No abstract

The fan mussel, or noble pen shell, Pinna nobilis Linnaeus, 1758 is an endemic species to the Mediterranean belonging to the Pinnidae family (Vázquez-Luis et al., 2017). The species is known as the largest bivalve for this region (Katsanevakis, 2006). Pinna nobilis lives at depths ranging from 0.5 to 80 m (Öndes, Kaiser, & Güçlüsoy, 2020). The habitats of P. nobilis include algae and phanerogam facies, muddy and sandy substrates (Katsanevakis, 2006; Prado, Caiola, & Ibáñez, 2014). Differences were found in the population density of P. nobilis among habitats, depth and ecoregions (Basso et al., 2015). This species plays key ecological roles including providing a habitat for many species, reducing turbidity and filtering water (Katsanevakis et al.

The sea urchin, Diadema setosum, is a poisonous species that originates in the Indo‐Pacific and the Red Sea. Although this species has been recorded in several areas in the Mediterranean Sea, its habitat selection, density, distribution and ecological impacts have not been comprehensively documented to date. This study combined the diving observations (n = 53 sites) and local ecological knowledge (LEK) of SCUBA divers (n = 100) to provide information on the distribution and density of this invasive sea urchin on the Aegean and Levantine coasts of Turkey between September and October 2020. The results indicated that D. setosum was more prevalent along the southern coast of Turkey compared with the western coast, where it is colder. The highest densities of D. setosum were observed in rocky habitats at a depth range of 0–5 m. Moreover, the densities increased with increasing bottom temperatures (up to 150 ind./100 m2). Recent reports from the Levantine and south Aegean coasts highlighted that the densities of D. setosum increased dramatically during the past year. The results of the present study suggested that D. setosum provides shelter for a total of four fish species, including Chromis chromis, Gobius sp., Cheilodipterus novemstriatus and Thalassoma pavo. This species of urchin poses a threat due to its potential grazing and bioerosion effects in the Mediterranean. Thus, future studies should focus on the feeding ecology of D. setosum and the competition with native species that share the same habitat to obtain an improved understanding of the ecological impacts of this invasive species. Although the present study provides the first comprehensive dataset on the density and distribution of this invasive sea urchin for Turkey in the eastern Mediterranean region, we suggest that its population should be monitored for long periods using direct observations, LEK and citizen science.

Scientific and technological progresses have introduced diverse data sources for seawater temperature over broad temporal and spatial ranges. Here, we investigated the performance of satellite and model-based seawater temperature data for different temporal composites and depths. We applied an in-situ temperature time-series obtained in a coastal bottom in the Aegean Sea over three years, as the reference. Both datasets showed largely significant relationships based on cross-correlation analyses and presented descriptive properties of the in-situ conditions at corresponding depths. Based on the results of analyses, the modeling datasets presented more reliable results and representations of in-situ conditions than the datasets obtained from satellite for the coastal region. However, the datasets obtained from the satellite also provided reliable data for all time frames investigated, particularly in the mixed surface layer. Monthly datasets were more effective in providing descriptive values in long term studies. This is the first detailed study to explore the descriptive capacities of modeling for water temperature in coastal environments. According to the results, the selection of a dataset as a proxy for seawater temperature requires careful consideration. The present study provides an extensive baseline for evaluating the suitability of the application of specific datasets as proxies in coastal ecosystems.

No abstract