A review on the biodiversity of hard substrate invertebrate communities in the Aegean Sea

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

Biological components of Greek lagoonal ecosystems: an overview

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

Molluscan species of minor commercial interest in Hellenic seas: Distribution, exploitation and conservation status

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

Distribution patterns of fish assemblages in an Eastern Mediterranean intermittent river

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

Dužinsko-maseni odnos za 9 komercijalnih vrsta riba iz sjevernog Egejskog mora

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.Prikazani su dužinsko-maseni odnosi za 9 komercijalnih vrsta riba s otoka Psara (sjever Egejskog mora). Istraživane vrste su bukva (Boops boops), marokanski zubatac Dentex maroccanus, bodečnjak veliki (Helicolenus dactylopterus), oslić (Merluccius merluccius), trlja kamenjarka (Mullus surmuletus), pagar (Pagrus pagrus), raža kamenica (Raja clavata), mačka bljedica (Scyliorhinus canicula) i šarun golemi (Trachurus picturatus). Prema saznanjima, nema objavljenih podataka o ribljem fondu ovog istraživanog područja. Procjena parametara dužinsko-masenog odnosa (LWR) iznesena je za zubaca Dentex maroccanus, šaruna golemog (Trachurus picturatus) i bodečnjaka velikog (Helicolenus dactylopterus), za koje u literaturi postoje malobrojni pouzdani podaci o dužinsko-masenom odnosu, dok nema nikakvih objavljenih podataka za mora oko Grčke. Uzorci su prikupljani iz epikontinentalnog pojasa i gornjeg nagiba koristeći neselektivne ribolovne alate (istraživačko plovilo i komercijalna pridnena koćarica) tijekom dva sezonska razdoblje uzorkovanja u studenom 2009. i svibnju 2010. godine. Rast bukve i mačke bljedice alometrijski je pozitivan, dok je izometrični uzorak rasta uočen kod drugih istraživanih vrsta. Smatra se da će dužinsko-maseni odnos koji je ovdje uočen biti ubuduće korišten prilikom upravljanja ribarstvom ili prilikom konverzacijskih istraživanja u istraživanom području, primjerice pretvorbom dužine u širinu, određivanja stanja ribe i procjene prostornih i vremenskih varijabilnosti u rastu riba

Coralligenous formations dominated by Eunicella cavolini (Koch, 1887) in the NE Mediterranean: biodiversity and structure

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.

Towards N=1 Super-Yang-Mills on the Lattice

We consider the lattice regularization of N=1 supersymmetric Yang--Mills theory with Wilson fermions. This formulation breaks supersymmetry at any finite lattice spacing; we discuss how Ward identities can be used to define a supersymmetric continuum limit, which coincides with the point where the gluino becomes massless. As a first step towards the understanding of the zero gluino-mass limit, we present results on the quenched low-lying spectrum of SU(2) N=1 Super-Yang--Mills, at $\beta=2.6$ on a $V=16^3 \times 32$ lattice, in the OZI approximation. Our results, in spite of the quenched and OZI approximations, are in remarkable agreement with theoretical predictions in the supersymmetric theory, for the states with masses which are not expected to get a large contribution from fermion loops.Comment: 25 Latex pages, 5 figure

The yellow gorgonian Eunicella cavolini: demography and disturbance levels across the Mediterranean Sea

The yellow octocoral Eunicella cavolini is one of the most common gorgonians thriving in Mediterranean hard-bottom communities. However, information regarding its distribution and ecology in several parts of the Mediterranean is lacking, while population trends and conservation status remain largely unknown. We investigated 19 populations of E. cavolini over three representative geographic regions: the NW Mediterranean, CE Adriatic, and N Aegean. Focusing on the upper bathymetric range of the species (30 cm). The CE Adriatic displayed intermediate densities, with well-structured populations, and continuous recruitment. In the N Aegean, most populations presented low densities, high proportion of large colonies, but low number of small colonies, signifying limited recruitment. Disturbance levels, as a function of extent and type of injury, are discussed in relation to past or present human-induced threats. This work represents geographically the most wide ranging demographic study of a Mediterranean octocoral to date. The quantitative information obtained provides a basis for future monitoring at a Mediterranean scale

Ecosystem processes: litter breakdown patterns in Mediterranean and Black Sea transitional waters

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

Five key attributes can increase marine protected areas performance for small-scale fisheries management

Marine protected areas (MPAs) have largely proven to be effective tools for conserving marine ecosystem, while socio-economic benefits generated by MPAs to fisheries are still under debate. Many MPAs embed a no-take zone, aiming to preserve natural populations and ecosystems, within a buffer zone where potentially sustainable activities are allowed. Small-scale fisheries (SSF) within buffer zones can be highly beneficial by promoting local socio-economies. However, guidelines to successfully manage SSFs within MPAs, ensuring both conservation and fisheries goals, and reaching a win-win scenario, are largely unavailable. From the peer-reviewed literature, grey-literature and interviews, we assembled a unique database of ecological, social and economic attributes of SSF in 25 Mediterranean MPAs. Using random forest with Boruta algorithm we identified a set of attributes determining successful SSFs management within MPAs. We show that fish stocks are healthier, fishermen incomes are higher and the social acceptance of management practices is fostered if five attributes are present (i.e. high MPA enforcement, presence of a management plan, fishermen engagement in MPA management, fishermen representative in the MPA board, and promotion of sustainable fishing). These findings are pivotal to Mediterranean coastal communities so they can achieve conservation goals while allowing for profitable exploitation of fisheries resources