Maria Zotou

Mediterranean rocky reef habitats are ecologically valuable yet increasingly degraded due to cumulative human pressures, necessitating efficient, large-scale ecological status assessments to inform management. Macroalgal communities are widely used as indicators of rocky reef conditions and are typically assessed via photoquadrat sampling. However, the manual annotation of benthic images remains time-consuming and costly. This study evaluates the performance of CoralNet (version 1.0), an AI-assisted image annotation platform, using a pre-annotated dataset of 2537 photoquadrat images from 89 rocky reef sites in the Aegean Sea, Greece, classified into 23 taxonomic and morphofunctional groups. Half of the dataset was used to iteratively train CoralNet classifiers, while the remainder was used to compute the reef-EBQI index and compare ecological status estimates with those derived from manual annotations. The classifier accuracy improved with training volume, reaching 67% using the entire dataset. Reef-EBQI scores derived from CoralNet showed 87% agreement with the manual classifications. Despite challenges and limitations, AI-assisted annotation proved effective in regional-scale ecological assessments based on broad taxonomic and morphofunctional categories. Automated tools like CoralNet can reduce post-processing bottlenecks and enable scalable, cost-effective monitoring, especially when integrated with standardized protocols and citizen science initiatives.

Non-indigenous species (NIS) are among the main drivers of native biodiversity loss, habitat alteration, and degradation of ecosystem services, with some NIS posing risks to human health. Efficient monitoring strategies are necessary to assess the distribution and impacts of NIS. In this study, we compared the performance of environmental DNA (eDNA) metabarcoding and visual surveys with SCUBA diving to detect marine fish NIS in Greek waters. We collected water samples from 20 coastal sites across the Aegean, Ionian, and Levantine Seas in both warm and cold periods, targeting the 12S rRNA region. A reference 12S Mediterranean NIS sequence database was created to improve regional monitoring. Underwater visual surveys were performed at the same sites to visually detect fish NIS. Overall, 15 non-indigenous fishes were detected, five with both eDNA and visual surveys, seven exclusively by eDNA, and three by visual surveys alone. The southern stations yielded more NIS detections than the northern stations in both periods. Our findings demonstrate that eDNA can provide a rapid, low-cost, and effective tool, advocating for its integration into systematic NIS monitoring in the eastern Mediterranean Sea. A comprehensive barcode reference database is essential in enhancing the effectiveness of eDNA approaches. Thus, the combination of eDNA metabarcoding and traditional underwater visual surveys is recommended for comprehensive monitoring of NIS in marine environments.

The Pinna nobilis, a Mediterranean mollusc, has suffered population declines due to a massive mortality event associated with various factors including the parasite Haplosporidium pinnae. Some populations show resilience, possibly due to local environmental conditions. In this study, a molecular multiplex PCR method was developed using species‐specific primers targeting Internal Transcribed Spacer (ITS) regions of P. nobilis and P. rudis, allowing accurate species identification and hybrid detection. Samples from Mediterranean areas were analysed, including putative hybrids and individuals from five other bivalve species. DNA was isolated, ITS regions were amplified and sequenced, and phylogenetic analyses confirmed species differentiation and primer specificity. The multiplex‐PCR successfully identified P. nobilis, P. rudis, and their hybrids based on distinct amplicon patterns. This study highlights the value of molecular tools in species conservation, especially for monitoring and managing hybridization, supporting effective biodiversity conservation strategies.

In the Mediterranean Sea, the genus Pinna encompasses two large fan-shaped bivalve species, Pinna nobilis and Pinna rudis. Historically, both species coexisted in the western Mediterranean until a mass mortality event (MME) brought P. nobilis to the brink of extinction. Notably, P. rudis remained unaffected by the MME, and its recent successful recruitment and further spread have been hypothesized to be linked to the local extinction of P. nobilis. Although P. rudis has been sparsely recorded in the eastern Mediterranean Sea (with some of these records being doubtful), reports emerging in the summer of 2023 from researchers and citizens have unveiled its sudden spread in the region. This study documents the recent presence of P. rudis within Greek waters through a dedicated survey and molecularly confirmation through two distinct molecular methods. Information derived from a citizen science initiative, following photo-identification of the species was also included. Furthermore, an updated review of the distribution of P. rudis in the Mediterranean Sea, integrating data from literature and online repositories is provided. This research confirms the recent spread of P. rudis in Crete, the Greek Ionian Sea, and Cyprus (first verified records of the species in the regions), in marine areas where P. nobilis has become extinct, further strengthening the hypothesis that P. rudis has benefited from the collapse of P. nobilis populations.