All females? Experimental nest temperature assessments will show.

Sea turtle sex is not determined at the time of fertilization like in humans, it is set by the temperature level during nest incubation. Recently for some small island rookeries througout the Caribbean researchers reported a shift towards a more female dominated hatchlings/populations as nest temperatures slightly increased in these areas (warmer beaches result in female turtles). At St. Eustatius we will further asses the driving factors of sand temperatures in natural nest and experimental treatments, link it to nest succes, and compare these with that of other Caribbean islands and beyond. Continue reading “All females? Experimental nest temperature assessments will show.”

New Publication shows Dutch Caribbean turtles migrate into risky waters

Lisa Becking (Wageningen University and IMARES) and I, together with Sea Turtle Conservation Bonaire (STCB) ; Mabel Nava, Sue Willis and Robert van Dam have shown in a recent publication that sea turtles who breed in Bonaire, Caribbean Netherlands, migrate great distances of up to 3500km to reach their foraging grounds across the Caribbean in 10 different countries. Continue reading “New Publication shows Dutch Caribbean turtles migrate into risky waters”

New! Review on herbivory on freshwater & marine macrophytes

Grazing is an important driver of ecosystem functioning! Not only in seagrass ecosystems :). This paper is a result of a very nice collaboration with Liesbeth Bakker and other colleagues working on herbivory in other ecosystems.

Paper highlights: Continue reading “New! Review on herbivory on freshwater & marine macrophytes”

2 times cake: 2 cool new papers! How to keep seagrass as happy as a clam?

Today 2 papers of our group were published online! This papers are the result of a successful collaboration between the University of Groningen, NIOZ and Radboud University, The Netherlands

The first study by Els van der Zee et al. demonstrates that food web structure and complexity can be fundamentally shaped by  Continue reading “2 times cake: 2 cool new papers! How to keep seagrass as happy as a clam?”

Guest post: Jurjan’s research – turtle genomics

Within the Dutch Caribbean, green and hawksbill turtle rookeries and foraging grounds are found. Green and hawksbill turtles have been decimated by human exploitation and habitat degradation, calling for knowledge of population structure and demographic history. Here we investigate migration patterns in these highly migratory species and evaluate current population status. In other words: How many turtles were there and where to they go? Those are the central questions in my PhD which I will address using population genomics and ancient DNA. 

Last summer I’ve spent three months in the Dutch Caribbean collecting tissue samples for my research. Most samples were collected on Bonaire, but a significant amount were collected on Curacao as well. A few samples were collected on Aruba as well. As soon as the samples arrive I will start on DNA extractions and analyses! Jurjan van der Zee20150910MC109214

Continue reading “Guest post: Jurjan’s research – turtle genomics”

Little-Curaçao-green-turtle swims 3100 km in 3 weeks

The track of green turtle female “MRC rentals” (after her sponsor) updated 10 october 2015. After nesting in Klein Curacao she swam 3100km in 30 days – and has now settled in Mexico, the foraging grounds in Chakmukchuuk or Laguna Manati.

Last week we* successfully placed a satellite transmitter on a big green turtle female after she nested at Little Curacao’s turtle beach. The signals of the ARGOS satellite are updated hourly and I am very happy to report that this female is swimming very fast in the direction of Nicaragua 1050km in the first 10 days. Continue reading “Little-Curaçao-green-turtle swims 3100 km in 3 weeks”

Satellite trackers show Bonaire green turtle habitat use

4 sub-adult green turtles that we caught in Lac Bay are now equipped with satellite transmitters to study their movements and use of the seagrass meadows, (see  photos below).

Mabel (STCB) and me deploying the satellite transmitter

The greens that forage in the shallow Lac Bay area are typically sub-adults. Continue reading “Satellite trackers show Bonaire green turtle habitat use”

Experiment on (invasive) seagrass & turtle grazing, Bonaire

Two weeks ago we arrived on Bonaire. Since then we worked non-stop and we made great progress! The first thing we did was to set up a turtle exclosure experiment on the seagrass beds in Lac Bay, after Funchi (STCB) and Sabine Engel (STINAPA) kindly showed us all the suitable seagrass areas. The native dominant seagrass species here are Thalassia testudinum (or turtle grass) and Syringodium filiforme. However after a quick snorkel survey across the bay the cover of invasive seagrass species Halophila stipulacea seems almost higher.

That is impressive since the species was reported only in 2010 for the first time in Lac Bay. NGO Sea Turtle Conservation Bonaire that works since 1991 on turtles here estimates the sea turtle population (green and hawksbill) between 1000-2000 turtles Continue reading “Experiment on (invasive) seagrass & turtle grazing, Bonaire”

Sea turtle fieldwork in Dutch Caribbean 2015

I am very excited to finally start our fieldwork on sea turtles and seagrass in the Bonaire, Aruba and Curacao! What started as a proposal (initiated by Lisa Becking and me) in August 2013, finally resulted in a research project May 2015 entitled  “Ecology and conservation of Green and Hawksbill turtles in the Dutch Caribbean”. Continue reading “Sea turtle fieldwork in Dutch Caribbean 2015”