Marine sponges commonly host a repertoire of bacterial-associated organisms, which significantly contribute to their health and survival by producing several anti-predatory molecules. Many of these compounds are produced by sponge-associated bacteria and represent an incredible source of novel bioactive metabolites with biotechnological relevance. Although most investigations are focused on tropical and temperate species, to date, few studies have described the composition of microbiota hosted by Antarctic sponges and the secondary metabolites that they produce. The investigation was conducted on four sponges collected from two different sites in the framework of the XXXIV Italian National Antarctic Research Program (PNRA) in November–December 2018. Collected species were characterized as Mycale (Oxymycale) acerata, Haliclona (Rhizoniera) dancoi, Hemigellius pilosus and Microxina sarai by morphological analysis of spicules and amplification of four molecular markers. Metataxonomic analysis of these four Antarctic sponges revealed a considerable abundance of Amplicon Sequence Variants (ASVs) belonging to the phyla Proteobacteria, Bacteroidetes, Actinobacteria and Verrucomicrobia. In particular, M. (Oxymycale) acerata, displayed several genera of great interest, such as Endozoicomonas, Rubritalea, Ulvibacter, Fulvivirga and Colwellia. On the other hand, the sponges H. pilosus and H. (Rhizoniera) dancoi hosted bacteria belonging to the genera Pseudhongella, Roseobacter and Bdellovibrio, whereas M. sarai was the sole species showing some strains affiliated to the genus Polaribacter. Considering that most of the bacteria identified in the present study are known to produce valuable secondary metabolites, the four Antarctic sponges could be proposed as potential tools for the discovery of novel pharmacologically active compounds.
Seamounts host some of the most important deep‐sea ecosystems. The unique environmental characteristics of seamounts sustain rich biological hot spots, which, in recent times, have suffered the effects of intense fishing pressure.
Biodiversity and vulnerability data are extremely scarce for Mediterranean seamounts, and this, in addition to the complex socio‐economic and juridical status of offshore sites, results in difficulty in identifying the best management strategies.
An extensive remotely operated vehicle (ROV) survey was used to characterize the megabenthic assemblages of the summits of two upper bathyal seamounts, Ulisse and Penelope (Ligurian Sea, north‐west Mediterranean Sea). The biogeographic implications of these findings and the possible environmental factors favouring the occurrence of these communities are discussed.
High densities of abandoned, lost, or otherwise discarded fishing gear (mainly longlines) and a reduction in the average size of the fragile and slow‐growing habitat‐forming gorgonian Callogorgia verticillata indicate the occurrence of high levels of anthropogenic impacts on the summit regions, which are fishing grounds for artisanal and recreational fishers.
The recovery of fishing data describing the first catches in the 1970s proved to be useful in inferring the short‐ and long‐term effects of fishing practices in these previously unexploited offshore areas. In particular, the local extinction of demersal top predators, subjected to exceptional catches nearly 50 years ago, highlights the slow recovery rate of such species.
Criteria defining vulnerability are discussed for the two study areas, and specific conservation actions, including the creation of regulated protected areas, are proposed.
Complex cell-to-cell interactions (including the production of antibiotics and the quorum sensing phenomenon) occur between benthic marine organisms and bacteria, leading to the establishment of synergistic interactions, especially in extreme and harsh environments, such as Antarctica. Despite this, current data concerning the composition, host-and site-relatedness, and biotechnological values of the bacterial community associated with Antarctic sponges are limited to few works, resulting in a still fragmented and incomplete knowledge. In this context, a total of 11 sponge species (belonging to Demospongiae and Hexactinellida) from the Terra Nova Bay area (Ross Sea) were explored for the associated bacterial diversity by the ION Torrent sequencing. An additional predictive functional analysis on 16S rRNA gene data was performed to unravel metabolic and biotechnological potentials of the associated bacterial communities. Data obtained highlighted the predominance of Proteobacteria, mainly affiliated to Alpha-and Gammaproteobacteria. Retrieved phyla were similarly distributed across samples, with dissimilarities encountered for the sponge Haliclona (Rhizoniera) dancoi (Topsent, 1901). Functional prediction results suggested that the associated bacterial community may be involved in the biosynthesis of antibiotics, quorum sensing, and degradation of aromatic compounds.
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