R. Ramesh . S. Ramachandran
The seagrass beds are found in open sea as well as in river basins, estuaries and
lagoons. Extensive seagrass beds are reported from Jaffna lagoon to Dutch Bay
and from Mannar to Rameshwaram island in India. In the southwestern part of the
island, smaller seagrass beds are found on the leeward side of the coral reefs.
Seagrass bed areas in Sri Lanka have not however, been precisely determined,
but 12 species of seagrass belonging to 9 genera have been identified. Seagrasses
are very sensitive to turbid water caused by pollution and sediments. Bottom
trawling and dragnetting also cause damage to seagrass bed communities. The collection of Polychaete worms (feed for brood shrimp) also affects the seagrass beds negatively.
In addition there are two types of estuaries found in Sri Lanka: the basin and the
riverine types. Estuaries and lagoons are distributed all along the national coastline
aI\d there are about 45 basin estuaries 40 lagoons in Sri Lanka. Their total area is estimated at 40000 ha and the major urban centres on the coast are all associated with
estuaries. The Puttalam estuary is one of the principal estuarine systems in Sri Lanka.
It sustains a thriving commercial fishery, which gives a livelihood to large number of
people engaged in fishery-related activities. The estuaries and lagoons are also used
as harbours, waste disposal sites for recreation, education, sand mining and aquaculture purposes. Waste disposal, aquaculture and mechanized fishing boats are the major causes for the degradation of the estuary (e.g. Kelani) and lagoon (e.g. Lunawa)
environments. Further, decreases in salinity due to the discharge of freshwater diverted
from irrigation work has been responsible for the depletion of fish and shrimp catches
in the lagoons.
13.5.2
Environmental Threats to the Coastal Environments
13.5.2.1
Domestic and Industrial Wastes
Densely populated human settlements are the primary cause of organic pollution of
both inland and marine waters. Lack of waste water treatment facilities, is a common
problem. There are ~pproximately 60 000 industrial establishments in Sri Lanka ranging from large scale industries to small mining and quarrying operations. Most of the
industries are in the Greater Colombo area covering almost 8000 units. Of these,
3000 were considered non-polluting, while the rest had polluting potential. Of the latter, 300 were high-level polluters.
13.5.2.2
Agriculture
Pesticides are used extensively in agriculture. However, the use of the more persistent
type of organochlorine pesticides is banned or restricted. Information on the levels of
pesticide residues in water and organisms is not available. Pesticides such as Arsenates, Arsenites, Chlorodimeform, DBCP, DDT, EDB, Endrin, Heptachlor, Parathion and
Methyl Parathion have been prohibited for import.
The seagrass beds are found in open sea as well as in river basins, estuaries and
lagoons. Extensive seagrass beds are reported from Jaffna lagoon to Dutch Bay
and from Mannar to Rameshwaram island in India. In the southwestern part of the
island, smaller seagrass beds are found on the leeward side of the coral reefs.
Seagrass bed areas in Sri Lanka have not however, been precisely determined,
but 12 species of seagrass belonging to 9 genera have been identified. Seagrasses
are very sensitive to turbid water caused by pollution and sediments. Bottom
trawling and dragnetting also cause damage to seagrass bed communities. The collection of Polychaete worms (feed for brood shrimp) also affects the seagrass beds negatively.
In addition there are two types of estuaries found in Sri Lanka: the basin and the
riverine types. Estuaries and lagoons are distributed all along the national coastline
aI\d there are about 45 basin estuaries 40 lagoons in Sri Lanka. Their total area is estimated at 40000 ha and the major urban centres on the coast are all associated with
estuaries. The Puttalam estuary is one of the principal estuarine systems in Sri Lanka.
It sustains a thriving commercial fishery, which gives a livelihood to large number of
people engaged in fishery-related activities. The estuaries and lagoons are also used
as harbours, waste disposal sites for recreation, education, sand mining and aquaculture purposes. Waste disposal, aquaculture and mechanized fishing boats are the major causes for the degradation of the estuary (e.g. Kelani) and lagoon (e.g. Lunawa)
environments. Further, decreases in salinity due to the discharge of freshwater diverted
from irrigation work has been responsible for the depletion of fish and shrimp catches
in the lagoons.
13.5.2
Environmental Threats to the Coastal Environments
13.5.2.1
Domestic and Industrial Wastes
Densely populated human settlements are the primary cause of organic pollution of
both inland and marine waters. Lack of waste water treatment facilities, is a common
problem. There are ~pproximately 60 000 industrial establishments in Sri Lanka ranging from large scale industries to small mining and quarrying operations. Most of the
industries are in the Greater Colombo area covering almost 8000 units. Of these,
3000 were considered non-polluting, while the rest had polluting potential. Of the latter, 300 were high-level polluters.
13.5.2.2
Agriculture
Pesticides are used extensively in agriculture. However, the use of the more persistent
type of organochlorine pesticides is banned or restricted. Information on the levels of
pesticide residues in water and organisms is not available. Pesticides such as Arsenates, Arsenites, Chlorodimeform, DBCP, DDT, EDB, Endrin, Heptachlor, Parathion and
Methyl Parathion have been prohibited for import.