Cryptic serpulid-microbialite bioconstructions in the Kakoskali submarine cave (Cyprus,Eastern Mediterranean)

The biostalactites from the Kakoskali cave in Cyprus represent a new example of the complex biotic relationships between skeletal organisms and microbial communities in building bioconstructions of cryptic marine environments. Biostalactites are mainly constituted of polychaetes of the family Serpulidae and, to a lesser degree, foraminifers and bryozoans. Within the skeletal framework of these organisms, two types of microcrystalline calcite (micrite) have been recognized: autochthonous and detrital micrite. The autochthonous fraction is syndepositionally lithified and occurs as clotted peloidal and, subordinately, aphanitic (structureless) textures, suggesting the presence of heterotrophic microbial activities thriving on decaying metazoan organic matter. This fraction is limited to the protected portions of the bioconstructions, especially in the inner and lower parts. The presence of iron and manganesiferous oxidizing bacteria is suggested by the deposition of ferromanganesiferous crusts and Frutexites-like structures. These microbial-induced biomineralizations are the main evidence of carbonatogenetic and Fe–Mn, autotrophic and chemoheterotrophic, bacterial activities. The Kakoskali cave is frequently visited by divers who, during their immersions, resuspend the fine bottom sediment, which later covers the surface of the bioconstructions, disturbing the delicate equilibrium of the biotic association. This perturbation, which is also caused by strong waves and currents, during winter months, reflects on the bioconstruction morphologies, community composition, and colonization pattern. Bioconstructions exhibit an upper smooth surface, produced by few taxa (e.g., polychaetes, foraminifers), hosting a low number of living individuals, and a lower comparably rough surface, colonized by a more abundant community showing a higher species richness. The ratio surface roughness/smoothness is related to micrite sediment type: the upper part is mainly characterized by loose detrital micrite while the internal and lower parts by syndepositional cemented autochthonous micrite.     

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.     

Rapid song divergence leads to discordance between genetic distance and phenotypic characters important in reproductive isolation

The criteria for species delimitation in birds have long been debated, and several recent studies have proposed new methods for such delimitation. On one side, there is a large consensus of investigators who believe that the only evidence that can be used to delimit species is molecular phylogenetics, and with increasing numbers of markers to gain better support, whereas on the other, there are investigators adopting alternative approaches based largely on phenotypic differences, including in morphology and communication signals. Yet, these methods have little to say about rapid differentiation in specific traits shown to be important in reproductive isolation. Here, we examine variation in phenotypic (morphology, plumage, and song) and genotypic (mitochondrial and nuclear DNA) traits among populations of yellow‐rumped tinkerbird Pogoniulus bilineatus in East Africa. Strikingly, song divergence between the P. b. fischeri subspecies from Kenya and Zanzibar and P. b. bilineatus from Tanzania is discordant with genetic distance, having occurred over a short time frame, and playback experiments show that adjacent populations of P. b. bilineatus and P. b. fischeri do not recognize one another's songs. While such rapid divergence might suggest a founder effect following invasion of Zanzibar, molecular evidence suggests otherwise, with insular P. b. fischeri nested within mainland P. b. fischeri. Populations from the Eastern Arc Mountains are genetically more distant, yet share the same song with P. b. bilineatus from Coastal Tanzania and Southern Africa, suggesting they would interbreed. We believe investigators ought to examine potentially rapid divergence in traits important in species recognition and sexual selection when delimiting species, rather than relying entirely on arbitrary quantitative characters or molecular markers.     

Retracted: A new species in town: New record of Hexanchus nakamurai Teng, 1962 from the Levantine Sea

Hexanchus nakamurai is a deep-water species, with very little scientific information. This study confirms the distribution of the species in the most eastern region of the Mediterranean Sea, Levantine Sea, in addition to providing some biological information from four pregnant individuals, which is being reported for the first time in the Mediterranean Sea. A total of four individuals were bycaught, in two sets on opposite coasts, three on the 13th of May 2020 from the western coast, and an individual on the 14th June 2020 from east coast of the island of Cyprus. The four specimens, all pregnant females, measured between 107 and 116 cm in total length and between 4,330 and 4,960 g in weight. All specimens were in early pregnancy according to the level of embryo development, which confirms that the size at maturity is smaller than previously reported. In the stomachs, remains of the hake Merluccius merluccius, the cephalopod Loligo vulgaris and two unidentified species of Hirudinea (Annelida) were found. This study provides important new information on the Mediterranean distribution of a globally rare and data deficient species, including an expansion of its known range, dietary preferences and insights of its reproduction biology; the first pregnant females reported in the Mediterranean Sea.     

Asexual reproduction in bad times? The case of Cladocora caespitosa in the eastern Mediterranean Sea

We analysed the patterns of genetic variability of eastern Mediterranean populations of the scleractinian coral Cladocora caespitosa, from the Aegean and Levantine seas, using 19 polymorphic microsatellite loci, 11 of which were newly characterized. The observed genetic pattern reflects a scenario of isolation by environment: F_ST comparisons showed a higher degree of genetic differentiation between the two Cypriot populations that are separated by only 11 km than between these two Levantine populations and the Aegean population in Greece, which are separated by 1300 km. We hypothesize that local-scale oceanographic factors influenced the dispersal of planulae between the geographically close populations, playing a crucial role in the genetic structure of this coastal coral. Yet, despite being characterized as a species with limited dispersal and high self-recruitment, large-scale migration does eventually occur as first-generation migrants were identified between the most distant populations. In line with previous findings of reproductive plasticity in C. caespitosa, we also found localized differences in reproduction mode (sexual vs. asexual) within a geographically limited context. Several individuals were identified as clones, indicating the predominance of asexual reproduction in one of the Cypriot populations. We interpret this predominance either as a direct response to or as an indirect consequence of perturbations suffered by this C. caespitosa population. These perturbations are caused by unfavourable environmental conditions that threatened local survival, in particular water temperature changes and windstorm swells. Asexual reproduction may be a mechanism used by C. caespitosa to counteract mortality events and recolonize devastated areas, and likely accounts for the occasional high levels of clonality and low levels of genetic diversity. Local adaptations such as these should therefore be considered in conservation and management strategies to maintain and preserve the gene pool of this endangered species.