National Center for Marine Research

Athens, Greece

National Center for Marine Research

Athens, Greece
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Spatharis S.,University of Aegean | Orfanidis S.,Greek National Agricultural Research Foundation | Panayotidis P.,National Center for Marine Research | Tsirtsis G.,University of Aegean
Estuarine, Coastal and Shelf Science | Year: 2011

The structure and diversity of sixteen macroalgal assemblages originating from two coastal locations in the Northern (Kavala gulf) and Central (Maliakos gulf) Aegean in Greece were explored by examining their relative abundance distributions (RADs) and fitting five stochastic niche-based models. A mechanistic interpretation of the underpinning assembly processes was attempted by relating the assumptions of the fitted models with available abiotic data corresponding to each assemblage. The random fraction niche-based model, assuming a random niche apportionment to species, was fitted to the majority of Maliakos assemblages characterized by more evenly distributed and speciose RADs, whereas the random assortment model, assuming no relationship among species abundance and niche size, was fitted to most of the Kavala assemblages characterized by steeper RADs with fewer species. Among the possible underlying mechanisms, wave exposure seems to play a key role in macroalgal assembly processes; however factors such as biogeography and hard substrate availability must be also taken into consideration. Short-term processes as changes in resource availability (nutrients and light), known as drivers of assembly rules in other primary producers (e.g. phytoplankton), do not considerably affect macroalgae in the oligotrophic Eastern Mediterranean, possibly due to their longer life spans. © 2010 Elsevier Ltd.

Koussis A.D.,Institute for Environmental Research and Sustainable Development | Georgopoulou E.,Institute for Environmental Research and Sustainable Development | Kotronarou A.,Institute for Environmental Research and Sustainable Development | Mazi K.,Institute for Environmental Research and Sustainable Development | And 10 more authors.
Hydrological Sciences Journal | Year: 2010

We investigate the general methodology for an intensive development of coastal aquifers, described in a companion paper, through its application to the management of the Akrotiri aquifer, Cyprus. The Zakaki area of that aquifer, adjacent to Lemessos City, ismanaged such that it permits a fixed annual agricultural water demand to be met, as well as and a fraction of the water demand of Lemessos, which varies according to available surface water. Effluents of the Lemessos wastewater treatment plant are injected into the aquifer to counteract the seawater intrusion resulting from the increased pumping. The locations of pumping and injectionwells are optimized based on least-cost, subject to meeting the demand. This strategy controls sea intrusion so effectively that desalting of only small volumes of slightly brackish groundwater is required over short times, while ~2.3 m33 of groundwater is produced for each 1 m3 of injected treated wastewater. The cost over the 20-year period 2000-2020 of operation is ~40 M€ and the unit production cost of potable water is under 0.2 €/m3. The comparison between the deterministic and stochastic analyses of the groundwater dynamics indicates the former as conservative, i.e. yielding higher groundwater salinity at the well. The Akrotiri case study shows that the proposed aquifermanagement scheme yields solutions that are preferable to the widely promoted seawater desalination, also considering the revenues fromusing the treated wastewater for irrigation. © 2010 IAHS Press.

Kazmin A.S.,RAS Shirshov Institute of Oceanology | Zatsepin A.G.,RAS Shirshov Institute of Oceanology | Kontoyiannis H.,National Center for Marine Research
International Journal of Climatology | Year: 2010

Satellite and reanalysis data for the period 1982-2004 were used to study the long-term variability of the winter-mean sea surface temperature (SST) in the Black and Aegean Seas and its connection with the major atmospheric forcing: surface air temperature (SAT), surface wind and North Atlantic Oscillation (NAO) and East Atlantic-West Russia (EAWR) teleconnection patterns. In spite of some differences, the general tendencies of SST variability in both basins are similar. The major climatic event (i.e. SST decreases below the climatic mean followed by the sharp increase of SST, occurred during the period 1986-1999) and its connection with the atmospheric forcing are evident both in the Black and Aegean Seas. During the investigated period, the south-western wind regime occurred over the Black Sea and the northeastern wind regime over the Aegean. It is shown that the variability of the meridional component of the surface wind (which provides the most of the atmospheric heat transport into the basins) is well correlated with the large-scale atmospheric patterns (NAO and EAWR). The major difference is that in the Black Sea the NAO intensification/weakening results in the weakening/strengthening of the southern wind, whereas in the Aegean Sea EAWR/NAO intensification/weakening produce strengthening/weakening of the northern wind. The long-term variability of the SST is well correlated with the variability of the SAT, which in turn is highly correlated with the meridional component of the surface wind. However, a remarkable feature is that in the Black Sea an increase/decrease of the SAT is associated with the strengthening/weakening of the southern wind. On the contrary, in the Aegean Sea, an increase/decrease of the SAT is associated with the weakening/strengthening of the northern wind. The simple basic scheme of influence of the large-scale atmospheric forcing on the long-term SST variability during the positive NAO and EAWR phase is proposed. © 2009 Royal Meteorological Society.

Berline L.,British Petroleum | Siokou-Frangou I.,National Center for Marine Research | Marasovic I.,Croatian Institute Of Oceanography And Fisheries | Vidjak O.,Croatian Institute Of Oceanography And Fisheries | And 12 more authors.
Progress in Oceanography | Year: 2012

We analyzed and compared Mediterranean mesozooplankton time series spanning 1957-2006 from six coastal stations in the Balearic, Ligurian, Tyrrhenian, North and Middle Adriatic and Aegean Sea. Our analysis focused on fluctuations of major zooplankton taxonomic groups and their relation with environmental and climatic variability. Average seasonal cycles and interannual trends were derived. Stations spanned a large range of trophic status from oligotrophic to moderately eutrophic. Intra-station analyses showed (1) coherent multi-taxa trends off Villefranche sur mer that diverge from the previous results found at species level, (2) in Baleares, covariation of zooplankton and water masses as a consequence of the boundary hydrographic regime in the middle Western Mediterranean, (3) decrease in trophic status and abundance of some taxonomic groups off Naples, and (4) off Athens, an increase of zooplankton abundance and decrease in chlorophyll possibly caused by reduction of anthropogenic nutrient input, increase of microbial components, and more efficient grazing control on phytoplankton. (5) At basin scale, the analysis of temperature revealed significant positive correlations between Villefranche, Trieste and Naples for annual and/or winter average, and synchronous abrupt cooling and warming events centered in 1987 at the same three sites. After correction for multiple comparisons, we found no significant correlations between climate indices and local temperature or zooplankton abundance, nor between stations for zooplankton abundance, therefore we suggest that for these coastal stations local drivers (climatic, anthropogenic) are dominant and that the link between local and larger scale of climate should be investigated further if we are to understand zooplankton fluctuations. © 2011 Elsevier Ltd.

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