Biodiversity in sediments at methane seeps on mud volcanoes in the Mediterranean Sea, Turkey
The deep-waters of the Mediterranean Sea host a diverse array of habitats including seamounts, mud volcanoes, and methane/cold seeps. In collaboration with the (E/V) Nautilus, we explored the Anaximander Seamounts located in the south of Turkey, at the junction of the Hellenic and Cyprus arcs. Five mud volcanoes including Amsterdam, Kula, Thessaloniki, Kazan, Athina at depths between 1250−2300 m, and a non-seep site (Anaximenes Ridge, 818-m depth) were sampled to collect some of the first quantitative biological samples for community analyses and DNA barcoding of the tiny organisms residing in soft-sediments.
Seamounts are undersea islands typically several km wide that rise up 100’s of meters high above the seafloor but do not reach the water’s surface. Mud volcanoes occur at tectonically active regions on seamounts. They are extreme environments where mud, rock fragments, fluids, and methane seep through the seafloor. Slow methane release from the seafloor, also called cold seeps, provide the chemical energy necessary for life in these deep-water environments where light for photosynthesis does not reach.
Importance
These habitats are of particular interest for the Mediterranean marine environment because they represent potential “hot spots” of biodiversity, are important for fishery and ecosystem conservation, and often contain numerous endemic species. In spite of this, they remain poorly known mainly due to the great depths at which they are found. This project will enhance the limited global scientific knowledge on biodiversity and community structure in these important and unique deep-water environments.
Remotely operated vehicle (ROV) Hercules being lowered into the sea making its way to the seafloor near a mud flow on a mud volcanoe.
Actively seeping fluid (14°C) containing methane was present at several volcanoes. The seabed was heterogeneous, consisting of soft-sediments interspersed with carbonate crusts harboring mussels and tubeworms.
Patchy, superficial microbial mats were the most common methane seep habitat in this area.
Robotic arm of Hercules taking a sediment core sample for invertebrates.
Project Aims:
We are investigating the distribution and community structure (species composition, diversity, and abundance) of tiny invertebrates living in these reduced, microbial-mat-covered sediments and are establishing molecular DNA barcodes for species to contribute to global genetic databases.
Specific questions of interest:
Do community composition and diversity differ: A. from one mud volcano to another (spatial scale of km), B. from communities in non-seep sediments, and C. at different locations/depths on mud volcanoes (spatial scale <1 m to km)? Do these areas contain species new to science? How unique and diverse are these communities compared to those in similar habitats elsewhere?