Landscapes Forest and Global Change - ESA - Escola Superior ...

E. Kouhgardi et al. 2010. Values of mangroves and its interaction with marine ecosystem
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is a similar reduction in the number of species with increasing latitude in the Northern
hemisphere.
Mangrove forests are important for a number of reasons:
1. Mangrove forests and estuaries are the primary nursery area for a number of commercially
important shrimp, crab and fish species. They are also important nursery areas for other
species which are they not used commercially, but which for, part of the food chain for
commercial species offshore.
2. Mangrove vegetation stabilizes shorelines and the banks of rivers and estuaries, providing
them with some protection from tidal bores, ocean currents and storm surges.
3. In many countries of South-east Asia and the Pacific, mangroves are used commercially
for the production of timber for building, firewood and charcoal. Experience has shown that
when these activities are managed appropriately it is possible to derive timber products from
mangrove forests without significant environmental degradation, and while maintaining their
value as a nursery and source of food for commercial capture fisheries.
2. Methodology
2.1 Mangrove ecosystem
Due to the projected sea level rise, changes are being caused in the mangrove swamps of Sunder
bans. In some areas, mangroves have died out while in other areas mangrove swamps have
become more saline and the composition of species of both fauna and flora is changing. It is
therefore proposed to study the ecology of mangroves of various salinity levels-low, medium
and high. In these areas it is proposed to study the physicochemical conditions, productivity of
benthos, phyto and zooplankton, availability of juveniles of prawns and fish and use them for
growing. In addition, it is also proposed to study the role of different kinds of ecosystems, for
the kind of species they will support for breeding and reproduction, as nursery grounds and as
habitat for growing adult fish.
2.2 Function and uses of mangroves
Mangrove forest ecosystems fulfill a number of important functions and provide a wide range of
services at the local and national levels (Box). Fishermen, farmers and other rural populations
depend on them as a source of wood (e.g. timber, poles, posts, fuel wood, charcoal) and nonwood
forest products (food, thatch – especially from nipa palm – fodder, alcohol, sugar,
medicine and honey). Mangroves were also often used for the production of tannin suitable for
leather work and for the curing and dyeing of fishing nets. However, this production has
declined in recent years, mainly because of the introduction of nylon fishing nets and the use of
chrome as the predominant agent for curing leather (FAO, 1994).
Mangroves support the conservation of biological diversity by providing habitats, spawning
grounds, nurseries and nutrients for a number of animals. These include several endangered
species and range from reptiles (e.g. crocodiles, iguanas and snakes) and amphibians to
mammals (tigers – including the famous Panthera tigris tigris, the Royal Bengal tiger – deer,
otters, manatees and dolphins) and birds (herons, egrets, pelicans and eagles, to cite just a few).
A wide range of commercial and non-commercial fish and shellfish also depends on these
coastal forests. The role of mangroves in the marine food chain is crucial. According to
Kapetsky (1985), the average yield of fish and shellfish in mangrove areas is about 90 kg per
hectare, with maximum yield of up to 225 kg per hectare (FAO, 1994). When mangrove forests
are destroyed, declines in local fish catches often result. Assessments of the links between
Forest Landscapes and Global Change-New Frontiers in Management, Conservation and Restoration. Proceedings of the IUFRO Landscape Ecology
Working Group International Conference, September 21-27, 2010, Bragança, Portugal. J.C. Azevedo, M. Feliciano, J. Castro & M.A. Pinto (eds.)
2010, Instituto Politécnico de Bragança, Bragança, Portugal.