Influence of environmental factors and sessile biota on vagile epibionts: The case of amphipods in marinas across a regional scale

Marinas are highly anthropized environments, with singular ecological characteristics. In the present study the spatial variability of the amphipod assemblage associated to floating pontoons was analyzed. Moreover, the influence of the environmental data and the sessile biota on the amphipod assemblage structure were assessed. Six marinas were selected along the Southern Iberian Peninsula, three in the Atlantic and three in the Mediterranean, and three floating pontoons were sampled at each marina. Four-teen amphipod species were identified, most of them corresponded to detritivores and generalist species. Statistical analyses considering amphipod composition and abundance did not show significant differences between the Atlantic and the Mediterranean, but there were significant differences among marinas. Copper had a significant correlation with the amphipod assemblage. The sessile species Bugula neritina and Ellisolandia elongata also showed a significant influence on the spatial patterns of the amphipod assemblages. Therefore, environmental conditions and sessile composition seem to affect, simultaneously, the spatial variability of amphipod assemblage associated to floating pontoons in marinas. Both factors are key to understand the singularity of marinas. This fact should be taken into consideration to prevent the use of a single management program in these environments.

First evidence of virus-like particles in the bacterial symbionts of Bryozoa

Bacteriophage communities associated with humans and vertebrate animals have been extensively studied, but the data on phages living in invertebrates remain scarce. In fact, they have never been reported for most animal phyla. Our ultrastructural study showed for the first time a variety of virus-like particles (VLPs) and supposed virus-related structures inside symbiotic bacteria in two marine species from the phylum Bryozoa, the cheilostomes Bugula neritina and Paralicornia sinuosa. We also documented the effect of VLPs on bacterial hosts: we explain different bacterial ‘ultrastructural types’ detected in bryozoan tissues as stages in the gradual destruction of prokaryotic cells caused by viral multiplication during the lytic cycle. We speculate that viruses destroying bacteria regulate symbiont numbers in the bryozoan hosts, a phenomenon known in some insects. We develop two hypotheses explaining exo- and endogenous circulation of the viruses during the life-cycle of B. neritina. Finally, we compare unusual ‘sea-urchin’-like structures found in the collapsed bacteria in P. sinuosa with so-called metamorphosis associated contractile structures (MACs) formed in the cells of the marine bacterium Pseudoalteromonas luteoviolacea which are known to trigger larval metamorphosis in a polychaete worm.

Draft genome of Bugula neritina, a colonial animal packing powerful symbionts and potential medicines

Many animal phyla have no representatives within the catalog of whole metazoan genome sequences. This dataset fills in one gap in the genome knowledge of animal phyla with a draft genome of Bugula neritina (phylum Bryozoa). Interest in this species spans ecology and biomedical sciences because B. neritina is the natural source of bioactive compounds called bryostatins. Here we present a draft assembly of the B. neritina genome obtained from PacBio and Illumina HiSeq data, as well as genes and proteins predicted de novo and verified using transcriptome data, along with the functional annotation. These sequences will permit a better understanding of host-symbiont interactions at the genomic level, and also contribute additional phylogenomic markers to evaluate Lophophorate or Lophotrochozoa phylogenetic relationships. The effort also fits well with plans to ultimately sequence all orders of the Metazoa.

Antifouling properties of chitosan coatings on plastic substrates

In the current study, chitosan coatings were fabricated on plastic substrata and investigated for their antifouling activities. Scanning Electron Microscopy (SEM) and water contact angle measurement (WCA) of the fabricated chitosan films showed smooth and hydrophilic surface with WCA below 60°. Chitosan coating on plastic substrate showed 88% reduction in settlement of bryozoan Bugula neritina larvae compare to the control after 3 hours incubation in dark conditions with no larval mortality during the experiment. The antimicrobial activity of chitosan was evaluated by coating of plastic panels with the prepared chitosan solution and immersing the coated samples in seawater with controlled environmental conditions. Biofilms scraped from immersed chitosan coated panels showed no bacteria after 1 week immersion. After the second week of immersion, less than 1500 bacteria/mm2 was observed on the chitosan-coated panels compared to more than 105 bacteria/mm2 on uncoated ones. Thus, this study prove the efficiency of chitosan coatings against micro- and macro-fouling.

Antifouling properties of chitosan coatings on plastic substrates

In the current study, chitosan coatings were fabricated on plastic substrata and investigated for their antifouling activities. Scanning Electron Microscopy (SEM) and water contact angle measurement (WCA) of the fabricated chitosan films showed smooth and hydrophilic surface with WCA below 60°. Chitosan coating on plastic substrate showed 88% reduction in settlement of bryozoan Bugula neritina larvae compare to the control after 3 hours incubation in dark conditions with no larval mortality during the experiment. The antimicrobial activity of chitosan was evaluated by coating of plastic panels with the prepared chitosan solution and immersing the coated samples in seawater with controlled environmental conditions. Biofilms scraped from immersed chitosan coated panels showed no bacteria after 1 week immersion. After the second week of immersion, less than 1500 bacteria/mm2 was observed on the chitosan-coated panels compared to more than 105 bacteria/mm2 on uncoated ones. Thus, this study prove the efficiency of chitosan coatings against micro- and macro-fouling.