Marine Pollution
Since oceans cover more than 75% of the earth , healthy oceans signify a healthy planet. According to UNDP , the ocean contains 200,000 identified species but the actual figure may be in the millions. The rich biodiversity of oceans supplies humans with essential ecosystem services like food, employment etc. Globally,the market value of coastal and marine resources and industries is estimated at US $ 3 trillion per year, nearly 5% of global GDP. But, marine life throughout the world is being subjected to immense pressure due to our perennial yearning for progress and comfort and greater carelessness in dealing with affairs of the oceans and of land too.
Key factors harming the Ocean :
Overfishing : Deep water treading hi – tech fishing equipment and ships have harmed the fish population FAQ says that 70% of the world’s fisheries are either completely exploited, over exploited or significantly depleted.
Plastic wastes in the ocean : An incredible amount of plastic waste is making its way into the oceans world over ; this trash is being eaten by marine life and even ending up in seafood. Plastic already forms 60-80% of marine litter and it is estimated that by 2025, oceans contain one tonne of plastic for every three tonnes of fish – 80% of it is coming from land resources. Plastic in water bodies has a disproportionately large impact on sea wildlife and habitats.
Other factors :
- Industrial discharge.
- Harmful chemicals >= endanger marine life.
- Agricultural Runoff.
- Causes eutrophication.
- River pollution.
- Oil spills, leaks.
- Shipping industry.
- Chemicals and sewage from container ships are major pollutants.
- Persistent organic pollutants (pops) , which spread through the atmosphere.
- Sediments flow.
- Tourist waste
- Global warming has added to the growing burden of marine pollution.
Impact : All the above factors are leading to irreversible damages including widespread disturbance in ocean circulation leading to changes in weather patterns and increasing loss of marine species.
- Coral Bleaching.
- Ocean Acidification: It threatens everyone from tiny planktons to huge whales and has the potential to affect the overall ecosystem resilience, stability, bio geochemical cycling and function.
According to IUCN , the pH level of oceanic water has dropped by 0.1 representing a nearly 30% rise in acidity over the last 200 years. This has been mostly due to increased CO2 concentration in the atmosphere.
Oxygen depletion > hypoxia > difficult for marine organisms to survive>creation of dead zones.
- Micro plastic gets into the bodies of marine organisms and hampers their digestion resulting in death. Oil spills other than being poisonous also hinders the movement of birds and other marine species and thus they are not able to survive. 2. Red tide (Algal blooms) It is a common name for algal bloom when caused by a few species of dinoflagellates and the bloom takes on a red or brown colour. These algal blooms may also deplete oxygen, reduce availability of sunlight in water and /or release toxins that may cause illness in humans and other animals. When algal blooms die , they sink to the bottom and may kill bottom dwelling organisms like crab , oysters etc.
3. Ocean Deoxygenation: It is the phenomenon of oxygen loss in the ocean caused by excessive growth of algae due to nutrient pollution. The nutrient pollution may be caused by fertilisers , sewage , animal or aquaculture wastes.
The IUCN Report “Ocean deoxygenation : Everyone’s Problem” is the largest peer reviewed study to date of the causes, impacts and potential solutions to ocean deoxygenation.
Key findings : Ocean regions with low oxygen concentrations have expanded to all depths of the ocean. The volume of area depleted with oxygen , known as anoxic waters/ dead zones have quadrupled.
What if the present situation continues? Under a business as usual scenario, the ocean is predicted to lose 3-4% of its global oxygen by 2100. Local changes will be more severe. Further, most of the oxygen loss will take place in the upper 1000 metres, which is the richest part of the ocean for biodiversity.
Reasons for ocean deoxygenation: Climate change and nutrient pollution are the main drivers of ocean oxygen loss. Ocean oxygen loss is also closely related to Ocean warming and acidification caused by anthropogenic carbon dioxide emissions and biogeochemical consequences related to anthropogenic fertilisation of the ocean.
What should be done?
- Strict regulation of chemical dumping, oil spills and toxic leaching from plastics.
- Stricter fishing regulation to check overfishing
- Restrictions on killing of wildlife such as dolphins , turtles, whales and seabirds.
- Choose eco friendly chemicals (for eg household cleaners)
- Dealing with other forms of pollution (like air pollution causing acid rains)
- Ironically, much of the stress on the world’s ocean originates from the land. There is a lot we too can do to prevent the burden on our oceans , including reducing the use of plastics , abstaining from littering the beaches , cleaning the beaches of rubbish and plastic, reducing the amount of chemicals that we release into our drains , reducing our carbon footprint and regulating our energy consumption.
Balance of Marine life : The IUCN report has started impacting the balance of marine life, favouring species tolerant of low oxygen conditions, like jellyfish , some squid and microbes , at the expense of species sensitive to low oxygen , including most fish and many marine species.
Way forward :
- Tackle climate change : There is an urgent need to raise our ambitions to tackle and immediately curb our emissions.
- Nutrient management: Ensuring optimal utilisation of fertilisers in agriculture to reduce the amount washing off to oceans.
Sargasso Seaweed
Between 2000-2010 there was little seaweed in the central Atlantic : most was found in the Gulf of Mexico and Sargasso sea. Explosion in sargassum seaweed first materialised in 2011 . It developed in subsequent years into a vast band in 2018 that stretched for 5500 miles.
The bloom peaks in the middle of the year and develops larger from small populations of the seaweed in the central Atlantic , with some contribution from west Africa. A number of natural and man made factors align together to make this happen.
Problems caused by this explosion:
- Thick mats can block sunlight.
- Sometimes , when they die and sink , they may be deadly for fish and corals.
- They are also proving disastrous for humans .
- Increasingly huge quantities are washing up in tourist destinations, creating stinking masses that threaten the tourism industry and pose a threat to health.
Reasons:
Alignment of circumstances like conducive sea surface temperature and salinity combined with an increase in nutrients in part from the upward movement of cool , nutrient rich water in the eastern Atlantic and an increase in discharge from the Amazon in the preceding years.
About the Sargasso Sea : Located entirely within the Atlantic Ocean , it is the only sea without land boundaries, while all other seas in the world are defined at least in part by land boundaries, the Sargasso Sea is defined only by ocean currents.
It lies within the Northern Atlantic Subtropical Gyre. The Gulf Stream establishes the Sargasso Sea’ western boundary, while the sea is further defined to the north by the North Atlantic currents, to the east by the canary current and to the south by the North Atlantic equatorial current.
Since this area is defined by boundary currents, its borders are dynamic, correlating roughly with the Azores high pressure centre for any particular season.
It has been named after the genus of a free floating seaweed called sargassum. While there are many different types of algae found floating in the ocean all around world, the Sargasso Sea is unique in that it harbours species of sargassum that are holopelagic- this means that the algae not only freely floats around the ocean , but it reproduces vegetatively on the high seas.
Other seaweeds reproduce vegetatively on the high seas. Other seaweeds reproduce and begin life on the floor of the ocean. Sargassum provides a home to an amazing variety of marine species. Turtles use sargassum mats as nurseries where hatchlings have food and shelter. It also provides essential habitat for shrimp, crab , fish and other marine species.