Marine sponges produce secondary metabolites that can be used as a natural source for the design of new drugs and cosmetics. There is, however, a supply problem with these natural substances for research and eventual commercialisation of the products. In situ sponge aquaculture is nowadays one of the most reliable methods to supply pharmaceutical companies with sufficient quantities of the target compound. In this study, we focus on the aquaculture of the sponge Dysidea avara (Schmidt, 1862), which produces avarol, a sterol with interesting pharmaceutical attributes. The soft consistency of this species makes the traditional culture method based on holding explants on ropes unsuitable. We have tested alternative culture methods for D. avara and optimized the underwater structures to hold the sponges to be used in aquaculture. Explants of this sponge were mounted on horizontal ropes, inside small cages or glued to substrates. Culture efficiency was evaluated by determination of sponge survival, growth rates, and bioactivity (as an indication of production of the target metabolite). While the cage method was the best method for explant survival, the glue method was the best one for explant growth and the rope method for bioactivity.

1. The American brine shrimp Artemia franciscana is important in aquaculture and has become invasive in other continents, aided by dispersal via waterbirds. However, little is known about processes underlying its genetic diversity and population structure in its natural habitat in North America. These processes, including dispersal and local adaptation, are pivotal drivers of species distribution and community structure, and therefore central to aquatic biodiversity.2. We studied 15 populations in natural saline lakes of Saskatchewan, Canada to determine the influence of variation in geological history, water chemistry, lake size, and location. We aimed to determine the relative importance of isolation by distance and isolation by environment using the cytochrome c oxidase subunit 1 gene (CO1) as a mitochondrial marker and five nuclear microsatellite markers.3. Geographic patterns for CO1 and microsatellites differed, with lakes clustering in different groups based on genetic distances according to the marker used. CO1 better indicated historical colonisation processes, suggesting potential routes of initial colonisation when lakes were formed after deglaciation 11,000-15,000 years ago. 4. Differentiation between lakes based on nuclear markers was strongly related to variation in hydrochemistry, suggested by distance-based redundancy analysis, but there was no indication of isolation by distance. The ratio between alkalinity and the sum of Ca and Mg concentrations was particularly important, although a lake with a high Cl concentration caused by potash mining also had a unique Artemia population. 5. Geochemistry is important in the adaptive radiation of anostracan crustaceans.Our study suggests that it also underlies intraspecific genetic variation between populations, promoting isolation by environment, and making dispersal ineffective when cysts are moved by birds between lakes with different hydrochemistry.

In the last 30 years since its first appearance in Portugal, the North-American Artemia franciscana has successfully invaded hypersaline habitats in several Mediterranean countries. Here, we review its spread in the Mediterranean Basin since its first occurrence in the 1980s and report its first occurrence in Croatia, based on both morphological identification (adults) and genetic evidence (cysts). The haplotypes we found in the population from this new locality (two of which were new to both the native and invaded ranges of A. franciscana) suggest either direct or secondary introduction from the main harvested cyst sources (Great Salt Lake or San Francisco Bay, USA) and indicate that some genetic native diversity in the species has not yet been captured by existing studies. Our finding means that the species has reached the eastern shores of the Adriatic Sea and therefore is now present on the Balkan Peninsula. We detected that its eastward spread is still continuing, posing a fundamental threat to remaining populations of native Artemia species in Eastern Europe. Keywords invasive species, Artemia franciscana, salt works, Mediterranean Con formato: Español (España) Código de campo cambiado Con formato: Español (España) Con formato: Español (España)

Zebra mussel populations in Ebro and Mijares Rivers (northern Spain) were analyzed to study the mechanisms by which this aquatic species deals with pollution. Variability analyses of mitochondrial cytochrome oxidase I gene and of one nuclear microsatellite were performed for ten populations from the Ebro River and one from the Mijares River. Comparison of these results with those from five additional European populations indicated that the Spanish populations constitute a homogeneous gene pool. Transcriptome analyses of gill samples from a subset of the Spanish populations showed changes on expression levels that correlated with variations in general fitness and loads of heavy metals. The less polluted upstream Ebro populations showed overexpression of mitochondrial and cell proliferation-related genes compared to the more polluted, downstream Ebro populations. Our data indicate that heavy metals were the main factors explaining these transcriptomic patterns, and that zebra mussel is resilient to pollutants (like mercury and organochlorine compounds) proved to be extremely toxic to vertebrates. We propose that zebra mussel populations sharing a common gene pool may acclimate to different levels and forms of pollution through modulations in their transcriptomic profile, although direct selection on genes showing differential expression patterns cannot be ruled out.

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