In this work, combined efforts by Greek and Turkish scientists produced an updated validated NIS inventory of the Aegean ecoregion, covering 120 years of records up to August 2024. Of the 342 NIS currently present in the Aegean Sea, the majority (281 species) have invaded the South Aegean, followed by the North Aegean (128 species out of 206 NIS). A total of 73 species were added to the list, while 56 were removed. Overall, unaided spread of Lessepsian immigrants from the Levantine Sea and shipping are equally responsible for NIS reported at the regional level. An increase in publications addressing NIS matches the upward trend of NIS since the mid-1990s, which continues to the present day. While unaided introductions of Lessepsian species and/or direct introductions via the Suez Canal peaked in the South Aegean during 2000–2005, they peaked in 2012–2017 in the North Aegean—a decade later. The opposite pattern was observed in ship-transferred NIS. The spatial distribution of introduction hotspots largely reflects the following phenomena/processes: unaided introduction is witnessed initially in the southeastern Aegean Sea; monitoring efforts are concentrated in vulnerable and at-risk areas; and research efforts relate to the spatial allocation of institutions and marine experts working on marine NIS along the Aegean coasts.

This study contains an updated checklist and new collections of marine algae from the coasts of the Aegean Sea and the Levantine Sea of Turkey. A total of 573 marine algal taxa at specific and infraspecific levels (137 brown algae, 318 red algae, and 118 green algae) are reported, 32 of which are regarded as endangered or threatened macroalgae (four green algae, nine red algae, and 19 brown algae). Of these, 36 taxa (10 brown algae, 17 red algae, nine green algae) are recorded as alien on the Aegean and Levantine coasts. In the present study, the red alga Palisada maris-rubri is reported for the first time from the eastern Mediterranean Sea for Turkey. In Iskenderun Bay, species were sampled from 1 m depth on a volcanic rock in May 2016.

The present study includes the results of the second benthic macrophytes? monitoring period of a survey of ecological status from the Turkish coasts. The biotic index Ecological Evaluation Index (EEI-c) was used to assess the ecological status classes (ESC) and MA-LUSI the anthropogenic pressures. Sampling was made by the quadrat (20 × 20 cm) method, and the samples were collected from 93 sites in Turkish coastal waters between 2017 and 2019. In total, 240 taxa were found in the Turkish marine waters. Forty sites were classified into High ESC, 24 sites into Good, 12 sites into Moderate, 13 sites into Poor, and 4 sites into Bad ESC. The relationship between the pressure index MA-LUSI and EEIeqr values was also tested, and a negative correlation (R²= 0.62) was found.

The red alga Gayliella fimbriata (Ceramiaceae, Rhodophyta) is reported for the first time from the Mediterranean Sea. This species was collected growing as an epiphyte on Laurencia obtusa in the sublittoral zone at Antalya (Mediterranean coast of Turkey). Gayliella fimbriata is characterized by its protruding clavate gland cells. Features to distinguish the four Turkish species of Gayliella from one another are provided.