Angélica Enrique-Navarro1, Carlier Antoine1, Burel Thomas2, Droual Gabin1, Gauff Robin P.M.3,4, Taormina Bastien5, Curd Amelia1
1Ifremer, France - 2Univ Brest, CNRS, IRD, Ifremer, LEMAR, France - 3University of Padova, Italy - 4Sorbonne Université, CNRS, UMR 7144, Adaptation et Diversité en Milieu Marin Station Biologique Roscoff, France - 5France Energies Marines, France
As part of the biodiversity offsetting efforts on marine coastal areas impacted by human activities, artificial reefs are increasingly implemented in urbanized zones to create new habitats. In 2019, the Port of Brest (France) built a new polder retained by an 890-meter-long dyke, designed to support the marine renewable energy sector. To enhance its biodiversity, 100 artificial concrete rockpools (each 0.5 m³) were embedded into the dyke rock revetment at three different intertidal levels (high, medium, and low). The benthic biodiversity (flora and fauna) of 27 rockpools, distributed along three dyke sections (western, central, and eastern), was monitored from 2021 to 2024 during winter and summer spring tides. Rapid Assessment Surveys and video recordings were employed to describe the rockpools benthic communities and characterize their spatio-temporal changes, with the aim to evaluate long term ecological benefits and identify key factors influencing community composition. Five years after installation, the rockpool benthic community appears to have reached its climax, with 240 taxa identified. Findings revealed no significant differences in community composition among the dyke sectors. Significant variations were however observed between water levels. High-level pools exhibited the highest biodiversity, while medium- and low-level pools showed no significant differences, both supporting comparatively lower biodiversity. The presence of introduced species was low (<10%) compared to overall observed richness. Notable non-native species included bryozoans Watersipora subatra and Bugula neritina, some red algae and the fan-worm Bispira polyoma, all found in high abundance. Certain taxa, such as the flat oyster (Ostrea edulis) and the slipper limpet (Crepidula fornicata), showed a preference for smooth concrete substrates. In order to capture the first succession phases of the rockpools, which could not be examined immediately after their installation, an experiment is currently underway. This involved defaunation of a limited number of rockpools and monitoring early colonization phases by high-frequency surveys. Obtained results will provide valuable insights into community dynamics within the rockpools and how the benefits and/or drawbacks of eco-engineering may evolve over time.
Biography
Angélica is a biologist with a master’s in coastal oceanography and a PhD (2023) on the effects of climate change, including ocean warming and acidification, on Mediterranean jellyfish populations. She is currently a postdoctoral researcher in Brest, studying benthic communities colonizing artificial reefs in urbanized coastal areas affected by human activities.