Methylene Blue adsorption on Sargassum muticum, an invasive macroalga in Europe, has been investigated using visible absorption spectroscopy. Different pre-treatments, protonation and chemical cross-linking with CaCl 2 or H 2 CO, have been tested in order to improve the stability as well as the adsorption capacity of the algal biomass. The equilibrium binding has been described in terms of Langmuir or Freundlich isotherms depending on the algal pre-treatment; from the maximum adsorption capacity values, an estimation of the algal specific surface area was made. Moreover, it has been found that adsorption kinetics can be described according to the first order Lagergren model, from which the rate constant and the adsorption capacity were determined. Finally, simple empirical equations were obtained to evaluate the amount of Methylene Blue removed at any initial concentration and reaction time. The results obtained have shown that this type of material has a high adsorption capacity for Methylene Blue dye, this feature together with the short times needed to reach the equilibrium suggest that Sargassum muticum can be used as a low-cost biosorbent in wastewater treatments.

Bacterial communities play an essential role for the function of marine macroalgae. Recent work has shown that bacterial communities associated with individual macroalgae possess on a local scale a functional core that is likely derived from diverse members of functional guilds. It is not known whether such functional cores also exist across large spatial scales or between closely related host species. To address this, we studied here the bacterial communities on three species of the green macroalgal genus Ulva from different geographic locations. While the taxonomic composition was too variable to describe a community core, we identified genes that were enriched across all Ulva samples as compared to the communities of the surrounding seawater. Of these core functions, 70% were consistently found and independent of the Ulva species and biogeography, while the remaining functions (~30%) are possibly involved in local or host-specific adaptations. For each host individual, the core functions are provided by bacteria with distinct phylogenetic origin and these bacteria could constitute a global guild of Ulva-associated bacteria. Together, our results demonstrate the presence of a stable core set of functional genes in the bacterial communities associated with closely related host species and across large biogeographies.

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Background Syngnathid fishes (Actinopterygii, Syngnathidae) are flagship species strongly associated with seaweed and seagrass habitats. Seahorses and pipefishes are highly vulnerable to anthropogenic and environmental disturbances, but most species are currently Data Deficient according to the IUCN (2019), requiring more biological and ecological research. This study provides the first insights into syngnathid populations in the two marine Spanish National Parks (PNIA—Atlantic- and PNAC—Mediterranean). Fishes were collected periodically, marked, morphologically identified, analysed for size, weight, sex and sexual maturity, and sampled for stable isotope and genetic identification. Due the scarcity of previous information, habitat characteristics were also assessed in PNIA. Results Syngnathid diversity and abundance were low, with two species identified in PNIA (Hippocampus guttulatus and Syngnathus acus) and four in PNAC (S. abaster, S. acus, S. typhle and Nerophis maculatus). Syngnathids from both National Parks (NP) differed isotopically, with much lower δ15N in PNAC than in PNIA. The dominant species were S. abaster in PNAC and S. acus in PNIA. Syngnathids preferred less exposed sites in macroalgal assemblages in PNIA and Cymodocea meadows in PNAC. The occurrence of very large specimens, the absence of small-medium sizes and the isotopic comparison with a nearby population suggest that the population of Syngnathus acus (the dominant syngnathid in PNIA) mainly comprised breeders that migrate seasonally. Mitochondrial cytochrome b sequence variants were detected for H. guttulatus, S. acus, and S. abaster, and a novel 16S rDNA haplotype was obtained in N. maculatus. Our data suggest the presence of a cryptic divergent mitochondrial lineage of Syngnathus abaster species in PNAC. Conclusions This is the first multidisciplinary approach to the study of syngnathids in Spanish marine NPs. Habitat preferences and population characteristics in both NPs differed. Further studies are needed to assess the occurrence of a species complex for S. abaster, discarding potential misidentifications of genus Syngnathus in PNAC, and evaluate migratory events in PNIA. We propose several preferential sites in both NPs for future monitoring of syngnathid populations and some recommendations for their conservation.

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The development of integrated multitrophic aquaculture (IMTA) systems in Spain has been rather limited so far. However, trials carried out in recent years at experimental and at small industrial scale have been very promising. One of the most encouraging experiences involves the development of seaweed farming for human consumption in combination with mussel rafts in Galicia (NW Spain). Here, we describe a new and more productive marine farming system of Saccharina latissima ("sugar kelp") combined with mussel rafts. We show its level of integration in terms of harvest and protein content as well as an assessment of the sources of assimilated nitrogen through the analysis of δ 15 N isotope ratios. Oceanographic conditions in Northwest Spain make S. latissima behave like a winter-spring species in culture with a growing period of just 5-6 months. Nonetheless, production values in our experiment equalled or exceeded those recorded in northern parts of the Atlantic where the culturing period is almost twice as long. Compared to natural populations, S. latissima from mussel-integrated culture systems had almost twice as much protein content, giving greater added value to the species both as food and feed.

We present an annotated checklist of the benthic marine and brackish algae of the Galician coasts (Spain) based on literature records and new collections. This checklist includes 618 species: 118 Cyanophyta, 296 Rhodophyta, 127 Ochrophyta, and 77 Chlorophyta. The number of specific, infraspecific taxa, and stages is 643: 121 Cyanophyta, 309 Rhodophyta, 135 Ochrophyta, and 79 Chlorophyta. Hyella caespitosa var. nitida, Calothrix fasciculata, Gracilariopsis longissima, Compsonema minutum, and Sphacelaria tribuloides are new records for Galicia, and there are also some new provincial records. We state the presence of each species for Lugo (Lu), A Coruña (Co), and Pontevedra (Po) provinces. The number of species found in Galicia is high, since 85% of the species recorded for the warm-temperate NE Atlantic Ocean grow in Galicia. Biogeographical comments comparing the Galician data with the neighboring areas of Britain and Ireland, Basque coast, Portugal, southern Iberian Peninsula, Canary Islands and Atlantic coast of Morocco are given. Finally, we present lists of cold-temperate, warm-temperate, Lusitanic Province endemics, and alien species growing in Galicia.

The present study critically analyses peer-reviewed literature addressing the potential of halophytes to remediate nutrient-rich effluents from marine and coastal aquaculture, as well as the potential for their economic valorization, from human consumption to an untapped source of valuable secondary metabolites with pharmaceutical potential. The growing body of evidence discussed in this review supports the perspective that halophytes can become a new source of nutrition and other high-value compounds and be easily incorporated into saltwater-based integrated multi-trophic aquaculture (IMTA) systems. In this context, halophytes act as extractors of dissolved inorganic nutrients, primarily nitrogen and phosphate, usually wasted in marine aquaculture farms. Phytoremediation using halophytes has been proven to be an efficient solution, and several ways exist to couple this practice with land-based marine aquaculture systems, namely through constructed wetlands and aquaponics. Focusing research on ecosystem-based approaches to aquaculture production will provide valuable data for producers and policy makers in order to improve decision making towards a sustainable development of this economic sector. Ecointensification of aquaculture through IMTA will potentially increase the overall productivity and resilience of the sector, and halophytes, in particular, are on the verge of becoming key players for the diversification and promotion of land-based IMTA. This work specifically documents the uncharted potential of Halimione portulacoides, an important halophyte in European salt marsh ecosystems, as a new extractive species for IMTA.