Ms Beatriz Rodrigues2
1Okeanos, University Of The Azores, Faial, Azores, Portugal, 2EU-CONEXUS, Valencia, Spain
Biography:
I am a marine biologist currently completing my Master’s thesis through the EU-CONEXUS Joint Master’s Programme in Marine Biotechnology with a fully funded Erasmus Mundus Scholarship, hosted at the OKEANOS Research Institute, University of the Azores. Throughout my academic path, I have had the opportunity to study in Portugal (University of Algarve and University of the Azores), Spain (Catholic University of Valencia), and France (La Rochelle University), gaining a broad international background in marine sciences.
My Master’s research focuses on the optimization of environmental DNA (eDNA) sampling methods for the monitoring of sea turtles in the Azores, with particular emphasis on comparing passive and active sampling approaches under controlled and field conditions.
Abstract:
Marine turtles are widely distributed marine megafauna that play important ecological roles in marine ecosystems through nutrient transport, habitat and food-web dynamics. However, their distribution and habitat use remain poorly understood in oceanic regions due to low densities, high mobility and limited detectability. In the North Atlantic, loggerhead turtle (Caretta caretta) and green turtle (Chelonia mydas) occur in the waters of the Azores, an important migratory habitat. Monitoring these species is challenging in open marine systems, highlighting the need for improved detection methods.
Environmental DNA (eDNA) is a promising non-invasive tool for species detection, and passive eDNA samplers (PEDs) have recently emerged as an alternative or complement to active water filtration. This study evaluated PED performance for marine turtle detection in the Azores using a two-phase approach.
A mesocosm experiment with C. caretta compared passive samplers (sterile cotton gauze in stainless-steel holders) deployed for 2, 8, and 24 hours with active filtration using 0.22 µm and 0.45 µm filters. A field study targeting C. mydas was conducted at two coastal sites on Faial Island.
Both methods successfully detected C. caretta in controlled conditions. Active filtration produced stronger quantitative polymerase chain reaction signals, while passive sampler performance increased with deployment time, with best results at 24 hours. No differences were observed between filter pore sizes. In field samples, no amplification of C. mydas was obtained despite detectable total eDNA, suggesting environmental constraints on detection.
Overall, passive eDNA sampling shows promise as a complementary tool for marine turtle monitoring in oceanic environments.