Current status (as of end of 2020) of marine alien species in Turkey

Non-native species in marine protected areas: Global distribution patterns

Marine protected areas (MPAs) across various countries have contributed to safeguarding coastal and marine environments. Despite these efforts, marine non-native species (NNS) continue to threaten biodiversity and ecosystems, even within MPAs. Currently, there is a lack of comprehensive studies on the inventories, distribution patterns, and effect factors of NNS within MPAs. Here we show a database containing over 15,000 occurrence records of 2714 marine NNS across 16,401 national or regional MPAs worldwide. To identify the primary mechanisms driving the occurrence of NNS, we utilize model selection with proxies representing colonization pressure, environmental variables, and MPA characteristics. Among the environmental predictors analyzed, sea surface temperature emerged as the sole factor strongly associated with NNS richness. Higher sea surface temperatures are linked to increased NNS richness, aligning with global marine biodiversity trends. Furthermore, human activities help species overcome geographical barriers and migration constraints. Consequently, this influences the distribution patterns of marine introduced species and associated environmental factors. As global climate change continues to alter sea temperatures, it is crucial to protect marine regions that are increasingly vulnerable to intense human activities and biological invasions.

Notes on the Spreading of Penaeus aztecus Ives 1891 (Decapoda, Penaeidae) in the Mediterranean Sea and on Its Repeated Misidentifications in the Region

The shrimp Penaeus aztecus, native to the western Atlantic, was first reported in the eastern Mediterranean Sea in 2010. New records, from different Mediterranean localities, multiplied in the following years. The accurate search of the literature on non-indigenous species discovered it was misidentified more than once as another alien shrimp, P. semisulcatus, native to the Indo-Pacific region, with the result that its earlier presence in the Black Sea went unnoticed. Morphological characteristics allowing the identification of these two species, the autochthonous P. kerathurus and two other alien Penaeus species present in the Mediterranean, are reprised. The present distribution of P. aztecus based on literature records and surveys carried out in the northern and central Adriatic between 2016 and 2021 is mapped. The unintentional transport of larvae carried in ballast water by transoceanic vessels departing from the U.S. East Coast is suggested as the most probable introduction pathway. The significance of the correct identification of non-indigenous species, a "Descriptor" adopted in the Marine Strategy Framework Directive for determining the good environmental status of marine waters in the European States, is emphasized.

Heavy Metal Bioaccumulation and Oxidative Stress Profile in Brachidontes pharaonis (Bivalvia: Mytilidae) from the Tunisian Coast: Insight into Its Relevance as Bioindicator of Marine Pollution

This study aims to verify the relevance of Brachidontes pharaonis to assess the ecotoxicological status of polluted sites. For this, the levels of some heavy metals (i.e. Zn, Cu, Pb, and Cd) and a battery of biomarkers including metallothionein (MT), malondialdehyde (MDA), reduced glutathione (GSH), glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) were assessed in mussels collected from the harbor of Rades (North), and the harbor of Zarzis (South). Moreover, abiotic parameters including temperature, salinity, pH, and dissolved oxygen were assessed. Results from the ICP-OES showed that the southern population exhibited a higher metal pollution index with significantly higher Zn, Cu, and Pb concentrations. Moreover, the specimens from Zarzis displayed significantly higher levels of MDA, MT, GSH, GPx, SOD, and CAT reflecting higher levels of oxidative and chemical stress. These results emphasize the potential utility of B. pharaonis for the monitoring of heavily impacted sites.

A Risk Screening of Potential Invasiveness of Alien and Neonative Marine Fishes in the Mediterranean Sea: Implications for Sustainable Management

Biological invasions have posed a major threat to global and regional biodiversity. The Mediterranean Sea, one of the major biodiversity hotspots in the world, has long suffered multiple and frequent invasion events. This paper represents the screening results of the potential invasiveness of 23 introduced marine fish species, which are classified as neonative and alien. To predict the invasiveness potential of species under current and predicted climate conditions, the Aquatic Species Invasiveness Screening Kit (AS-ISK) is applied. Thresholds have been constituted to classify low, medium and high-risk species by receiver operative characteristic curve analysis (ROC). The calibrated basic and climate-change threshold assessment scores used to classify species from low, to medium to high risk were computed between 27.5 and 33.0 respectively. Based on these thresholds, under current climatic conditions, 15 species were high risk, while the remaining species were medium risk, and the Chaetodipterus faber and the Holocentrus adscensionis switched from the medium-risk to the high-risk group under future climatic conditions. The highest score belonged to Fistularia petimba, followed by Siganus fuscescens, Abudefduf spp., Acanthurus monroviae and Lutjanus argentimaculatus. This study focused on the species that have not been assessed for their invasiveness potential, and the results can provide important insights into their sustainable management in the future.

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.

Does Sand Beach Nourishment Enhance the Dispersion of Non-Indigenous Species?—The Case of the Common Moon Crab, Matuta victor (Fabricius, 1781), in the Southeastern Mediterranean

Sand beach nourishment (BN) is one of the commonest “soft solutions” for shore protection and restoration. Yet it may have ecological consequences. Can this practice enhance the introduction and dispersal of non-indigenous species (NIS)? There has been little research on the impacts of nourishment on NIS, especially in the southeastern Mediterranean, a region considered most affected by invading biota. However, so far only one study referred to the possible interaction between BN and the success of invading species. It reports increasing numbers and densities of the aggressive, omnivorous Indo-Pacific moon crab, Matuta victor (Fabricius, 1781) in Haifa Bay (northern Israel) between 2011 and 2017. This research suggests a possible role of anthropogenic disturbance in the outbreak of M. victor and blames the Israel Ministry of Environmental Protection for authorizing a (rather small scale) BN in Haifa Bay in 2011 as an alleged cause for this outbreak. Circumstantial indirect evidence is not sufficient to establish the role of nourishment in promoting the establishment and dispersal of NIS. There are plenty of examples of successful settlement and rapid and large-scale distribution of NIS (including another member of the genus Matuta), especially in the eastern Mediterranean, without any BN in the region. Furthermore, the location where the M. victor specimens were sampled was exposed to more prevailing and frequent anthropogenic marine stressors than BN, such as eutrophication, pollution, fishing activities and particularly port construction. To firmly establish an assumed role of nourishment in the invasion of NIS, assessments must be based on solid and orderly planned scientific research to be designed well before the beginning of any BN. It is suggested that direct communication between environmental regulators and scientists is crucial for improving both scientific research and environmental management policies.