AQUATIC ECOSYSTEM: CONSERVATION STRATEGY
While rivers, lakes, and wetlands contain a mere 0.01 % of the Earth's water, these ecosystems support a disproportionately large part of global biodiversity. Freshwater fishes alone account for approximately one quarter of all living vertebrate species and it is estimated that there are 44,000 scientifically named species of freshwater biota. Tallies of endangered species indicate that freshwater biodiversity is generally more threatened than terrestrial biodiversity. For example, of those species considered in the World Conservation Union's (IUCN) Red List for 2000, 20% of amphibians and 30% of fishes (mostly freshwater) were considered threatened. Freshwater biodiversity faces a broad range of threats. These include the direct impacts of dams, exotic species, over-fishing, pollution, stream channelisation, water withdrawals, and diversions, as well as the indirect consequences of terrestrial activities such as logging, agriculture, industry, housing development, and mining (Prasad et al., 2002). Conservation strategies need to be evolved and implemented to protect freshwater biodiversity. The Aquatic Conservation Strategy focuses on conservation and maintaining the ecological health of watersheds and aquatic ecosystems so as to (Ramachandra, T.V. et al, 2002):
- Maintain and conserve the distribution, diversity, and complexity of watershed and landscape-scale features to ensure protection of the aquatic systems to which species, populations, and communities are uniquely adapted.
- Maintain and conserve spatial and temporal connectivity within and between watersheds. Lateral, longitudinal, and drainage network connections include flood plains, wetlands, up slope areas and headwater tributaries. These linkages must provide chemically and physically unobstructed routes to areas critical for fulfilling life history requirements of aquatic and riparian-dependent species.
- Maintain and restore the physical integrity of the aquatic system, including shorelines, banks, and bottom configurations.
- Maintain and preserve water quality necessary to support healthy riparian, aquatic, and wetland ecosystems. Water quality must remain in the range that maintains the biological, physical, and chemical integrity of the system and benefits survival, growth, reproduction, and migration of individuals composing aquatic and riparian communities.
- Maintain the sediment regime under which an aquatic ecosystem evolved. Elements of the sediment regime include the timing, volume, rate, and character of sediment input, storage, and transport.
- Maintain in stream flows sufficient to create and sustain riparian, aquatic, and wetland habitats and to retain patterns of sediment, nutrient, and wood routing (i.e., movement of woody debris through the aquatic system). The timing, magnitude, duration, and spatial distribution of peak, high, and low flows must be protected.
- Maintain the timing, variability, and duration of flood plain inundation and water table elevation in meadows and wetlands.
- Maintain and conserve the species composition and structural diversity of plant communities in riparian zones and wetlands to provide adequate summer and winter thermal regulation, nutrient filtering appropriate rates of surface erosion, bank erosion, and channel migration, and to supply amounts and distributions of coarse woody debris sufficient to sustain physical complexity and stability.
- Maintain and conserve habitat to support well-distributed populations of native plant, invertebrate, and vertebrate riparian-dependent species.
- Aquatic ecosystem conservation and management requires collaborated research involving natural, social, and inter-disciplinary study aimed at , understanding. the various components, such as monitoring of water quality, socio-economic dependency, biodiversity, and other activities, as an indispensable tool for formulating long term conservation strategies (Kiran & Ramachandra, 1999). This requires multidisciplinary-trained professionals who can spread the understanding of ecosystem's importance at local schools, colleges, and research institutions by initiating educational programmes aimed at raising the levels of public awareness and comprehension of aquatic ecosystem restoration, goals, and methods. Actively participating schools and colleges in the vicinity of the water bodies may value the opportunity to provide hands-on environmental education, which could entail setting up laboratory facilities at the site. Regular monitoring of water bodies (with permanent laboratory facilities) would provide vital inputs for conservation and management.
Watershed restoration should be an integral part of the conservation programme to aid recovery of habitat, riparian habitat, and water quality. The most important components of an aquatic restoration programme are control and prevention of pollution and sediment production, restoration of the condition of riparian vegetation, and restoration of in-stream habitat complexity (Ahalya, N. & Ramachandra, T.V., 2001).