This article gives an insight into the degree of establishment and potential impact of escaped sea bass in shallow coastal habitats of Tenerife. We studied spatial distribution, abundance, size frequency and use of habitat by visual census. Stomach contents and gonadal maturity of escaped sea bass were analysed. Results show that abundance of escaped sea bass is related to distance from to the nearest fish farm and to the habitat complexity. The most frequent size found in the wild corresponds to that of first marketing size. Stomach contents indicate that escaped sea bass were able to exploit natural resources, especially fish. The presence of a female with mature gonads indicates that conditions for successful maturation exist. However, further studies are needed to ensure whether or not escaped sea bass are able to establish self-reproducing populations. Thus, we can conclude that sea bass seem to be already established in shallow coastal habitats of Tenerife, but the population may depend mainly on escapees. As a result of being an opportunistic piscivore, sea bass could be predating on and competing with other native species that are economically important. These results are useful to develop a risk assessment based on quantitative data to predict negative effects. Moreover, management policies such as communication of massive escapes or mitigation measures are needed to prevent future impact on the marine environment.

Jellyfish blooms cause important ecological and socio-economic problems. Among jellyfish, cubozoans are infamous for their painful, sometimes deadly, stings and are a major public concern in tropical to subtropical areas; however, there is little information about the possible causes of their outbreaks. After a bloom of the cubomedusa Carybdea marsupialis (Carybdeidae) along the coast of Denia (SW Mediterranean, Spain) in 2008 with negative consequences for local tourism, the necessity to understand the ecological restrictions on medusae abundance was evident. Here we use different models (GAM and zero-inflated models) to understand the environmental and human related factors influencing the abundance and distribution of C. marsupialis along the coast of Denia. Selected variables differed among medusae size classes, showing different environmental restriction associated to the developmental stages of the species. Variables implicated with dispersion (e.g. wind and current) affected mostly small and medium size classes. Sea surface temperature, salinity and proxies of primary production (chl a, phosphates, nitrates) were related to the abundances of small and large size classes, highlighting the roles of springtime salinity changes and increased primary production that may promote and maintain high densities of this species. The increased primary (and secondary) production due to anthropogenic impact is implicated as the factor enabling high numbers of C. marsupialis to thrive. Recommendations for monitoring blooms of this species along the study area and applicable to Mediterranean Sea include focus effort in coastal waters where productivity have been enriched by anthropogenic activities.

Spatiotemporal patterns of distribution of sea bass, Dicentrarchus labrax, and sea bream, Sparus aurata, and their influence on artisanal fisheries are explored before and after an escape event that released 1.5 million fish into the wild off La Palma (Canary Islands). Data were collected by in situ visual census and first sale data as a proxy of artisanal fisheries landings. Permutational anova of escapee abundances in shallow coastal habitats revealed consistent spatial patterns that linked densities of these fish to distance from escape point, whereas temporal patterns were related to a higher biomass released during winter. A nearby marine protected area did not show different densities of escaped fish. Local artisanal fleet catches accurately reflected the massive escape event and offer the main contingency force to mitigate the potential negative effects of massive escape events over shallow coastal habitats.

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