Global warming and human activities, a major threat to coral reefs

Six years ago, fishermen at Mkunguni in Msambweni, Kwale County gave up on fishing in the Indian Ocean.

They no longer caught huge amounts of fish as before. If anything, several fish species started diminishing and what they got could not sustain their livelihoods.

Their poverty levels rose since they could not manage to get enough to sell. They knew very little about the ocean ecosystem where they were getting their source of livelihood.

They did not know that besides global warming, they too were participating in the destruction of coral reefs (diverse underwater ecosystems held together by calcium carbonate structures where fish produce fingerlings).

Mkunguni Beach Management Unit Secretary Sadiki Hassan says Coastal Oceans Research and Development – Indian Ocean (CORDIO) East Africa employees made them aware of the existence of coral reefs.

"Actually, we did not even know that coral reefs are living things. To us, they were just insignificant rocks. When we found out that about one-third of all marine fish species depended on coral reefs, that is when we realised that we had been doing something wrong," he says.

Hassan says the organization gathered over 156 fishermen in their beach and educated them about how important corals are to the ocean ecosystem.

"From the sensitisation, we came to learn that corals need a stable environment to grow but might soon be completely destroyed due to global warming," he says.

Global warming is the increase of Earth's average surface temperature due to effect of greenhouse gases, such as carbon dioxide emissions from burning fossil fuels or from deforestation.

The warmer air and ocean surface temperatures brought on by climate change impact corals and alter coral reef communities.  When the ocean warms, the oxygen content reduces and leads to bleaching events and altering of ocean chemistry.

"We also understood that there is nothing much we as fishermen can do to prevent global warming, but that we too have been contributing in the destruction of coral reefs," he says.

Munje Beach Management Unit Chairman Mohamed Masudi says they too learned that much as the corals are sensitive to warmth, they are also sensitive to use of very huge nets that breaks them and polluted environments.

"When we learned that apart from climate change, human activities like fishing are also affecting the coral reefs, we put rules and regulations of the type of nets that should be used for fishing to avoid destruction," he says.

CORDIO has also helped them in conducting monitoring and mapping of fish breeding sites which are usually not interfered with to improve the quality of fish they get.

"Corals need to be protected because they are the Savannah of the waters," he says.

They also came to realise that it is easy to destroy corals but it takes longer for them to recover.

"Ever since we started being careful how we handle the ocean ecosystem, we have seen an improvement in the number of fish. There are so many changes currently. Our people now have faith in scientists," he says.

Cordio's Coordinator Dr David Obura who has been studying corals ever since, says corals are being affected both by global warming and human activities.

He started delving much on the topic following the impact of coral bleaching during the 1998 El-Nino.

Obura says following global warming, there is a possibility of a big bleaching event to take place in the Western Indian Ocean between January and April 2016.

"Coral bleaching is a stress response of corals. This year, coral bleaching was seen a lot at the Pacific Ocean in summer. The effect of the same might be felt here in the marine environment. Other factors are sedimentation, pollution and use of large-meshed nets," he says.

He says corals are sensitive and vulnerable ecosystems hence it is very easy to notice any slight change when they are affected.

"Corals are important in many ways. They are like the tropical forest. If we are not careful, we are likely to lose them in the next decade. Apparently, not only sea urchins will suffer, but humans too," he says.

He states that they are working with the fishermen in order to sensitise them about the important of fisheries and the connection with fish populations.

"We want them to understand that Individual corals grow quite slowly at the rate of one centimetre per year. Their framework takes one year for a millimetre to grow, while branching takes five to 10cm a year," he says.

Obura says it takes approximately 20 years for new corals to grow back and form a complex reef system, and even 30 years if there is pollution or over fishing since algae grows on its structure and slows its growth.

"We are working with fishermen to help in the growth of corals. When you have too many fishermen, a lot of impact is seen out of their activities. Demarcation of breeding sites helps because when an area has plenty of fish, they help in the growth of corals. We should also reduce pollution so that if there is a bleaching event, they can recover faster," he says.

They are also working with them to ensure they limit the number of fishermen so that they can be able to control their activities.

"They now know that they should not allow everyone to go fishing. They are also helping in ensuring external fishermen don't damage reefs. We are also working with the Kenya Marine and Fisheries Research Institute (KMFRI) to manage the reefs,"Obura says.

Importance of reefs to humans

Apart from being vulnerable, coral reefs are one of the most valuable and diverse ecosystems on Earth. They not only provide food and home to fish, but also help human beings in many ways.

Healthy reefs contribute to local economies through tourism. Diving tours, fishing trips, hotels, restaurants, and other businesses based near reef systems provide millions of jobs and contribute billions of dollars all over the world.

The World Wide Fund (WWF) states that coral reefs protect coastlines from the damaging effects of wave action and tropical storms apart from providing habitats and shelter for many marine organisms.

They also help to prevent coastal erosion, flooding, and loss of property on the shore.

Coral reef species are expected to contribute to medical advances in future. Already coral reef organisms are being used in treatments for diseases like cancer and HIV.