Are the deaths of marine mammals a sign of degradation of marine life?
Pollution is the not the primary reason for the deaths of sea turtles, whales and dolphins. This is the breeding season of turtles and they approach the shore to lay eggs. When they come to the shore, they get entangled in large nets and die. Juvenile dolphins feed on plankton and come to coastal areas to feed. So, either the fishing nets injure them or they get hit by propellers.
Many marine creatures washed ashore dead were covered in oil, what can the reason be?
As a part of the agency that conducted a study on the impact of oil spills in the last two years, the spillage had no adverse impact on marine mammals. But, as no post mortem has been carried out, it is difficult to point to a particular cause of death. Oil leaked for just five days and the effect of the spillage could not have affected these creatures. Though I don’t rule out the role of deep-sea fishing harming marine mammals. In my view, 99% of the mammals have died in the deep sea and floated to the shore. Marine mammals normally avoid areas where oil spillage occurs as fish have gills and will have breathing problems. It is quite possible the carcasses may have floated past the off-shore oil rigs because of which their bodies were covered in oil.
What are the main sources of marine pollution in the city and how is sewage water managed?
Domestic and industrial effluents are the main source of pollutants found in the sea. Every day around 3,000 million litres of sewage is released along the west coast. Also, we release it after partial treatment. The sea has a larger propensity to dilute and flush out pollutants. But, in the creeks and bay areas, it is necessary to treat the waste partially. After treating domestic waste, we have to recycle the water. As dilution is more in the sea, partially untreated sewage water is released in the sea.
But why is most sewage released in the open sea?
The basic principle of releasing sewage in the sea is to not allow it to come back to the shore. The disposal points are under the sea and farther from the shore. If released 1km from the shore, the pollutants will come back with the tide. But if it is released 3.5 km from the shore, it does not float back.
How does dumping of garbage and plastic affect the creeks and beaches?
Garbage, plastic and debris decompose, increasing the bacterial levels and decreasing dissolved oxygen levels. When organic matter degrades, it consumes dissolved oxygen and causes problems to plankton and aquatic life. First, there is depletion of oxygen in water, then plankton accelerates their photosynthesis which leads to algal bloom and causes super saturation, which is also not ideal.