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Si us plau utilitzeu sempre aquest identificador per citar o enllaçar aquest document: https://hdl.handle.net/2445/222658
Rhodolith beds in the Menorca Channel. Taxonomic diversity, structural complexity, and monitoring strategies for conservation
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[eng] Rhodolith beds, formed by free-living calcareous red algae, represent ecologically valuable and structurally complex habitats that contribute significantly to benthic biodiversity and ecosystem functioning. Their intricate three-dimensional architecture provides refugia for other organisms, positioning them among the most important biogenic habitats in the marine realm. However, in the Mediterranean Sea, these habitats remain insufficiently characterized, both in terms of their structural complexity and species composition, which hampers the development of effective conservation and management strategies. This thesis investigates the ecological, taxonomic, and functional dimensions of rhodolith beds in the Menorca Channel (western Mediterranean), integrating morphological, molecular, and ecological approaches across four complementary studies.
First, I assessed rhodolith morphological diversity using three-dimensional analyses and comparing core zones of the bed (high rhodolith density) to adjacent areas with lower density. The results revealed that rhodoliths in core areas exhibited more complex morphologies, larger size, and higher interstitial space—key indicators of habitat complexity that are often underestimated by traditional two- dimensional methods. Second, I addressed the knowledge gap in species composition by combining classical taxonomy with molecular techniques, revealing a cryptic diversity of at least 15 rhodolith- forming species. These findings contrast with current Habitats Directive, which focus on just two species predominant in the Atlantic, and underscore the need to revise conservation policies to reflect the true diversity of rhodoliths in the Mediterranean. Third, I clarified the taxonomic status of the poorly known species Sporolithon mediterraneum, for which I designated a neotype based on a specimen from mesophotic depths of the Tyrrhenian Sea. Morphological and molecular analyses confirmed the distinctiveness of this species from other Sporolithon taxa and established a robust framework for future identifications. Finally, I explored the application of three non-intrusive monitoring tools— environmental DNA, underwater video, and passive bioacoustics—to characterize fish assemblages associated with rhodolith beds. Their combined use revealed high species richness, including endangered and cryptic species, while also capturing variability related to habitat heterogeneity and trawling exposure.
Altogether, this thesis highlights the underestimated structural and taxonomic complexity of rhodolith beds in the western Mediterranean and emphasizes the value of integrating multidisciplinary tools to understand and monitor these vulnerable habitats. The results contribute to the refinement of habitat assessments, species inventories, and conservation frameworks, with direct implications for regional marine biodiversity management and the development of non-destructive monitoring strategies.
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CABRITO RUBAU, Andrea. Rhodolith beds in the Menorca Channel. Taxonomic diversity, structural complexity, and monitoring strategies for conservation. [consulta: 3 de desembre de 2025]. [Disponible a: https://hdl.handle.net/2445/222658]