Biodiversity, the Ocean’s the hidden treasure

Dr. Will Le Quesne
Senior Marine Scientist, Kuwait
Fisheries & Ecosystems Division,
Cefas is the largest marine science organisation in the UK and an agency
of the UK Government Department for Environment Food and Rural Affairs.

When you think of marine biodiversity, the hidden treasure of the oceans, what do you think of? Whales, turtles, coral reefs? These are all examples of marine biodiversity and are some of the most well-known animals that live in the sea, but there is far more too marine biodiversity than just these large well known species.

Most people know very little about marine biodiversity because we cannot easily see into the sea. When you walk along the coast, or stand on a boat, it is difficult to see all the animals and species that are in the water around you, and also many of the species are too small to see without the help of a microscope or live far away from the coasts.

‘Biodiversity’ does not just refer to individual species, but refers to the diversity of all life on the planet from the diversity of individuals within a population, all the way up to the diversity of habitats and ecosystems at the national and regional scale. Marine biodiversity is not just whales and turtles but also microscopic organisms and coastal marshes.

So why should we care about marine biodiversity? The marine environment, and marine biodiversity, provides a wide variety of benefits to society. There are obvious benefits, such as fisheries that are an important source of food at both a local and global scale. But also less obvious benefits such as helping to regulate climate change; it has been estimated that half of all the carbon dioxide released by humans has been absorbed by the oceans.

The full list of benefits that the seas and marine biodiversity provide for society is too long to list in this article. One example of the benefits of marine biodiversity for coastal towns and cities is the role that coral reefs, coastal wetlands and mangroves can provide in protecting coastlines from erosion and storm damage. The coast and sea are also important areas for recreational activities. These recreational activities provide a large benefit to people’s quality of life and can make the real difference to whether a coastal town or city is a pleasant place to live.

In addition to the examples above, marine organisms are the source of a wide variety of chemicals used in the food and pharmaceutical industry and the marine environment can provide an important cultural link to the past helping people develop a sense of personal and cultural identify and self-respect. These are just a limited number of examples of the many benefits that the seas provide to society.

So people and society derive a large number of benefits from the seas, but I still don’t understand why we need to care about marine biodiversity? The reason is that many of the benefits that society gains from the oceans depends on the state of marine biodiversity. This can be having abundant fish populations to support productive and sustainable fisheries, healthy coastal habitats to provide natural defences against coastal erosion and storms, or natural communities of marine micro-organisms that keep coastal waters clean and safe for swimming and recreational activities.

If we damage marine biodiversity we can affect the ability of the seas to provide these benefits to society.

We now have an understanding that marine biodiversity is all species and habitats in the oceans, and that it provides a wide variety of benefits to society, but how do coastal towns and cities affect biodiversity?

Coastal towns and cities affect the marine and coastal environment in a wide number of ways. There are three main types of impacts that can be caused by coastal cities and the activities that occur in and around it, these are:

  • habitat loss and change due to coastal development
  • input of pollution
  • removal and damage to marine animals

Urban coastal development is rapidly changing coastal habitats. This can be building harbours complete with dredging deep-water shipping lanes, draining and reclaiming coastal wetlands, or building hard coastal defences.

These developments lead to loss of natural habitats and can affect the natural flow of coastal sediments. Interrupting the natural flow of coastal sediments can lead to erosion, and therefore lead to the need for building expensive coastal defences, or can affect offshore habitats such as coral reefs. Coastal habitats are also some of the most productive and biodiverse natural habitats occurring anywhere on the planet. They can provide feeding areas for migrating birds and can be important nursery areas for juvenile fish supporting local fish populations. The productivity of coastal wetlands also means they absorb nutrients in the water and can soak up and absorb pollution.

Pollution can have a variety of different impacts and can significantly affect the quality of sea water close to urban centres. Sewage is a particular problem frequently associated with rapidly developing towns and cities. Sewage pollution can make water unhealthy for recreational activities and seafood unfit for human consumption, and in severe cases lead to large fish kills.

Commercial and recreational fishing remove and damage marine animals and has an impact on biodiversity. One such impact is overfishing which leads to a reduction in the amount of food that the fishery can provide, and also reduces the economic productivity of the fishery.

Now that we have seen that marine biodiversity provides a lot of benefits society, but that towns and cities can impact this, what can we do to protect or manage our impacts on biodiversity?

There is no simple answer to this question, as it will vary from case to case. Also there are many benefits associated with development, so it is not practical to try and stop all activities that effect the environment. What we want to try and achieve is ‘sustainable development’, the balance between allowing development to occur while minimising impacts and ensuring sustainable use.

One of the main tools for achieving this is the process of marine spatial planning. In summary this involves developing a map of the marine biodiversity, and developing a map of the human activities that impact the sea. These are then be compared to see which are the most important aspects of the environment that need protecting, and which are the most damaging activities. This allows a structured and prioritised approach to introducing environmental management that provides the most benefit to the environment whilst causing the least impact to human activities. Marine spatial plans can be developed at a variety of different scales from the national scale to the scale of individual cities.

Now that we can see the benefit of marine biodiversity, the ocean’s hidden treasure, you should ask does your town or city have a marine spatial plan?

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