Small Mediterranean coastal Lagoons Under Threat: Hydro-ecological Disturbances and Local Anthropogenic Pressures (Size Matters)

Viviana Ligorini; Eléa Crayol; Frédéric Huneau; Emilie Garel; Nathalie Malet; Marie Garrido; Louise Simon; Philippe Cecchi; Vanina Pasqualini

doi:10.1007/s12237-023-01182-1

Small Mediterranean coastal Lagoons Under Threat: Hydro-ecological Disturbances and Local Anthropogenic Pressures (Size Matters)

Estuaries Coast. 2023 Feb 27:1-24. doi: 10.1007/s12237-023-01182-1. Online ahead of print.

Authors

Viviana Ligorini^{1

2

3}, Eléa Crayol^{1

3}, Frédéric Huneau^{1

3}, Emilie Garel^{1

3}, Nathalie Malet⁴, Marie Garrido⁵, Louise Simon^{1

2

3}, Philippe Cecchi⁶, Vanina Pasqualini^{1

2

3}

Affiliations

¹ Université de Corse Pascal Paoli, Campus Grimaldi, Corte, BP52, 20250 France.
² CNRS, UAR 3514 Stella Mare, Cordon Lagunaire de la Marana, lieu-dit U Casone, Biguglia, 20620 France.
³ CNRS, UMR 6134 SPE, BP 52, Corte, 20250 France.
⁴ Ifremer, Laboratoire Environnement Ressources Provence-Azur-Corse (LER/PAC), Implantation de Bastia, Z.I. Furiani, Immeuble Agostini, Bastia, 20600 France.
⁵ Environmental Agency of Corsica, 14 Avenue Jean Nicoli, Corte, 20250 France.
⁶ MARBEC, Univ. Montpellier, CNRS, Ifremer, IRD, Montpellier, France.

Abstract

Mediterranean coastal lagoons are affected by multiple threats (demographic pressures, eutrophication, climate change) expected to increase in the future and impact the ecosystem services provided. Conservation norms and scientific studies usually focus on large lagoons (> 0.5 km²) due to their economic importance, while they ignore smaller lagoons. These are poorly understood and often unprotected, despite their prevalence within the Mediterranean region and their importance. Qualitative and quantitative characterisation of small lagoons, in terms of functioning and sensitivity to global and local changes, are needed to develop appropriate management strategies. For this purpose, this work provides the first inventory of all Corsican lagoons and has investigated three of them of small size (Arasu, Santa Giulia, Balistra), characterised by contrasting anthropogenic contexts (highly modified/disturbed, medium disturbance, quasi-pristine). At the regional level, 91 of the 95 lagoons identified are < 0.5 km², making Corsica a good example for the study of small Mediterranean lagoons. The three case studies showed differences in their seasonal biogeochemical cycles and phytoplankton communities (biomass, diversity, photosynthetic efficiency). Arasu and Santa Giulia lagoons showed an increase in watershed urbanisation (+ 12% and + 6% in 30 years), high phytoplankton biomass, low diversity and blooms of potentially harmful dinoflagellates. Conversely, Balistra lagoon showed a good status overall, but some anthropogenic pollution sources within its watershed. This study demonstrates the importance of small lagoons at regional and Mediterranean scale, and provides knowledge on studied local sites but also potential applications elsewhere. The importance of an integrated approach considering lagoons within their adjacent connected systems (watershed and sea) and anthropogenic contexts is highlighted.

Supplementary information: The online version contains supplementary material available at 10.1007/s12237-023-01182-1.

Keywords: Ecological functioning; Hydrogeology; Management; Phytoplankton; Small Mediterranean coastal lagoons; Threats.