A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas : the PERSEUS experience

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES. 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.peer-reviewe

Decreased levels of the invasive ctenophore Mnemiopsis in the Marmara Sea in 2001

Mnemiopsis leidyi, an endemic ctenophore of the western Atlantic, was first reported in the Marmara Sea in summer 1992, at an average abundance of 27 ind. m(-3). We investigated its abundance and distribution together with that of the mesozooplankton (most species are prey organisms of M. leidyi) at eight stations during August 2001, in order to evaluate recent population developments with regard to the impact of its predator, Beroe cf ovata. The abundance of M. leidyi was found to be quite low (range 0.5-8.8 ind. m(-3), average 1.62 ind. m(-3)) compared to 1992. B. cf ovata was, although at very low abundance (0.1 - 1.1 ind. m(-3)), only present at stations where M. leidyi occurred. The zooplankton abundance was higher during our investigation than in previous years, which should at least partly be due to a decreased predation impact by M. leidyi

Distribution and mortality of mesozooplankton in the Bosphorous area of the Black and Maramara Seas: salinity tolerance of Acartia clausi and Acartia tonsa.

In October 2005 a sharp decrease of the zooplankton biomass has been recorded from Black to Marmara seas, due to the pronounced decrease of Calanus euxinus, Pseudocalanus elongatus, Acartia clausi and A. tonsa. maximum mortality of the dominant species was found in the salinity gradient layer of the Marmara se

New contributions to the jellyfish fauna of the Marmara Sea

This manuscript deals with the first records of five jellyfish species in the Marmara Sea (Turkey) of previously unrecorded medusozoan species (four hydrozoan taxa, Liriope tetraphylla, Aglaura hemistoma, Solmundella bitentaculata, Neoturris pileata, and one scyphozoan, Paraphyllina ransoni) from plankton collections made in the years 2001-2008. Jellyfish abundances and distribution patterns are reported here, with a discussion about their possible introduction pathways and potential predatory outcomes into the fragile pelagic ecosystem of the Marmara Sea

First inventory of the shallow-water benthic hydrozoan assemblages of the Gökçeada Island (northern Aegean Sea)

The hydroid fauna of the Mediterranean Sea is considered one of the best known in the world, but the hydrozoans of the Aegean Sea remain poorly studied, hindering efforts to identify alien and invasive species in the region. The spatial and seasonal composition of the shallow-water (0–20 m depth) benthic hydrozoan assemblage from Gökçeada Island was investigated in summer 2012 and winter 2013. Overall, 48 hydrozoan taxa were identified, and their presence and ecological features are discussed herein. Twelve species are recorded for the first time in the Aegean Sea, and the same number for the Turkish coasts. Differences in species composition were detected between the northern and southern coasts of Gökçeada by cluster, multidimensional scaling (MDS) and permutational multivariate analysis of variance (PERMANOVA) analysis, whereas seasonal and vertical distribution patterns were not statistically significant. Differences in species richness and composition between the northern and southern coasts may be explained by the distinct geomorphological aspects of the shores, providing a spatial heterogeneity in the availability of substrates for the hydroid colonies. Observed differences are attributable to the occurrence and/or abundance of common species such as Sertularella ellisii, Aglaophenia tubiformis, Clytia hemisphaerica, Clytia linearis, Eudendrium racemosum, Plumularia obliqua, Eudendrium capillare, Turritopsis dorhnii and Dynamena disticha, rather than to the presence of rare, exclusive species

Development and lipid storage in Calanus euxinus from the Black and Marmara seas: Variabilities due to habitat conditions

Oil sac volume, gonad size and moulting patterns were investigated in the copepod Calanus euxinus inhabiting deep and shallow zones of the Black Sea and penetrating into the Marmara Sea. In summer the C. euxinus population in deep layers of the Black Sea was dominated by pre-diapause and diapausing postmoult copepodite stage V (CV) with small sexually undifferentiated gonads and mean lipid content of 14.1 +/- 6.0% of body volume. The lipid content of deep-living females was 7.2 +/- 4.2% of body volume. At the same time, intermoult and premoult CV with enlarged gonads and low lipid content (7.7 +/- 5.1% of body volume) and females with oil sac volume of 1.4 +/- 1.0% were found at shallow stations. Premoult CV with oil volume of 0.6 0.8% and mature females with little visual evidence of substantial lipid storage dominated in the Marmara Sea. The differences in moulting patterns and oil sac volumes of C. euxinus from deep zones and shallow regions suggest that vertical migrations to the oxygen minimum zone (OMZ) are necessary for formation of large lipid reserves providing high reproductive potential of this species. On the basis of an energy balance model it was shown that under low phytoplankton concentration of about 30 mu g C 1(-1) preadults and adults migrating to the OMZ could accumulate lipids (up to 5% of body energy content daily), in contrast to copepods constrained to shallow oxic water columns of the Black Sea and from the Marmara Sea

New records of jellyfish species in the Marmara Sea

This manuscript reports the first observations of three species of Hydrozoa (Podocorynoides minima, Koellikerina fasciculata and Gastroblasta raffaelei) and one species of Scyphozoa (Discomedusa lobata) in the Marmara Sea that were sampled in 2006-2011. Their possible introduction pathways, some ecological and distributional details are briefly discussed here

Development and lipid storage in Calanus euxinus from the Black and Marmara seas: Variabilities due to habitat conditions

Oil sac volume, gonad size and moulting patterns were investigated in the copepod Calanus euxinus inhabiting deep and shallow zones of the Black Sea and penetrating into the Marmara Sea. In summer the C. euxinus population in deep layers of the Black Sea was dominated by pre-diapause and diapausing postmoult copepodite stage V (CV) with small sexually undifferentiated gonads and mean lipid content of 14.1 +/- 6.0% of body volume. The lipid content of deep-living females was 7.2 +/- 4.2% of body volume. At the same time, intermoult and premoult CV with enlarged gonads and low lipid content (7.7 +/- 5.1% of body volume) and females with oil sac volume of 1.4 +/- 1.0% were found at shallow stations. Premoult CV with oil volume of 0.6 0.8% and mature females with little visual evidence of substantial lipid storage dominated in the Marmara Sea. The differences in moulting patterns and oil sac volumes of C. euxinus from deep zones and shallow regions suggest that vertical migrations to the oxygen minimum zone (OMZ) are necessary for formation of large lipid reserves providing high reproductive potential of this species. On the basis of an energy balance model it was shown that under low phytoplankton concentration of about 30 mu g C 1(-1) preadults and adults migrating to the OMZ could accumulate lipids (up to 5% of body energy content daily), in contrast to copepods constrained to shallow oxic water columns of the Black Sea and from the Marmara Sea. (c) 2005 Elsevier B.V. All rights reserved

Adaptability and vulnerability of zooplankton species in the adjacent regions of the Black and Marmara Seas

During 2005-2008 species composition, abundance patterns, natural mortality rates and salinity effects on zooplankton were studied in the Bosphorus regions of the Black and Marmara Seas. The tendencies to diminish for abundance and biomass of the Black Sea originated zooplankton species and to increase for the proportion of their carcasses in the direction from the Black Sea toward the Marmara Sea were found. The mortality in the Black Sea species increased with depth in the Marmara Sea. The contribution of organic matter of carcasses of the Black Sea originated organisms to bacterial processes in the deep strata of the Marmara Sea was estimated. Different salinity and temperature regimes restrict mutual penetration of the species in these seas. (C) 2010 Elsevier B.V. All rights reserved

Salinity tolerance of Calanus euxinus in theBlack and Marmara Seas

We investigated how stenohalinic Black Sea Calanus euxinus, when migrating to the north-eastern Marmara Sea, can adapt to the pronounced salinity gradient there. During field observations (2005 to 2008) females of Calanus euxinus with significantly smaller body length (compared with those inhabiting the brackish Black Sea at 17 to 18 psu) were found in the deep, high-saline (~38.5 psu) layers of the Marmara Sea. Similar diameters of eggs laid by small- and large-sized females and similar respiration rates in nauplii hatched from these eggs indicated the Black Sea origin of the C. euxinus population found in the Marmara Sea. To understand the morphological and physiological changes in C. euxinus during acclimation to high salinity, we studied the effect of salinity on behaviour, food consumption, growth patterns, hatching success and respiration rate of C. euxinus individuals collected in the Black and Marmara Seas. It was shown that the range of salinity tolerance for adult C. euxinus (17 to 30 psu) from the Black Sea was extended gradually to 40 psu after 1 d of acclimation to the high salinity of the Marmara Sea. Long-term parental salinity acclimation facilitates survival of eggs descending through the salinity gradient of the Marmara Sea, from brackish upper layers to deep, high-saline strata, or eggs laid in deep layers. While weight-specific respiration rates at the same temperature did not differ for C. euxinus juveniles from the Black and Marmara Seas, they were ~2 times higher in preadults and adults from the Marmara Sea than from the Black Sea. This may be the reason for the decrease in length and weight increments of these stages probably leadin