Threats to coral reefs
By Marjorie Henry, Contributor

Students get down at Fame FM's School Rules, held at York Castle High, on Thursday, November 3. - Contributed

AS I continue this week with the review lessons on coral reefs, I will focus on sharing the information needed to answer the questions I gave you at the end of the last lesson. I do trust, however, that you took time out to research the answer for yourselves. One question was: 'What are the activities that can lead to the destruction of the coral reefs?'

I used the word 'activities' in the question since the information from the recommended textbooks links the damage of coral reefs primarily with human activities, whether on land or sea. Take time to read for yourselves the relevant sections on the topic in the new edition of The Caribbean Environment by Mark Wilson and New Caribbean Geography by Vohn A. M. Rahil, two of the recommended textbooks. Listed below are some of the major points taken from both sources.

* Too much fresh water. Where there is deforestation or urban development, these human activities result in an increase of overland flow of water. This increased volume of fresh water flows to the river and eventually into the sea.

* Too much sediment. There are several activities that can lead to increase of sediments. These include quarrying, construction of buildings, marine construction, channel dredging, logging operations and improper farming practices that lead to soil erosion. The sediments may smother the reefs.

* Organic pollution. Chemical fertiliser run-off, pesticides used on farms, oil pollution and sewage may be washed into the sea. The growth of algae is encouraged by the increased nutrients in the seawater. This can suffocate the corals.

* Chemical pollutants. Herbicides and other pollutants may poison coral and marine life when they are washed into the sea.

* Developments on adjacent coastal lands. Industrial developments, landfills and land reclamation alter the natural habitat of corals.

* Tourism development. The construction of hotels, taking souvenirs from the reef and the activities of snorkellers, divers and boats, all have a negative impact on the reefs. If sand is kicked up, corals may die due to suffocation. The collection of coral souvenirs may eventually lead to the destruction of the natural habitat of the coral. Dive boats may cause anchor damage.

* Over-exploitation by fishermen. Fish, like snapper and grouper, feed on herbivorous fish. The removal of large numbers of both kinds of fish leads to changes in the abundance and types of algae or fish food.

* Fishing methods. Damaging fishing methods, for example dragnet fishing, is a threat to coral reefs. Damage may be caused by anchors, or by badly placed or discarded fish traps and nets.

* Oil spills. Oil and other chemicals can cause permanent damage.

As you go through the information on the threats to coral reefs, bear in mind the conditions that are necessary for successful reef formation.

In addition to human activities, the literature also informs us that, "Small rises in sea temperatures caused by global warming have resulted in episodes of coral bleaching. Tiny algal plants live inside the coral polyp tissue in a symbiotic relationship with the corals, and a rise in sea temperature of only 1-2ºC is enough to expel them from their host into the ocean, causing the corals to lose their colour pigmentation. Bleaching has increased in frequency and intensity over the last two decades and although reefs can recover, mortality of corals has long-term negative impacts on reef biodiversity." [The Contemporary Caribbean by Robert B. Potter et al.]

The coral reef is also threatened by an increase in the levels of carbon dioxide in the seawater. This slows down the growth of the coral, and may also make the seawater slightly more acidic.

Are any of these threats listed above, evident in Jamaica and the wider Caribbean?

I will go on to the other question in the next lesson.