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Farm sabotage can cause massive fish escape events with significant ecological and socio-economic risks. This study examined the fate of Mediterranean seabass Dicentrarchus labrax escapees following a large-scale escape event caused by sabotage in the Western Mediterranean Sea. We monitored the escapee density and size structure over 3 mo after the escape at increasing distances from the escape point, up to 45 km away. Fish density adjacent to the escape location 5 d after the sabotage was, on average, 114 ± 44.7 (SE) fish per 100 m2. Our analyses showed that fish density decreased by 17% for every km away from the location, dropping to 2 and 1% after 1 and 2 mo, respectively, following the escape event. As escapee density declined throughout time and space, the size distribution of seabass shifted towards larger sizes. The rapid decrease in fish densities highlights the need for contingency plans focusing on fishing efforts in the coastal areas near the escape location (

Biodiversitat i estructura de la comunitat íctica litoral del substrat rocós del Parc Natural de serra Gelada (sud-oest del mar Mediterrani) Aquest estudi analitza la comunitat íctica litoral sobre substrat rocós del Parc Natural de serra Gelada (Alacant) i s’aporten dades de base que permetran avaluar a llarg termini els canvis deguts a diverses mesures de gestió. Es van fer censos visuals en transsectes lineals sobre fons rocosos entre 1 i 32 m de profunditat. A les set localitats estudiades es van comptar 44 espècies. El nombre d’espècies, l’abundància, la biomassa i l’estructura de talles van ser similars entre les zones amb alta i baixa protecció. La composició d’espècies observada va ser similar a les d’altres àrees marines protegides del Mediterrani occidental. Les diferències entre localitats podrien ser causades per l’alta heterogeneïtat i complexitat de l’hàbitat a petita escala.

The seagrass Posidonia oceanica plays an important role as habitat for invertebrates. A correlative study was done in El Campello (SE Spain) to understand the relationships between assemblage structure of crustaceans and modification of P. oceanica structure caused by bottom trawling. We compared the changes of community structure of the most important groups of crustaceans, amphipods and decapods with changes of cover, density, detritus and rhizome fragments. Sampling was carried out in four control and four impact locations, along a gradient of degradation (17 m depth, August 1992). Multivariate analysis was used for community data (nm-MDS) and P. oceanica structure (PCA). Both groups showed a similar number of species. The amphipod community showed a clear pattern of community changes with significant differences between impact and control locations (global R = 0.298, p

The effectiveness of marine protected areas (MPAs) and the conservation of marine environments must be based on reliable information on the quality of the marine environment that can be obtained in a reasonable timeframe. We reviewed studies that evaluated all aspects related to the effectiveness of MPAs in order to describe how the studies were conducted and to detect fields in which research is lacking. Existing parameters used to evaluate the effectiveness of MPAs are summarised. Two–hundred and twenty–two publications were reviewed. We identified the most commonly used study subjects and methodological approaches. Most of the studies concentrated on biological parameters. Peer reviewed studies were based on control vs. impact design. BACI and mBACI designs were used in very few studies. Through this review, we have identified gaps in the objectives assigned to MPAs and the way in which they have been evaluated. We suggest some guidelines aimed at improving the assessment of the effects of protection in MPAs. Key words: Marine conservation, Management, Assessment, Descriptors, Subject of study, Marine protected areas.

A hierarchical sampling design was used to study the population structure and the horizontal (differences among islands, locations within islands and sites within locations) and vertical (differences among intertidal bands) distribution patterns of the gastropod molluscs Osilinus atrata and O. sauciatus along the rocky intertidal zone of the Canary Islands. Differences in the spatial patterns of abundance, size and distribution were recorded for both species. Osilinus atrata was more abundant than O. sauciatus throughout the archipelago. Its abundance varied among islands and it presented a heterogeneous distribution in the bands from one island to another, though it was more frequent in the middle and high bands. Osilinus sauciatus was only found at the eastern islands and did not exhibit significant differences between the bands, even though 91.35% of the individuals appeared in the high band and the rest in the middle band. On the other hand, O. sauciatus had a larger mean size than O. atrata, but both species presented the largest mean sizes in the high band.

The article discusses research which aims to evaluate aspects related to the effectiveness of marine protected areas (MPA) in terms of their objectives based on previous studies. It also intends to investigate areas of improvement where future research initiatives are necessary. MPA are considered essential in fisheries management due to their capabilities to conserve fish stocks, increase fish breeding population, and act as nurseries. Reviews of studies based on sampling design quality, statistical analysis conducted, and editorial evaluation are also presented.

Posidonia oceanica seagrass meadows have been degraded in the Mediterranean Sea by trawling. To reduce this impact, antitrawling artificial reefs have been deployed. The introduction of artificial structures on seagrass meadows, however, could potentially change the composition of fishes. Using visual techniques, we examined changes in fish assemblage and density of key species by comparing fish abundances at four seagrass sites with and without artificial reef blocks in El Campello (Alicante), southeastern Spain, between October 1992 and August 1995. The fish assemblage on plots with artificial reefs changed substantially a year after their installation in October 1992. Differences in fish abundance (total counts of 6,692 fish on artificial reefs and 3,565 fish on Posidonia) and in species richness (41 species on artificial reefs and 29 on Posidonia) were found. The abundance of key species were quite different between habitats. Diplodus vulgaris and Chromis chromis were most abundant in all samples, whereas Oblada melanura recruited to the artificial reefs during winter 1994. Two species, Apogon imberbis and Sciaena umbra were found at all times on artificial reefs but were not present in P. oceanica plots. The antitrawling artificial reefs influenced the spatial distribution of fishes on a scale of tens to hundreds of meters but did not affect the overall Posidonia fish assemblage. Antitrawling artificial reefs protect seagrass from trawling and had little overall effect on seagrass fish assemblages in areas away from the artificial reefs. [ABSTRACT FROM AUTHOR]

Abstract Trace elements in otoliths of sea bass (Dicentrarchus labrax L.) and sea bream (Sparus aurata L.) from fish farms and coastal wild populations in the western Mediterranean Sea were analysed by inductively coupled plasma-mass spectrometry. Results showed that concentrations of Mg, K, and Mn differed significantly between wild and farmed sea bass, while concentrations of Mg, K, Mn, Fe, Zn, Sr, and Ba varied significantly between wild and farmed sea bream. Discriminate analysis and cross-validation classification showed that the trace element profile in otoliths can be used to separate farmed fish from wild stocks with high accuracy on both sea bass (individuals correctly classified: 90.7 %) and sea bream (individuals correctly classified: 96.6 %). Moreover, trace elements in otoliths resulted to be useful to discriminate among wild fish stocks within each species.

In this study, we assessed plastic accumulation in marine sediments due to finfish aquaculture using floating net-pens. We studied plastic concentrations around three fish farms located at the Mediterranean coastline of Spain. The macroplastic categories and abundances were determined by video monitoring, detecting the majority of elements (78%), including ropes, nets and fibres, a basket trap and a cable tie, close to the facilities, which were not exclusively linked to fish farming but also to fishing activities. Concentrations of microplastics (<5 mm) ranged from 0 to 213 particles/kg dry weight sediment with higher values in sites directly under the influence of the fish farms. Most particles (27.8%) were within the size fraction from 1.1 to 2.0 mm and fibre was the most common shape with 62.2%. The Infrared spectroscopy analysis showed that PE and PP were the predominant types of polymers analysed. In addition, changes in the enthalpy of melting (ΔH m (J/g)) and the degree of crystallinity indicate degradation of the microplastics analysed. This study shows that, in the studied fish farms, levels of microplastic pollution can be one order of magnitude lower compared to other areas suffering other anthropogenic pressures from the same or similar regions. Nevertheless, more research effort is needed to get concluding results. Image 1 • Plastic accumulation in marine sediments due to finfish aquaculture has been studied. • Concentrations of microplastics ranged from 0 to 213 particles/kg dry weight sediment. • The FTIR analysis showed PE and PP as the predominant types of polymers analysed. • Changes in the enthalpy and crystallinity indicate degradation of microplastics. [ABSTRACT FROM AUTHOR]

Benthic soft–bottom assemblages are good indicators of environmental disturbance, such as coastal aquaculture, considering their rapid response in terms of diversity and abundance. The aim of this study was to evaluate the response of peracarid assemblages to the release of waste from coastal farming as these organisms play an important ecological role. Abundance and species richness did not show significant differences between farm and control localities but did show a high spatial variability at the two studied scales. Non–metric multi–dimensional scaling (MDS) analysis showed a separation between farms and controls, indicating that peracarid assemblages are modified as a result of aquaculture activities, and some species such as Ampelisca spp. showed statistical differences. Peracarids, at both species and community level, may therefore be applied as helpful indicators to assess benthic effects of coastal farming. Key words: Benthos, Aquaculture, Impact, Indicators, Management, Sustainability.

The article discusses the highlights of the Iberian Symposium of Studies on Marine Biology held at the University of Alicante in Spain from September 6 to 10, 2010. The event, which was attended by 268 participants from different countries, served as an opportunity for interaction between researchers and marine scientists. It featured 70 oral presentations concerning marine ecosystems and conservation of marine biodiversity. Daily plenary conferences on landscape ecology were also conducted.

In the present study the fish assemblages in the rocky-bottom habitat of the Sierra Helada Natural Park (Alicante, Spain) were recorded to provide data for future evaluation of any changes induced by long-term management. Visual censuses were carried out along strip transects by Scuba diving on rocky bottoms at depths between 1 and 32 m. In the seven localities sampled, 44 species were recorded. Number of species, abundance, biomass and size structure values recorded did not show differences between high and low protection areas. Species composition was similar to other marine protected areas of the western-Mediterranean. The main differences found between localities can be attributed to the high heterogeneity and complexity of the habitat at smaller spatial scales.

The SIEBM (Iberian Symposium of Studies on Marine Biology) has a long tradition. The conference was first convened in 1979 and it has since been held approximately biannually. It was originally focused on marine benthos, but two editions ago it was decided to widen its objectives to include other related subjects. The 15th edition was held at the University of Alicante from 6th to 10th September 2010. One of the strong points of SIEBM is that it provides the opportunity for interaction between well–known researchers and young marine scientists, mainly from Spain and Portugal. In the 2010 edition, however, it was attended by 268 participants from 15 countries. SIEBM 2010 focused on the human impact on marine ecosystems and the conservation of marine biodiversity to coincide with the United Nations declaring 2010 the International Year of Biodiversity. From a total number of 330 communications received, the Scientific Committee selected 70 for oral presentations and the rest were presented as posters. Each day a plenary conference covered what we considered as the fastest growing areas in marine biology: landscape ecology. The impact of global warming on marine ecosystems, approaches to fisheries management and the study and conservation of deep ecosystems. The oral presentations were divided into 15 sessions that included both basic research on biodiversity, phylogeny or marine ecology, and applied research in management, fisheries, conservation and the human impact on marine ecosystems. Abstracts, posters and presentations are available at http://www.siebm.org. The studies included in this volume show the variety of subjects and approaches addressed during the conference. These papers were selected and edited by a group of referees and we wish to thank them for their efforts and conscientious work. A list of their names is included. Of the 28 studies received, 13 were finally accepted for this volume. We also would like to thank all the people who helped in one way or another to make the 15th SIEBM Conference and the proceedings such a success. We thank the Scientific Committee for revising the abstracts and selecting the oral presentations. Most members of this committee also chaired sessions and undertook this task with commitment and dedication. The planning, logistics and running of the conference were made possible thanks to the enthusiasm of the organising committee and a group of student helpers. We are profoundly indebted to Carlos Valle and Aitor Forcada for their invaluable contribution to the organisation. Finally, we thank all the sponsors who contributed to the meeting, and especially the Fundación Biodiversidad and the Natural History Museum of Barcelona for their support in publishing this special issue of Animal Biodiversity and Conservation.

Environmental genomics is a promising field for monitoring biodiversity in a timely fashion. Efforts have increasingly been dedicated to the use of bacteria DNA derived data to develop biotic indices for benthic monitoring. However, a substantial debate exists about whether bacteria-derived data using DNA metabarcoding should follow, for example, a taxonomy-based or a taxonomy-free approach to marine bioassessments. Here, we showcase the value of DNA-based monitoring using the impact of fish farming as an example of anthropogenic disturbances in coastal areas and compare the performance of taxonomy-based and taxonomy-free approaches in detecting environmental alterations. We analysed samples collected near to the farm cages and along distance gradients from two aquaculture installations, and at control sites, to evaluate the effect of this activity on bacterial assemblages. Using the putative response of bacterial taxa to stress we calculated the taxonomy-based biotic index microgAMBI. The distribution of individual amplicon sequence variants (ASVs), as a function of a gradient in sediment acid volatile sulphides, was then used to derive a taxonomy-free bacterial biotic index specific for this data set using a de novo approach based on quantile regression splines. Our results show that microgAMBI revealed a organically enriched environment along the gradient. However, the de novo biotic index outperformed microgAMBI by providing a higher discriminatory power in detecting changes in abiotic factors directly related to fish production, whilst allowing the identification of new ASVs bioindicators. The de novo strategy applied here represents a robust method to define new bioindicators in regions or habitats where no previous information about the response of bacteria to environmental stressors exists., (© 2021 John Wiley & Sons Ltd.)

Marine sediments are a major sink of organic matter, playing a crucial role in the global cycling of major elements. Macrofauna, through the reworking of particles and movement of solutes (bioturbation), enhances oxic conditions and the sediment metabolic capacity. Increases in the inputs of organic matter can lead to profound changes in the seabed and impact benthic ecological functions. Through a microcosm experiment, the effect of bioturbation of the polychaete Lumbrineris latreilli on biogeochemical fluxes under scenarios of increasing loads of organic matter was quantified. We found that bioturbation can buffer the negative consequences of anoxic conditions produced by organic enrichment, preventing the build-up of toxic by-products derived from anaerobic metabolic pathways by maintaining oxic conditions. However, the maintenance of oxic conditions by bioturbation is at the expense of limiting the sediment metabolic capacity. The maintenance of oxic conditions may limit anaerobic metabolic pathways, and consequently, the metabolic capacity of sediment. Thus, under organic matter pollution conditions, bioturbation may lessen the metabolic capacity of the sediment., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Published by Elsevier Ltd.)

Marine protected areas (MPAs) could be useful as fisheries management tools for the exportation of pelagic eggs, larvae and adult fish. A decreasing gradient of fish biomass across MPAs boundary may indicate export. We determine whether gradients of decreasing biomass of fish assemblage occurred in Tabarca Marine Reserve over two habitats with different continuity across the boundaries, to test if the patchy nature of the marine environment might act as a barrier for the fish export. In general, significant decreasing gradients in total fish biomass and biomass of some species were observed on P. oceanica and rocky substrates, independently of their different continuity through the reserve boundaries. Changes in the multivariate structure of the fish assemblage were correlated with the distance from integral reserve. All of these results support the hypothesis that the exportation of adult fish from Tabarca Marine Reserve occurs, and this process may influence the surrounding fished areas.