Maria Salomidi

Cystoseira sensu lato (s.l.) (Fucales, Phaeophyceae) form structurally complex marine forests along the warm-temperate coasts of the Mediterranean Sea and the eastern Atlantic Ocean. They are experiencing widespread decline, yet their conservation and restoration are hindered by taxonomic uncertainty. Within Cystoseira sensu stricto (s.s.), species boundaries among taxa traditionally referred to as C. compressa, C. foeniculacea, C. humilis (including the C. canariensis morphotype), and C. pustulata have long been debated due to the high plasticity and partial overlap of diagnostic morphological traits. Here we reassess species boundaries within the Cystoseira s.s. complex using an integrative approach combining morphology, ecology, and multilocus genetic data. We collected specimens from 20 sites spanning the Mediterranean–Atlantic distribution. Genomic DNA was extracted from 220 specimens and Sanger sequencing generated 243 new sequences (ITS2: n = 99; cox1: n = 88; rbcL–rbcS: n = 56). We inferred single-locus and concatenated phylogenies, reconstructed haplotype networks, and applied multiple single-locus species delimitation approaches to test the robustness of inferred boundaries. We consistently recovered two primary lineages corresponding to C. foeniculacea and a C. compressa complex, the latter including specimens historically identified as C. pustulata and the C. humilis with the C. canariensis morphotype. Within an integrative framework that prioritises cross-locus concordance and diagnosability, we recognise two species-level lineages in Cystoseira s.s. and treat the morpho-ecologically coherent entities within C. compressa at the variety rank. Accordingly, we propose the new status and combination Cystoseira compressa var. pustulata (Ercegović) D’Ambros Burchio & Falace, comb. et stat. nov.

This study presents the first quantitative analysis of live red coral (Corallium rubrum) populations in Greek waters (North-Western Aegean Sea) and contributes to the limited knowledge of mesophotic benthic assemblages in the Eastern Mediterranean Sea. Utilizing ROV and stereo-video SCUBA surveys at two previously harvested sites (47-60 m depth), we quantified red coral density and morphometric parameters. Associated benthic communities, comprising 101 taxa with Porifera as the dominant group, were characterized, and the Mesophotic Assemblages Conservation Status (MACS) index was applied for the first time in this region, revealing an overall “Good” ecological status despite locally degraded facies. While red coral entanglement by widespread ghost fishing gear appeared low, high frequencies of necrosis and epibiosis were observed in the larger canopy-forming gorgonian Paramuricea clavata, potentially indicating current and past mechanical damage, although the synergistic effects of other physical stressors cannot be excluded. This research offers crucial baseline data on red coral populations and associated mesophotic communities in an under-studied region and ecological zone. Our findings are discussed in the context of existing national management frameworks and conservation measures, emphasizing the need for further monitoring and research to inform effective management and conservation strategies in view of increasing anthropogenic and environmental pressures.

UAV technology is used to map the beach morphological characteristics aiming to the impact of the presence of Posidonia οceanica beach-cast seagrass litter in the area of Schinias national Park, Marathon, Greece. Additionally, shoreline change investigation with remote sensing techniques covering a period of 76 years was realized. The role of banquettes seems to be of particularly significant as it is affecting the configuration of coastal front. More extensive monitoring, is required to better comprehend the role of Posidonia banquettes for management planning and decision-making processes.

The coralligenous habitat was studied at the large Mediterranean scale, by applying a standardized, non‐destructive photo‐sampling protocol, developed in the framework of the CIGESMED project. The results provided evidence to support the following statements: (a) the assemblage pattern is not homogeneously distributed across the four Mediterranean ecoregions studied (biotic gradients hypothesis); and (b) the assemblage pattern does not change significantly when the information is aggregated to higher taxonomic levels (taxonomic sufficiency hypothesis). Surrogate taxonomic categories higher than species, such as genus and family, can be used to reveal the multivariate pattern of the coralligenous assemblages. Although preliminary at the pan‐Mediterranean scale, these outcomes set the scene for future comparisons as more data sets become available but also for comparisons between taxonomic and functional patterns.