The existing oceans take over the majority 70% of our home planet Earth. Their contribution to biodiversity and organism wellbeing is incomparable. The Ocean Institute of Canada (OIC) and Canada’s International Centre for Ocean Development (ICOD) came up with the concept of World Oceans Day with intentions to celebrate the oceans that the countries of the world share and raising awareness about its relationship with our welfare.

They first issued this proposal at the Earth Summit in Rio de Janeiro back in the year of 1992. Ever since, 8th of June has been observed every year as “World Oceans Day”. Like many other environmental days, this very significant one also gets a designated theme every different year. The focus of the occasion this year is on “Planet Ocean: Tides are Changing”.

The oceans of the world produce and consist of at least 50% of the world’s biodiversity. But numerous human induced factors that are initiated from both marine and on land environments, contribute to the destruction of its ecosystems and biodiversity. Some of these factors are plastic, trash, pollution, climate change, overexploitation of fishing resources, unsustainable aquaculture, marine engineering and oil drilling, destruction of habitats, ocean acidification and coral bleaching, high levels of mercury, sea temperature rise, etc. All these human induced factors and more cause damages like marine habitat destruction, species extinction, generation of pollution and ecological imbalances to the marine ecosystems.

The marine habitat destruction and loss is known to occur where the marine environment or ecological set up is not capable of supporting life as a result of degradation. Loss or destruction of marine habitat and environment is where the marine environment or a particular ecosystem squish down in quality to a point where it is unable to support the animal and plant life that would usually reside there.

As a result of this habitat loss, these environments get stunted from providing what are termed ecosystem services, that are of immense ecological, social and economic relevance. For the last 50 years, over 90% of global warming that humans bring on has been absorbed into the ocean.

This ends up causing the rise of temperatures in the ocean and ocean acidification. This is especially harmful to a large population of fish species and ends up causing damage to habitats such as coral. With coral being the producers of the materials such as carbonate rock and calcareous sediment, the production creates a very unique and valuable ecosystem not only providing food and shelter for marine creatures. But this also has a number of benefits for humans too.

Ocean acidification due to the increasing levels of carbon dioxide that leads to coral bleaching where the rates of calcification, also defined as the increase in calcium levels is lowered affecting and stunting coral growth. In addition, another problem caused by people which has impacts on marine life is marine plastic pollution.

This issue poses a threat to both living and non-living marine organisms. “many marine species across various groups since 1950 have undergone shifts in geographical range and seasonal activities in response to ocean warming, sea ice change and biogeochemical changes, such as oxygen loss, to their habitats” according to the Intergovernmental Panel on Climate Change (IPCC) in 2019. Estimation shows that only about 13% of the ocean area still to date remains to be wilderness, most of which is in open ocean areas instead of being along the coast.

According to a report by the Food and Agriculture Organization of the United Nations (FAO) from the year of 2018, overfishing is known to be taking place in one third of world fish stocks. In addition, the observers of industry believe that illegal, unreported and unregulated fishing takes place in most of the fisheries. This also accounts for up to 30% of total catches in a few of the significant fisheries.

In a phenomenon that is called “fishing down the food web”, the mean trophic level of world fisheries has gone down because of overfishing high trophic level fishes. Marine pollution tends to take place where substances that are used or spread by human beings, for instance; industrial, residential and agricultural wastes, particles, excess carbon dioxide, noise, invasive organisms and materials, etc. affect and result in significant menaces.

It has also been found that up to 80% of the waste, which is the majority, originated from land-based activity even though marine transportation and other underwater factors are significant contributors as well. As majority of the damage input are resulted from land by dint of the rivers. This goes on to represent that the continental shelves face higher vulnerability to pollution and damage.

Another unusually significant contributing factor happens to be air pollution as polluted air can carry substances like iron, carbonic acid, nitrogen, silicon, sulphur, pesticides and dust particles into the ocean surfaces and depths.

This pollution often originated from non-point sources such as agricultural run-off, wind-blown debris and dust. These particular sources are hugely caused by run-off that enters the ocean through rivers. But wind-blown debris and dust is able to play a role as well. As these substances and pollutants can settle into waterways and oceans.

The pollution pathways consist of direct discharge, land run-off, ship pollution, bilge pollution, atmospheric pollution and potentially deep-sea mining as well. The kinds of marine pollution are grouped as pollution from marine debris, plastic pollution; including microplastics, ocean acidification as previously mentioned, nutrient pollution, underwater noise and toxins.

Pollution in the ocean is a significant type of marine pollution by plastics that range in size from large original materials, for example; bottles and bags, down to microplastics that are formed from the process of fragmentation of plastic material.

Marine debris is mainly discarded human rubbish which floats on, or is suspended in the ocean. As you have previously read, ship pollution is one of major sources of threats posed to our oceans. Shipwrecks are one of the main causes of this.

These incidents can result in huge structures sinking and settling at the sea bed, while leaving lighter pollutants on the upper sea levels on its way of going down. These sunken structures take up shelter space of marine organisms, surprise and scare them, and release harmful substances and materials affecting their health as well.

It is crucial to be informed and aware about the damage sources and damage control procedures in these scenarios. Several steps and initiatives have already been taken, but implementations and needed to be continued and taken a lot more seriously. On a lighter note, UN delegates have reached a historic agreement on protecting marine biodiversity of the international waters after being in the talks for almost two whole decades.

It is being referred as the “Hight Sea Treaty” and being looked at as a ray of hope for ocean biodiversity. Hopefully, this legal framework putting more funds into marine conservation and covering access to and using the marine genetic resources to come up with and execute mitigation.

Here’s to not only hoping, but also working towards taking more accountability for the damages we have done. The existing initiatives have proven themselves to be sufficient, so all we need to do is learn, understand and help carry them out.

The wellbeing of the world’s total biodiversity is both directly and passively dependent on the maintenance of marine lives and environment. So besides paying attention to the designated day, it is our responsibility to focus on its highlights and work on them year-round. Damages can’t be taken back, but damage control and further harm prevention can surely be done.

Contact: Professor Dr. Ahmad Kamruzzaman Majumder, Dean, Faculty of Science, Chairman, Dept. of Environmental Science, Stamford University Bangladesh, Joint Secretary, Bangladesh Poribesh Andolon (BAPA) & Founder and Chairman, Center for Atmospheric Pollution Studies (CAPS) and Sanjana Tasfia, Research Assistant, Center for Atmospheric Pollution Studies (CAPS).