Surveying Guadeloupe


Image: A family of Dolphins swim in the clear waters away from the island. Image courtesy of Alex Zeni - www.souslevent.book.fr

 

The team has just completed its second day of sampling in Guadeloupe, a French overseas region situated in the Lesser Antilles. So far we have had two very contrasting days of work. We have noticed that the coverage of hard corals has been relatively high when compared to other places surveyed on the Caribbean, yet, at the same time areas of the reef are massively dominated by macroalgae.

 

How the topography of an island affects it's coral reefs

The first day of sampling saw us start the day in very gloomy and rainy weather, with our first sampling sites adjacent to Rivière Moustique à Petit Bourg (Mosquito river at Petit Bourg) on the east side of Basse Terre island. The river system comes from La Grande Soufrière, a volcano that is the highest peak in the Lesser Antilles at 1467m. This is a very high peak when compared with the highest peak at our last location Turks and Caicos, being the Blue Hills at 49m. The out flow of fresh water from the river mouth caused the top 2 metres of water to be very murky, there was almost zero visibility here. The visibility increased underneath this layer of fresh water, but the turbidity was still high from the amount of sedimentation in the area. The reef was on a fairly steep slope, flattening off at about 12m, with high amounts of finger coral, Porites porites seen on the first dive.

One of the more alarming parts of the day was seeing the amount of fish traps in the area. They littered the sea floor in places and it was obvious most had been discarded and left to rust. At one stage Pete and myself saw a rope for one of the traps completed entwined around a dying purple sea fan, Gorgonia ventalina. We had a few close calls being entangled ourselves, but Pete’s ability to navigate the SVII saw us finish the dive safely!

 

The difference that an Marine Protected Area (MPA) can make

Our second day brought us the Guadeloupe passage side of the Island on the north. We dived exposed barrier reefs, one of which was a Marine Protected Area (MPA) close to Ilet Fajou. We managed to cross the MPA boundary and it was interesting to see a change from a highly diverse habitat with lots of hard and soft corals inside the MPA, to a reef highly dominated by Dictyota sp algae outside the MPA boundary.

Manuel and Ana finished the day surveying a reef adjacent to the town of Port Louis and were surprised to see a high amount of hard coral cover here too. Like the rest of the team they were very surprised by the amount of Dictyota sp macroalgae dominating the reef. This could possibly be explained by the alarming number of fish traps in the area, in this area the traps were full of fish, many of which could been herbivorous species such as parrot fish and surgeon fish who would have controlled the amount of algae on the reef were they not captured in the fish traps.

We are now making our way to Marie-Galante, an Island situated on the southern side of Guadeloupe. Hopefully its distance from coastal development will lead to even healthier coral cover with less domination by macro algae and less fish traps.

 

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