A Dendrophyllia ramea Population in the Ionian Sea (Central Mediterranean Sea) Threatened by Anthropogenic Impacts

This study reports the first attempt to quantitatively describe a Dendrophyllia ramea population on the Apollo bank (Ionian Sea), revealed in summer 2021 through a remotely operated vehicle (ROV) survey. The habitat description, bathymetric distribution, population density, and structure of the species were assessed by image analysis. A well-developed population of D. ramea, located on boulders on a sedimentary plateau at 70-80 m depth, was observed. The density ranged on average between 0.17 +/- 0.04 and 0.8 +/- 2.4 colonies m(-2) with dense patches up to 8 colonies m(-2). The population consisted primarily of many isolated single corallites and colonies of various sizes, some of which reached a maximum height of more than 40 cm. Deepwater fishing activities, primarily longline fishing, negatively affected this species. The newly collected data add knowledge about this vulnerable scleractinian coral. The documented negative effect of fishing activities on vulnerable marine ecosystem (VME) species further highlights the need for urgent conservation measures.

Automated summary

This study is the first to quantitatively describe a population of Dendrophyllia ramea on the Apollo bank, which was discovered during a ROV survey in the Ionian Sea in summer 2021. The study assesses the habitat description, bathymetric distribution, population density, and structure of the species through image analysis. The findings reveal a well-developed population of D. ramea on boulders at a depth of 70-80 m, with varying densities and negative impacts from deepwater fishing activities.