The Earth is called the blue planet as two-thirds of the surface of the earth is covered with oceans. They provide ecosystem services for both terrestrial and aquatic biospheres, and act as a buffer on changes in the composition of the atmosphere. The global thermal equilibrium is maintained by oceans. The oceans regulate the hydrological cycle, and are a sink for all types of waste, facilitate the formation of different sedimentary and metamorphic rocks and oceans serve the largest pool of flora and fauna.
Oceans are important in global warming because they act as a sink of carbon dioxide. They provide fishery and seaweeds, salt and minerals, drinking water in some countries, petroleum resources including oils and gases under the sea bed. The importance of the ocean is manifested in the declaration of Sustainable Development Goals (SDGs). Goal 14 clearly states, “Conserve and sustainably use the oceans, seas and marine resources for sustainable development” and has outlined seven main and three associated targets to achieve the goal.
Unprecedented threats
Any threat to the oceans’ ecosystem could impact severely on the well-being of humans. Despite their importance, oceans face unprecedented threats, because of human activities. Over exploitation and harvesting, dumping of waste, pollution, alien species, land reclamation, dredging and global climate change have become prominent factors that disrupt the balance of the marine ecosystem.
Sri Lanka, which is 65,610 sq.km in extent, is located in the Indian Ocean, south of the Indian subcontinent. Sri Lanka has a warm climate with ocean wind and substantial moisture. She is known as the Pearl of the Indian Ocean due to the varying climatic conditions. Sri Lanka is a biodiversity hotspot among the 36 biodiversity hotspots in the world. From the central part of the country 103 main rivers flow to the coastal low lands, and they are the basic sediment suppliers to the coastal region, where about 59 per cent of the total population live.
The highly industrialised and densely populated areas are located in the western and southern coastal regions where most of the effluents come from industries such as ship repairing, tyre and thermal industries, petroleum refining, batik industries and municipal and domestic leachate which are mixed with natural water bodies that end up in the sea.
Marine pollution
Sri Lanka has a wonderful coastline about 1,585 Km long. Many beaches in the country are wide and sandy and provide ideal habitats for nesting turtles. Both land based and sea based sources are contributing to marine pollution. Solid waste, sewage, nutrients, heavy metals and chemicals are prominent pollutants which come from land bases. Oil spills, wastes and ballast water are common in the sea based sources.
Marine debris is defined by the United Nations Environment Program (UNEP) as ‘any persistent, manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment.’ More than 80 percent of marine debris is plastic which includes macroplastics and microplastics. These are negative effects on all marine species such as sea turtle, marine mammals and seabirds. The impact of plastic includes entanglement, ingestion, toxic exposure, disease and death. Most plastic litter in the oceans are from land based sources.
Plastics vary in their specific weight in the marine environment, some items float lighter than sea water while others sink to the bottom. According to studies scientists have estimated that the global abundance of pieces of plastic is at least 5.25 trillion pieces or 720 items for every person alive today.
Plastic debris
Also the total weight of floating plastic debris worldwide has been estimated to be about 93,000 – 267,000 tons. The plastic which are not floating, called, ‘missing plastics’ contribute towards microplastic debris. An additional 28-71 million of plastic are said to have been added to the oceans from land-based sources between 2011 and 2017. A majority of the marine plastic take decades or centuries to fully degrade. The removing of some of the marine plastic is possible but is expensive, time intensive and inefficient.
The ingestion of plastic debris is a major issue the world over. Another issue is chemical absorption. The accumulation of chemicals on plastic debris in sea water would increase with time. This is now under research which is a serious risk to marine organism.
The experiments have proved that microplastic particles have the ability to inhibit hatching, decrease growth rate, alter behaviour, interfere with energy uptake, and badly affect reproduction. Most sea turtles have been listed as vulnerable to critically endangered in the International Union for Conservation of Nature (IUCN) red list. Plastic litter ingestion and entanglement of plastic litter have been recognised as serious threats to these species worldwide. Persistent organic pollutants (POPs) in plastic litter can accumulate in marine animals and be biomagnified in higher organisms including humans within food chains.
Marine plastic also acts as an attractive substrate to quickly colonise by opportunistic species such as bacteria and algae. This could be a negative effect on the wider ecosystem.
The ultimate message is don’t throw any non degradable disposable items on land, because their ultimate end point is the ocean. As human beings with super intelligence we should be more responsible than at present, for the better habitats of our future generations.
“The shining water that moves in the streams and rivers is not just water, but the blood of our ancestors.”
“The rivers are our brothers. They quench our thirst. They carry our canoes and feed our children. So you must give the rivers the kindness that you would give any brother.”
“The earth does not belong to man, man belongs to the earth. All things are connected like the blood that unites us all. Man did not weave the web of life, he is merely a strand in it. Whatever he does to the web, he does to himself.”
-Chief Seattle-
The writer is the Environmental Officer, Central Environmental Authority, Sabaragamuwa Provincial Office.
She holds a BSc.sp Agric. Degree from the Peradeniya University, and is Reading for her MSc in Environmental Science.