Marine forests loss: causes and effects in the framework of their conservation and restoration
| Type | : | AP |
|---|---|---|
| Nature | : | Production scientifique |
| Au bénéfice du Laboratoire | : | Oui |
| Statut de publication | : | Publié |
| Année de publication | : | 2023 |
| Type de thèse | : | Thèse de Doctorat |
| Date | : | 31/01/2023 |
| Nombre de pages | : | 194 |
| Directeur de thèse | : | Luisa Passeron Mangialajo, Mariachiara Chiantore, Rodolphe Lemée |
| Université | : | Université de Nice |
| Département académique | : | Sciences de l’Environnement |
| Auteur | : | MONSERRAT BARCELO Margalida |
| DOI | : | - |
| URL | : | https://theses.hal.science/tel-04071065/ |
| Abstract | : | Large brown forest-forming macroalgae are dominant foundation species, ecosystem engineers of marine macroalgal forests. In the Mediterranean Sea, they are mainly represented by Cystoseira sensu lato spp. most of wich are endemic. They are also characterized for being long-lived species with short dispersal of the zygotes. Marine forests are one of the most productive and diverse ecosystems on earth. However, anthropogenic impacts are pushing them to the edge, causing regime shifts towards less complex communities such as shrubs, turfs, or even barren grounds. Marine forest loss affects the whole ecosystem, eventually making it more vulnerable to emergent phenomena such as benthic harmful algal blooms (BHAB). BHAB of the genus Ostreopsis spp. have been expanding in recent decades through temperate regions such as the Mediterranean Sea, where they have important public health, ecological and economic consequences. Major blooms are generally observed on macroalgal turfs and shrubs, suggesting that less structurally complex macroalgal communities could have an active role in promoting the proliferation of blooms.The main objectives of this thesis are (i) to assess some abiotic (climate change) and biotic (herbivory) causes of marine forests loss in the Mediterranean Sea and (ii) the potential consequences this loss can have in the context of BHABs proliferation. In the first two chapters, the causes of Cystoseira s.l. spp. loss were assessed. In Chapter 1, the effects of climate change and species facilitation on the recruitment of Cystoseira compressa were studied in controlled laboratory experiments. The major results from this chapter show that the interactive effects of ocean warming and acidification negatively affect C. compressa recruits, which are also negatively affected by the presence of crustose coralline algae. In Chapter 2 the grazing pressure and the effects of different invertebrates on recruits of C. compressa were assessed through field surveys and both field and laboratory-based experiments. The results obtained show a high grazing rate of several common invertebrate species (molluscs, decapods et isopods) on recruits of C. compressa, representing a threat to natural populations in the long term, but also affecting the success of restoration actions. In chapters 3 and 4 the consequences of forest loss and in particular, the facilitation of Ostreopsis spp. blooms was approached by a literature review and field experiments. The review, reported in Chapter 3, focussed on the role of habitat in the facilitation of Ostreopsis spp. blooms. Despite an evident lack of information at the global scale on the meso- and macro-habitat fostering Ostreopsis spp. blooms, the present knowledge suggests a relationship between the abundance of Ostreopsis spp. and the complexity of the macroalgal communities. In Chapter 4 Ostreopsis spp. blooms have been studied in relation to macroalgal communities in field experiments in Italy and in France. A high variability on Ostreopsis spp. abundances was observed in the different macroalgal species and communities sampled, in some cases likely hiding other potential patterns of Ostreopsis spp. preferences. Larger scale studies would be needed to confirm these results.These findings provide important insights into the causes and effects of Cystoseira s.l. spp. loss and are of major interest for the conservation of Mediterranean marine forests, contributing to the development of effective management measures. The results presented support the importance of marine forests restoration in the Mediterranean Sea, as recommended by the 2030 European Biodiversity Strategy, the United Nations Decade on Ecosystem Restoration and the 2030 Agenda for Sustainable Development objectives. Such restoration actions will not only increase the productivity and biodiversity of coastal ecosystems but could potentially mitigate the public health, ecological and economic consequences of Ostreopsis spp. blooms. |
| Mots-clés | : | - |
| Commentaire | : | Jury : Elisa Berdalet, Institut de Ciències del Mar – CSIC, rapporteur Christopher Cornwall, School of Biological Sciences, Victoria University of Wellington, rapporteur Rodolphe Lemée, Laboratoire d’Océanographie de Villefranche, Sorbonne Université, examinateur Marie-Yasmine Dechraoui-Bottein, ECOSEAS, Université Côte d'Azur, examinateur Cecilia Totti, Dipartimento di Scienze della Vita e dell'Ambiente, Università Politecnica delle Marche, examinateur Didier Laurent, Ville d’Antibes, invité Coralie Meinesz, Metropole Nice Côte d’Azur, invité Luisa Mangialajo, ECOSEAS, Université Côte d’Azur, directeur Steeve Comeau, Laboratoire d’Océanographie de Villefranche, Sorbonne Université, co-directeur Mariachiara Chiantore, Dipartimento di Scienze della Terra dell’Ambiente e della Vita, Università degli Studi di Genova, co-encadrante |
| Tags | : | CHOC |
| Fichier attaché | : | - |
| Citation | : |
Monserrat Barcelo M (2023) Marine forests loss: causes and effects in the framework of their conservation and restoration. Université de Nice Sciences de l’Environnement, 194
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