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Branched polymeric niobia-silica (NS) mixed-oxide sols with a Nb:Si molar ratio between 0.33 and 0.8 were made by acid-catalyzed sol-gel synthesis and characterized using small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS). The growth rate of NS sols after addition of a niobium alkoxide precursor to a prehydrolyzed silica sol in alcohol under highly acidic conditions was monitored. The results indicated a fractal structure, with radii of gyration and fractal dimensions that increased simultaneously as a function of time. The radii of gyration were between 2 and 5.5 nm, whereas the fractal dimensions were in the range of 1.5-2.0 within experimental error. The experimental data are indicative of growth via a diffusion-limited cluster aggregation (DLCA) mechanism on a time scale of hours. The dominant growth mechanism in the very early stage of reaction must have been different. Sols with higher Nb:Si molar ratios grew faster, which is due to the higher reactivity of Nb compared to Si alkoxides. Dilution and control over temperature can be employed to control the size of the sols precisely.

Gaidropsarus Rafinesque, 1810 is a genus of marine fishes, commonly known as rocklings, comprising 14 living species and showing a high ecological diversity from the intertidal zone to the deep sea. The systematics of this group has been controversial due to a general lack of representative specimens and the conservative morphology exhibited. A multidisciplinary approach combining the analysis of meristic data and the DNA barcode standard was applied in a species delimitation approach. Individuals representing eight valid and three unnamed species were collected, morphologically identified and archived in several museum collections. Comparison of DNA sequences shows complex results, furthering the idea of the difficult identification of specimens based on traditional taxonomy. DNA barcoding supports synonymies, like G. biscayensis-G. macrophthalmus and G. guttatus-G. mediterraneus, agreeing with the extensive overlaps observed in the meristic variables analysed and suggesting a reduction in the number of species. Genetic distances showed pairs of closely related species like G. granti-G. vulgaris and G. argentatus-G. ensis, the latter being only distinguished by one main distinctive character. Four deep-water specimens, morphologically classified only to the genus level, constituted three independent taxa apart from the ones present in this study and with no barcode matches in the repository databases. They could represent new records for the North Atlantic or unknown species of this genus. The results obtained show that more studies will be necessary to solve the systematics of this branch of the Gadiformes.

International audienceIn this study we develop and evaluate a macroalgal bioassay tool for monitoring the spatial extent of dissolved wastes loaded from offshore fish farms into the marine coastal ecosystem. This tool is based on the analysis of the nitrogen stable isotope ratio (δN) in tissues of several benthic primary producers (macroalgae and epiphytes) incubated, by means of incubation devices, in the water column at increasing distances (from 0 m to 1000 m) from the fish cages. The bioassays were performed in three fish farms situated in different geographical locations (the Canary Islands, Murcia and Catalonia) and we test: the suitability of the different macroalgae species used in relation with their resistance to incubation and their sensitivity to fish-farm wastes and the most appropriate incubation depth (5m or ~20m) and incubation time (2, 4 or 6 days) to detect the spatial distribution of δN around fish farms. In general terms, the results showed a significant increment of δN values towards the fish cages with respect to the reference (initial) and control values for all the species of macroalgae tested except for the red algae from Canary Islands. The magnitude and shape of the reported spatial responses varied as a function of the experimental settings analyzed as well as a function of the nutrient regime characteristics of each coastal area. The spatial gradient was more consistent in the shallow part of the water column (5m depth), than in the deeper part (~20m) and was statistically significant after an incubation period of four days. These results confirm the effectiveness and reliability of the method proposed, enabling the spatial extent of nutrients derived from fish farms to be assessed in an effective and simple manner, suitable for use in monitoring programs around offshore fish farms

Notacanthiformes Goodrich, 1909, is an order of deep‐sea teleost fishes with a leptocephalus larval stage whose biology and systematics are not widely known. The aim of this work was to apply the DNA barcode standard, based on COI sequence variation, to the delimitation of the species of this order, which is composed by the families Halosauridae (halosaurus) and Notacanthidae (spiny eels). The sequence data used for the analyses were obtained from two sources: 71 samples collected during oceanographic surveys in the North Atlantic Ocean (including the rare species Lipogenys gillii Goode & Bean, 1895) and 95 sequences collected from the BOLD data set. The neighbor‐joining analysis of the barcodes was successful in identifying 96% of the specimens, representing 9 of 16 and 9 of 10 of the recognised species of halosaurus and spiny eels, respectively, including all the current genera. The comparison between the Atlantic and the BOLD data sets also flagged the possibility of occurrences of misidentification and cryptic species. A modern molecular tool like the DNA barcoding supports the previously morphological‐based systematics of the order Notacanthiformes and will provide better access to the taxonomic knowledge of these deep‐water fishes.