A guide for planners and managers - IUCN

PART II
Protected Areas for Lagoons and Estuaries
Should be preceded by environmental impact assessments.
Should be sited in areas with suitable soil chemistry to avoid expensive remedial
measures, crop failures, and low yields.
Should alternate with natural areas managed to provide nurseries (in many cases
for seed stock), and the range of traditional uses maintained at sustainable levels.
Should be components of multiple use management and should be confined to
zones in wetlands where it interferes least with critical habitats and coastal
protection function.
Conversion for Mariculture
Has a mixed history of success, with some major and expensive failures from around
the world, and should be generally considered non-sustainable.
Has limited potential because of acidification of soils.
May have severe impact on productivity of coastal waters and introduce poisons and
disease to natural populations when conducted on grand scales.
May be more appropriate on small community level scales.
Loss of mangroves and other wetland plant communities results in loss of natural
productivity.
Should be subject to comprehensive environment impact assessment and rigorous
monitoring, and designed with the lessons learned from other failed enterprises.
Dyking and Construction of Retaining Walls, Groins, Docks, Piers, Causeways,
and Roads
Should be preceded by studies of water and faunal movements.
Should be sited and constructed to avoid interference with the freshwater inputs from
streams, rivers, and sheet flow (e.g., roads should follow the direction of stream
flow and include adequate culverts).
Should be sited and constructed to avoid interfering with the tidal flushing of
wetlands.
Should be sited and constructed to avoid interfering with movements of detritus and
fauna (larvae, juveniles, and adults).
In many instances retaining walls may be inferior and expensive substitutes for barriers
of natural vegetation.
If conservation countermeasures are not employed, the result can be rapid
and severe degradation of the lagoon and estuary ecosystems and depletion of natural
resources. But approaches other than MPA designation may be necessary for a
successful conservation programme; for example, the Coastal Zone Management
approach that includes pollution control and land use management.
In Gambia, India, and Bangladesh, conversion of mangrove stands of coastal
lagoons to rice fields has caused considerable loss of natural productivity. In Indonesia,
Ecuador, and Costa Rica, the cost of conversion has proved high and the yield
generally low because of resultant acidic conditions. Coconut plantations have
preempted mangrove forests in Sri Lanka (Salm, 1981a) (Figure II-19).
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