Ports are gateways for many marine organisms transported by ships worldwide, especially non-indigenous species (NIS). In this study carried out in North Iberian ports (Cantabrian Sea, Bay of Biscay) we have observed 38% of exotic macroinvertebrates. Four species, namely the barnacle Austrominius modestus, the tubeworm Ficopomatus enigmaticus, the Pacific oyster Crassostrea gigas and the pygmy mussel Xenostrobus securis, exhibited clear signs of invasiveness. A total of 671 barcode (cytochrome oxidase subunit I or 18S rRNA) genes were obtained and confirmed the species status of some cryptic NIS. Negative and significant correlation between diversity estimators of native biota and proportion of NIS suggests biotic resistance in ports. This could be applied to management of port biota for contributing to prevent the settlement of biopollutants in these areas which are very sensitive to biological invasions.

With the increase of antimicrobial resistances due to the widespread use of antibiotics, the search of new probiotics to control aquaculture diseases has a growing public interest. The aim of this study was to isolate bacteria with antimicrobial effect from the gut of marine healthy fishes and select lactic acid bacteria (LAB) as potential probiotics, being strains considered as generally regarded as safe (GRAS) by the European Food Safety Agency (EFSA). Of a total of 45 Gram-positive strains with antimicrobial activity found in a screening of the gut microbiota of 13 marine fishes, nine were identified as LAB by 16S rRNA gene sequencing. LAB strains (five Lactococcus lactis subsp. lactis, two Enterococcus spp., one Lactobacillus plantarum, and one Leuconostoc mesenteroides subsp. mesenteroides) also showed a broad-spectrum antibacterial activity against aquaculture pathogens such as Vibrio harveyi, V. splendidus, and Photobacterium damselae and survived in experimental gastrointestinal conditions when grown in culture media modified with different values of pH and bile salts. These results showed the potential of LAB obtained from the indigenous microbiota of wild marine fishes for use as probiotics in aquaculture.

The vertical distribution and vertical migrations of fish larvae and implications for their cross-shelf distribution were investigated in the northern limit of the NE Atlantic upwelling region during the late winter mixing period of 2012. The average positive values of the upwelling index for February and March of this year were far from normal, although the average hydrographic conditions during the period of study were of downwelling and the water column was completely mixed. Fish larvae, most in the preflexion stage, were concentrated in the upper layers of the water column and their distribution was depth stratified, both day and night. However, the larval fish community was not structured in the vertical plane and fish larvae did not show significant diel vertical migration (DVM), although five species showed ontogenetic vertical migration. In regions of coastal upwelling and in the absence of DVM, the location of fish larvae in the water column is crucial for their cross-shelf distribution. Thus, the cross-shelf distribution of the six most abundant species collected in this study can be explained by the surface onshore flow associated with coastal downwelling, retaining larvae of the coastal spawning species with a relatively shallow distribution in the shelf region and transporting larvae of slope spawning species onto the shelf. The wide vertical distribution shown by larvae of the offshore spawning species could be an adaptation of these species to ensure that some larvae reach the inshore nursery areas.

No abstract

No abstract