Sea turtles are highly mobile species that use oceanic, neritic, and coastal habitats as nursery, foraging, wintering, breeding and migration areas at distant locations throughout their lifetime. Due to their highly migratory nature and large-scale habitat use, they are subjected to multiple threats across marine and coastal ecosystems that can impact every stage of their life cycle and result in increased mortality rates. Here, we present new data on stranding events across the eastern Ionian Sea (central Mediterranean). Our analysis on stranding data, collected over a 6-year period, provided clear evidence of continuing and increased mortality events in the region (n = 413, Caretta caretta: 79%, Chelonia mydas: 4%, and unknown: 17%). Based on the alarming results of increased mortality, and taking into account the limitations posed by the nature of stranding data, we further identified potential risk hotspots within critical marine and coastal sea turtle habitats. To do so, we performed a spatially explicit cumulative pressure assessment at different spatial scales in an effort to identify, map, quantify, and synthesize the multiple anthropogenic pressures that are recognized to potentially impact sea turtles. Our results clearly demonstrated that the Ionian Sea is subjected to intense pressures (i.e. fisheries, marine traffic, and underwater noise). We identified three main hotspots of very high risk related to critical foraging grounds, nesting sites, and migration corridors for sea turtles regardless of the spatial scale of the analysis. We found high sea turtle mortality associated with locations characterized as high and very high risk areas. This study offers key information on mortality and spatial risk for sea turtles that can facilitate their effective conservation. Thus, our findings can be used in the light of marine spatial planning, allowing planners to more realistically assess where conservation resources should be directed to control harmful activities and to mitigate impacts on sea turtles.

Meadows of Posidonia oceanica harbor rich biodiversity and ecosystem functions, yet Biological Traits Analysis on the resident benthic communities are lacking. This study aims to provide insight on the functional diversity of polychaetes communities, a dominant benthic group, between the different habitat types of P. oceanica (plain meadow, strips/patches and dead matte), as well as pilot indicators of habitat modification. The results showed how specific traits relate to the different habitat types. Plain meadow was different to strips/patches and dead matte in functional composition, diversity and thus, the ecosystem functions involved. However, an overlap was observed in functional composition between dead matte and living P. oceanica, due to the remaining matte structure. This highlights the importance of the former on ecosystem functioning and the serious consequences of its current exclusion from conservational legislation. In addition, the classification of species to ecosystem en-gineering types showed interesting potential as an indicator.

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.

This study presents the length-weight relationships (LWR) for 12 commercial fish species from coastal waters off South Corfu Island (N. Ionian Sea, Greece). All fish originated from the catches made by a single artisanal fisherman during April – September 2009. Multiple types of predominantly static fishing gear were used, mainly gillnets (mesh size: 28 mm) operated at depths of 10–40 m and trammel nets (mesh sizes: 22, 24, 28, 32, 34, 36, 40 mm) operated at depths of 7–70 m. Moreover, bottom longlines and trolling lines were occasionally used, at depths of 20–50 m and 35 m, respectively. Length (TL) in cm and weight in g of all the individuals in the catches were measured in the laboratory. Estimates of the b parameter ranged between species from 2.652 to 3.593. For none of the fish species examined in the present paper has LWR information been published before for the N. Ionian Sea, and for six of them (i.e. for Epinephelus costae, Labrus viridis, Oblada melanura, Sarda sarda, Scomber colias and Scorpaena porcus) there is no LWR information for the Ionian Sea as a whole. The results of this study may thus contribute in fisheries management and marine conservation in the Ionian Sea by providing baseline LWR information for several commercial fish species based on samples of local populations. Moreover, this study contributes in complementing the few LWR datasets that exist in the international literature for E. costae and L. viridis.

Ecosystem-based management requires an assessment of the cumulative effects of human pressures and environmental change. The operationalization and integration of cumulative effects assessments (CEA) into decision-making processes often lacks a comprehensive and transparent framework. A risk-based CEA framework that divides a CEA in risk identification, risk analysis and risk evaluation, could structure such complex analyses and facilitate the establishment of direct science-policy links. Here, we examine carefully the operationalization of such a risk-based CEA framework with the help of eleven contrasting case studies located in Europe, French Polynesia, and Canada. We show that the CEA framework used at local, sub-regional, and regional scales allowed for a consistent, coherent, and transparent comparison of complex assessments. From our analysis, we pinpoint four emerging issues that, if accurately addressed, can improve the take up of CEA outcomes by management: 1) framing of the CEA context and defining risk criteria; 2) describing the roles of scientists and decision-makers; 3) reducing and structuring complexity; and 4) communicating uncertainty. Moreover, with a set of customized tools we describe and analyze for each case study the nature and location of uncertainty as well as trade-offs regarding available knowledge and data used for the CEA. Ultimately, these tools aid decision-makers to recognize potential caveats and repercussions of management decisions. One key recommendation is to differentiate CEA processes and their context in relation to governance advice, marine spatial planning or regulatory advice. We conclude that future research needs to evaluate how effective management measures are in reducing the risk of cumulative effects. Changing governance structures takes time and is often difficult, but we postulate that well-framed and structured CEA can function as a strategic tool to integrate ecosystem considerations across multiple sectorial policies.

Parupeneus forsskali has been the latest Indo-Pacific goatfish species to expand its range into the Mediterranean. It is the least studied alien mullid in the Eastern Mediterranean, and specific information on its diet is generally lacking in the literature. The objectives of this paper are (1) to comprehensively document the progress of its invasion in the Mediterranean through a systematic literature review to retrieve all published records of the species in the region, and (2) to present preliminary quantitative information on its diet in its non-native range. Parupeneus forsskali, first recorded in Cyprus in 2014, has established self-sustaining, reproducing, commercially important populations in the nearshore waters of Cyprus at least since 2017. Significant P. forsskali catches by artisanal fisheries in Cyprus began in late 2017 and have been increasing since. Its particularly successful establishment and spread across Cyprus occurred after a time lag of several years since its introduction in the Mediterranean, possibly during the 1990s or earlier. As the westernmost records of the species along both the southern and the northern Mediterranean coastlines were made in recent years, it is assumed that P. forsskali is currently expanding its range in the Mediterranean. The prey items identified in the stomach contents analysis, ranked by their frequency of occurrence, belonged to the following taxonomic groups: Crustacea (67%), Mollusca (37%), Polychaeta (19%), Foraminifera (12%), Actinopterygii (5%).

Ecological monitoring is a prerequisite for ecosystem-based management and conservation. There is a need for developing an efficient and non-destructive method for monitoring marine benthic arthropods on soft substrate, as the currently applied methods are often inadequate. Pitfall trapping has been used extensively to sample terrestrial arthropods, but has not been seriously considered yet in the marine environment. In this study, the effectiveness of pitfall traps for monitoring marine benthic arthropods was assessed through a case study in the shallow sublittoral zone of Kalloni Gulf, Lesvos Island, Greece. Two different trap types were installed in August 2016 at five depths, during two 12 h periods (day and night). Pitfall traps performed well, collecting a large number of individuals. The hermit crab Diogenes pugilator dominated the catches. The catch of this species significantly differed by trap type, while the interaction between depth and period was also found significant. Further research is needed to evaluate the efficiency of different types of pitfall traps and field protocols in the marine environment.

Biological invasions threaten biodiversity in terrestrial, freshwater and marine ecosystems, requiring substantial conservation and management efforts. To examine how the conservation planning literature addresses biological invasions and if planning in the marine environment could benefit from experiences in the freshwater and terrestrial systems, we conducted a global systematic review. Out of 1,149 scientific articles mentioning both "conservation planning" and "alien" or any of its alternative terms, 70 articles met our selection criteria. Most of the studies were related to the terrestrial environment, while only 10% focused on the marine environment. The main conservation targets were species (mostly vertebrates) rather than habitats or ecosystems. Apart from being mentioned, alien species were considered of concern for conservation in only 46% of the cases, while mitigation measures were proposed in only 13% of the cases. The vast majority of the studies (73%) ignored alien species in conservation planning even if their negative impacts were recognized. In 20% of the studies, highly invaded areas were avoided in the planning, while in 6% of the cases such areas were prioritized for conservation. In the latter case, two opposing approaches led to the selection of invaded areas: either alien and native biodiversity were treated equally in setting conservation targets, i.e., alien species were also considered as ecological features requiring protection, or more commonly invaded sites were prioritized for the implementation of management actions to control or eradicate invasive alien species. When the "avoid" approach was followed, in most of the cases highly impacted areas were either excluded or invasive alien species were included in the estimation of a cost function to be minimized. Most of the studies that followed a "protect" or "avoid" approach dealt with terrestrial or freshwater features but in most cases the followed approach could be transferred to the marine environment. Gaps and needs for further research are discussed and we propose an 11-step framework to account for biological invasions into the systematic conservation planning design.

Length-weight relationships are presented for 9 commercial fish species from Psara Island (North Aegean Sea). The species studied are Boops boops, Dentex maroccanus, Helicolenus dactylopterus, Merluccius merluccius, Mullus surmuletus, Pagrus pagrus, Raja clavata, Scyliorhinus canicula and Trachurus picturatus. To our knowledge, there are no published data on the fish stocks of the study area. Estimates of LWR parameters are provided for Dentex maroccanus, Trachurus picturatus and Helicolenus dactylopterus, for which reliable LWR datasets are few in the literature, while none has been published for the Greek seas. The samples were collected from the continental shelf and the upper slope, by using non-selective fishing gear (with a research vessel and a commercial bottom trawler), during two seasonal sampling periods: November 2009 and May 2010. The growth pattern of Boops boops and Scyliorhinus canicula was found to be positive allometric, whereas an isometric growth pattern was determined for the other species in the study. We hope that the LWR obtained here will be used in future fisheries management or conservation research in the study area, for example, to convert lengths to weights, determine fish condition and assess spatial or temporal variability in fish growth.

Cumulative human impacts have led to the degradation of marine ecosystems and the decline of biodiversity in the European and contiguous seas. Effective conservation measures are urgently needed to reverse these trends. Conservation must entail societal choices, underpinned by human values and worldviews that differ between the countries bordering these seas. Social, economic and political heterogeneity adds to the challenge of balancing conservation with sustainable use of the seas. Comprehensive macro-regional coordination is needed to ensure effective conservation of marine ecosystems and biodiversity of this region. Under the European Union Horizon 2020 framework programme, the MarCons COST action aims to promote collaborative research to support marine management, conservation planning and policy development. This will be achieved by developing novel methods and tools to close knowledge gaps and advance marine conservation science. This action will provide support for the development of macro-regional and national policies through six key actions: to develop tools to analyse cumulative human impacts; to identify critical scientific and technical gaps in conservation efforts; to improve the resilience of the marine environment to global change and biological invasions; to develop frameworks for integrated conservation planning across terrestrial, freshwater, and marine environments; to coordinate marine conservation policy across national boundaries; and to identify effective governance approaches for marine protected area management. Achieving the objectives of these actions will facilitate the integration of marine conservation policy into macro-regional maritime spatial planning agendas for the European and contiguous seas, thereby offsetting the loss of biodiversity and ecosystem services in this region.

This paper describes an occurence dataset, also including numerical abundance and biomass data, pertaining to the macrobenthic molluscan assemblages from a marine - lagoonal environmental transition. The study system was the soft-substrate benthoscape of the area of the Kalloni solar saltworks (Lesvos Island, Greece). Specifically, the study area extended from the infralittoral zone of the inner Kalloni Gulf (marine habitat) to the bottoms of the first two evaporation ponds of the Kalloni solar saltworks (lagoonal habitat). Bottom sediment samples (3 replicates) were collected with a Van Veen grab sampler (0.1 m2) at four sampling sites, along a 1.5 km long line transect that spanned the marine - lagoonal environmental transition. A total of four surveys were carried out seasonally in 2004. A total of 39,345 molluscan individuals were sorted out of the sediment samples and were identified to 71 species, belonging to the Gastropoda (36), Bivalvia (34) and Scaphopoda (1) classes. Numerical abundance and wet biomass (with shells) data are included in the dataset.The dataset described in the present paper partially fills a significant gap in the scientific literature: Because ecological research of coastal lagoons has seldom explicitly considered the marine - lagoonal habitats interface, there are no openly accessible datasets pertaining to the particular structural component of the transitional waters benthoscapes of the Mediterranean Sea. Such datasets could prove valuable in the research of the structure and functioning of transitional waters benthoscapes. The present dataset is available as a supplementary file (Suppl. material 1) and can also be accessed at http://ipt.medobis.eu/resource?r=kalloni_saltworks_phd.

a. evagelopoulos, d. poursanidis, e. papazisi, v. gerovasileiou, n. katsiaras and d. koutsoubas Department of Marine Sciences, University of the Aegean 81100 Mytilene, Greece, Department of Zoology, School of Biology, Aristotle University, 54124 Thessaloniki, Greece, Foundation for Research and Technology – Hellas (FORTH), Institute of Applied and Computational Mathematics, N. Plastira 100, Vassilika Vouton, 70013 Heraklion, Greece, Institute of Oceanography, Hellenic Centre for Marine Research, 46.7 km Athinon-Souniou Ave, 19013 Anavissos, Greece

Structure of four ecotonal environments consisted of lagoons, estuaries and marshes were investigated in comparison with their adjacent marine areas across Kalloni Gulf (Island of Lesvos, NE Aegean) for the first time. Significant differences were detected between and within ecotonal and marine ecosystems in terms of benthic community organization. Ecotonal areas were consisted of typical marine/estuarine and lagoonal species in a varying degree of numerical dominance. Observed differences concerning the prevailing environmental conditions at each ecosystem suggest a strong gradient from the sea towards the ecotones. Biocommunities seemed to experience a pronounced environmental stress only in the ecotones and not in the marine areas. Findings of this study support the role of confinement in the paralic domain in the Mediterranean as a function of a number of environmental factors governing biological communities’ patterns.

This paper focuses on the structure of the phytoplankton and macrobenthic invertebrates communities in a productive solar saltworks, as well as the major abiotic determinants of the observed biotic patterns. The observed patterns in the structure of the biotic communities attest that the ecosystem of the low salinity ponds of Kalloni Saltworks is similar to a productive coastal lagoon. Major abiotic determinants include the salinity and confinement gradients, as well as inorganic nutrients loads. The episodic enrichment of the water column in the ponds with either new nutrients from the incoming seawater, or regenerated nutrients released from the sediment, was shown to stimulate the growth to bloom levels of phytoplankton species indicative of organic enrichment and coastal eutrophication. Algal biomass and the accumulated detritus and organic matter on and within the sediment are exploited by opportunistic herbivores and deposit feeders tolerant to organic enrichment. Management measures are needed for the mitigation of the productiveness of the low salinity ponds, e.g. lower water residence times, a shallower water column, facilitation of the oxygenation of the sediment, sediment removal in winter and culture and harvesting of the naturally occuring, edible Cerastoderma glaucum bivalves.

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.

Solar saltworks are extremely heterogeneous coastal aquatic ecosystems whose benthic biodiversity patterns have not been comprehensively investigated yet. The present study focuses on the seasonal community structure of the macrobenthic molluscs at the marine-lagoonal environmental transition that takes place at Kalloni solar saltworks (Lesvos Island, NE Aegean Sea, Greece). The molluscan community was studied by means of four seasonal collections carried out in 2004 at four sites in the study area. The molluscan community was found to be considerably species-rich and forming a coenocline, as marine species were gradually replaced by lagoonal species with increasing distance from the sea. The major variable in the implied environmental gradient structuring the molluscan community appeared to be confinement rather than salinity, although zonation of the molluscan community structure was rather broad. The pattern of spatial organization of the molluscan fauna did not appear to change seasonally, although seasonal shifts of the zones did occur in the study area.

1. Solar saltworks are man-made systems for the production of salt and tire 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 tire 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 ill this study ranged from the regional scale (Kalloni Saltworks. NE Aegean anti Margherita di Savoia Saltworks. S. Adriatic) down to a local scale of 100s of inetrcs 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 anti 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/coloniztion/extinction processes were also found to play an important role ill structuring the macrobenthic fauna both in space and tinge.5. A strong similarity of the macroinvertebrate faunal composition and community structure of the lower salinity ponds of solar saltworks with that oh natural transition ttl waters ecosystems was observed. Therefore, solar saltworks ecosystems can be considered as important sites oh study for the purposes of the Water Framework Directive. Copyright (c) 2008 John Wiley & Sons, Ltd.

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. Copyright © 2008 John Wiley & Sons, Ltd.

1 - Spatial and seasonal variations of two important biological quality elements (phytoplankton and macrobenthic invertebrates) in Transitional Water (TW) ecosystems were studied in Kalloni Saltworks, located at the island of Lesvos (NE. Aegean Sea, Greece). 2 - A total of 36 phytoplankton taxa, belonging to 5 classes, were collected in the study area during both seasonal samplings. Many of the species found in the study area are coastal/brackish waters species that are commonly encountered in transitional waters ecosystems. A substantial seasonal change in species composition, as well as in the observed trends in density and biomass variations along the salinity gradient was revealed. Blooms of Euglena acusformis, Mesodinium rubrum and phytoflagellates were recorded in the study area. 3 - A total of 43 macrobenthic invertebrates taxa, belonging to 6 major groups, were collected in the study area during both seasonal samplings. Most of the abundant macrobenthic invertebrate species in the study area were typical lagoonal or marine/estuarine species commonly occuring in coastal lagoons, whereas typical marine species gradually disappeared downstream the pond sequence. The patterns of variation of macrobenthic invertebrates' density and biomass along the salinity gradient were different between seasons, partly due to the strong dominance of Hydrobia acuta in autumn, while species richness declined along the salinity gradient in both seasons.

1 - Leaf litter decomposition rates, in aquatic ecosystems, are known to be related to many different abiotic and biotic factors. 2 - Here, we focus on the influence of abiotic factors, searching for patterns of reed litter decay rates on gradient of physiographic, hydrological and physico-chemical components of transitional water ecosystems. 3 - Field experiments were carried out in 16 water ecosystems in the Eastern Mediterranean and Black Sea in spring 2005. 4 - Significant differences of leaf litter decomposition were observed among ecosystems along univariate gradient of tidal range, index of sinuosity, water temperature and salinity. At least 71% of variance in the litter breakdown rate was explained by the considered abiotic factors. 5 - It is concluded that, at the macro-ecological scale of study, some key abiotic factors, such as tidal range and salinity, are suggested to play a major role as drivers of plant detritus decomposition processes. 6 - The relevance of the described abiotic drivers as descriptor of the most commonly used classification schemes for transitional water ecosystems (i.e., Confinement and Venice System classifications), is a further support to their role as environmental forcing factors.