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With over a thousand of introduced species, the Mediterranean is the most heavily invaded marine region in the world. Yet, the spatio-temporal dynamics of this bioinvasion has never been analysed. Examination of a comprehensive dataset of 4015 georeferenced observations, extracted from the scientific literature, allowed (i) reconstructing the invasion and the introduction and post-introduction dynamics of exotic fish species, (ii) calculating introduction and spread rates, and (iii) investigating the time correlates since introduction. Our analysis encompasses 188 fish species that entered the Mediterranean from 1896 to 2020, including 25 Atlantic species that naturally expanded their range through the Strait of Gibraltar. Cumulative occurrences, reported in 264 distribution maps, documented the progressive expansion of the most represented species and the spatio-temporal patterns associated with three introduction routes: the Suez Canal (CAN); other human-mediated vectors (HM) and the Strait of Gibraltar (NRE). The arrival rate of the species introduced through all three routes increased steeply after 1990, without a sign of saturation. Data analysis highlighted some temporal and geographical patterns, such as the effect and eventual weakening of the biogeographical barriers represented by the Strait of Sicily and the North Aegean Sea and the asymmetrical distribution of occurrences along the northern and southern Mediterranean coasts. Finally, there was an exponential increase in the secondary spread rates of CAN and NRE immigrants, as the more recent introductions achieved the fastest geographical expansions. Our findings provide a detailed and spatially explicit summary of a massive invasion that has changed the history of the Mediterranean biota and represent a remarkable example of rapid biotic homogenization in the global ocean., (© 2022 The Authors. Global Change Biology published by John Wiley & Sons Ltd.)

The Mediterranean Sea is recognized today as the World's most invaded marine region, but observations of species occurrences remain scattered in the scientific literature and scarcely accessible. Here we introduce the ORMEF database: a first comprehensive and robust compilation of exotic fish observations recorded over more than a century in the Mediterranean. ORMEF consists today of 4015 geo-referenced occurrences from 20 Mediterranean Countries, extracted from 670 scientific published papers. We collated information on 188 fish taxa that are thus divided: 106 species entered through the Suez Canal; 25 species introduced by shipping, mariculture, aquarium release or by means of other human activities; 57 Atlantic species, whose arrival in the Mediterranean has been attributed to the unassisted immigration through the strait of Gibraltar. Each observation included in the ORMEF database was submitted to a severe quality control and checked for geographical and taxonomic biases. ORMEF is a new authoritative reference for Mediterranean bio-invasion research and a living archive to inform management strategies and policymakers in a period of rapid environmental transformation., (© 2022. The Author(s).)

Marine bioinvasions and other rapid biodiversity changes require today integrating existing monitoring tools with other complementary detection strategies to provide a more efficient management. Here we explored the efficacy of fishermen observations and traditional port surveys to effectively track the occurrence of both indigenous and non-indigenous megafauna in the Adriatic Sea. This consisted mainly of mobile taxa such as fishes, crustaceans and molluscs. Port surveys using traps and nets within 10 major Adriatic harbours, were compared with the information obtained from 153 interviews with local fishermen. Information gathered by traps and nets varied significantly and generally resulted of limited efficacy in exotic species detection. Interviews allowed tracking the occurrence of new species through time and space, providing complementary knowledge at the low cost. This combined approach improves our capability of being informed on the arrival of species of different origin, providing a more rational, improved basis for environmental management and decision making., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

The seasonal timing of recurring biological processes is essential for organisms living in temperate regions. While ample knowledge of these processes exists for terrestrial environments, seasonal timing in the marine environment is relatively understudied. Here, we characterized the annual rhythm of habitat use in six fish species belonging to the Sparidae family, highlighting the main environmental variables that correlate to such rhythms. The study was conducted at a coastal artificial reef through a cabled observatory system, which allowed gathering underwater time-lapse images every 30 minutes consecutively over 3 years. Rhythms of fish counts had a significant annual periodicity in four out of the six studied species. Species-specific temporal patterns were found, demonstrating a clear annual temporal niche partitioning within the studied family. Temperature was the most important environmental variable correlated with fish counts in the proximity of the artificial reef, while daily photoperiod and salinity were not important. In a scenario of human-induced rapid environmental change, tracking phenological shifts may provide key indications about the effects of climate change at both species and ecosystem level. Our study reinforces the efficacy of underwater cabled video-observatories as a reliable tool for long-term monitoring of phenological events.

Marine cabled video-observatories allow the non-destructive sampling of species at frequencies and durations that have never been attained before. Nevertheless, the lack of appropriate methods to automatically process video imagery limits this technology for the purposes of ecosystem monitoring. Automation is a prerequisite to deal with the huge quantities of video footage captured by cameras, which can then transform these devices into true autonomous sensors. In this study, we have developed a novel methodology that is based on genetic programming for content-based image analysis. Our aim was to capture the temporal dynamics of fish abundance. We processed more than 20,000 images that were acquired in a challenging real-world coastal scenario at the OBSEA-EMSO testing-site. The images were collected at 30-min. frequency, continuously for two years, over day and night. The highly variable environmental conditions allowed us to test the effectiveness of our approach under changing light radiation, water turbidity, background confusion, and bio-fouling growth on the camera housing. The automated recognition results were highly correlated with the manual counts and they were highly reliable when used to track fish variations at different hourly, daily, and monthly time scales. In addition, our methodology could be easily transferred to other cabled video-observatories.

Biological invasions have become major players in the current biodiversity crisis, but realistic tools to predict which species will establish successful populations are still unavailable. Here we present a novel approach that requires only a morphometric characterisation of the species. Using fish invasions of the Mediterranean, we show that the abundance of non-indigenous fishes correlates with the location and relative size of occupied morphological space within the receiving pool of species. Those invaders that established abundant populations tended to be added outside or at the margins of the receiving morphospace, whereas non-indigenous species morphologically similar to resident ones failed to develop large populations or even to establish themselves, probably because the available ecological niches were already occupied. Accepting that morphology is a proxy for a species' ecological position in a community, our findings are consistent with ideas advanced since Darwin's naturalisation hypothesis and provide a new warning signal to identify invaders and to recognise vulnerable communities., (© 2014 John Wiley & Sons Ltd/CNRS.)

At the end of May, 17 scientists involved in an EU COST Action on Conservation Physiology of Marine Fishes met in Oristano, Sardinia, to discuss how physiology can be better used in modelling tools to aid in management of marine ecosystems. Current modelling approaches incorporate physiology to different extents, ranging from no explicit consideration to detailed physiological mechanisms, and across scales from a single fish to global fishery resources. Biologists from different sub-disciplines are collaborating to rise to the challenge of projecting future changes in distribution and productivity, assessing risks for local populations, or predicting and mitigating the spread of invasive species.

One of the expected effects of global change is increased variability in the abundance and distribution of living organisms, but information at the appropriate temporal and geographical scales is often lacking to observe these patterns. Here we use local knowledge as an alternative information source to study some emerging changes in Mediterranean fish diversity. A pilot study of thirty-two fishermen was conducted in 2009 from four Mediterranean locations along a south-north gradient. Semi-quantitative survey information on changes in species abundance was recorded by year and suggests that 59 fish species belonging to 35 families have experienced changes in their abundance. We distinguished species that increased from species that decreased or fluctuated. Multivariate analysis revealed significant differences between these three groups of species, as well as significant variation between the study locations. A trend for thermophilic taxa to increase was recorded at all the study locations. The Carangidae and the Sphyraenidae families typically were found to increase over time, while Scombridae and Clupeidae were generally identified as decreasing and Fistularidae and Scaridae appeared to fluctuate in abundance. Our initial findings strongly suggest the northward expansion of termophilic species whose occurrence in the northern Mediterranean has only been noted previously by occasional records in the scientific literature.

The effects of sewage outfalls on subtidal fish assemblages were studied along the NW coasts of Malta (Sicily channel, Mediterranean Sea) by means of underwater visual census. The presence of two spatially distinct outfalls discharging untreated wastewaters allowed to use a balanced symmetrical after control/impact (ACI) design that consisted of two putatively impacted locations and two controls, with four sites nested in each location. Surveys were performed in 2006 at two random dates. The study highlighted significant changes at both assemblage and individual species levels. Fish assemblages structures were different between controls and sewages, where total abundance of fish were higher. The responses of individual species to sewage pollution were mostly related to an anomalous increase of two small opportunistic species i.e. Gobius bucchichii and Parablennius rouxi and to a decrease of species of the genus Symphodus, particularly S. roissali and S. ocellatus. Moreover in correspondence of the outfalls, significant changes of the fish size distribution were detected for several species. These results support the use of fish assemblages as biological indicators for marine coastal waters and demonstrated the possibility to obtain sharp signals of environmental impact from some individual fish species.

Our current understanding of the mechanisms that lead to successful biological invasions is limited. Although adaptations play a central role in biological invasions, genetic studies have so far failed to produce a unified theory. The bluespotted cornetfish, a recent Red Sea invader in the Mediterranean Sea via the Suez Canal, provides an ideal case study for research in the mechanisms of invasive genetics. In this study, we show that the invading bluespotted cornetfish underwent a severe population bottleneck that reduced the genetic diversity of this immigrant to only two mitochondrial haplotypes. Although loss of genetic diversity is considered detrimental to the need to adapt to new environments, bluespotted cornetfish experienced an unprecedented success and rapid spread across the Mediterranean.

Parrotfishes of the genus Sparisoma (Scaridae) are ecologically important tropical reef fishes restricted to the Atlantic Ocean. We investigated phylogenetic relationships among the eight extant species within this genus using mitochondrially encoded 12S and 16S ribosomal genes. Our molecular data support the view that (i) Sparisoma originated approximately 14-35 million years ago (mya), probably in the tropical western Atlantic, off Brazil; (ii) there have been at least four discrete bouts of cladogenesis within the genus, with the most recent one ( approximately 2.8-5.6 mya) involving four events in both the east and the west Atlantic and across the Atlantic; and (iii) the genus invaded the eastern Atlantic on two different occasions, probably by at least two different routes. The data also offer support for Bellwood's ideas concerning the evolutionary changes in adult feeding patterns and habitat use within Scarids. Specifically, they support the evolutionary position of the ecological traits of Sparisoma as intermediate within the family., (Copyright 2000 Academic Press.)

The article offers information related to the occurrence of bluefin driftfish Psenes pellucidus fishes in the Mediterranean sea. Topics discussed include occurrence of Psenes pellucidus in Tunisia, possibilities of species occurrence in the area for process of geographical expansion, observations regarding reproductive population of fishes in the Mediterranean Sea due to distance as their arrival is less from the Atlantic Ocean.

Coastal exposure may affect the structure of littoral fish assemblages. To evaluate its effects, fish assemblages associated with shallow (0-3 m depth) rocky reefs were investigated by visual census at the Asinara Island National Park (northwestern Sardinia, Italy, Mediterranean Sea) during autumn 2003. Distribution patterns of ichthyofauna in sheltered and exposed rocky reefs were assessed over the spatial scales of locations (i.e. kilometres) and sites (i.e. hundreds of metres). Overall, 38 fish taxa belonging to 17 families were recorded, with Labridae, Sparidae and Serranidae being the families with the most species. Univariate analyses showed that the average density of Labridae and Serranidae was significantly greater at sheltered locations, while particulate organic matter feeders (i.e. Mugilidae) were more abundant at the exposed ones. Significant differences in species richness, total fish abundance and densities of Labridae and planktivorous fish were observed at the spatial scale of sites. Multivariate analyses revealed that whole fish assemblages differed more at the scale of locations than among sites. Planktivorous species contributed most to the dissimilarity between fish assemblages associated with exposed and sheltered stretches of coast. Direct and indirect effects of coastal exposure were hypothesized to explain the potential role of wave action in structuring fish assemblages associated with shallow rocky reefs. In particular, direct effects could affect the distribution patterns of fish, depending on their swimming ability, while indirect effects could include changes in the benthic cover (especially macroalgae) caused by wave action, which then had a repercussion on the fish. [ABSTRACT FROM AUTHOR]

Fish assemblages associated with offshore platforms were surveyed using two underwater visual census techniques: strip transects and mobile point counts. Data were collected from four depth ranges at three platforms off Crotone, Italy (Ionian Sea). A total of 25 fish species belonging to 12 families were recorded for the three platforms. Significant differences between sampling methods and depth were observed in the fish assemblage structure, species richness and fish abundance. The mean number of species recorded with the strip transect method was always greater than that obtained with mobile point counts, whilst the opposite pattern was observed for mean abundances. Gregarious species such as Boops boops, Chromis chromis, Anthias anthias and Oblada melanura were responsible for most of the differences in the assemblage structure. According to our results, both methods allowed us to observe species that are not usually caught by means of fishing gear. When both census techniques are used, they provide complementary information about the fish assemblages strictly associated with the platform structures. [ABSTRACT FROM AUTHOR]