On the swarming of Creseis acicula (Rang 1828) (Mollusca, Gastropoda) in the Western Arabian Gulf

An incidental swarming event of a zooplankton species took place in the anchorage area of Ras Tanura (Western Arabian Gulf), between June 10th and 13th 2020, causing serious problems to the anchored vessels. Examination of the samples collected from the clogged water pump of a vessel showed that the swarming was caused by the gastropod species Creseis acicula. Incidentally, it happens to be the first documented report on planktonic Gastropoda swarming in the Saudi waters of the Arabian Gulf. The swarming lasted only 2-3 days. Examination of the satellite images before, during, and after the swarming event indicated some changes in the color patterns of Ras Tanura surface waters, which could be linked to the swarm event. Due to bad weather conditions during and after the swarm period, it was not possible to collect seawater samples from the anchorage area and hence it was not possible to confirm whether this event could be linked with an algal or cyanobacterial bloom, as previously reported in another area of the Indian Ocean. Although most of the studies that reported C. acicula swarming indicated that this phenomenon is a natural one rather than being caused by external factors, some general precautionary/mitigation measures were proposed. Further studies and field observations are needed to better understand the causes of sea slug swarming and to avoid the issues it can cause to vessels, as it happened in the Western Arabian Gulf

Caulerpa taxifolia var. distichophylla: a further stepping stone in the western Mediterranean

Background In the Mediterranean sea, about 150 species of invasive macroalgae are recorded until now these alien species have produced serious effect due to their capability to modify the physical and chemical property of the invaded habitats and to compete with native assemblages so as threatening the biodiversity and the ecosystem functioning

Integrative Taxonomy of the Bubble Snails (Cephalaspidea, Heterobranchia) Inhabiting a Promising Study Area: The Coastal Sicilian Faro Lake (Southern Italy)

The worldwide diffused bubble snails, Haminoeidae, although characterized by an extreme morphological homogeneity, display the most diverse radiation inside the order Cephalaspidea. This hidden diversity within the family Haminoeidae was recently unraveled by molecular studies, which helped to understand the evolutionary history of this group by clarifying some aspects of its systematics. In fact, the type genus Haminoea W. Turton and Kingston (1830) was proved to be polyphyletic and, consequently, the genus Haminoea sensu stricto was restricted to the Mediterranean, Atlantic and East Pacific species, with the Mediterranean Haminoea hydatis Linnaeus (1758) as the type taxon. However, at the specie rank, many aspects need to be clarified, especially concerning the Mediterranean fauna. Due to low reliability of macro-morphological characters, the minimal quantity of molecular data currently available on Mediterranean specimen adds to the lack of molecular comparison in most reports. Based on such considerations, Haminoea species from an interesting Mediterranean study area, Faro Lake, a Sicilian coastal lake that is considered a hot spot for both alien and endemic marine Heterobranchia, have been studied using an integrative taxonomic approach. Eleven Mediterranean specimens belonging to four Haminoea bubble snails have been collected, identified and compared with samples from other localities, integrating ecological, morphological, anatomical (reproductive apparatus) and molecular data. Based on molecular investigations carried out on three different molecular markers (H3, 16S and COI), the morphological identifications of the species collected in the Faro Lake have been confirmed, and 37 new sequences are provided for future comparisons. Furthermore, results from this integrative systematic study shed light on the phylogenetic relationships occurring in this group of bubble snails that could be useful in identifying valid diagnostic morphological characters. Haminoea hydatis and H. navicula were confirmed to be close to each other, with H. orteai as sister to them and with H. orbignyana as the basal taxon. Given external morphological features are unreliable with species identification in Haminoea genus open questions on the geographical distribution of the species and on their ranges of intraspecific variability have yet to be addressed and further in-depth studies are needed. Finally, the presence of three sympatric Haminoea species, two of which are considered native or long-time naturalized, along with other occasional congeneric species, and the absence of the introduced invasive Haloa japonica, reflects both the resilience and stochastic space-temporal dynamics of Faro Lake. This confirms it as an inexhaustible source of case-studies

Dnevna i sezonska dinamika populacije Brachynotus sexdentatus (Risso, 1827) (Varunidae: Brachyura: Decapoda) u umjerenom priobalnom jezeru

The grapsoid Brachynotus sexdentatus (Risso, 1827) is a small sized Mediterranean crab, whose ecology is poorly known despite frequently cited in the scientific literature. High densities occasionally recorded in estuarine habitats suggest this opportunistic species might play a functional role in connecting benthic primary production with consumption at higher trophic levels. The brackish Lake Ganzirri (north-eastern Sicily) hosts a population of this varunid crab, whose differential distribution of juveniles and adults, respectively found on hard and soft substrates, involves different habitat preferences and consequent resource partitioning. Investigation on daily and seasonal dynamics of the soft-bottom dwelling adults showed a male biased population, with size-related differences between sex, station, season and female reproductive phase. Our data, suggesting an annual life span, prolonged spawning and related continuous recruitment, are in agreement with the intrinsic unpredictability of the colonized brackish environment. At last, preliminary in aquaria observations on the characteristic male cheliped vesicles, showed they might involved in agonistic and courtship behaviour.Grapsoidni rak iz porodice Varunidae, Brachynotus sexdentatus (Risso, 1827) mali je mediteranski rak čija je ekologija slabo poznata unatoč tome što je često citiran u znanstvenoj literaturi. Visoke gustoće koje se povremeno bilježe u staništima ušća ukazuju da bi ova oportunistička vrsta mogla igrati funkcionalnu ulogu u povezivanju primarne proizvodnje u bentosu s potrošnjom na višim trofičkim razinama. U bočatom jezeru Ganzirri (sjeveroistočna Sicilija) živi populacija ovog raka, čija različita distribucija juvenilnih i odraslih jedinki, na tvrdim i mekim podlogama, uključuje različite preferencije staništa i posljedičnu podjelu resursa. Istraživanje dnevne i sezonske dinamike odraslih primjeraka na mekom dnu pokazalo je da je populacija pristrasna muškoj, s razlikama u veličini između spola, stanice, sezone i reproduktivne faze ženki. Naši podaci, koji upućuju na godišnji životni vijek, produljeno mriješćenje i povezano kontinuirano regrutiranje, u skladu su s intrinzičnom nepredvidljivošću koloniziranog bočatog okoliša. Konačno, preliminarna opažanja u akvarijima na karakterističnim muškim vezikulama kliješta, pokazala su da bi oni mogli biti uključeni u agonističko i udvaračko ponašanje

The origin and dispersal pathway of the spotted sea hare Aplysia dactylomela (Mollusca : Opisthobranchia) in the Mediterranean Sea

The spotted sea hare Aplysia dactylomela Rang, 1828 is a large and conspicuous opisthobranch sea slug that since 2002 has rapidly colonized the eastern Mediterranean, establishing populations in numerous localities. The source of the Mediterranean populations has been the subject of debate, with two main hypotheses considered (Atlantic and Red Sea origin). A recent study on the taxonomy of A. dactylomela has shown that the spotted sea hare is a complex of at least two genetically distinct species (A. dactylomela in the Atlantic and A. argus in the Indo-Pacific), facilitating the correct identification of Mediterranean specimens by molecular means. We used sequence data from the mitochondrial cytochrome oxidase I gene to identify the Mediterranean individuals for the first time and to infer their origin. Our results confirmed that all the specimens collected in the Mediterranean belong to A. dactylomela and therefore have an Atlantic origin. The limited sample size does not allow identification of the dispersal pathway of A. dactylomela into the Mediterranean, but the colonization sequence is consistent with a “natural” dispersal event. This hypothesis is evaluated in light of local surface circulation patterns. Possible causes for the recent and rapid invasion of the eastern Mediterranean by A. dactylomela are discussed.peer-reviewe

Population genetics of Bursatella leachii (De Blainville, 1817) and implications for the origin of the Mediterranean population

Abstract The sea hare Bursatella leachii (de Blainville 1817) (Mollusca: Gastropoda: Heterobranchia: Aplysiidae) is a pantropical sea slug that has colonized the Mediterranean Sea in modern times. Because the initial records in the non-native range started in the Eastern Mediterranean, and its pattern of spread was relatively consistent with those observed in well-known Lessepsian invaders, B. leachii is commonly considered to be a migrant from the Red Sea. In this study, we investigate for the first time the origin of the Mediterranean populations of B. leachii inferring their population structure and assessing relatedness levels of different regional populations. Sequence data from the cytochrome oxidase I were used to conduct population genetic analyses on this species, particularly by investigating the genetic structure of Atlantic, Mediterranean, and Indo-Pacific populations. Our results confirm that B. leachii is a truly pantropical species which displays geographic structure among major ocean basins. More importantly, sequenced Mediterranean and Atlantic animals share similar or identical haplotypes, which are distinct in at least 5 substitutions from haplotypes recovered from Indo-Pacific specimens. The results suggest that the Mediterranean population of B. leachii here examined probably have an Atlantic origin, and for the first time casts doubts on the assumed primary pathway of migration into the Mediterranean Sea

Recruitment Disruption and the Role of Unaffected Populations for Potential Recovery After the Pinna nobilis Mass Mortality Event

A devastating mass mortality event (MME) very likely caused by the protozoan Haplosporidium pinnae first detected in 2016 in the Western Mediterranean Sea, is pushing the endemic bivalve Pinna nobilis to near extinction. Populations recovery, if possible, will rely on larval dispersal from unaffected sites and potential recolonization through recruitment of resistant juveniles. To assess the impact of the MME on the species’ larval recruitment, an unprecedented network of larval collector stations was implemented over several thousands of kilometers along the Western Mediterranean coasts during the 3 years after the onset of the MME. The findings of this network showed a generalized disruption in recruitment with dramatic consequences for the recovery of the species. However, there were exceptions to this pattern and recruits were recorded in a few sites where the resident population had been decimated. This hints to the importance of unaffected populations as larval exporting sources and the role of oceanographic currents in larval transport in the area, representing a beacon of hope in the current extremely worrying scenario for this emblematic species.En prens

Tracking a mass mortality outbreak of pen shell Pinna nobilis populations: A collaborative effort of scientists and citizens

A mass mortality event is devastating the populations of the endemic bivalve Pinna nobilis in the Mediterranean Sea from early autumn 2016. A newly described Haplosporidian endoparasite (Haplosporidium pinnae) is the most probable cause of this ecological catastrophe placing one of the largest bivalves of the world on the brink of extinction. As a pivotal step towards Pinna nobilis conservation, this contribution combines scientists and citizens’ data to address the fast- and vast-dispersion and prevalence outbreaks of the pathogen. Therefore, the potential role of currents on parasite expansion was addressed by means of drift simulations of virtual particles in a high-resolution regional currents model. A generalized additive model was implemented to test if environmental factors could modulate the infection of Pinna nobilis populations. The results strongly suggest that the parasite has probably dispersed regionally by surface currents, and that the disease expression seems to be closely related to temperatures above 13.5 °C and to a salinity range between 36.5–39.7 psu. The most likely spread of the disease along the Mediterranean basin associated with scattered survival spots and very few survivors (potentially resistant individuals), point to a challenging scenario for conservation of the emblematic Pinna nobilis, which will require fast and strategic management measures and should make use of the essential role citizen science projects can play.info:eu-repo/semantics/publishedVersio

New Mediterranean Biodiversity Records (December 2019)

This paper is a collection of novel distributional records of 20 species belonging to 8 phyla (Chlorophyta, Rhodophyta, Cnidaria, Ctenophora, Annelida, Mollusca, Arthropoda and Chordata) from 11 Mediterranean countries, namely, Spain: an additional record of the Canary dentex Dentex canariensis is reported from Spain (Valencia), this is the northernmost record of this species in the Mediterranean; Algeria: the first documented record of Caulerpa chemnitzia is reported from the Algerian coast; France: the first record of the Spotted sea hare Aplysia dactylomela is reported from the eastern coast of Corsica; Italy: the first records of the Lessepsian polychaete Dorvillea similis and the alien bivalve Isognomon legumen are reported from Italian waters while additional records of Mnemiopsis leidyi in the south Adriatic are provided;  Libya: the first record of an alien mollusc Crepidula fornicata is reported from Libyan waters; Malta: multiple sightings of gelatinous species Apolemia uvaria, Phacellophora camtschatica and Physophora hydrostatica are reported for the first time from Maltese waters, as well as the first tentative record of the Orange-spotted grouper Epinephelus cfr. coioides; Greece: an occurrence of a rare Bigeye thresher shark Alopias superciliosus is reported from Hellenic Ionian waters, while the first records of the alien Mertens’ prawn-goby Vanderhorstia mertensi, the recently described cyclopoid copepod Oithona davisae and the alien red seaweed Asparagopsis armata are reported from the Aegean Sea. The presence of the micromollusc Euthymella colzumensis is confirmed for Greece; Cyprus: the first record of the red cornetfish Fistularia petimba is reported from Cyprus; Turkey: the first record of the alien jellyfish Marivagia stellata is reported from south-eastern Turkey; Israel: the first records of the sea nettle Chrysaora sp. in the Levant are reported