Genetic diversity and phylogenetic relationships of threadfin breams (Nemipterus spp.) from the Red Sea and eastern Mediterranean Sea.

The present work utilized partial sequences of cytochrome c oxidase subunit I (COI) to study Red Sea populations of threadfin breams (Nemipteridae), and compare their genetic diversity to that of Mediterranean Sea (Nemipterus randalli only) and Indo-Pacific populations. A Maximum Likelihood tree separated four fish species - N. randalli, N. japonicus, N. bipunctatus, and N. zysron - into four clades. Haplotype analyses revealed a strong case of the founder effect for the Lessepsian migrant N. randalli: Three haplotypes represented all sampled geographical ranges in the Mediterranean Sea and only one haplotype was shared with a Red Sea individual, presenting evidence that the colonizing population was founded by a small number of migrants. The Red Sea population of N. japonicus shared haplotypes with Persian Gulf and Indian Ocean populations, but South China Sea populations remained fully isolated. The haplotype networks of N. randalli and N. bipunctatus also revealed haplotype sharing between Red Sea and Indian Ocean populations. For N. zysron, one haplotype was shared between Indonesia and the Persian Gulf. We discuss the impact of continued usage of public database sequences of initially misidentified organisms and provide recommendations for avoiding distribution of sequences with incorrect scientific names.

They are here to stay: the biology and ecology of lionfish (Pterois miles) in the Mediterranean Sea.

The lionfish, Pterois miles, is one of the most recent Lessepsian immigrants into the Mediterranean Sea, and it poses a serious threat to marine ecosystems in the region. This study assesses the basic biology and ecology of lionfish in the Mediterranean, examining morphometrics, reproduction and diet as well as population structure and distribution. The population density of lionfish has increased dramatically in Cyprus since the first sighting in late 2012; by 2018 aggregations of up to 70 lionfish were found on rocky grounds with complex reefs and artificial reefs in depths of 0-50 m. Lionfish in Cyprus become mature within a year, and adults are capable of spawning year-round, with peak spawning in summer when the sea-surface temperature reaches 28.4°C. The Cypriot lionfish grow faster and bigger than in their native range, and females are more common than males. Lionfish are generalist predators in these waters, as also found in their native range, consuming a range of teleost and crustacean prey, some of which are of high economic value (e.g., Spicara smaris and Sparisoma cretense) or have an important role in local trophic webs (e.g., Chromis chromis). Overall, the reproductive patterns, the presence of juveniles and adults throughout the year, the rapid growth rates and the generalist diet indicate that lionfish are thriving and are now already well established in the region and could potentially become the serious nuisance that they are in their temperate and tropical western Atlantic-invasive range.

Remarkable size-spectra stability in a marine system undergoing massive invasion.

The Mediterranean Sea is an invasion hotspot, with non-indigenous species suspected to be a major driver behind community changes. We used size spectra, a reliable index of food web structure, to examine how the influx of Red Sea fishes into the Mediterranean Sea has impacted the indigenous species community. This is the first attempt to use changes in the size spectra to reveal the effect of biological invasions. We used data from trawl catches along Israel's shoreline spanning 20 years to estimate changes in the community size spectra of both indigenous and non-indigenous species. We found that the relative biomass of non-indigenous species increased over the 20 years, especially for small and large species, leading to a convergence with the indigenous species size spectra. Hence, the biomass of indigenous and non-indigenous species has become identical for all size classes, suggesting similar energetic constraints and sensitivities to fishing. However, over this time period the size spectrum of indigenous species has remained remarkably constant. This suggests that the wide-scale invasion of non-indigenous species into the Mediterranean may have had little impact on the community structure of indigenous species.

Host-Microbiome Interactions in a Changing Sea: The Gill Microbiome of an Invasive Oyster under Drastic Temperature Changes.

The gill tissue of bivalve mollusks hosts rich symbiotic microbial communities that may contribute to host health. Spondylus spinosus is an invasive Lessepsian oyster in the Eastern Mediterranean Sea that has become highly abundant while constantly expanding its range northwestward. Using 16S rRNA gene amplicon sequencing, we examined how temperature affects S. spinosus oysters and their gill microbiota in a series of experiments: exposing them to the current annual seawater temperature range, to the colder temperature of the Western Mediterranean Sea, and to the elevated temperature as predicted under global warming scenarios. The bacterial genus Endozoicomonas dominated the communities of the S. spinosus, mainly upon exposure to winter-like (16 °C) temperatures. Exposure to the elevated seawater temperature resulted in a significant change in the bacterial communities, while the oysters maintained normal functioning, suggesting that the oyster may survive a seawater warming scenario. Exposure to 11 °C led to the health deterioration of the oysters, the emergence of opportunistic pathogens, such as Arcobacter, Vibrio, Colwelliaceae, and Pseudoalteromonas, and a decline in the relative abundance of Endozoicomonas, suggesting that S. spinosus might not survive Western Mediterranean Sea winters. Both the host and its gill bacteria are thus greatly affected by temperature, which could consequently restrict the range of expansion of this and other invasive oysters.

Shark shuffle: segregated co-occurrence of multiple dusky and sandbar lineages at a human-altered habitat in the eastern Mediterranean Sea.

Requiem sharks (genus Carcharhinus) have previously been reported to form large aggregations around marine infrastructures in the eastern Mediterranean Sea. While this behaviour may offer fitness advantages at the individual level, the implications of extended residency at human-altered habitats for population persistence have yet to be assessed. In this work, we investigated the phylogeographic and demographic composition of sharks near a coal-fired power and desalination station in Israel. Our aim was to infer habitat use and the mechanisms underlying the aggregation behaviour, and to highlight potential conservation impacts. We sampled, measured, and released 70 individuals between 2016 and 2022 to assess genetic variability within the cytochrome C oxidase I (COI) region and to analyse the aggregation's structure based on the sharks' size and sex distribution. In addition, we performed meristic counts on a reference specimen collected dead at another power station in Israel to supplement species identification using the abovementioned techniques. Our findings indicate size-based sex segregation of adult female dusky and male sandbar sharks (Carcharhinus obscurus and Carcharhinus plumbeus, respectively), with each species comprising two COI haplotypes. In the dusky shark, one haplotype corresponded to an Indo-Pacific lineage, and the other matched an Atlantic lineage. In the sandbar shark, we observed a haplotype previously sampled in the Mediterranean Sea, the Red Sea, the Northwest Indian Ocean, and South Africa, and another haplotype that was unique to our study site and genetically closer to the former than to sequences sampled in other ocean basins. This study provides the first indication of sympatric aggregation amongst phylogeographically distinct dusky and sandbar shark lineages, suggesting that human-altered habitats in the eastern Mediterranean Sea may influence the distribution of these species. Based on the observed segregation pattern, we conclude that the site does not function as a nursery, parturition, or mating area, and discuss other plausible explanations that warrant further research. Finally, we highlight important directions for future research and the implications of our findings for management and conservation.

New Record of Dendronephthya sp. (Family: Nephtheidae) from Mediterranean Israel: Evidence for Tropicalization?

Bio-invasions have the potential to provoke cascade effects that can disrupt natural ecosystems and cause ecological regime shifts. The Mediterranean Sea is particularly prone to bio-invasions as the changing water conditions, evoked by climate change, are creating advantageous conditions for Lessepsian migrants from the Red Sea. Recently, in May 2023, a new alien species was documented in the Mediterranean Sea-a soft coral of the genus Dendronephthya. This discovery was made by divers conducting 'Long-Term Ecological Research' surveys, along the coast of Israel, at a depth of 42 m. Genetic and morphological testing suggest that the species identity may be Dendronepthya hemprichi, an Indo-Pacific coral, common in the Red Sea. According to life history traits of this species, such as accelerated attachment to available surfaces and fast growth, we expect it to rapidly expand its distribution and abundance across the Mediterranean Sea.

Invading bivalves replaced native Mediterranean bivalves, with little effect on the local benthic community.

The construction of the Suez Canal connected the Red Sea and the Mediterranean Sea, which allowed rapid marine bio-invasion. Over the last century, several bivalve species have invaded the Levantine basin, yet their distribution and impact on the benthic community have not been thoroughly studied. Large-scale benthic surveys along the rocky substrate of the Israeli Mediterranean coastline indicate that invading bivalves, such as Spondylus spinosus, Brachidontes pharaonis, and Pinctada radiata, now dominate the rocky environment, with densities of tens to hundreds of individuals per m2. No native bivalve specimens were found in any of the transects surveyed. The small-scale ecological effects of the established invading populations on the benthic community were examined over a year using an in-situ exclusion experiment where all invading bivalves were either physically removed or poisoned and kept in place to maintain the physical effect of the shells. Surprisingly, the experimental exclusion showed a little measurable effect of bivalve presence on the invertebrate community in close vicinity (~ 1 m). Bivalve presence had a small, but statistically significant, effect only on the community composition of macroalgae, increasing the abundance of some filamentous macroalgae and reducing the cover of turf. The generally low impact of bivalves removal could be due to (1) wave activity and local currents dispersing the bivalve excreta, (2) high grazing pressure, possibly by invading herbivorous fish, reducing the bottom-up effect of increased nutrient input by the bivalves, or (3) the natural complexity of the rocky habitat masking the contribution of the increased complexity associated with the bivalve's shell. We found that established invading bivalves have replaced native bivalve species, yet their exclusion has a negligible small-scale effect on the local benthic community. Supplementary Information: The online version contains supplementary material available at 10.1007/s10530-022-02986-1.

Parasites of pufferfish, Lagocephalus spp. and Torquigener flavimaculosus of the Israeli Mediterranean: A new case of Lessepsian endoparasites.

With the opening of the Suez Canal as a link between the Red Sea and the Mediterranean Sea in 1869, the biogeographical event of the Lessepsian migration has been starting. Aided by beneficial conditions in the new habitat, almost 500 marine species have immigrated and often established themselves in the Mediterranean Sea, including several pufferfish species, with all of them extending their range and becoming important components of the local fauna. The parasitic fauna of these pufferfish has scarcely been examined in the Mediterranean Sea or in their native range, which provides the opportunity to study host-parasite interaction in a new habitat. The present study describes the parasitic fauna in four alien invasive pufferfish species (Lagocephalus guentheri, L. sceleratus, L. suezensis, and Torquigener flavimaculosus) of various sizes and ages on the Israeli Mediterranean coast. The parasite fauna of these species was diverse (Maculifer dayawanensis Digenea; Calliterarhynchus gracilis, Nybelinia africana and Tetraphyllidea larvae Cestoda; Hysterothylacium reliquens, Hysterothylacium sp. and Raphidascaris sp. Nematoda; Trachellobdella lubrica Hirudinea and Caligus fugu and Taeniacanthus lagocephali Copepoda) and consisted of mostly generalist species, most likely acquired in the new habitat, and specialist copepod ectoparasites, having co-invaded with the pufferfish. Additionally, the oioxenic opecoelid digenean Maculifer dayawanensis was found in two pufferfish species. The genus was previously only known from the Indo-Pacific Ocean, representing the eighth reported case of a Lessepsian endoparasite so far. Our results suggest a change in parasite fauna to native Mediterranean species in the pufferfish like previously reported in other Lessepsian migrant predatory fish species and a wider spread of co-invasion of fish endoparasites to the Mediterranean Sea than previously assumed. The study also provides several new host records and the first report for parasites in T. flavimaculosus.

Cryptocentrus steinhardti (Actinopterygii; Gobiidae): a new species of shrimp-goby, and a new invasive to the Mediterranean Sea.

A new species of shrimp-goby was collected at depths of 60-80 m off the southern Israeli Mediterranean coast. A unique 'DNA barcoding' signature (mtDNA COI and Cytb) revealed that it differs from any other previously bar-coded goby species clustered phylogenetically with the shrimp-gobies group, in which Cryptocentrus is the most speciose genus. A morphological study supported the assignment of the fish to Cryptocentrus and differentiated the new species from its congeners. The species is described here as Cryptocentrus steinhardti n. sp. However, the present phylogenetic analysis demonstrates a paraphyly of Cryptocentrus and emphasizes the need for revision of the genus based on integrating morphological and genetic characteristics. This finding constitutes the third record of an invasive shrimp goby in the Mediterranean Sea. An intriguing ecological issue arises regarding the possible formation of a fish-shrimp symbiosis in a newly invaded territory. Describing an alien tropical species in the Mediterranean prior to its discovery in native distribution is an unusual event, although not the first such case. Several similar examples are provided in the present article.

Comparative genetics of scyphozoan species reveals the geological history and contemporary processes of the Mediterranean Sea.

Jellyfish are useful genetic indicators for aquatic ecosystems as they have limited mobility and are highly exposed to the water column. By using comparative genomics and the molecular clock (timetree) of Rhizostoma pulmo, we revealed a divergence point between the East and West Mediterranean Sea (MS) populations that occurred 4.59 million years ago (mya). It is suggested that the two distinct ecological environments we know today were formed at this time. We propose that before this divergence, the highly mixed Atlantic and Mediterranean waters led to the wide dispersal of different species including R. pulmo. At 4.59 mya, the Western and Eastern MS were formed, indicating the possibility of a dramatic environmental event. For the first time, we find that for the jellyfish we examined, the division of the MS in east and west is not at the Straits of Sicily as generally thought, but significantly to the east. Using genomics of the Aurelia species, we examined contemporary anthropogenic impacts with a focus on migration of scyphozoa across the Suez Canal (Lessepsian migration). Aurelia sp. is among the few scyphozoa we find in both the MS and the Red Sea, but our DNA analysis revealed that the Red Sea Aurelia sp. did not migrate or mix with MS species. Phyllorhiza punctata results showed that this species was only recently introduced to the MS as a result of anthropogenic transportation activity, such as ballast water discharge, and revealed a migration vector from Australia to the MS. Our findings demonstrate that jellyfish genomes can be used as a phylogeographic molecular tool to trace past events across large temporal scales and reveal invasive species introduction due to human activity.

Bacterial Taxa Migrating from the Mediterranean Sea into the Red Sea Revealed a Higher Prevalence of Anti-Lessepsian Migrations.

In 1869, the Suez Canal was opened, which brought the waters of the Mediterranean and the Red Sea into direct contact. Notably, the Suez Canal was constructed for navigation purposes without focusing on the ecological impacts. The Suez Canal paved the way for species migration from the Red Sea to the Mediterranean Sea through Lessepsian migration, named after Ferdinand de Lesseps, while the migration from the Mediterranean Sea to the Red Sea is called the anti-Lessepsian migration. It has been argued in the past that the migrating species had negative consequences for the host environment as well as of humans. Few studies to date have attempted to map the microorganism migration problem because the traditional ways of measuring the community's richness and dissimilarities failed to provide enough detection of the migrating taxa. We collected 22 seawater samples from different locations in Egypt, in relationship to the migration across and to/from the Suez Canal. The V3-V4 regions of 16s genes were amplified and sequenced by the next generation Illumina MiSeq sequencer. Bioinformatics analysis revealed 15 taxa that migrated from the Mediterranean Sea to the Red Sea (i.e., anti-Lessepsian migration) such as the genera Fluvicola, HTCC2207, and Persicirhabdus. The family OCS155 is the only one that migrated from the Red Sea to the Mediterranean Sea (Lessepsian migration). Seven anti-Lessepsian migrants colonized the Suez Canal more than the Mediterranean Sea such as the genera Marinobacter and Halomonas. These findings collectively suggest that the anti-Lessepsian migration is more predominant than the Lessepsian migration in the bacterial community. This study paves the way for future research questions as well. For example, why is the anti-Lessepsian migration more common than the Lessepsian route in bacteria? Why do certain taxa stop migration at the Suez Canal, and why do certain taxa present in higher frequencies in the Suez Canal? Which taxa continue migration to the Indian Ocean and the Atlantic Ocean, and what is the impact of the anti-Lessepsian migration on the bacterial community? Understanding microbial diversity in a context of microorganism migration across seas and oceans remains a prime topic in biodiversity research and systems science.

Ocean warming is the key filter for successful colonization of the migrant octocoral Melithaea erythraea (Ehrenberg, 1834) in the Eastern Mediterranean Sea.

Climate, which sets broad limits for migrating species, is considered a key filter to species migration between contrasting marine environments. The Southeast Mediterranean Sea (SEMS) is one of the regions where ocean temperatures are rising the fastest under recent climate change. Also, it is the most vulnerable marine region to species introductions. Here, we explore the factors which enabled the colonization of the endemic Red Sea octocoral Melithaea erythraea (Ehrenberg, 1834) along the SEMS coast, using sclerite oxygen and carbon stable isotope composition (δ 18OSC and δ 13CSC), morphology, and crystallography. The unique conditions presented by the SEMS include a greater temperature range (∼15 °C) and ultra-oligotrophy, and these are reflected by the lower δ 13CSCvalues. This is indicative of a larger metabolic carbon intake during calcification, as well as an increase in crystal size, a decrease of octocoral wart density and thickness of the migrating octocoral sclerites compared to the Red Sea samples. This suggests increased stress conditions, affecting sclerite deposition of the SEMS migrating octocoral. The δ 18Osc range of the migrating M. erythraea indicates a preference for warm water sclerite deposition, similar to the native depositional temperature range of 21-28 °C. These findings are associated with the observed increase of minimum temperatures in winter for this region, at a rate of 0.35 ± 0.27 °C decade-1 over the last 30 years, and thus the region is becoming more hospitable to the Indo-Pacific M. erythraea. This study shows a clear case study of "tropicalization" of the Mediterranean Sea due to recent warming.

The clinical effects of the venomous Lessepsian migrant fish Plotosus lineatus (Thunberg, 1787) in the Southeastern Mediterranean Sea.

CONTEXT: Plotosus lineatus is a venomous fish that has migrated from the Indo-Pacific region to the Mediterranean Sea (Lessepsian migrant). Its presence in the Mediterranean Sea was first recorded in 2002 and was observed in growing schools. Its spines contain toxins with lytic, hemolytic and edematous activities. OBJECTIVE: To characterize the injuries caused by Plotosus lineatus in the Southeastern Mediterranean Sea. METHODS: A prospective observational case series of consultations provided by a national Poison Center pertaining to Plotosus lineatus from 2007 to 2016. Demographic and clinical data and method of fish identification were retrieved from the medical toxicological records, and described. RESULTS: Eighty four cases were included; the main findings are: median age 35 (range 3-80) years, 91.7% males, 51.2% fishermen, 78.6% palm injuries, 94% and 4.8% were mildly and moderately injured, respectively. Main local manifestations included pain, puncture wound, swelling, and erythema (90.5%, 70.2%, 33.3%, and 16.7%, respectively). Systemic signs were minor and infrequent (≤7.1%), including hypertension, tachycardia, vomiting, chills, and weakness. Management included wound disinfection, immersion in hot water, tetanus prophylaxis, and analgesics. No patient required hospital admission. The fish was identified mostly by the victim with the aid of the Poison Center (mainly by typical description, and a picture), and some by marine biologists. CONCLUSIONS: Plotosus lineatus is a new fish in the Southeastern Mediterranean Sea. It affects fishermen handling fishing nets, and beach hikers stepping on or holding it. Injuries caused by its spines usually result in minor effects; pain may be intense. Treatment includes disinfection, analgesics, and antitetanus and antibiotics as needed. No lethal cases were recorded, unlike exposure of animals to the venom of the Indo-Pacific species; reason is unclear. Our series illustrates the consequences of manmade disruption of ecosystem resulting in invasion of toxic species to a new environment, affecting human health.

First evidence of establishment of the rayed pearl oyster, Pinctada imbricata radiata (Leach, 1814), in the eastern Adriatic Sea.

The Mediterranean Sea is increasingly under threat from invasive species that may negatively affect biodiversity and/or modify ecosystem structure and function. The bivalve mollusc Pinctada imbricata radiata is listed among the 100 most invasive species in the Mediterranean. A first finding of an established population of P. imbricata radiata in the coastal waters of the eastern Adriatic Sea, is presented in this paper. Six and then 30 live specimens were collected in 2015 and in 2017, respectively, at depths of 5 to 15m from the island of Mljet, Croatia. DNA sequencing of the mitochondrial cytochrome c oxidase I gene (COI) revealed three different haplotypes. All samples showed greatest similarity (98 to >99%) to P. radiata COI sequence records in GenBank (=P. imbricata radiata as used in this paper). A Neighbour Joining tree placed all Croatian samples within the 100% bootstrap supported clade for P. imbricata radiata.