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Friday, October 14, 2011

THREATENED: Sri Lanka’s Marine Life

A resplendent isle with much to boast about, Sri Lanka is fast losing its most valuable resources to neglect and irresponsibility. While most of us are too busy berating the authorities, we conveniently forget our individual roles in the protection of our environment.

Death by dynamite

Coral rubble
The mere existence of mankind has had an impact on global marine environments. The oceans are seen as ‘bottomless’ sources of food and natural resources, convenient repositories for trash and poisonous waste, or something to be dredged, filled, or drained when deemed necessary. Although we know better in these environmentally-aware times, misuse continues at home and all around the world, while areas with improving attitudes and practices will remain scarred for years to come.

The Sri Lankan context

Sri Lanka has a total land area of 65,000 km2 and maritime rights to an area of 230,000 km2. Its 1,585 km coastline comprises of 300km of beaches and sand dunes. Fisheries are the major economic use of the maritime area, and the fishery sector contributes nearly 3 percent to the GDP and is an important source of employment and foreign exchange to the country. Of this, coastal fisheries constitute about 72 percent of the total marine fish catch and support nearly 90 percent of employment in the fishery sector while fish provides 65 percent of the protein in the Sri Lankan diet. 100 percent of Sri Lanka’s population lives within 100km of the coast and are directly or indirectly dependent on it.

The threats

The threats faced by the marine environment are both anthropogenic and natural. Some of the primary threats include climate change, fragmentation and habitat loss, overexploitation and pollution.

Natural threats:
Natural threats include coral bleaching, storms and predation. The environmental imbalance caused by human activities has exacerbated climate change effects that have increased the frequency with which coral bleaching episodes and storms occur. However because of the intangible nature of our impact, humans are quick to shirk off responsibility. Moreover, the tangible destruction caused by humans has meant that when natural events such as tsunamis occur, the damage caused is far more prolific.

Coral bleaching which is caused by unusually high sea surface temperatures is the process by which corals lose their colouration either due to stress-induced expulsion of symbiotic unicellular algae or due to the loss of pigmentation within the algae. The massive 1998 global bleaching event had an impact on many of our reefs including those within Hikkaduwa National Park and Bar Reef Marine Sanctuary. Recovery of the former has been much slower than at the Bar Reef because of the added anthropogenic pressure resulting from unregulated visitation.

Anthropogenic threats:
Dynamite fishing is a prime cause of reef damage and mass fish kills, most of which go to waste due to non-collection. Dynamite is also used in the ‘laila’ net fisheries which involve the surrounding of large shoals of fish with nets that hang vertically in the water column and in recent times has led to the demise of pods of Spinner dolphins that associate with the target fish species. Other destructive fishing methods include the use of synthetic vs. cotton nets. Because these nets are visually and acoustically undetectable, by-catch of charismatic species such as dolphins and turtles are frequent. In addition to being undetectable, the fibers are strong and nearly unbreakable thereby preventing animals from escaping once caught. Nets that are lost at sea continue to kill marine life for hundreds of years because of the durability of the synthetic fiber – a process known as ‘ghost fishing’.

The dugong, a large-bodied herbivorous marine mammal, which was once common along the north western coastal waters of Sri Lanka, was taken at a rate of 100-150 individuals per year in the 1950s. They are now rarely seen due to a continued harvest and as a result of the destruction of their primary food source – sea grasses. The illegal harpooning of dolphins around the coast of the country has also led to a decreased inclination to ‘bow ride’. ‘Bow riding’ is the behaviour of dolphins in which they frequently swim or ‘ride’ the crests of ocean waves. As dolphins are frequently used as ‘back up’ species (an attraction in the absence of the target whale species) by the whale watching industry, this reluctance towards a natural behavior may prove disadvantageous.

Coral mining for lime spelt the demise of many of Sri Lanka’s southern reefs. In place of the once live and flourishing corals that provided habitats for fish and numerous other marine organisms lie vast tracts of coral shards and empty spaces. The future for these areas is bleak and the protection of the reefs which once provided the coastline against the high energy waves, is now lost. A direct result of this destruction was the unfortunate loss of lives in Peraliya on the south west coast during the 2004 tsunami.

Harvesting of fish without consideration of sustainable yields has shifted the future of our protein source into the hands of aqua-culturists. Although aquaculture is not without its own problems, it will form the only alternative as more fish stocks begin to collapse. Collection of reef fish and seahorses, also known as ‘cut flower’ species because of their short life span, for the ornamental fish trade also occurs freely around our coastlines and such activities may cause an imbalance in the reef ecosystem. The prolific and unsustainable collection of chank and sea cucumber over the years has lead to the sequential demise of inshore stocks and led to the exploitation of the deeper off shore stocks.

Upstream activities also have an impact on the marine environment. Deforestation inland is one such example. Although the marine and inland terrestrial systems seem so disparate, they are not. The denuding of forests in the upstream catchment areas causes erosion and unusually large amounts of soil to enter the rivers and eventually exit through the lagoon mouths into the sea. Corals being living organisms, are suffocated by the sediment that settles on them and die. Coral destruction causes the loss of habitat for fish and also sources of food.

Garbage and pollutants absent mindedly or purposely tossed into the oceans have many detrimental effects on marine life. Contaminants such as heavy metals and PCBs used in upstream areas also enter the sea via rivers and lagoons and result in a change in water quality. Wastes such as acids, radioactive materials, matter used for biological and chemical warfare and other highly toxic substances are also regularly dumped directly into the ocean despite the introduction of the Ocean Dumping Act in 1972 that renders such actions illegal.  Despite being dumped into ‘isolated’ oceans their sheer interconnectedness and global circulation patterns ensure that the wastes end up on everyone’s doorstep and are incorporated into the food webs. As coral reefs are biological assemblages adapted to waters with low nutrient content, the addition of nutrients in this manner favors species such as algae that disrupt the balance of the reef communities. Pollution such as plastics and polythene are documented to cause the death of many organisms. Many species of marine turtles that feed on jellyfish are known to mistakenly consume polythene bags which block the mouth and throat and inhibit breathing and feeding. Furthermore, if they are ingested they inhibit digestion due to the extended stomach sending confusing signals to the brain causing the turtle to stop eating and ultimately die of starvation. Entanglement in marine debris also inhibits surface breathing of turtles and marine mammals, foraging, predator escape and mating behavior.

All these threats acting individually or in combination result in severe impacts on the biological production of the world’s oceans and the services they provide to billions of people today. With the acceleration of climate change, the impacts on marine life from other stressors will become severely exacerbated and the ability of ecosystems to recover will be impaired. We now live in a world that has to contend not only with so called natural threats, but those posed on the system by our everyday actions. It is imperative that when we live by the philosophy of ‘leave only footprints, take only memories’. Is it not up to us to make the right decisions in an attempt to save our marine life for future generations?

Do you know how long it takes for the following items to degrade?
Glass bottle – 1 million years

Fishing line – 600 years
Plastic bottle – 450 years
Aluminium can – 80-200 years
Plastic cup – 50 years
Plastic bag – 10-20 years
Cigarette filter – 1-5 years
Newspaper – 6 weeks

Now sit back and reflect on the impact they have over their lifespan. Dispose responsibly.

 (Article published in Big Issue magazine in 2009)

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