Search

The loss of Mediterranean macroalgal populations dominated by Cystoseira sensu lato is driven by a multitude of pressures. In the eastern Mediterranean Sea, climate change and the establishment of Lessepsian herbivore species have further intensified the ongoing decline of these canopy-forming algae. Knowledge of the reproductive phenology, embryology and growth of Cystoseira species is the first step towards successful reforestation measures. Gongolaria montagnei is one of the most common canopy-forming algal species with a wide horizontal and vertical distribution along the Greek coasts. Mature receptacles were collected from Saronikos Gulf (Aegean Sea), and germlings were cultured in mesocosms for 34 days, reaching up to 1.30 mm in length. Divisions and early developmental stages of G. montagnei are described and possible implications for future restoration efforts are discussed. A new approach to growth rate modeling, based on surface measurements of embryos and germlings is presented.

Data with high spatial resolution on the structure and diversity of marine assemblages are valuable for fisheries management and conservation planning but are seldom available. This study provides fisheries-independent, baseline information on the structure and diversity of the demersal fish assemblages of the continental shelf and upper slope off the island of Psara (Central Aegean Sea). Experimental bottom trawl hauls were conducted during 2009–2010, using identically designed trawls. All the fish in the catches were identified onboard, enumerated, and weighted to the nearest g. Species abundance and biomass were transformed to CPUE. Forty-seven taxa were identified in the catches. For 18 of the species caught no other fisheries-independent information on their abundances and distributions is available for the wider area. Among the Elasmobranchii species collected, Squalus acanthias, Dipturus oxyrinchus, and Raja clavata are species of conservation concern. Species composition was generally more similar to that reported for assemblages of the Cretan Sea and the South Aegean Sea than for assemblages of the North Aegean. The assemblages were structured with depth, a pattern that may be driven in part by the differences in benthic habitat between depth zones. No trends by depth in total numerical abundance and species diversity were identified, whereas the bathymetric change in taxonomic diversity was attributed to the depth distributions of certain species-rich orders and families. The frequency distribution of the trophic level of the species followed the broad-scale pattern that applies in the Mediterranean Sea.

Research known as Citizen Science (CS) has been recognized as an important tool for both biodiversity restoration and fisheries management projects through active involvement of citizens and therefore for public environmental awareness too. CS projects should be well designed and state clear questions, that will benefit both the research goals and the citizen scientists themselves. In January 2019, the “Red Fish Project” group was created on Facebook consisting of SCUBA divers and fishers and offering the main data source and the relevant digital material. The project’s establishment was based on previous personal experience and following specific protocols. Further information was provided by personal communications. Till October 21st, 2020 the FB group consisted of 464 members who recorded 348 European spiny lobster individuals from all sub-regions of the Aegean Sea. Based on the findings of the present study it seems that most of the citizens were unaware that the species is listed as “Vulnerable” in the IUCN Red List. Lastly, we discuss the important role of the spiny lobster in the country’s culture and that it can be listed as a charismatic, flagship species for citizens to be ocean-literate since it has been shown, that it can raise the interest of recreational divers and increase their awareness.

The European spiny lobster Palinurus elephas is a vulnerable species that inhabits and is harvested in the Mediterranean Sea and the adjacent Atlantic waters. The fisheries associated with the spiny lobster are mainly conducted with tangle nets, trammel nets, pots, and creels. The fishing pressure has greatly reduced their numbers, changing them from a common shallow coastal species to a largely remnant population. The relative research on the species&rsquo, biology and fisheries from the eastern Mediterranean Sea is almost absent. The fishery along the Chalkidiki Peninsula, Greece, is multispecies, and fishing is conducted by a small number of artisanal fishermen mainly using trammel nets. The lobster stock&mdash, both spiny and clawed lobsters&mdash, declined significantly during the late 1980s and early 1990s, later than most cases in the Mediterranean Sea. However, data regarding the nature and status of the fishery associated with the spiny lobster in Greece are lacking. Data regarding the characteristics of the spiny regional fishery were obtained by interviews and questionnaires. Additionally, fishery surveys were conducted during the main lobster fishing season from 1 May 2017 to 31 August 2017. Sixteen species were identified (15 finfish species and one invertebrate species) as targeted. In total, 79 spiny lobsters were sampled in this study, the population&rsquo, s sex ratio significantly diverts from the theoretical 1:1 (&chi, 2 = 4.57, p &lt, 0.05), and males were dominant. Both male and female individuals demonstrate negative allometric growth profiles. In addition, no significant differences were observed between sexes. In Greece, thus far, the knowledge and information are sporadic, limited, and/or species-specific, most of which regard finfish fisheries. Furthermore, the national legislation is rather complicated&mdash, or too generalized&mdash, thus creating great uncertainties. The in-depth knowledge and experience of fishermen should be further acknowledged and utilized, and wider collaborations among scientists, practitioners, and policy-makers should be established. The present study poses some thoughts on the effectiveness of the recent EU Landing Obligation and its contribution to the potential restoration of the species.

International audience; While in recent years intermittent rivers and ephemeral streams (IRES) are receiving increasing attention from ecologists, fish metacommunity dynamics have drawn less attention than other taxa. In this study, we explored fish metacommunity dynamics at a Mediterranean intermittent river (Evrotas River, Southern Greece) to unravel which factors (i.e. environmental and/or spatial) best explain fish metacommunity structure. To this end, we investigated fish compositional structure in perennial and intermittent sites distributed longitudinally along the river during the low flow period of a wet year (2009), following two extremely dry years (2007-2008). To disentangle the effects of spatial control versus local environmental variables in shaping fish metacommunities, asymmetric eigenvector map (AEM) analysis designed to model directional spatial processes, and variation partitioning were applied. Our results point out that fish metacommunity structure was largely explained by spatial (53%) rather than local environmental (3%) factors, whereas only a small fraction (16%) was explained by the spatial structure of the environmental variables. Irrespectively of their hydrological regime, neighboring sites harbored similar fish communities, with a strong longitudinal gradient in local community structure, suggesting a homogenizing effect of dispersal. Local environmental factors were not associated with shifts in community structure. These results differ markedly from those drawn from most perennial aquatic ecosystems, where environmental factors are prevailing. Overall, this study emphasizes the need to account for regional processes in IRES and adopt a metacommunity perspective for guiding conservation and restoration efforts, by promoting the connectivity within the river network and the protection of perennial refugia. (C) 2020 European Regional Centre for Ecohydrology of the Polish Academy of Sciences. Published by Elsevier B.V. All rights reserved.

The NaGISA project (Natural Geography Ιn Shore Areas) is a global initiative within the framework of the Census of Marine Life. The Mediterranean Sea has joined with 4 stations, 2 in Italy and 2 on the island of Crete, Greece. Two different sites were sampled during two consecutive years (2007 and 2008) by means of SCUBA diving. On the basis of the evidence offered by the collected material from the hard substrates of Crete, and the literature mined datasets concerning the molluscan assemblages, two main issues are investigated: (a) is the molluscan fauna sampled in the two NaGISA sites representative of the regional Mediterranean one? and (b), is the molluscan fauna sampled from the two sites randomly assembled from the regional species pool across different spatial scales? Although a strong tendency of the local molluskan composition to be randomly sampled from the regional pools at all scales, it is not possible to demonstrate with a degree of certainty whether their observed local diversity is independent of local and regional processes or if it is determined by a combination of the two acting either in concert or antagonistically.

The efficacy of a Mediterranean Marine Protected Area (National Marine Park of Zakynthos – NMPZ, Ionian Sea, Greece) that implements a seasonal no-take zone as part of its management scheme was assessed using fish data collected in situ with underwater visual census. Sampling was conducted at two habitat types (Posidonia oceanica meadows and rocky reefs) that occur at sites of different protection level with respect to fisheries (high protection: seasonal no-take zone within the MPA; intermediate: zones within the MPA where small-scale fishing is allowed; none: areas outside the MPA, where all types of fishing are allowed, including trawlers, purse seiners, and recreational fishing). The data were used to examine the effects of protection level and habitat type on community parameters, trophic structure and functional diversity of fish populations that occupy the upper sublittoral zone. Overall, habitat type had a more pronounced effect than protection level on all investigated parameters. Biomass, density and number of fish species with low commercial value were higher in sites of intermediate protection, but no substantial fisheries-related ecological benefits were detected for targeted fish in the seasonal no-take zone. Conducted 8 years after the initial implementation of the seasonal no-take management scheme, our study suggests that existing fishing regulations in the NMPZ provide some measurable effects, but fall short of maintaining sufficient protection for the recovery of apex predators or other commercially important fish species. A revision of the existing zoning system to include permanent no-take zones, alongside the regulation of professional fishing and all extractive activities in the rest of the MPA, are strongly encouraged in order to enhance the effectiveness of fisheries management.

The spread of artificial night lighting is increasingly acknowledged as a major threat to global biodiversity. Identifying and exploring the impacts of nightlight pollution upon species behavior, ecology and population dynamics could enhance conservation capacity. Sea turtle hatchlings emerge from nest at night and use visual cues to direct towards the brightest and lowest horizon, eventually leading them to the sea. Nightlight pollution could alter the cues perceived, disorienting the fragile hatchlings. We examined the level of artificial lighting and orientation patterns of sea turtles hatchling, in Zakynthos Island, Greece, one of the main nesting rookeries of the loggerheads ( Caretta caretta ) in the Mediterranean Sea. We analyzed movement patterns of 5967 hatchlings from 230 nests, and demonstrate that nightlight pollution could reduce population recruitment by more than 7%, suggesting that mitigation measures should become a high conservation priority. Our results further suggest that the responses of sea turtle hatchlings to artificial nighttime lighting could vary significantly depending on various factors, either anthropogenic or natural. Local conditions operating at the nesting site level determine the fine scale responses of hatchlings, thus conservation measures should be drawn in respect to site-specific properties.

The present study investigates the structure and intra-annual variation of the benthic macrofaunal community associated with a monospecific C. prolifera meadow in a shallow semi-enclosed coastal marine ecosystem of the eastern Mediterranean Sea (Elounda Bay, Crete Island). The samples were collected on five occasions (May, September and November 2006, February and April 2007) by using an epibenthic sledge (0.5 mm mesh size). The analysis of the macrofauna revealed 319 taxa with densities ranging from 71 to 410 individuals m −2 . The most diversified animal groups were polychaetes, gastropods and amphipods. Crustaceans were by far the most abundant group with densities exceeding 50% of the total macrofauna during the study period. The dominant species were the amphipods Caprella acanthifera acanthifera, C. rapax and Microdeutopus stationis, the gastropod Pusillina lineolata, the tanaid Leptochelia sp. and the bivalve Abra alba. The results of the present study revealed a relatively high diversified and abundant benthic macrofauna, which is supported by the presence of the dense and continuous canopy of C. prolifera in this shallow wave-sheltered area characterized by high organic matter input.

The coralligenous habitat was studied at the large Mediterranean scale, by applying a standardized, non-destructive photo-sampling protocol, developed in the framework of the CIGESMED project. the results provided evidence to support the following statements: (a) the assemblage pattern is not homogeneously distributed across the four Mediterranean ecoregions studied (biotic gradients hypothesis); and (b) the assemblage pattern does not change significantly when the information is aggregated to higher taxonomic levels (taxonomic sufficiency hypothesis). Surrogate taxonomic categories higher than species, such as genus and family, can be used to reveal the multivariate pattern of the coralligenous assemblages. Although preliminary at the pan-Mediterranean scale, these outcomes set the scene for future comparisons as more data sets become available but also for comparisons between taxonomic and functional patterns. 1.2.3.4., CNRS - ANRFrench National Research Agency (ANR)Centre National de la Recherche Scientifique (CNRS) [12-SEAS-0001-01, 12-SEAS-0001-02, 12-SEAS-0001-03]; General Secretariat for Research and TechnologyGreek Ministry of Development-GSRT [12SEAS-2-C2]; Turkiye Bilimsel ve Teknolojik Arastirma KurumuTurkiye Bilimsel ve Teknolojik Arastirma Kurumu (TUBITAK) [112Y393], CNRS - ANR, Grant/Award Numbers: 12-SEAS-0001-01, 12-SEAS-0001-02, 12-SEAS-0001-03; General Secretariat for Research and Technology, Grant/Award Number: 12SEAS-2-C2; Turkiye Bilimsel ve Teknolojik Arastirma Kurumu, Grant/Award Number: 112Y393

15 pages, 6 figures, 4 tables, Coralligenous formations are biogenic structures typical of the underwater Mediterranean seascape. Their intricate, multi-layered species assemblages are composed of perennial, long-lived organisms, particularly vulnerable to natural or human-induced disturbances. Despite their high ecological role and conservation value, few studies have addressed the assemblages outside the NW Mediterranean. This is the first quantitative assessment of coralligenous in the N Aegean Sea (NE Mediterranean), specifically focusing at the upper bathymetric limit of assemblages that are dominated by the yellow gorgonian Eunicella cavolini. The number and percent cover of macrobenthic species were studied at depths of 18 to 35 m, using a photoquadrat method. A total of 99 benthic taxa were identified, out of which 89 perennial ones were used to investigate spatial patterns in assemblage structure, composition, and biodiversity. A mean number of 47 perennial taxa were recorded per site, with encrusting coralline algae and sponges being the dominant groups in percent cover and species number, respectively. Across the studied localities, structural complexity and community composition were overall similar, but assemblages presented distinctive differences at the level of sites highlighting the role of local abiotic and anthropogenic factors in the shaping of the coralligenous. Compared to the rest of the Mediterranean, assemblages hosted a similar number of taxa. However, the number and percent cover of erect bryozoans were generally low, while, apart from E. cavolini, other erect anthozoan species were absent. This work provides an important baseline for comparisons and monitoring at a local or Mediterranean scale level, This work has been co-financed by the EU Social Fund and Greek National Funds through the NSRF 2007-2013 Research Funding Program: Heracleitus II, Investing in knowledge society

The present study investigated for the first time in the eastern Mediterranean Sea species composition, density, wet biomass and body size of fish and cephalopod species associated with a Caulerpa prolifera meadow in a shallow semi-enclosed coastal marine ecosystem (Elounda Bay, Crete Island). Quantitative sampling with a local boat seine, revealed 34 fish species belonging to 22 families and three cephalopod taxa. The number and density of species peaked during the summer sampling period due to high numbers of juveniles, while the highest wet biomass was observed during the autumn sampling period. The fish species Boops boops , Spicara smaris , Mullus barbatus and the non-indigenous Siganus luridus were dominant, making up a high proportion of the total fish fauna of the studied area. The cephalopod Sepia officinalis was the most important species, in terms of wet biomass. The results of the study indicated that the semi-enclosed coastal marine ecosystem of Elounda Bay, characterized by a dense monospecific C. prolifera bed as well as specific abiotic and biotic features could be regarded as an important habitat for the development of fish and cephalopod species, thus contributing to the conservation and maintenance of marine biological resources of the area.

Environmental change can alter both species distribution range patterns at a regional scale and their feeding habits at a local scale. While several studies have highlighted the mechanisms driving such changes separately, little is known on their combined effect on the local communities. In this manuscript, we used both feeding and distributional traits of macro-benthic species and examined their combined response across an environmental gradient induced by an aquaculture unit. Our results mainly suggest that specialized predators with narrow geographic distributions and niches were more sensitive to environmental change than the less specialized groups. Moreover, under harsh environmental conditions, predatory species with a wide dispersion capacity can sustain viable populations through niche generalization. In contrast, in areas of low environmental disturbance, predatory species with a more restricted dispersal capability (i.e. some endemic species) can coexist via niche differentiation. In this context, our findings contribute towards a better understanding of benthic communities’ functional response to environmental change and may be of use in environmental impact assessment.

The benthic boundary layer (BBL) macrofauna consists of epibenthic, hyperbenthic and zooplanktonic organisms with different degrees of mobility and bottom dependence. The top-level predators within this habitat include demersal fish species. The BBL species are considered to be the most readily available prey for these fish making them an attractive source of food and therefore key taxa in marine food webs. The present study is a field experiment in the oligotrophic continental shelf of Heraklion Bay (Cretan Sea, eastern Mediterranean) investigating the ways in which demersal fish utilize BBL sources as food. Species diversity patterns derived from samples collected by using a modified hyperbenthic sledge as well as different benthic, hyperbenthic and pelagic samplers are described. These patterns are compared with those derived from stomach content analysis of demersal fish species inhabiting the same area. Results reveal that BBL macrofaunal communities which comprise most of the available prey communities are largely exploited by demersal fish species. Furthermore, the application of different samplers provides complementary information on prey selectivity of macrofaunal organisms by demersal fish species, highlighting further the trophic interactions within the BBL habitat.

The effective conservation of marine biodiversity through an integrated ecosystem-based management approach requires a sound knowledge of the spatial distribution of habitats and species. Although costly in terms of time and resources, acquiring such information is essential for the development of rigorous management plans and the meaningful prioritization of conservation actions. Located in the northeastern part of the Mediterranean, the Aegean Sea represents a stronghold for marine biodiversity. However, conservation efforts are hampered by the apparent lack of spatial information regarding marine habitats and species. This work is the first to address this knowledge gap by assembling, updating, and mapping information on the distribution of key ecological components. A range of data sources and methodological approaches was utilized to compile and complement the available data on 68 ecological features of conservation interest (58 animal species, six habitat categories, and four other vulnerable ecological features). A standardized data evaluation procedure was applied, based on five semi-quantitative data quality indicators in the form of a pedigree matrix. This approach assessed the sufficiency of the datasets and allowed the identification of the main sources of uncertainty, highlighting aspects that require further investigation. The overall dataset was found to be sufficient in terms of reliability and spatiotemporal relevance. However, it lacked in completeness, showing that there are still large areas of the Aegean that remain understudied, while further research is needed to elucidate the distribution patterns and conservation status of several ecological features; especially the less charismatic ones and those found in waters deeper than 40 m. Moreover, existing conservation measures appear to be inadequate to safeguard biodiversity. Only 2.3% of the study area corresponds to designated areas for conservation, while 41 of the ecological features are underrepresented in these areas. Considering the high geomorphological complexity and transnational character of the Aegean Sea, this study does not offer a complete account of the multifaceted diversity of this ecoregion. Instead, it represents a significant starting point and a solid basis for the development of systematic conservation plans that will allow the effective protection of biodiversity within an adaptive management framework.

Beachrocks are common coastal formations, constructed through the lithification of beach sediments by carbonate cements. The objectives of the present contribution were to (a) assess the impacts of beachrock benthic communities on nearshore wave dynamics; (b) present a numerical model, developed to simulate wave propagation over shallow nearshore waters characterized by both loose sediment beds and colonized/non-colonized beachrocks; and (c) discuss the structure and dynamics of beachrock macro-benthic communities in an E. Mediterranean micro-tidal beach (Vatera, Lesbos Island, NE Aegean Sea), as well as their interactions with the wave forcing. Field measurements of wave height and flow velocity were processed to assess shoaling wave energy dissipation due to bottom friction from the colonized beachrock outcrops. The equivalent Nikuradse hydraulic roughness of the beachrock surface, estimated through spectral wave attenuation calculations, was found to be around kN=0.13 m. The corresponding wave friction factors were incorporated into a wave propagation model to obtain estimates of the wave-induced bed shear stress τw acting on the beachrock benthic communities. Information about the structure and characteristics of the latter was obtained through the collection and analysis of samples from 15 stations along a beach transect, during two months of the year (April and September) and the results showed that benthic communities at the beachrock habitat were very similar to the ones typically found at NE Mediterranean hard substrates. Wave-induced bed shear stress τw values were able to explain cross-shore variations in population density and biomass, both decreasing significantly above water depths of about h=1.8–2 m. The latter values corresponded, for the studied conditions, to shear stresses of about τw=2.2 Nt/m2. The present findings clearly show that nearshore wave patterns not only control to a certain extent the spatial structure of the beachrock habitats, but can be also influenced by them. Thus, hydrodynamics and beachrocks habitats constitute a complex system which remains very little understood and demands for further investigation.

The present study aims to detect functional diversity as well as functional redundancy patterns of soft bottom benthic communities in relation to the prevailing environmental factors, across several brackish water areas. We further tested whether differences in spatial scale can account for the possible variability in functional trait distribution, as well as for the local community assembly processes driven by species functional traits. Our main results suggested that environmental variation induces a large amount of variability in functional trait distribution at local and regional scale, a result which underscores the importance of habitat and environmental variation in the functioning of soft sediments in brackish areas. Conversely to functional diversity, functional redundancy remained invariable in both local and regional scales, therefore acting as an insurance against the enhanced environmental variability and maintaining ecosystem processes and services. Our findings led us also to conclude that environmental factors control the distribution of certain functional traits thus acting as environmental filters, in both local and regional scales. On the other hand, dominant species interactions accounted for the reduced levels of functional divergence at the less confined brackish water areas. This finding supported the view that interactions among dominant species can potentially induce negative effects on the functionality of brackish water soft sediments. From all the above, it is reasonable to assume that community shaping and functioning of the examined brackish water areas are governed by both biotic interactions and environmental filters, which are acting simultaneously at varying degrees of influence.

The relation of macrobenthic species turnover (beta diversity) and species plylogenetic variation with functional diversity patterns, across an environmental gradient induced by an aquaculture unit, in a coastal area of the island of Lesvos (NE Aegean) has been investigated in this study. The contribution of rare species response and species dispersal ability in the variation of functional diversity patterns along the environmental gradient, on a spatio-temporal scale, has been also examined. Our results revealed that benthic functional diversity was decreasing monotonically with increasing species turnover rate and hence with increasing spatial variability along the environmental gradient. Increased environmental stress which was detected in the immediate vicinity of the fish cages resulted to low species functional redundancy, since different species didn’t perform the same functional role at the most disturbed part of the established gradient. Functional diversity patterns were found to be correlated with species population size, whereas a strong linear relationship was also detected with phylogenetic diversity patterns, thus supporting the claim that wider local taxonomic trees can support a wider range of species functions even in small spatial scales. Rare species loss seemed to be one of the dominant factors ruling functional diversity variation. Species with the minimum possible dispersal ability, which were mostly rare, tend to diminish both in species number and population size faster than species with wider dispersal ability towards the most disturbed areas. The aforementioned results indicate that rare species variation and endemic species loss are critical factors in determining functional diversity loss across a human-induced environmental gradient in soft bottom benthic communities.

1. Leaf litter decomposition rates in aquatic ecosystems are known to be related to many abiotic and biotic factors. 2. Field experiments were carried out during spring 2005 in 16 ecosystems, each with four sampling sites, using the litter bag technique to investigate the influence of abiotic factors on patterns of reed litter breakdown in different physiographic, hydrological and physico-chemical gradients occurring in transitional water ecosystems in the Eastern Mediterranean and Black Sea. 3. Significant differences in leaf litter decomposition were observed among the studied ecosystems along univariate gradients of tidal range, water temperature, salinity and sinuosity index. 4. Overall, 71% of variance in the litter breakdown rate was explained by the hydrological, physico-chemical and physiographic components. Specifically, tidal range, salinity and sinuosity index are among the key factors in the most commonly used typological schemes for classifying transitional water ecosystems (i.e. Confinement Concept and Venice System), due to their influence on abundance and distribution of benthic macroinvertebrates and other guilds. 5. The patterns observed at the regional scale of the study suggest that certain key abiotic factors are likely to play a major role as drivers of plant detritus decomposition processes, through their influence on the overall metabolism of microorganisms and benthic macroinvertebrates. 6. These observations have implications for the identification of reference conditions for transitional water ecosystems in the studied area, on which all processes of classification and conservation of their ecological status are based.

1. This paper is focused on the identification of patterns of variation in phytoplankton abundance and taxonomic composition at the eco-regional scale. In addition, these patterns were evaluated with respect to climatic, hydrological and physiographic drivers. 2. A hierarchical sampling design was used to integrate seasonal and spatial variations in taxonomic richness, abundance and taxonomic composition of phytoplankton guilds. Data were collected synoptically during two seasons (autumn and spring) in 12 transitional water bodies in Italy, Albania and Greece. 3. The number of taxa and the cell density of phytoplankton guilds varied between seasons and across ecosystems. Overall, physiographic and hydrological components accounted for 61% of the variation in the number of taxa, but just 19% of the variation in cell density. 4. At the univariate level, cell density varied significantly with temperature, whereas the number of taxa was found to vary significantly with depth, sinuosity index and outlet structure, lagoon surface area and geographic location. 5. The taxonomic composition of phytoplankton guilds varied markedly among lagoons. More than 61% of the 242 taxa identified overall were detected in only one of the lagoons. 6. The average similarity of phytoplankton taxonomic structure among ecosystems was 33.15±15.02. Taxonomic similarity varied substantially across both ecosystems and seasons. Overall, more than 70% of variance in taxonomic similarity was explained by physiographic and hydrological forcing factors. Specifically, differences in taxonomic structure were found in transitional ecosystems showing differences in outlet structure, depth and salinity, as well as geographic location. A recurrent pattern of decreasing taxonomic similarity with increasing Euclidean distance was observed for each factor. 7. The results obtained in this study suggest that certain large-scale driving forces can explain eco-regional scale patterns of species richness and taxonomic composition but not of cell abundance, which are probably more affected by local forcing factors.

1. Solar saltworks are man-made systems for the production of salt and are characterized by high habitat heterogeneity owing to the existence of a strong salinity/confinement gradient. Although solar saltworks are considered to be artificial systems, they are also coastal aquatic ecosystems sharing common characteristics with natural transitional waters ecosystems, which are of special interest to the Water Framework Directive (2000/60/ EC). 2. Spatial and seasonal distribution of macrobenthic invertebrates in relation to the abiotic environment of two Mediterranean solar saltworks ecosystems were assessed in this study. The spatial distribution investigated in this study ranged from the regional scale (Kalloni Saltworks, NE Aegean and Margherita di Savoia Saltworks, S. Adriatic) down to a local scale of 100s of metres in each ecosystem. 3. The macrobenthic community was variable at most spatial and seasonal scales examined in this study: spatial variability at the regional level was greater than seasonal variability within ecosystems and spatial variability among the salinity/confinement gradient levels was greater than within-level variability. 4. The abiotic environment, in both its spatial and seasonal aspects, was found to be crucial in determining the macrobenthic community structure. Biotic factors such as the life cycle of key species, the inter-specific competition as well as dispersion/colonization/extinction processes were also found to play an important role in structuring the macrobenthic fauna both in space and time. 5. A strong similarity of the macroinvertebrate faunal composition and community structure of the lower salinity ponds of solar saltworks with that of natural transitional waters ecosystems was observed. Therefore, solar saltworks ecosystems can be considered as important sites of study for the purposes of the Water Framework Directive.

The distribution patterns of fish assemblages within streams can provide insights for river type classifications and may warrant specific conservation actions. However, there is limited knowledge of how fish assemblages assort along a longitudinal axis in Mediterranean intermittent streams. Patterns in spatial and temporal distribution of fish communities were analysed in a Mediterranean intermittent river (Evrotas River) located in Southern Greece, hosting three endemic range restricted species of high conservation concern, during the period 2007−2009, with 80% of the river’s total length desiccating in the 2007 and 2008 droughts. The general trend was an increase in fish density and species richness along an upstream-downstream gradient. Fish assemblages from upstream to downstream were characterized by a decrease of the most rheophilic species (Squalius keadicus) and an increase of the most stagnophilic species (Tropidophoxinellus spartiaticus). Three river segments, characterized by a high degree of homogeneity were delineated. Habitat and environmental preferences for the studied fish species were identified, with elevation and low flowing habitats being the most important environmental factors affecting fish distribution patterns. The current study provides evidence that even in an intermittent river an assemblage pattern following a longitudinal gradient can be identified, mainly due to the lack of instream barriers that allows recolonization after flow resumption.

Cross-community congruence patterns of species diversity metrics and community sim- ilarity between macrobenthic infauna, epibenthic megafauna, demersal fish and microzooplankton ciliates were studied in 6 areas in the Eastern Mediterranean. These species-rich communities, co- occurring in space and time, were intensively sampled during 2 cruises, in seasons reflecting differ- ent levels of subtle anthropogenic stress. Comparisons of patterns showed high positive correlation of similarities in community structure between macrofauna and megafauna, megafauna and fish and fish and microzooplankton. However, the employed diversity metrics varied between communities, occasionally showing negative correlations. We suggest that the species composition and diversity of these communities reflect different environmental gradients and sources of heterogeneity, and there- fore none of them can be used as a surrogate for ecosystem biodiversity in the context of marine conservation planning.

Time series analysis techniques (ARIMA models), artificial neural networks (ANNs) and Bayesian dynamic models were used to forecast annual loliginid and ommastrephid landings recorded from the most important fishing ports in the Northern Aegean Sea (1984–1999). The techniques were evaluated based on their efficiency to forecast and their ability to utilise auxiliary environmental information. Applying a “stepwise modelling” technique, namely by adding stepwise predictors and comparing the quality of fit, certain inferences concerning the importance of the predictors were made. The ARIMA models predicted the test data very precisely (high R 2 ), especially if the target time series contained a strong autoregressive character, after they were first differenced to obtain stationarity ( R 2 > 0.96). The disadvantage of the ARIMA, as with most statistical models, is their assumption that the relationships and system parameters remain the same across the observation and forecasting periods. The influence of temperature on catches was mainly investigated by applying neural models, which predicted the monthly landings with high precision ( R 2 = 0.89), even when incorporating in the model exclusively monthly SST descriptors. Similarly, ANN models of annual landings containing monthly mean temperatures provided high precision ( R 2 = 0.87) and valuable inference concerning the possible effect of the SST in certain months. Bayesian dynamic models also provided a high precision ( R 2 = 0.96). They combined the information of both environmental and landing time series, namely the monthly mean temperatures and the monthly seasonality of the landings. The impact factors estimated from the model have the form of time series representing the temperature effect. The results reveal that both the monthly and the annual landings can be predicted and that the Bayesian model is the best performer overall, characterised by a higher number of stable forecasts, and forecasts with higher precision and accuracy, than the other methods. It is evident, from application of the “stepwise modelling” technique, that the incorporation of temperature descriptors can significantly improve the model performance.

This review attempts to estimate the biodiversity of the macrobenthic communities that develop on hard bottoms in the Aegean Sea. Literature analysis revealed that 1,171 species inhabit the hard substrate communities, constituting 20.9% of the total Mediterranean species. The hierarchical cluster analysis of the available data identified five major types: (1) the supralittoral communities, (2) the midlittoral communities, (3) the port communities, (4) the various facies of the photophilic algae community, and (5) the facies of the sciaphilic algae community. Thus, hard bottom communities in the Aegean seem to be separated mainly according to vertical zonation. A total of 68 hard-bottom species are under multiple exploitation, providing considerable economic profit. Taking into account the structural complexity of hard substrate benthic communities and their sensitivity to disturbances, it is essential to preserve the biodiversity of these biotopes.

An attempt is made to compare the results of different rapid biodiversity assessment techniques at the pan-Mediterranean, sectorial and local levels. A uniform multivariate pattern exists at the pan-Mediterranean and national (sectorial) levels: lagoons can be different when they host only a few species, but as species numbers increase, lagoons become homogenous in composition. Multivariate techniques cannot distinguish anthropogenically-impacted lagoons from those, which are naturally disturbed. In the pan-Mediterranean context it is the higher taxonomic levels, but in the national and local context it is the most abundant macrobenthic groups (polychaetes, molluscs and crustaceans) and meiobenthos which provide patterns closest to that derived from the species level. Taxonomic distinctness indices applied to polychaete and mollusc inventories provide meaningful results at most levels and scales of observation. These indices seem to be robust enough to discriminate anthropogenically impacted from naturally disturbed lagoons.

Scientific information on the biodiversity of marine caves in the eastern Mediterranean is limited, especially when considering the extensively studied caves of the north-western and central Mediterranean. Aiming to enhance current knowledge regarding cave communities, this study represents a first assessment of the marine cave biota of the eastern Mediterranean, as this has been defined by the European Union’s Marine Strategy Framework Directive (MSFD). Information retrieved from an extensive overview of relevant scientific documents was combined with original data recorded from 23 marine caves of the north-eastern Mediterranean. Our results report a total of 520 taxa recorded in eastern Mediterranean marine caves to date, the majority of which are sponges, polychaetes, rhodophytes, bivalves, fishes, and gastropods. These include several protected, endemic, and alien species. However, not all taxonomic groups have been equally studied among different areas and future studies are expected to raise the number of endemic and alien species. The overall observed trend is that the reported species number is generally related to sampling effort and scientific expertise. The most well-studied marine cave communities of the eastern Mediterranean are those of the Aegean Sea (especially its northern sector), which presented the highest number of species, followed by those of the Levantine. Furthermore, our research in Aegean caves revealed numerous new records for the marine cave fauna of the eastern basin, while several species are reported for the first time in the marine cave habitat. The critical need for further scientific research, monitoring, and conservation of this unique ecosystem was highlighted by (i) the presence of certain species endemic to the eastern Mediterranean coupled with a high proportion of alien species, especially in the Levantine, and (ii) the marine cave habitat availability in isolated insular areas of the eastern Mediterranean.

Ten alien species were recorded in a first-time survey of the benthic biodiversity of the upper sublittoral at Sigri Bay (Lesvos Island, north-eastern Aegean Sea). The record of the mollusc Syrnola fasciata is the first in Hellenic territorial waters. The records of the brown alga Stypopodium schimperi, the bivalve Septifer cumingii, the gastropods Syrnola fasciata and Smaragdia souverbiana and the bony fish Siganus luridus constitute evidence for a further northwards extension of their geographic ranges in the Aegean Sea. The record of Cerithium scabridum is the first in Lesvos Island and partially fills the gap in the distribution of the species in the eastern Aegean Sea. We also recorded the green alga Caulerpa cylindracea, the angiosperm Halophila stipulacea and the bivalve Pinctada imbricata radiata, which are widely distributed in the eastern Mediterranean. The polychaete Marphysa adenensis, which was also found at Sigri Bay, has recently been reported for the first time from the Mediterranean as a cryptogenic species.

According to reports, the following 16 species have extended their distribution to other Mediterranean areas or have made a new appearance in other regions. The first category includes the following organisms: The rare and common Indo-Pacific seaweed Codium arabicum (Lebanese coasts), the acari Thalassarachna affinis (Marmara Sea), and the non-indigenous nudibranch Flabellina rubrolineata , which has also been found in many other areas of the Aegean Sea. In addition, the rare sea slug Thecacera pennigera (Piccolo of Taranto), the fangtooth moray Enchelycore anatina (National Marine Park of Zakynthos, Ionian Sea), the carangid Seriola fasciata (Gulf of Antalya), Lagocephalus sceleratus (SE. Ionian Sea), the reticulated leatherjacket Stephanolepis diaspro s (Slovenia, N. Adriatic Sea), the marbled stingray, Dasyatis marmorata (NE Levantine), the starry smooth-hound Mustelus asterias (Iskenderun Bay, NE Mediterranean), the cephalopod Ommastrephes bartramii (Ionian Sea) have also been reported. The Atlantic crab Dyspanopeus sayi has expanded to many Italian areas and the blue crab Callinectes sapidus to a lake in N. Greece and in the S. Adriatic Sea. Finally, Farfantepenaeus aztecus has been found in the Ionian Sea, thus showing its wide expansion in the Mediterranean. The larval stages of Faccionella oxyrhyncha have been found, after many years, in the Aegean Sea and the first report of an existence on intersexual acari Litarachna duboscqi in Split (Adriatic Sea) was reported.

Gialova Lagoon, a coastal marine ecosystem in the Ionian Sea, suffered the impact of an oil spill incident in October 1993, leading to the extensive fish deaths when the oil tanker “Iliad” hit bottom in the entrance of the neighbouring Navarino Bay. A multidisciplinary study investigating the structure and functioning of Gialova Lagoon for the development of an integrated economic, social, and environmental management policy consistent with its conservation was carried out on a seasonal basis during 1995/1996. One of the research priorities was to investigate the structure and dynamics of the macrozoobenthic communities and assess whether these communities had recovered from the impact of the oil spill. The various methods applied (abundance/biomass comparison, distribution of species in geometric abundance and geometric size classes) revealed no detectable disturbance of the macrobenthic communities due to anthropogenic impact. However, it was proved that the lagoonal macrofauna suffered extreme natural disturbance due to a dystrophic crisis that occurred during autumn although they successfully recovered in subsequent seasons. Different sets of environmental factors were found to be highly correlated with the temporal and spatial distribution pattern of the macrobenthic communities and are discussed in detail. The coenocline observed in Gialova Lagoon appears to be strongly correlated with the degree of water exchange with adjacent marine and continental environments.

Macrobenthic faunal composition, abundance, biomass and diversity together with a suite of sedimentary environmental parameters were investigated on a seasonal basis in order to determine factors regulating faunal distribution over the oligotrophic continental margin of the island of Crete (South Aegean Sea, North Eastern Mediterranean). Macrofaunal species composition was similar to that of the western Mediterranean and the neighboring Atlantic having several common dominant species. Mean benthic biomass, abundance and diversity decreased with depth, with a major transition zone occurring at 540 m, beyond which values declined sharply. At comparable depths biomass and abundance values were considerably lower to those found in the Atlantic, high-lighting the extreme oligotrophy of the area. The continental margin of Crete was characterised by a high diversity upper continental shelf environment (dominated by surface deposit feeding polychaetes) and a very low diversity slope and deep-basin environment (dominated by carnivorous and filter feeding polychaetes). Classification and ordination analyses revealed the existence of four principle clusters divided by a faunal boundary between 200 and 540 m, as well as beyond 940 m depth. Significant correlations between macrofauna and sediment parameters led to the conclusion that besides depth, food availability (as manifested by the concentration of chloroplastic pigments) is the principle regulating factor in the system. Such being the case, the prevailing hydrographic features that structure the pelagic food web and are directly responsible for the propagation of organic matter to the benthos also affect its community structure.

The deep sea molluscan fauna of the Cretan Sea (Eastern Mediterranean) was investigated from living material collected by the R/Vs“AEGAEO” and“PHILIA” cruises in the framework of the MTP/MAST EU research programme CINCS, carried out by the I.M.B.C. Examination of the deep sea benthos, with particular reference to the phylum Mollusca, over a grid of stations from depths between 40 and 1570 m, revealed the presence in the area of a diverse fauna consisting of 147 species belonging to 6 different classes. Large numbers of species (44) are new elements of the molluscan fauna of the Cretan Sea while another 4 species (1 Polyplacophora, 2 Gastropoda, and 1 Bivalvia) have not been reported so far from the Aegean or the Eastern Mediterranean. The majority of the species exhibit a wide bathymetrie distribution, from the continental shelf region to the bathyal slope, and only a few species are considered as deep sea species (reported only from the latter). The faunal composition of the collected material from the studied area (in depths over 200 m) clearly demonstrates the presence in the Cretan Sea of theAbra longicallus-association, already reported in other deep basins of the Mediterranean where similar research has been carried out. However, the presence of the bivalveNuculoma aegeensis even in the shallow waters of the continental shelf strengthens the opinion of other authors (Janssen 1989;Dounas &Koukouras 1992) that theNuculoma aegeensis “facies” of the above association is not found as deep asdi Geronimo (1974) had claimed (1500 m). Most of the deep sea mollusc species collected from the Cretan Sea are distributed from the Mediterranean to the Atlanto-Mediterranean and Boreal province while no species with an Indo-Pacific origin (Lessepsian immigrants) were found. Taking into consideration results of studies on the molluscan fauna from shallow waters of the Cretan Sea (Koutsoubas et al. 1992) it can be concluded that this part of the Mediterranean could not be considered as an impoverished system, as it hosts a rather enriched and diverse molluscan fauna numbering more than 400 species.

The higher taxonomic structure of a meiofaunal community was investigated in an Eastern Mediterranean lagoon (Gialova lagoon, Ionian Sea). Seven stations were sampled on a seasonal basis during 1995–1996. Stations within the lagoon were found to support a maximum of 14 meiofaunal taxa with densities ranging from 17 to over 2000 individuals per 10 cm2. Nematodes were not always the most abundant taxa, although they dominated about half of the total 28 samples. Uni- and multivariate analyses were employed to study the community structure. The distribution pattern of the meiofaunal community varied both across the lagoon and over the seasons. On the basis of the spatial differences a meiofaunal coenocline, correlated with the degree of isolation, was observed, composed of mainly two zones: one defined by the area close to the marine channel and the other the more isolated area in the inner lagoon. Meiofaunal distribution pattern was not clearly correlated to one environmental variable, but rather to many, and spatial and seasonal effects could be seen.

The annelid community of a shallow Mediterranean lagoon (Gialova Lagoon, Ionian Sea) was studied on a seasonal basis. Out of the 39 species identified eight are reported for the first time from the central Mediterranean. The dominant species were the polychaetes Capitella capitata, Neodexiospira pseudocorrugata, Malacoceros fuliginosus, Perinereis cultrifera, Hediste diversicolor, Heteromastus filiformis and the oligochaete Limnodriloides maslinicensis. Uni- and multivariate methods were employed to study the community structure. The coenocline observed is strongly related to the degree of isolation; its main features (i.e. number of species, density, geometric abundance and size-classes) in space and time are presented and discussed in detail. The distribution pattern of the annelid community has been found to be governed by a different set of environmental factors in each season. Although this narrow lagoonal habitat suffers severe dystrophic episodes it manages to recover, demonstrating a seasonal community pattern.

Katsanevakis, Stelios ... et. al.-- 9 pages, 5 figures, supplementary data associated with this article can be foundin the online version at https://doi.org/10.1016/j.marpol.2014.07.013, In the Mediterranean Sea, socio-economic drivers may accelerate the process of exclusive economic zone (EEZ) declarations. Despite the challenges, the EEZ declarations may provide important opportunities for leveraging change to national policy towards the development of large-scale conservation of marine ecosystems and biodiversity in this zone. Using the Mediterranean Sea as a case study, we aim to highlight a set of best practices that will maximize the potential for the development of large-scale marine conservation initiatives. These include a range of approaches, such as using surrogates to fill the many biodiversity data gaps in the region, further the development of consistent and open access databases, and the utilization of technological developments to improve monitoring, research and surveillance of less accessible and under-explored marine areas. The integration of Mediterranean-wide and local conservation efforts, the facilitation of transboundary collaboration, and the establishment of regional funds for conservation will further enhance opportunities for marine conservation in this region. © 2014 Elsevier Ltd., SG was supported by the project “NETMED” co-funded by the European Social Fund and the Greek State. MC was funded by the Marie Curie Career EU Integration Grant Fellowships to the BIOWEB project and by the Spanish National Program ‘Ramon y Cajal’. PM was supported by the National Foundation for Civil Society Development and the project ‘NETCET’ funded by the IPA Adriatic CBC program. SaK is an Australian Research Council Future Fellow

Five opisthobranch species (Pleurobranchus testudinarius, Caloria elegans, Dondice banyulensis, Janolus cristatus and Flabellina babai) unrecorded up-to-date in the Greek seas along with Scyllaea pelagica and Notarchus punctatus species reported after more than a century from their first finding in the Mediterranean (southern Aegean—Milos and Serifos Islands) by Forbes (1844), and zoogeographical and ecological details, are presented in this study. Scyllaea pelagica, N. punctatus and F. babai seem to have a narrow distribution in Greek waters while the rest of the species seem well established similar to what has been reported from other seas in the western Mediterranean or the Atlantic.

Molluscan diversity associated with sublittoral soft-bottoms was studied in Heraklion Bay as part of a long-term multidisciplinary research programme in the coastal environment of northern Crete (eastern Mediterranean). Quantitative benthic samples were collected in a pilot survey from a grid of 28 stations, followed by a seasonal sampling carried out over a seven- station transect located from 10 to 40 m depth. Univariate and multivariate analyses indicated the presence of a clear zonation along the depth gradient for the molluscan fauna and three main associations were identified in bathymetric zones parallel to the coastline. The structure of the local molluscan communities revealed the existence of an extended transition zone (ecotone) between a shallow sandy association and a deeper muddy one and a functional pattern, based on the feeding guilds, was evident along the environmental gradient. Application of graphical techniques, by using molluscan taxocoenosis, indicated a rather naturally disturbed habitat. Beta-diversity measures indicated different seasonal community adaptations to the prevailing environmental conditions. Results derived from this study revealed that beta-diversity may be a good descriptor for the assessment of the strength and breadth of sublittoral transition zones along environmental gradients., La diversidad malacológica asociada a la zona infralitoral de fondos blandos se ha estudiado en la bahía de Heraklion como parte de un programa de investigación multidisciplinar a largo plazo en la costa norte de Creta (Mediterráneo Oriental). Muestras cuantitativas del bentos fueron recogidas durante un muestreo piloto realizado en una parrilla de 28 estaciones. A continuación se realizó un muestreo estacional en un transecto de siete estaciones situadas entre 10 y 40 m de profundidad. Los análisis univariables y multivariables indicaron la presencia de una clara zonación malacológica a lo largo del gradiente de profundidad, identificándose tres asociaciones principales en zonas batimétricas paralelas a la línea de costa. La estructura de las comunidades locales de moluscos puso de manifiesto la existencia de una extensa zona de transición (ecotono) entre la asociación de arena somera y la de fango profundo y evidenció un patrón funcional basado en los tipos de alimentación a lo largo del gradiente ambiental. La aplicación de técnicas gráficas, empleando la taxocenosis de moluscos, indicó un hábitat perturbado. Lla diversidad beta indicó diferentes adaptaciones de las comunidades estacionales a las condiciones ambientales reinantes. Los resultados obtenidos en este estudio muestran que la diversidad beta puede ser un buen descriptor para la evaluación de la capacidad y la amplitud de las zonas de transición sublitoral a lo largo de gradientes ambientales.

The paper summarises the available information on the main biological components – phytoplankton, zooplankton, phytobenthos, zoobenthos and fish – of Greek lagoonal ecosystems. Meiobenthos was also studied in one of the lagoons. All components show great variability both in space and time, which is attributed to the variability of environmental conditions. The most important variable influencing species distribution and diversity is the degree of communication with the sea and the nutrient load introduced through fresh water inputs. Certain new methods, which have been applied for evaluation of the ecological quality state of the lagoons, are also presented.

Recognising the need for data gathering at taxon level besides the taxa of commercial interest and those listed as endangered in the Protocol of the Barcelona Convention, but still exploited by Man, the present study attempts to gather and review the available scientific information on molluscs of minor commercial importance in order to assist in the adequate management and protection of their populations. Forty one species (18 gastropods, 13 bivalves, and 10 cephalopods) of minor commercial interest are treated in the present work with details on their biogeographic distribution, exploitation and conservation status in Hellas. Apart from a few species (e.g., Pinna nobilis, Lithophaga lithophaga, Donacilla cornea), and these only at a local scale, there is no population assessment in Hellenic seas. The existing legislation for eleven of these species is not enforced in practice, and seems insufficient to guarantee their conservation. It is suggested that targeted collection data, networked nationally and internationally, should be promoted so this invaluable source of biodiversity information can be accessed for conservation and planning purposes.

Nutrient dynamics for phosphate, nitrate, ammonium and silicate have been simulated with the European Regional Seas Ecosystem Model in a Mediterranean lagoon. This generic model designed for the open sea can be usefully applied also to coastal lagoon ecosystems with minimum modifications. The annual cycles of the nutrients phosphate and silicate compare quite well with the observed ranges of variability. This does not hold for ammonium and nitrate where the increased concentrations could be attributed to external inputs from the land. Nutrient budgets calculated from the model results indicate some competition between phytoplankton and bacteria for nutrients, a common characteristic of lagoons. To further develop the model, an adaptation of the phytoplankton submodel to represent benthic primary production, as well as the modification of the benthic nutrient model to cope with anoxic events, are suggested.