Two-way bioinvasion: tracking the neritic non-native cyclopoid copepods Dioithona oculata and Oithona davisae (Oithonidae) in the Eastern Mediterranean Sea

Accelerated anthropogenic changes in the Eastern Mediterranean Sea (EMS) have facilitated the introduction, spread and establishment of invasive copepod species in this region. Here, we report the introduction of two non-native cyclopoid copepods Dioithona oculata and Oithona davisae for the first time in the Israeli coastal waters and describe their temporal variability. The species were identified by morphological characteristics, DNA barcoding and phylogenetic inference. Molecular identification and phylogenetic analysis supported the taxonomical identification, nevertheless, showed cryptic speciation within D. oculata, separating the Western Pacific and EMS clades. In the Israeli coastal waters, D. oculata presented a temporally restricted occurrence, appearing from September 2019 to December 2019 (30.0±0.7 – 21.0±1.1 °C) and October 2020 (28.0±0.7 °C). The highest abundances of D. oculata occurred in the autumn (October 2019 and 2020), when the water temperature reached 28.0 °C (7 and 10 ind. m-3, respectively). The lowest abundance occurred in December 2019 (0.35 ind. m-3), when the water temperature decreased to 21.0 °C, indicating that the thermal affinity of D. oculata for warm-temperate conditions, for reproduction and the maintenance of viable populations, has persisted in the introduced range. In contrast, O. davisae appeared almost all year around (17.0±0.5 – 28.0±0.7 °C). This species demonstrated peaks in abundance both in October 2019 and October 2020, when the water temperature reached 28.0 °C (406 and 92 ind. m-3), as well as when the temperature decreased to 17.0 °C (31 ind. m-3, February 2020), confirming its wide eurythermal tolerance. Based on our findings and previous observations, we suggest that D. oculata may have invaded the EMS through the Suez Canal and is now at the onset of its spread in the Mediterranean Sea, whereas O. davisae has been introduced via shipping, likely from the Northeast Atlantic, widely spreading and successfully establishing viable populations across the entire Mediterranean Sea, until the coastal Levantine Sea.

Alien Species Threat across Marine Protected Areas of Turkey—An Updated Inventory

This study presents the first comprehensive assessment of alien species occurrences within the selected 11 Marine Protected Areas (MPAs) located on the Aegean and Levantine coasts of Turkey. The inventory includes a total of 289 species belonging to 15 phyla, in which lowest and highest diversities were observed in Saros Bay MPA (27 species, northern Aegean Sea) and Fethiye-Göcek Bay MPA (150 species, northwest Levantine Sea), respectively. Alien species distributions that were revealed in protected areas located in the southern Aegean and Levantine Seas were 56.9% similar (based on presence vs. absence data), while northern Aegean sites formed another distinct group. According to the breakdown of major phyla through the entire study areas, Mollusca had the highest alien diversity (22.1% of alien species), followed by Actinopterygii (19.0%), Arthropoda (15.2%) and Annelida (13.5%). Casual aliens were represented by very low proportions in each MPA, proving that most species were already established in the region, with a significant proportion of invasive species. Regardless of the localities, the majority of the species originated from the Red Sea, whose primary pathway of introduction is the corridor, the Suez Canal. In the absence of effective management actions against bioinvasions, MPAs located along the Turkish coastline do not currently seem to provide any protection, revealing a large conservation gap to be filled.

Sightings and stranding reports of Fin whales (Balaenoptera physalus) in the Levantine Sea, with recent sightings from Turkey

Fin whales (Balaenoptera physalus) are the most commonly observed mysticetes within the Mediterranean Sea, however their status remains vulnerable (VU) and their population in decline mainly due to increasing anthropogenic activities. Sightings of fin whales in the eastern Mediterranean are negligible relative to the central and western basins which eludes to the impression that the eastern Mediterranean provides a less favourable habitat for these cetaceans. This study outlines the sighting and stranding reports of fin whales in the Levantine Basin, the latest of which (an opportunistic sighting of four sub-adults off the coast of Anamur, Turkey in March, 2019) demonstrates the continued presence of this species in the eastern Mediterranean. The current report highlights the need for increased targeted survey effort and collaborative research between neighboring waters to enhance our understanding of the population status of this vulnerable species and aid in the implementation of the necessary conservation actions that are long-missing.

Spatiotemporal and ecological distribution of megabenthic crustaceans on the shelf-shelf break of Antalya Gulf, the eastern Mediterranean Sea

The spatiotemporal distribution and ecology of the suprabenthic and benthic mega-crustaceans were studied in the shelf-shelf break of Turkish waters of the eastern Mediterranean Sea (Antalya Gulf). Sampling was conducted seasonally in May 2014, August, October, and February 2015 using an otter trawl at depths of 10, 25, 75, 125 and 200 m along three transects. A total of 59 species were identified comprising 53 decapods (Eumalacostraca: Eucarida), 3 isopods (Eumalacostraca: Peracarida), and 3 stomatopods (Hoplocarida). Eighteen of the total identifiable species were invasive, and some of them significantly influenced the crustacean community structure. Parapenaeus longirostris, Pagurus prideaux, Charybdis (Goniohellenus) longicollis and Medorippe lanata were the most common species. Parasquilla ferussaci was reported for the first time in Turkish water of the Levantine Sea. Community structure showed seasonal patterns and differed along the depth gradient of habitat heterogeneity. The megabenthic crustacean assemblage was driven mainly by seafloor depth and was related to the fishing disturbance in the area (fishing/no-fishing zones). Environmental parameters were measured for each sample and tested in relationship to crustacean abundance by multivariate analysis CCA (canonical correspondence analysis). The results revealed significant differences in community structure related to substrate and the fine fraction of the bioseston.

Integrating Literature, Biodiversity Databases, and Citizen-Science to Reconstruct the Checklist of Chondrichthyans in Cyprus (Eastern Mediterranean Sea)

Chondrichthyans are apex predators influencing the trophic web through a top-down process thus their depletion will affect the remaining biota. Notwithstanding that, research on chondrichthyans is sparse or data-limited in several biogeographic areas worldwide, including the Levantine Sea. We revise and update the knowledge of chondrichthyans in Cyprus based on a bibliographic review that gains information retrieved from peer-reviewed and grey literature, Global Biodiversity Information Facility (135 records of at least 18 species) and the Ocean Biodiversity Information System (65 records of at least14 species), and the citizen science project Mediterranean Elasmobranchs Citizen Observations (117 records per 23 species). Our updated checklist reports 60 species that account for about 70% of the Mediterranean chondrichthyan biota. The list includes 15 more species than the previous checklist and our study reports three new species for Cyprus waters, namely the blackmouth catshark Dalatias licha, the round fantail stingray Taeniurops grabatus, and the sawback angelshark Squatina aculeata. Our research highlights the need for conservation measures and more studies regarding the highly threatened blackchin guitarfish Glaucostegus cemiculus and the devil ray Mobula mobular, and stresses the importance for training a new generation of observers to strengthen the knowledge and conservation of elasmobranchs in the region.

Ecotrophic Effects of Fishing across the Mediterranean Sea

The status of the Mediterranean Sea fisheries was evaluated across the seven subdivisions of the General Fisheries Commission for the Mediterranean (GFCM), using ecotrophic and catch-based indicators for the period 1970–2017. All indicators confirmed that the fishery resources across the Mediterranean Sea are no longer sustainably exploited and that the structure and function of marine ecosystems has been altered as a result of overexploitation. Although declining catches were a common feature across the Mediterranean Sea, the pattern of exploitation and the state of stocks differed among the subdivisions, with the Levantine Sea and Sardinia having a better status. Although they only include the exploited biological resources of marine ecosystems, catch and ecotrophic indicators can provide insight on ecosystem status and fishing pressure. In the case of southern Mediterranean countries, catch and trophic levels are the only information available, which is extremely valuable in data-poor ecosystems.

First report of Evelineus mcintoshii (Langerhans, 1880) (Heteronemertea, Lineidae) from the Mediterranean Sea

The ribbon worm Evelineus mcintoshii is reported for the first time from the Mediterranean Sea. Observations that took place, during two algal surveys, on the intertidal abrasion platforms at the middle of the Levantine Sea of Israel indicated that this species is hiding inside a mixture of local and non-indigenous marine seaweeds. It is probably another alien species, one of many, that adopted the Levantine basin of the Eastern Mediterranean due to tropical environmental conditions that characterize this sea. We discuss the first record of this species and its possible origins as well as the first report of Notospermus geniculatus, the other marine nemertean species recently reported from Israel.