Sunday, 17 November 2013


Saint Martin/Sint Maarten

Northeast corner of the Caribbean (Anguilla to St. Barts).  St. Maarten is left of center.

When I first starting thinking about which coral reefs should be studied in the Caribbean, I realized the focus should be the reefs of the eastern Caribbean known as the Antilles.   Since I’m starting in the north and working to the south, my initial focus will be the islands of Anguilla and St. Martin.  We sailed to St. Martin because it is a sailor’s paradise with sail lofts, and marine chandleries for buying and fixing what we need for Alaria.  So, we studied the coral reef there first....

Alaria in St. Maarten
Sint Maarten

Sint Maarten and Saint Martin are two names for a small island with an identity crisis.  They reflect the two nationalities (Dutch and French) that lay claim to this tiny 7 mile diameter island.

The island has attractive rolling hills and moderately high relief.  However, the steeply sloping shores leaves little room for coral reefs to develop.  Corals are physiologically plants that need to have good light and water motion to grow. Because of St. Maarten’s steep slopes, there’s just not much space for extensive coral reef development.

Despite modest coral reef development, the Sint Maarten government has worked hard to preserve what they have.  There is no fishing within their marine park.  They have a federally -funded Nature Foundation that patrols the park.  We worked with them to learn about the challenges to the island’s coral reefs.

The Nature Foundation's Marine Park Patrol boat with Chief Marine Park Ranger, Etienne Lake and George Stoyle (our fish expert).

My hosts were Tadzio Bervoets who is the Manager of the Nature Foundation and Etieene Lake who is the Chief Marine Park Ranger.  They took us to their reef sites via their patrol boat.

Tadzio Bervoets, Manager of The Nature Foundation St. Maarten

Coral Reefs of St. Maarten

We asked Tadzio to take us to their most important reefs.  We survey all the reef sites in the same way by quantifying the abundance of all coral species, seaweeds, and other reef-dwellers (this was my task) as well as all reef fishes (this was George’s task).  The fish transects are 30 m long and 4 m wide in which George counts and records the body size of all the important species of reef fishes.  Later this can be changed into biomass (or weight) per species per unit area for the sake of comparison with other reefs and other islands.

The reefs Tadzio and Etieene took us to were coral assembles on rock but not really coral reef ecosystems.  There is almost no coral build up over the rock outcrops.  So, what does that tell us? 

St. Maarten's reefs with low coral cover over rocks with a scattering of seaweeds

Coral reefs are the only ecosystem on planet Earth defined by the rock habitat they create.  Corals calcify limestone so when the corals die, the limestone remains and over time it builds up forming a distinct structure known as coral reefs.  With the exception of bogs that accumulate plant matter, coral reefs are unique by being defined by what they leave behind.  So coral reef ecosystems have a measurable geological growth rate which is essentially how many meters of reef rock they produce per thousand years.  The fastest growing coral reef was “clocked” growing 12 meters per thousand years (or 12 millimeters per year).  That is breakneck speed … geologically speaking.

The St. Maarten reefs we studied mostly had thin veneers of coral over bedrock.  Coral cover ranged between 2 and 20% of the reef surface.  Seaweed is relatively abundant except in areas where the long-spined sea urchin Diadema thrived.  Diadema is a very effective herbivore capable of removing all but the calcareous “coralline” algae in its grazing range

Seaweed carpet makes life hard for reef corals

The long-spined sea urchin Diadema 

Diadema's lair.  They stay in crevices during the day and much seaweed at night
The seaweed covering the rocks is similar to most Caribbean reefs.  Seaweed can kill corals by poisoning them and it can prevent baby corals from getting started on reefs.  So I watch for seaweed on all of the coral reefs I study.  Interestingly, because the Diadema sea urchin can mow algae down, where they are abundant, the corals do well.

Three Diadema with little seaweed except the limestone grazer resistant pink coralline algae (which is a good habitat for corals!)

Reef fish in St. Maarten had been hunted for years by spearfishing, hook and line and trap fishing.  In December of 2011 all fishing was banned from the marine park.  This is a great step in the right direction because reef fish grow very slowly and generally cannot be harvested sustainably.  However, Tadzio and Eiteene told us that every week they find people fishing in the park.  They get warned or arrested but it will take the best part of a decade to see functional reef fish communities.  What I found most encouraging is the “can-do” attitude of the Nature Foundation trying to educate and improve the conditions of the reefs of St. Maarten.

Alaria from the top of the mast (photo: Paul Calder... thankfully)
Now onto Anguilla

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