea water
input.
cyclones and strong winds may uproot trees
b) Species, sites, regions and processes particularly vulnerable to climate change
As species vulnerability is mostly linked to sites vulnerability, the group discussed more on
identifying the sites that are vulnerable. There are:
- Riverin mangroves
Belo-sur-Tsiribihina : flooding and sedimentation
Bombetoka : flooding, sedimentation, land use practices (rice cultivation)
Mahajamba : flooding, sedimentation, land use practices (aquaculture)
Sahamalaza : flooding, sedimentation (deforestation, road construction, erosion upstream)
- sites exposed to cyclones du nord est : cyclones,
Sites of the North East
- islets mangrove sites with no or poor sediment input, no space for landward migration are
strongly vulnerable to climate change
2- Resistant and resilient to climate change mangroves
Conditions :
-
Mixed species mangroves stands
Gradual sedimentation (allowing enough time for colonization)
uneven aged stands
topography + zonation
freshwater input
Identification of sites matching these conditions
- all mangrove sites (off the west coast) have mixed stands, at least 3 or 4 species
- all sites off the West coast from Manombo except Belo-sur-mer : freshwater input
- deltaic mangroves : from Bombetoka to Ambaro developping in bays, favourable
topography (light slope) allowing landward migration, freshwater input
such as Belo-sur-tsiribihina : topography supposing gradual sedimentation and
landward migration possibility, freshwater input
- Sites of the Nord-East : freshwater input
- Belo-sur-mer : lagoon mangrove with high regeneration, topography, stands of 14-15
m tall
3 - Key non climate stressors
Anthropic activities ;
Overlogging, overexploitation (e.g. for charcoaling, timber, …)
Clearing
Urbanization
Aquaculture
Pollution (e.g. sewage)
Mining (sedimentation, pollution, …)
land use practices : overgrazing, poor farming practices,
4) Most important geographic area in terms of marine biodiversity
Most of the West coast mangrove sites : commercial fisheries among which shrimp fishery
Sites of the Nord
CORAL REEFS
Network considerations and principles
Network design principles need to be expressed in forms necessary for policy uptake (CEP),
and in MPA selection and management (many publications can support this process). Key
concepts mentioned include:
 Currents and connectivity - insufficiently understood for improving informed design
of an MPA network.
 Source/sink relationships – larvae/spillover.
 Linkages among marine ecosystems - coral reef, mangrove, seagrass ecosystems
 Land-sea interactions - ICZM around the MPAs.
 Multiple sites and replication – encourage recovery in the long term.
 Multiple objectives and reasons for MPAs – biodiversity, fisheries, etc need to be
synergized
Priority sites and regions
 not enough knowledge to effectively prioritize among sites to suggest new ones.
 existing MPAs and efforts should be strengthened while prioritizing new sites for
MPAs.
 The total area for MPAs needs to be increased significantly
Gaps in research and monitoring
1. Revize and update the coral susceptibility maps with improved indicators/variables.
2. Current and basic oceanographic understanding of the Madagascar coast, incorporating:
- modeling of currents at a reasonable scale to infer connections between sites along the
coast
- groundtruthing and validation of the models at a few key sites that can also serve to
inform zoning and network decisions at the MPA site level.
3. Measurement of more environmental variables to understand natural variability to better
understand anthropogenic impacts – e.g. sedimentation. With good spatial/temporal
design.
4. More RAPs (Rapid Assessment surveys), priorities and gaps need to be identified and
coordinated among groups to streamline information flow.
5. Data management and coordination – need for database/GIS centralization integrated with
large/remote sensing datasets, e.g. with Rebioma.
6. Coastal erosion vulnerability critically needed, e.g. where barriers such as Tulear reef are
eroding.
Driving the policy process in support of an MPA network
 strong synergy needed between outputs and follow-up from this workshop and the
CEP policy process
 to support this, we addressed broader concepts behind MPA selection to steer policy
formulation at the highest level.
SPECIES GROUP
Marine mammals:
Up to 28 cetaceans species and the dugong
Some resident populations, some migratory (large baleen whales)
Some species live near shore, others off-shore
Hunting is primary threat to near shore in some areas
Commercial by-catch and extractive industries likely impact, poorly understood
Actions:
Reduce non-climate stressors
Include climate change effects in outreach and education
Integrate mammals into MPA design, location choice, goals, management
Create networks of reserves to allow range shifts
Work with long-term monitoring projects to gather more scientific data
Work with fisheries, whale-watchers, others to collect more data
Caveat: need financing to analyze data, and some means of quality control
Work with communities to create local laws, “Dina,” for conservation of local populations
Use national laws to regulate industrial activities (mining, oil/gas, major development)
Data gaps:
Basic distribution and abundance information
Basic information on trophic interactions
What do mammals feed on and where?
How will climate change affect the distribution and abundance of these food items?
How will changes in mammal populations interact with other climate change effects?
Marine turtles
5 species in Madagascar; 4 breed here
Extensively hunted in many areas, but poorly documented
Maps of nesting beaches from 1992; overharvest may’ve eliminated some beaches
Actions
Use community-based turtle tagging to increase local buy-in to turtle conservation and gain
data
Develop alternative food sources
Difficult because requires cultural change
Reforestation above nesting beaches to reduce flooding, sedimentation
Integrate turtles into MPA design, location choice, goals, management
Create networks of reserves
Allows range shift with increasing temperature
Allows change of nesting beach location in the event of local beach loss
Protect natural vegetation along nesting beaches
Data gaps
Current nesting beach distribution
Location of feeding grounds, juvenile staging areas, hatchling migration paths