Jelly surge in the Mediterranean Sea: threat or opportunity?

The rise in water temperature in the Mediterranean Sea, and associated migrations of temperate marine biota, are occurring in the context of a global warming causing an expansion of the tropical jellyfish range, exacerbating jellyfish outbreaks linked to coastal development, nutrient loading, and overfishing. The gelatinous component of plankton is considered as 'the dark side of ecology' capable of appearing and disappearing at unpredictable times. In the last decade an increasingly high number of gelatinous plankton blooms are occurring and this makes us wonder if 'a Mediterranean Sea full of jellyfish is a probable future'. The reasons for rising jellyfish blooms are, probably, manifold. Current studies are aimed to highlight how climatic change is interacting with the Mediterranean ecosystem favouring entrance, abundances and success of alien species and triggering 'regime shifts' such as from fish to jellyfish. Jellyfish damage the economic success of power plants, fish farms, tourism, and affect fisheries consuming larvae of commercial fish species. On the other hand, several studies were also taken into account on uses for jellyfish as biofuels and foods but more experimentation is needed to improve the first encouraging results

Planuloid budding from a cutting plane of polyp stalk of Cassiopea sp.(Cnidaria, Scyphozoa)

Cassiopea polyps that appeared in culture vessels of Turritopsis sp. polyps at the Seto Marine Biological Laboratory, Kyoto University in 2014 were experimentally amputated their stalks from the calyxes. On the cutting plane, planuloid buds were exclusively produced and stalks were never regenerated. Planuloids became polyps but some of them were never produced stalks. It is assumed that the polyp that accidentally lost its stalk has a chance to raise their survival rate by releasing multiple of planuloids

The historical reconstruction of distribution of the genus Halecium (Hydrozoa: Haleciidae): a biological signal of ocean warming?

The distribution of 130 nominal species of the genus Halecium, based on published records, has been mapped for the first time in a comprehensive set of marine ecoregions, to analyse their distribution. Most Halecium species are found at mid- and high latitudes, with some overlaps in distribution ranges across regions. The species richness of Halecium is strongly related to the latitudinal gradient, with maximal diversity at polar and temperate latitudes. Previous detailed studies in the Mediterranean Sea show that large Halecium species of coldwater affinity have regressed or disappeared in recent years, probably due to global warming. Worldwide, however, the overall species richness of Halecium has not changed along the latitudinal gradient over recent decades, with some changes in species composition at temperate-tropical latitudes in both hemispheres, even though the majority of the species that have not been recorded for more than 50 years are of coldwater affinity. The genus can be considered an indicator for biological responses to climate changes for the Mediterranean Sea, but the available distribution data do not allow extending this possibility to the rest of the world. A focused evaluation on the distribution of Halecium species with the addition of new field data might reinforce the picture stemming from the present analysis

Hydrozoan species richness in the Mediterranean Sea: past and present

The Mediterranean hydrozoan fauna (Siphonophora excluded) comprises 400 species; most (68%) occur in the Atlantic Ocean, 20% are endemic to the Mediterranean, 8% are of Indo-Pacific origin, and 4% are non-classifiable. There are 69 nonindigenous (NIS) species in the basin: 44% of these are casual (recorded just one or very few times), 28% established (widely recorded in the basin), 6% invasive (established NIS that are able rapidly or largely to dissemi- nate away from the area of initial introduction, having a noticeable impact on the recipient community), and 22% questionable (of doubtful taxonomic sta- tus). Entry through the Suez Canal and range expansion through the Gibraltar Strait, often enhanced by ship traffic, appear to be the main processes for recent species introductions, but uncertainties remain for many NIS. Species additions immediately result in larger local or regional species pools, but the newcomers might impact on populations of native species, altering extinction probabilities. A more reliable evaluation of the species pool can be accom- plished by adding new species when they enter the taxonomic record (i.e. the records of any taxon in all types of literature), and by removing species that have not been found for a ‘reasonable’ time (e.g. several decades). Of the 400 non-siphonophoran hydrozoan species known to occur in the Mediterranean Sea, positive records in the last 10 years are available for 156 species (39%), whereas records of the remaining 244 species are older than a decade: 67 spe- cies have not been recorded for 41 years, 13 for 31–30 years, 79 for 21– 30 years, and 85 for 11–20 years

Project “Biodiversity MARE Tricase”: A Species Inventory of the Coastal Area of Southeastern Salento (Ionian Sea, Italy)

Biodiversity is a broad concept that encompasses the diversity of nature, from the genetic to the habitat scale, and ensures the proper functioning of ecosystems. The Mediterranean Sea, one of the world’s most biodiverse marine basins, faces major threats, such as overexploitation of resources, pollution and climate change. Here we provide the first multi-taxa inventory of marine organisms and coastal terrestrial flora recorded in southeastern Salento (Ionian Sea, Italy), realized during the project “Biodiversity MARE Tricase”, which provided the first baseline of species living in the area. Sampling was carried out by SCUBA and free diving, fishing gears, and citizen science from 0 to 70 m. Overall, 697 taxa were found between March 2016 and October 2017, 94% of which were identified to the species level. Of these, 19 taxa represented new records for the Ionian Sea (36 additional new records had been reported in previous publications on specific groups, namely Porifera and Mollusca Heterobranchia), and two findings represented the easternmost records in the Mediterranean Sea (Helicosalpa virgula and Lampea pancerina). For eight other taxa, our findings represented the only locality in the Ionian Sea, besides the Straits of Messina. In addition to the species list, phenological events (e.g., blooms, presence of reproductive traits and behaviour) were also reported, with a focus on gelatinous plankton. Our results reveal that even for a relatively well-known area, current biodiversity knowledge may still be limited, and targeted investigations are needed to fill the gaps. Further research is needed to understand the distribution and temporal trends of Mediterranean biodiversity and to provide baseline data to identify ongoing and future changes

Marine alien species in Italy: A contribution to the implementation of descriptor D2 of the marine strategy framework directive

The re-examination of marine alien species or Non-indigenous species (NIS) reported in Italian Seas by December 2018, is here provided, particularly focusing on establishment success, year of first record, origin, potential invasiveness, and likely pathways. Furthermore, their distribution is assessed according to marine subregions outlined by the European Union (EU) Marine Strategy Framework Directive: Adriatic Sea (ADRIA), Ionian Sea and Central Mediterranean Sea (CMED), and Western Mediterranean Sea (WMED). In Italy, 265 NIS have been detected with the highest number of species being recorded in the CMED (154 species) and the WMED (151 species), followed by the ADRIA (143). Most of these species were recorded in more than one subregion. The NIS that have established stable populations in Italian Seas are 180 (68%), among which 26 have exhibited invasive traits.Among taxa involved, Macrophyta rank first with 65 taxa. Fifty-five of them are established in at least one subregion, mostly in the ADRIA and the CMED. Crustacea rank second with 48 taxa, followed by Polychaeta with 43 taxa, Mollusca with 29 taxa, and Pisces with 28 taxa, which were mainly reported from the CMED. In the period 2012-2017, 44 new alien species were recorded, resulting in approximately one new entry every two months. Approximately half of the NIS (~52%) recorded in Italy have most likely arrived through the transport-stowaway pathway related to shipping traffic (~28% as biofoulers, ~22% in ballast waters, and ~2% as hitchhikers). The second most common pathway is the unaided movement with currents (~19%), followed by the transport-contaminant on farmed shellfishes pathway  (~18%). Unaided is the most common pathway for alien Fisshes, especially in CMED. Escapes from confinement account for ~3% and release in nature for ~2% of the NIS. The present NIS distribution hotspots for new introductions were defined on the first recipient area/location in Italy. In ADRIA the hotspot is Venice which accounts for the highest number of alien taxa introduced in Italy, with 50 newly recorded taxa. In the CMED, hotspots of introduction are the Taranto and Catania Gulfs, hosting 21 first records each. The Strait of Sicily represents a crossroad between the alien taxa from the Atlantic Ocean and the Indo-Pacific area. In the WMED, hotspots of bioinvasions include the Gulfs of Naples, Genoa and Livorno.This review can serve as an updated baseline for future coordination and harmonization of monitoring initiatives under international, EU and regional policies, for the compilation of new data from established monitoring programs, and for rapid assessment surveys.

Biodiversity of Prokaryotic Communities Associated with the Ectoderm of Ectopleura crocea (Cnidaria, Hydrozoa)

The surface of many marine organisms is colonized by complex communities of microbes, yet our understanding of the diversity and role of host-associated microbes is still limited. We investigated the association between Ectopleura crocea (a colonial hydroid distributed worldwide in temperate waters) and prokaryotic assemblages colonizing the hydranth surface. We used, for the first time on a marine hydroid, a combination of electron and epifluorescence microscopy and 16S rDNA tag pyrosequencing to investigate the associated prokaryotic diversity. Dense assemblages of prokaryotes were associated with the hydrant surface. Two microbial morphotypes were observed: one horseshoe-shaped and one fusiform, worm-like. These prokaryotes were observed on the hydrozoan epidermis, but not in the portions covered by the perisarcal exoskeleton, and their abundance was higher in March while decreased in late spring. Molecular analyses showed that assemblages were dominated by Bacteria rather than Archaea. Bacterial assemblages were highly diversified, with up to 113 genera and 570 Operational Taxonomic Units (OTUs), many of which were rare and contributed to <0.4%. The two most abundant OTUs, likely corresponding to the two morphotypes present on the epidermis, were distantly related to Comamonadaceae (genus Delftia) and to Flavobacteriaceae (genus Polaribacter). Epibiontic bacteria were found on E. crocea from different geographic areas but not in other hydroid species in the same areas, suggesting that the host-microbe association is species-specific. This is the first detailed report of bacteria living on the hydrozoan epidermis, and indeed the first study reporting bacteria associated with the epithelium of E. crocea. Our results provide a starting point for future studies aiming at clarifying the role of this peculiar hydrozoan-bacterial association

Rare distribution of green fluorescent protein (GFP) in hydroids from Porto Cesareo, Lecce, Italy, with reference to biological meaning of this rarity

A reliable taxonomic character, distributional pattern of green fluorescent protein (GFP), that is contributable to species demarcation by observing living materials under the fluorescent microscope, has not been much done in hydroids in contrast to hydromedusae. We carried out such a fundamental study in diverse hydroids collected from Porto Cesareo, Lecce, Italy. In contrast to diversified distribution of GFP in the hydromedusae, GFP distribution in hydroids are unexpectedly very rare, and its biological meaning is deduced