The position of estuaries at the interface of the terrestrial and marine environment makes them vulnerable to the impacts of human activities, whether land-based or marine, including the impacts of climate change. Estuaries are also a magnet for human activity. Thus, managing estuaries as protected areas can be particularly challenging and management of estuarine protected areas require cooperative governance between a number of community and government.
Estuarine functioning is primarily driven by the quantity and quality of freshwater and marine mediated by freshwater inflows and tides, fresh and salt waters mix in a nutrient-rich environment that supports a diversity of aquatic species.
The link between estuaries and their surrounding terrestrial, freshwater and marine systems is vital for many species whose life depend on movement between these systems. This includes many marine species of conservation and commercial value. Thus, estuaries should not be managed as isolated systems
In addition to the quantity of water entering estuaries, catchment activities and infrastructure such as loads of sediments, nutrients and other pollutants also affect the quality of this water. This can result in smothering of habitats, increased turbidity and eutrophication—all of which can result in significant changes in biotic communities and local extinctions.
The protection of an estuary requires that the quantity and quality of freshwater inflows are maintained as close to natural as possible, in order to maintain ecological functioning and biodiversity in a relatively natural state.
A wide array of human impacts compromise their ecological integrity of estuaries, because of rapid population growth and uncontrolled development. Long-term environmental problems such as pollution inputs, the loss and alteration of estuarine habitat and other anthropogenic stress require remedial actions to improve the viability and health of these valuable coastal systems.
- water quality in estuaries, particularly urbanized systems, is often compromised by the overloading of nutrients and organic matter, the influx of pathogens, and the accumulation of chemical contaminants.
- The destruction of fringing wetlands and the loss and alteration of estuarine habitats usually degrade biotic communities.
- Estuaries are characterized by high population densities of microbes, plankton, benthic flora and fauna, and nekton; however, these organisms tend to be highly vulnerable to human activities. By 2025 estuaries will be most significantly impacted by habitat loss and alteration associated with an increase of coastal population.
- Habitat destruction which modify the structure, function, and controls of estuarine ecosystems lead to the decline of biodiversity.
- Excessive nutrient and sewage inputs to estuaries, principally from land-based sources lead to the greater incidence of eutrophication as well as hypoxia and anoxia.
- Overfishing is a more pervasive and significant anthropogenic factor, also capable of mediating global-scale change to estuaries.
- Chemical contaminants, notably synthetic organic compounds, remain a serious problem, especially in heavily industrialized areas.
- Freshwater diversions appear to be an emerging global problem as the expanding coastal population places greater demands on limited freshwater supplies for agricultural, domestic, and industrial needs.
- Altered freshwater flows could significantly affect nutrient loads, biotic community structure, and the trophodynamics of estuarine systems.
- Ecological impacts are also caused by introduced species, sea level rise, coastal subsidence, and debris/litter.
Thus, the health of estuary ecosystems is threatened by increased nutrients and algal blooms, loss of habitat and biodiversity, contaminants and pollutants, accelerated rates of sedimentation, disturbance of soils, changes to freshwater and tidal flows, invasive species, climate change.
In order for the protection of estuaries to be successful, all of the following interventions at local to national scales are necessary:
- integrated conservation planning
- ensure quantity and quality of inflows to maintain the protected estuaries in a desired state of health
- provide nursery areas for crustaceans and fish, carbon sequestration and coastal protection
- prioritise conservation of biodiversity
Wetlands
Since the advent of industrialization and urbanization the wetlands came under severe threat due to increased anthropogenic-pressures. As per an estimate, India has lost 38 percent of its wetlands between 1991 and 2001 alone.
Threats
• Urbanization and land use changes: During the 90 year period from 1901 to 1991, the number of urban centres doubled while urban population has increased eightfold. This magnitude of growth exerted tremendous pressure on wetlands and flood plain areas for meeting water and food demand of growing population.
• For example, the Kanwar lake in Bihar, Asia’s largest freshwater oxbow lake, has shrunk to one-third of its size due to encroachment, much like Jammu and Kashmir’s Dal lake. And, about 34000 hectares of the water spread area of the Kolleru lake (Andhra Pradesh) have been reclaimed for agriculture in recent years.
• Agricultural residues: As a result of intensification of agricultural activities over the past four decades, fertilizer consumption in India has increased. As per estimates, 10–15 percent of the nutrients added to the soils through fertilizers eventually find their way to the surface water system. High nutrient contents stimulate algal growth, leading to eutrophication of surface water bodies.
• Municipal and Industrial pollution: Domestic wastewater from Indian urban centres is largely discharged in the natural water bodies such as streams and rivers.
For example, River Yamuna, which passes through 6 Indian States, receives untreated waste water from the capital city of Delhi which comes to about about 78 percent of the total pollution load that flows in to the river.
• Similarly, untreated industrial effluents have become a major threat to the survival of wetlands. For instance, the Bellandur Lake in Bengaluru city was ‘on fire’ in May 2015 due to the discharge of effluents (especially nutrient rich foams) by the surrounding industries.
• Climate Change: Global climate change is expected to become an important driver of loss and change in wet-land ecosystem.
•Wetlands located in high altitude as well as coastal areas, like mangroves and coral reefs, are some of the most sensitive classes that will be affected by climate change. For example, climate change caused rise in level of Tsomoriri Lake in Ladakh, a glacial fed high altitude lake, thereby causing submerged important breeding islands in the lake where endangered migratory birds like the Black-necked Crane and Bar-headed Goose would breed.
• Introduced Species: Indian wetlands are threatened by exotic introduced plant species such as water hyacinth and salvinia. They clog waterways and compete with native vegetation.
Apart from the above major threats, immersion of idols and religious ritual waste, introduction of exotic species, encroachments and unregulated aquaculture, dredging, un planned urbanization and development projects are some of the other dangers threatening the existence of wetlands across the country.
Wetlands are amongst the most productive ecosystems on the Earth. Historically, they have been at the centre of evolution of human civilization for millennia as they are means of precious ecological goods and services. However, unfortunately, they are also ecologically most sensitive eco-systems and are under threat due to increased anthropogenic-pressures.
Management
Ramsar Convention
The Convention came into force in 1975 for preserving the ecological character of wetlands.
The Convention’s mission is “the conservation and wise use of all wetlands through local and national actions and international cooperation, as a contribution towards achieving sustainable development throughout the world”.
India has 37 Ramsar Sites which are the Wetlands of International importance.
Wetlands (Conservation and Management) Rules, 2017:
Nodal authority: As per the Wetlands Rules, the Wetlands Authority within a state is the nodal authority for all wetland-specific authorities in a state/UT for the enforcement of the rules.
Prohibited activities:
- Setting up any industry and expansion of existing industries,
- Dumping solid waste or discharge of untreated wastes and effluents from industries and any human settlements, and
- Encroachment or conversion for non-wetlands uses.
Integrated Management Plan: The guidelines recommend that the state/UT administration prepare a plan for the management of each notified wetland by the respective governments.
Penalties: Undertaking any prohibited or regulated activities beyond the thresholds (defined by the state/UT administration) in the wetlands or its zone of influence, will be deemed violations under the Wetlands Rules. Violation of the Rules will attract penalties as per the Environment (Protection) Act, 1986.
No comments:
Post a Comment