Ocean News

The five threats to our Oceans and what you can do

21st April 2010

Our Oceans are vital to the health of our planet but they are facing severe threats. In honour of Earth Day tomorrow we’re taking a look at the 5 biggest threats to our Oceans and what you can do about them. Since after all, without the Oceans, the Earth would just be a barren rock, and Earth Day would be a lot less fun.

1. Overfishing depletes stocks of fish beyond their ability to recover, disrupting the ecosystem and eliminating a valuable source of food and income.
In recent years the insatiable demand for both Atlantic cod and bluefin tuna has caused their populations to have declined dramatically leaving them on the edge of extinction.

2. Predator loss releases prey populations from both the pressure and risk of predation. Their removal can cause a potentially irreversible cascade of complex knock-on effects, destabilising marine ecosystems to their – and our – severe detriment.
Severe declines in sharks off the coast of North Carolina, USA, led to the complete collapse of a century-old scallop fishery that supported the local community. The removal of the sharks caused their prey, the cownose ray, to boom in numbers. These rays decimated the scallop populations in the area resulting in massive losses to the local economy.

3. Climate change is warming the oceans and making them more acidic. This will create vast dead zones as plankton and corals – the primary producers for nearly all marine life – struggle to survive under increasingly inhospitable conditions.
Ocean acidification, caused by excess CO2 dissolving in the sea to form carbonic acid, has the potential to literally dissolve the skeletons and shells of marine creatures such as corals leading to devastating effects on marine ecosystems.

4. Pollution can poison marine life and decimate entire marine environments. Vast quantities of solid and chemical waste from human activities are continually dumped and leach into the oceans, including plastics, sewage, sediment, oil and toxins that accumulate in food webs.
Both fertilisers and untreated sewage are high in nutrients and so can cause eutrophication in coastal areas (flourishing algal blooms that thrive on the nutrients) thereby smothering other marine life by dramatically depleting available oxygen. This can create vast expanses of dead ocean, as is already apparent in the Gulf of Mexico and Baltic Sea.

5. Habitat loss physically limits the suitable living space available to marine life. Coastal development, trawling, and aquaculture all destroy important marine habitats vital for supporting ocean health, such estuaries and mangrove systems that function as nurseries.
Approximately 10% of the world’s mangrove systems were cleared during the 1980’s and 1990’s to develop shrimp farms, causing increased coastal erosion and the loss of nursery habitats for many fish species.

What Can You Do?

Unless we act now to curtail the devastation of our oceans, the inevitable outcome is a cataclysmic loss of biodiversity. So what can we do to help combat these threats? Although as individuals we may feel powerless to help save our seas, in reality it’s quite the opposite. Supply is tailored to meet demand and the power lies with the consumer, so one of the most important changes we can make as consumers with regards to marine conservation is simply knowing where the fish we eat is from: is it from a sustainable source?

A sustainable fishery means that catch rates do not exceed the recovery rate of the population – there is little to no bycatch and minimal environmental impact. Using our purchasing power to favour sustainable fisheries can instantly help combat many of the threats our oceans face. Overfishing is of course addressed directly, but choosing sustainable fish can also help prevent the loss of important habitats and predators. Most declines in shark populations are attributable to bycatch in other targeted fisheries, such as those long-lining for tuna and swordfish, and some unsustainable fishing methods such as bottom trawling and certain types of aquaculture (fish farming) can cause considerable habitat destruction. Aquaculture can even contribute directly to overfishing as vast quantities of wild fish are caught to supply the farms; for instance each pound of salmon farmed typically requires five pounds of wild fish caught to make fish meal.

One of the other major ways in which we can help minimise our impact on the oceans and ensure its natural resources are available for future generations is to be as efficient with our energy usage and waste disposal as possible. The more we can reduce our use of things such as electricity, fuel, water and plastic bags, as well as recycling as much as possible, the better. Lowering our contributions to carbon emissions will count directly towards preventing further warming and acidification of our oceans, whilst being mindful of our waste and choosing to recycle will help minimise our personal contributions to pollution.

Another way in which we can make a difference is by exercising our votes to empower political parties that advocate the sustainable management of marine resources in an objective and practical manner.

One of the most important things we can do is just talk about it, many people simply don’t know where their fish is from or even why that might be important. This Earth Day bear in mind the threats our oceans face, and perhaps take the opportunity to start making some small and simple lifestyle changes that can really help make a difference.