Biodiversity of the upper-mesophotic octocoral habitats at Sporades Archipelago (Aegean Sea)

Study Extent

Octocoral forests created by the yellow sea fan Eunicella cavolini and the red sea fan Paramuricea clavata were studied at the National Marine Park of Alonissos Northern Sporades (Aegean Sea, Greece), between 30 and 45 m depth, in order to assess their conservation status and the occurrence of both natural and anthropogenic stressors.

Sampling

Equipment used are GoPro cameras, Canon Cameras, Visual Census. During June 2021, technical scuba diving operations were carried out at every site to verify the occurrence of coral forests and perform noninvasive monitoring from 30 to 45 m depth, with qualitative explorations up to 60 m depth. Underwater videos were carried out using 4K cameras equipped with two video lights of 12,000 lm each and two parallel laser beams for scaling. Image analysis and processing for the coral forests were performed using ImageJ/Fiji software, and sampling units of 2.5 ± 0.2 m2 were defined along each transect, according to the minimal area used for the quantification of Mediterranean octocoral habitats.

Quality Control

Taxonomic Data mapped to WoRMS.

Method steps

1. Based on local knowledge and interviews with diving centers, five sites have been selected for the assessment of upper mesophotic coral forests. Three of them are located in the straits of Skopelos–Alonnisos, at Agios Georgios islet and Mikro islet, and at the tip of Fanari in Alonnisos. Two more sites are located 1.5 nautical miles northeast of Dyo Adelfia islet, at the so-called Barketa reef, and off the twin islets Moro and Moules.

Algae, Ascidiacea, Bryozoa, Cnidaria, Crustacea, Echinodermata, Mollusca, Pisces, Polychaeta, Porifera

1. Ascidiacea
   rank: class
2. Bryozoa
   rank: phylum
3. Cnidaria
   rank: phylum
4. Crustacea
   rank: subphylum
5. Echinodermata
   rank: phylum
6. Mollusca
   rank: phylum
7. Pisces
   rank: superclass
8. Polychaeta
   rank: class
9. Porifera
   rank: phylum
10. Algae

National Marine Park of Alonissos Northern Sporades (Aegean Sea, Greece)