The marine environment
The marine environment is the largest habitat on earth, occupying more than two thirds of the earth’s surface. This continuous body of water is principally divided into five oceans plus a number of smaller seas. The five oceanic divisions are the Pacific, Atlantic, Indian, Arctic & Southern (or Antarctic) and are mostly defined by the continents and various archipelagos that ‘separate’ them. It is estimated that over 90% of biodiversity exists in the ocean. All life that has ever existed on earth evolved from the ocean and, as a result, all life is dependent on this vital support system.
Although over 70% of the earth’s surface is covered in water, we still have a limited understanding of our oceans and the life they support. According to the amazing work of the scientists involved in the Census of Marine Life, nearly 250,000 marine species are now known to science, but it is thought the total could be more than ten times that number.
The oceans are crucial to our survival and the huge diversity of habitats and species they support. Coastal habitats, such as mangrove forests and coral reefs, are highly complex but fragile ecosystems that represent the most productive regions of our oceans, yet they are increasingly under threat. For example, while the Great Barrier Reef in Australia covers only around 0.1% of the ocean’s surface, it contains about 8% of the world’s fish species. The full extent of all marine life on Earth is still unknown and undocumented, yet nearly 20% of the 1,045 sharks and ray species, 12% of groupers and 86% of marine turtle species are threatened with extinction.
In less than 100 years, the human population has doubled to roughly 6.9 billion, with approximately 60% living within 60km of the coast. As a result, the demand for food, fuel and development has increased greatly. In addition, current estimates suggest the world population will reach 9 billion by 2050. Many people now believe that human activity has directly or indirectly triggered the sixth major extinction event in the history of life on earth. Activities in the ocean environment such as overfishing, coastal development, pollution and introduction of alien species have led to a decrease in the marine ecosystem’s structure and function. Today, this includes areas almost untouched less than 30 years ago, such as the ocean floor, now affected by bottom trawling. According to the United Nations, around 75% of the world’s fisheries are now either ‘fully exploited’, ‘over exploited’ or ‘significantly depleted’. There are already examples of species fished to commercial extinction such as the Atlantic Cod, and many more are on the verge of collapse, for example, the northern Blue-Fin Tuna.
With a huge percentage of the population living near the coast, this has a huge environmental consequence. This is particularly important because coastal areas are some of the most biologically diverse and productive on the planet. To add to these concerns, 80% of tourism takes place in coastal regions, with beaches and coral reefs being some of the most popular attractions. The coastal development that has resulted in the last 100 years has included whole new coastal cities, dykes, dams, hotels and their vast associated infrastructures.
Currently, less than 1% (0.6%) of our oceans has protected status and much of this includes areas not managed properly and/or regulations not enforced. The remainder is largely regarded as a free, inexhaustible resource available to everyone, an outdated attitude that is the root cause of marine degradation. Unfortunately, this view continues to be held by much of the world despite overwhelming evidence that humans can, and have, detrimentally affected the oceans’ biodiversity, processes and habitats.
The importance of our oceans and why we should care
The air we breathe
The primary producer of oxygen is phytoplankton, which live in our oceans.. These tiny organisms consume more CO² than any other plant on earth. In doing so, they produce around 50% of the oxygen present in the earth’s atmosphere (by comparison, all the world’s trees produce an estimated 30-40%; the rest comes from soil, volcanoes and the splitting of water molecules by ultraviolet radiation).
The ocean has a major effect on the biosphere. Evaporation from the ocean is a phase of the water cycle, and the source of most rainfall. Ocean temperatures determine climate and wind patterns that affect life on land. The global thermohaline circulation (THC) (also known as the great ocean conveyor) transports both energy (in the form of heat created by surface currents) and matter (gases and solids) around the earth. In doing so, the ocean circulation impacts greatly on the earth’s climate. Examples of this include the Gulf Stream that is driven northeast by the THC and provides a temperate climate to Western Europe. It also supplies heat to the poles, which helps regulate the amount of sea ice in the regions.
Fish is an important source of food. It is estimated that one billion people, predominantly in developing countries, depend on fish as their primary source of protein. In addition, it is likely that most of you reading these pages enjoy eating fish too and the vast majority of this will have come from the ocean as opposed to lakes, rivers or farms.
Without our oceans, life wouldn’t exist on land. No matter which explanation you accept of how life came to be on earth, whether you think life started in smoke stacks at the bottom of the ocean or by bacteria transported here from an alien world, the reality is that life on land evolved from life in the ocean. In fact, it wasn’t possible for organisms to colonise land until the ozone layer was formed, which would not have been possible if early aquatic organisms called blue-green algae had not produced the oxygen required over millions of years.
The solution: what we can do
There are many practical ways in which we can help protect the oceans, from beach cleaning to eating a wider variety of fish to campaigning. However, the single most important thing is to overcome the collective worldwide view that the ocean is so vast that we cannot detrimentally affect it in any major way. The fact is, we already have.
The ocean floor has been so poorly explored and yet so dramatically altered through bottom trawling that few images of its original form exist and when we see the flat featureless expanse it has become, we think that’s how it always was. Until the governments, multinationals and the general public realise that we, along with almost every species on the planet, rely entirely on some aspect of the ocean, we are going to struggle to make progress. Just because we do not fully understand the consequences of our actions now, does not mean that future generations will not pay the price. We cannot continue to consume fish as though they are inexhaustible; we cannot continue to pump toxins into the ocean and not expect them to reach our own food chain; we cannot continue to pump CO₂ and other greenhouse gases into the atmosphere and not expect them to impact the pH of our oceans.
As a result, the most important tool we have is knowledge. We must educate ourselves about these issues. Please visit our ‘make a difference’ page by clicking here for more information about what you can do. In this section we have compiled a list of twenty ways you can help, and we hope that you will find at least one of the points from the list to suit your lifestyle. However, keep things in perspective. Being aware of the bigger problems is fundamental, but can often seem overwhelming, so focus on solving them through the small things you can do every day.
Please continue to read about these issues on our website and also visit other websites such as Greenpeace, Oceana, Sea Shepherd Foundation, Project Aware and others. Watch films such as End of the Line and Sharkwater. We also need to get the message out. Talk to your friends; this affects everyone. If you can organise a group of people together then book one of our talks.