Green turtles and invasive seagrass mission continues in Martinique and Guadeloupe

By: Vincent Quiquempois and Elizabeth Whitman

Once again, the Heithaus lab returned to Martinique and Guadeloupe, of the French West Indies, to collect data on the effect of an invasive seagrass, Halophila stipulacea, on the distribution and feeding behavior of green sea turtles. Our team, Ph.D. candidate Elizabeth Whitman, Dr. Jeremy Kiszka and research intern Vincent Quiquempois, was excited to get back into the water with our many collaborators and conclude our turtle and seagrass surveys for this portion of the project.

We first landed in Martinique where we met with our collaborators from the Réseau Tortue Marines de Martinique, Marie-Fance and Maxym. They offered to assist us with our surveys for the entire week we will were in Martinique! To estimate the density of sea turtles, we conducted snorkel surveys along transects throughout the bay of Grande-Anse located in the South west part of Martinique in Les Anses d’Arlets. We recorded sightings of all turtles within the transects and collected additional data on feeding behavior, seagrass assemblages and other megafauna. On this trip, we were even lucky enough to see an eagle ray during one of our transects!

Left: green turtle swims over bed of Halophila stipulacea; Right: fragments of Halophila stipulacea, like this one floating by a mooring, are capable of colonizing new areas

For a more detailed study of the seagrasses and algae found in the bay, we estimated abundances of each species within quadrats and collected samples for nutrient analysis back at FIU. For the shallow part of the bay, we managed to free dive to realize our objectives but for the deeper part, we used SCUBA. During these dives, we also saw some interesting marine life!

Elizabeth Whitman (left) and Jeremy Kiszka (right) conduct
detailed surveys of the seagrass and algae in Grande-Anse

While on SCUBA we found other interesting animals
like this tiny nudibranch in the invasive seagrass

By the end of the week in Grande-Anse, Martinique we completed 124 transects for a total of more than 75 km of swimming! Our seagrass surveys revealed that there is a great deal of damage to the seagrass beds caused primarily by anchors and abandoned fish traps which likely promote expansion of the invasive seagrass.

Left: Scar left by anchor chain in seagrass bed; Right: Abandoned fish trap surrounded by juvenile fish

For the second part of the trip, Elizabeth and Vincent moved on to Guadeloupe to continue the turtle and seagrass surveys in Malendure, a tourist beach in front of the Cousteau Marine Reserve. Here, the bay is much smaller than Grande-Anse but we are always impressed by the difference between the two sites. We see schools of adult fish in Malendure, whereas in Grande-Anse the fishes are mostly juveniles and scarce.

Flounder found in the shallow water of Malendure

On Guadeloupe, we received the help of the National Parc and Jeffrey Bernus who assisted us with our transect surveys every day. We also received help, in the form of field assistance, seagrass sample processing and advice, from the Réseau tortue de Guadeloupe, of Cap Naturel and Evasion Tropicale. With all of this help managed 469 turtle sightings across 126 transects for a total of 50.4 km snorkeled in just 5 days in Malendure!

After two intense but exciting weeks, we returned to Miami with our seagrass samples and a complete data set for analysis. We could not have done it without our local collaborators! Go team!