Known locally as the Sea Egg, the long-spined sea urchin is probably best known to everyone after they touch it and receive a number of small but painful puncture wounds from its very long black spines. It is one of the best reasons for divers, snorkelers and swimmers in general to avoid rocky areas as these places are where it makes its home. The reason for it dwelling here is not primarily for protection - the arsenal of spines serve this function - but rather because it feeds off algae (seaweed) that grow on the rocks.

Sea Egg

Because it can inflict such sudden and painful minor injuries the sea egg is not the best friend of most people who live in coastal areas throughout the Caribbean. This however is quite ironic because without it our lives here would be dramatically different, although to understand the reasons for this it is necessary to learn a little about how our coral reef habitat functions.

Coral reefs are highly important structures for the survival of tropical island nations. One of the most important ecological aspects of what makes a coral reef healthy is the balance between live coral and algae. This health is reflected in a coral reef’s beauty and diversity and is one of the reasons why tourists visit the region with such frequency. Algae grow much faster than corals and so the reef needs plant eating organisms to keep the algae at a low enough level to allow coral to colonise (attach to hard rock structures) and grow. This is especially important after hurricanes when coral is quite often badly damaged, and if grazing organisms such as sea eggs were not present the algae would likely take over. Without fresh coral growth our coral reefs would gradually erode away and leave us undefended from future storms. As this happens the reef slowly begins to resemble an ugly graveyard. Furthermore, the fish that most of us love to eat would no longer have very many places left to live.

Sea Eggs on ocean bottom

Of course, we do not only have the sea egg to thank for keeping our reefs healthy, there are also a great many other factors that play a part in this important balance. For example, increases in nutrients in the ocean mean algae can grow faster than normal; fish traps placed on the reef can damage living coral giving algae a helping hand to establish themselves; rising ocean temperatures can kill coral; and removing too many other important algae grazers such as parrotfish and surgeonfish will also push the balance in favour of an algae dominated reef. Although all these factors work together in complex ways, it is known that removal of the sea egg from a coral reef habitat will cause dramatic changes in a very short time, especially if this occurs hand-in-hand with some of the other factors mentioned. However, even if other detrimental factors are in play, a recovering sea egg population can mitigate these making a positive difference to the amount of algae present on a reef.
So what is the relevance of all this to us in Anguilla? During the mid nineteen eighties a virus spread throughout the Caribbean and decimated sea egg populations. Back then the relevance of this and its importance was not fully understood. It wasn’t until algae began to take over reefs after hurricane damage that the sea egg’s function as a key part of coral reef ecology was fully appreciated. This occurred in Anguilla as well as in other parts of the Caribbean and is likely one of the biggest reasons for the algae dominated reefs that we see now in our waters.

Thankfully however it seems that sea egg populations are gradually once again on the increase. If we visit some areas around Anguilla, for example: Pelican Point near Crocus Bay; the sea rocks around Maundays Bay (see photograph below taken in May this year); and some of the patch reefs in Shoal Bay East, healthier populations can be observed than were present a number of years ago. Although this may not be the best news for unsuspecting swimmers it is very good news for the health of our reefs. However, recovery is slow, a fact in part attributed to how the sea egg reproduces. Instead of coordinating reproductive effort so that all individuals present in a population reproduce at once, it is more of a random affair. Thus small populations take a longer time to re-establish themselves. It also appears, from observations made under the Anguillian Marine Monitoring Programme (AMMP), an initiative recently undertaken by the Department of Fisheries and Marine Resources (DFMR), that although sea egg populations may increase in a specific area, it can take much longer than hoped for this population to spread to surrounding regions.

With this being the case DFMR is investigating other options to help the recovery of sea egg populations. A review of current scientific research is being made to assess the viability of moving a proportion of the population from an area with an abundance of sea eggs to an area that is lacking them. Also areas potentially suffering a short or long term impact from coastal development will be assessed and if viable, sea eggs will be removed from harms way and placed in areas that will benefit from their presence. For example, the site of the new marina project in Shoal Bay West is due to be assessed for such a project. It is proposed that any sea eggs present in the area that can be removed will be transported to selected regions in the Shoal Bay & Island Harbour Marine Park.

So, if you have recently been spiked by one of these vicious looking creatures, remember their importance to the health of coral reef ecosystems and the invaluable benefits that they provide; and spare a happy thought for the fact they are gradually making a recovery in the region.

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