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Effective monitoring of non-indigenous seaweeds and combatting their effects relies on a solid confirmation of the non-indigenous status of the respective species. We critically analysed the status of presumed non-indigenous seaweed species reported from the Mediterranean Sea, the Northeast Atlantic Ocean and Macaronesia, resulting in a list of 140 species whose non-indigenous nature is undisputed. For an additional 87 species it is unclear if they are native or non-indigenous (cryptogenic species) or their identity requires confirmation (data deficient species). We discuss the factors underlying both taxonomic and biogeographic uncertainties and outline recommendations to reduce uncertainty about the non-indigenous status of seaweeds. Our dataset consisted of over 19,000 distribution records, half of which can be attributed to only five species (Sargassum muticum, Bonnemaisonia hamifera, Asparagopsis armata, Caulerpa cylindracea and Colpomenia peregrina), while 56 species (40%) are recorded no more than once or twice. In addition, our analyses revealed considerable variation in the diversity of non-indigenous species between the geographic regions. The Eastern Mediterranean Sea is home to the largest fraction of non-indigenous seaweed species, the majority of which have a Red Sea or Indo-Pacific origin and have entered the Mediterranean Sea mostly via the Suez Canal. Non-indigenous seaweeds with native ranges situated in the Northwest Pacific make up a large fraction of the total in the Western Mediterranean Sea, Lusitania and Northern Europe, followed by non-indigenous species with a presumed Australasian origin. Uncertainty remains, however, regarding the native range of a substantial fraction of non-indigenous seaweeds in the study area. In so far as analyses of first detections can serve as a proxy for the introduction rate of non-indigenous seaweeds, these do not reveal a decrease in the introduction rate, indicating that the current measures and policies are insufficient to battle the introduction and spread of non-indigenous species in the study area. Non-indigenous seaweed species in the Northeast Atlantic Ocean, the Mediterranean Sea and Macaronesia are critically reanalysed. > 19,000 distribution records revealed considerable variation in diversity of non-indigenous seaweed species in the study area. Taxonomic and biogeographic uncertainties hamper a critical evaluation of the non-indigenous status of many seaweed species. [ABSTRACT FROM AUTHOR]

In this study we explore the introduction of the brown alga Dictyota acutiloba in the Mediterranean Sea and provide a substantive update on the geographic distribution of this species, which was long thought to be confined to the Pacific Ocean. A critical assessment of published distribution records and additional identifications based on cox1, psbA and rbcL genetic markers confirm the presence of D. acutiloba at a number of locations in the Indo-Pacific as well as three locations along the Israeli coastline in the south-eastern Mediterranean Sea. The close genetic affinity between introduced specimens and those from a population in Hurghada (Red Sea) strongly suggests an introduction via the Suez Canal. The occurrence of D. acutiloba in these regions is further supported by predictions made by correlative ecological niche models (ENMs), which show high suitability values in the northern Red Sea and the Levantine Basin. In contrast, environmental conditions in the western Mediterranean and parts of the north-eastern Mediterranean are currently less favourable, as evidenced by the lower predicted probability of occurrence. Under future scenarios, the suitability of these regions increases. The further spread of D. acutiloba in the eastern Mediterranean seems imminent, and the species may even extend its range to the western Mediterranean Sea, depending on the climate change scenario considered. While D. acutiloba can be relatively easily distinguished from the majority of Mediterranean Dictyota species, it remains difficult to differentiate this species from narrow growth forms of D. dichotoma. Therefore, we recommend the use of molecular markers such as cox1, psbA and rbcL, to unequivocally identify this species and monitor its further spread. The geographic distribution of Dictyota acutiloba was substantially updated. D. acutiloba was probably introduced into the Mediterranean Sea via the Suez Canal. The Mediterranean Sea will become increasingly suitable for this species. [ABSTRACT FROM AUTHOR]

The Gulf of Suez is a crucial shipping route and a hub for mining and oil drilling operations, making its area particularly susceptible to the accumulation of marine plastic waste. This study evaluates the abundance and composition of microplastics (MPs) along the Gulf of Suez shores. A total of 268 MPs particles were extracted from the sediments, with an average of 204.3 ± 146.6 MPs/kg dry weight. The Kruskal-Wallis test did not show significant variations among stations. The recovered MPs were mostly hard fragments and fibers. Most of the sampled stations had a low Pollution Index (PLI), indicating a low prevalence of MPs. The predominance of polyethylene vinyl acetate (PEVA) and polytetrafluoroethylene (PTFE) suggests that marine-based sources and associated industrial activities are the main contributors. These findings offer a preliminary assessment of marine plastic pollution along the Gulf of Suez shores, highlighting the crucial need for monitoring offshore waters and sediments. Given the heavy shipping activity in the region, the offshore zone of the Gulf of Suez is expected to have higher levels of plastic pollution. The study also contributes to the expanding understanding of marine plastic pollution in the Red Sea region. [ABSTRACT FROM AUTHOR]

The red seaweed, Grateloupia gibbesii, was recently reported as an introduced species in the Mediterranean Sea. Being non-indigenous species with limited distribution, where it was recorded only in Egypt, it was assumed that it has developed several defensive mechanisms to adapt to the new environment through the production of various biological active metabolites. This species was distinguished by its high lipid content in comparison to other seaweeds; accordingly, spectroscopic screening was performed for the chemical characterization of different extracts of G. gibbesii using UV–Vis spectrophotometer and FTIR spectroscopy. In addition, the lipids and fatty acid profile of chloroform extract were characterized using GC-MS. About 45 molecular species were reported in crude and esterified lipid extracts. Among these chemical species, important volatile organic compounds were identified which have many applications in pharmaceutical and chemical industries. The nutritional quality indices of lipids such as ω6/ω3, P/S, IA, IT, and HH were found to be comparable to or higher than those reported for commercial fish species. In addition to the high nutritional value of G. gibbesii, the long-chain UFAs are valuable constituents for cosmetic production, where they play an important role in maintaining healthy skin by regaining the elasticity level and resisting the harmful effects of UV radiation as indicated in UV–visible spectroscopic analysis. On the other hand, the distinct level of TL (12%), TFA to TL (72.1 %), and SFAs to TFA (44.4%) makes G. gibbesii suitable for the production of biodiesel. Pilot-scale production of this seaweed species for sustainable production of pharmaceuticals or biofuel is highly recommended. [ABSTRACT FROM AUTHOR]

The Mediterranean Sea is a hotspot for introduced marine species, including seaweeds. Among red algae, Grateloupia, with no less than eight introduced species, occupies a prominent position. Here, we report a large foliose Grateloupia species collected in Eastern Harbour, Alexandria, Egypt, which had previously been reported as G. acuminata and G. doryphora. Comparison of rbcL gene sequences revealed that the specimens represent G. gibbesii, a species originally described from Charleston, South Carolina, USA and potentially distributed in the warm temperate and tropical western Atlantic Ocean. The species has been known only from a single location in Alexandria since the early 1990s, it has not been reported in extensive surveys prior to that date, and there are no reports from other Mediterranean sites. This indicates a recent introduction, with shipping the likely vector. We describe the vegetative and reproductive morphology of G. gibbesii as the basis for evaluating variation in female reproductive structures and generic concepts in Grateloupia. [ABSTRACT FROM AUTHOR]