scholarly journals Lithistid Demosponges of Deep-Water Origin in Marine Caves of the North-Eastern Mediterranean Sea

2021 ◽  
Vol 8 ◽  
Author(s):  
Andrzej Pisera ◽  
Vasilis Gerovasileiou
Keyword(s):  
Deep Water ◽  
Eastern Mediterranean ◽  
Aegean Sea ◽  
Western Mediterranean ◽  
Elevated Concentration ◽  
The North ◽  
Deep Waters ◽  
Marine Caves ◽  
North Eastern ◽  
Tropical Areas

Desmas-bearing demosponges known as lithistids have heavily silicified skeleton and occur typically in bathyal environments of warm and tropical areas but may be found in certain shallow marine caves. Here we report, for the first time two lithistid species, i.e., Neophrissospongia endoumensis, and N. cf. nana, that were earlier known from Western Mediterranean marine caves, from four marine caves in the north-eastern Mediterranean, and their congener Neophrissospongia nolitangere from deep waters (ca. 300 m) of the Aegean Sea. All marine caves, and sections within these caves, where lithistids occur, have freshwater springs. We interpret this surprising association between lithistids and freshwater input by elevated concentration of silica in water in cave sections where such springs occur, being 8–11 times higher in comparison with shallow water outside caves, and comparable to that of deep waters, that promoted lithistids’ development. One of the studied caves harbored an abundant population of N. endoumensis which formed large masses. The age estimation of these lithistids, based on known growth rate of related deep-water sponges, suggest that they could be approximately 769–909 years old in the case of the largest specimen observed, about 100 cm large. These sponges could have colonized the caves from adjacent deep-water areas not earlier than 7,000–3,000 years ago, after the last glaciation, because earlier they were emerged. High variability of spicules, especially microscleres, and underdevelopment of megascleres may be related to silicic acid concentration.

scholarly journals Temporal and spatial variability of nutrients and oxygen in the North Aegean Sea during the last thirty years

2014 ◽  
Vol 15 (4) ◽  
pp. 805 ◽  
Author(s):  
Ε. SOUVERMEZOGLOU ◽  
Ε. KRASAKOPOULOU ◽  
A. PAVLIDOU
Keyword(s):  
Deep Water ◽  
Eastern Mediterranean ◽  
Aegean Sea ◽  
Inorganic Nutrients ◽  
Deep Water Formation ◽  
The North ◽  
Deep Waters ◽  
Water Formation ◽  
North Aegean ◽  
North Aegean Sea

Inorganic nutrient and dissolved oxygen data collected in the North Aegean Sea during 1986 - 2008 were analyzed in order to evaluate the role of the inflowing Black Sea originated surface water (BSW) in the nutrient regime of the area.  In periods of high buoyancy inflow from Dardanelles strait, a reduction of inorganic nutrients in the surface layer is observed along the north-west route of the BSW; in parallel, the underlying layer of Levantine intermediate water revealed an increase of inorganic nutrients, receiving the degradation material from the surface layer. The above spatial patterns suggest a contribution of the BSW to the observed enhanced production of the North Aegean Sea. Anomalously low buoyancy inflow of BSW combined with severe winter meteorological conditions promote deep water formation events. The physical and chemical characteristics of the deep waters found in the different basins of the North Aegean Sea in 1997 (following the deep water formation in winters of 1992-1993) differed from those observed after the formation in winter 1987. These differences were probably related to the drastic changes occurred in the deep waters of the Eastern Mediterranean in the early 1990, by the Eastern Mediterranean Transient. Considering that deep water formation processes provide occasionally inorganic nutrients to the euphotic layer, it seems that BSW through its uninterrupted supply of small quantities of nutrients should play an additional role in the production in the North Aegean Sea.

scholarly journals Tracers confirm downward mixing of Tyrrhenian Sea upper waters associated with the Eastern Mediterranean Transient

2010 ◽  
Vol 7 (4) ◽  
pp. 1533-1557
Author(s):  
W. Roether ◽  
J. E. Lupton
Keyword(s):  
Deep Water ◽  
Time Scale ◽  
Eastern Mediterranean ◽  
Western Mediterranean ◽  
The Other ◽  
Tyrrhenian Sea ◽  
Convective Mixing ◽  
Deep Waters ◽  
Major Process ◽  
Gibraltar Strait

Abstract. Observations of tritium and 3He in the Tyrrhenian Sea, 1987–2009, confirm the enhanced convective mixing of intermediate waters into the deep waters that has been noted and associated with the Eastern Mediterranean Transient in previous studies. Our evidence for the mixing rests on increasing tracer concentrations in the Tyrrhenian deep waters, accompanied by decreases in the upper waters, which are supplied from the Eastern Mediterranean. The downward transfer is particularly evident between 1987 and 1997. Later on, information partly rests on increasing tritium-3He ages; here we correct the observed 3He for contributions released from the ocean floor. The Tyrrhenian tracer distributions are fully compatible with data upstream of the Sicily Strait and in the Western Mediterranean. The tracer data show that mixing reached to the bottom and confirm a cyclonic nature of the deep water circulation in the Tyrrhenian. They furthermore indicate that horizontal homogenization of the deep waters occurs on a time scale of several years. Various features point to a reduced impact of Western Mediterranean Deep Water (WMDW) in the Tyrrhenian during the enhanced-convection period. This is an important finding because it implies less upward mixing of WMDW, which has been named a major process to enable the WMDW to leave the Mediterranean via the Gibraltar Strait. On the other hand, the TDW outflow for several years represented a major influx of enhanced salinity and density waters into the deep-water range of the Western Mediterranean.

Parasites of Scyliorhinus canicula (Linnaeus, 1758) in the north-eastern Aegean Sea

2017 ◽  
Vol 98 (8) ◽  
pp. 2133-2143 ◽  
Author(s):  
Vasileios Bakopoulos ◽  
Euaggelia Tsepa ◽  
Anastasia Diakou ◽  
Giorgos Kokkoris ◽  
Markos Nikolaos Kolygas ◽  
...  
Keyword(s):  
Prey Availability ◽  
Eastern Mediterranean ◽  
Aegean Sea ◽  
Sampling Period ◽  
First Record ◽  
Scyliorhinus Canicula ◽  
The North ◽  
Eastern Aegean ◽  
North Eastern ◽  
Eastern Aegean Sea

The parasitic fauna of the small-spotted catshark, Scyliorhinus canicula in the north-eastern Aegean Sea was investigated. Twenty-one out of the 52 (prevalence 40.4%) specimens collected were found infected with parasites; an arthropod and two nematode genera. Seven specimens (prevalence 13.5%) were infected by a Neoalbionella sp. copepod. Ten and 14 specimens were infected by the nematodes Proleptus obtusus (prevalence 19.2%) and Anisakis sp. (prevalence 26.9%), respectively. Female S. canicula specimens were significantly more heavily infected during autumn and when the whole sampling period is considered. Nematode infection was significantly related to season, becoming progressively heavier from spring to autumn. No correlation was found between TL of specimens and number of parasites for males or females, irrespective of gender. The present study provided a first record of Neoalbionella sp., P. obtusus and Anisakis sp. infections of S. canicula in the north-eastern Mediterranean. The lower prevalence of Proleptus obtusus and the higher prevalence of Anisakis sp. infection recorded in this study may be due to prey availability and parasite populations in this locality.

Comparison of fish assemblages between the Sea of Marmara and the Aegean Sea (north-eastern Mediterranean)

2011 ◽  
Vol 91 (6) ◽  
pp. 1307-1318 ◽  
Author(s):  
Cetin Keskin ◽  
Francesc Ordines ◽  
Beatriz Guijarro ◽  
Enric Massutí
Keyword(s):  
Environmental Conditions ◽  
Fish Assemblages ◽  
Eastern Mediterranean ◽  
Aegean Sea ◽  
Demersal Fish ◽  
Sea Of Marmara ◽  
The North ◽  
Eastern Aegean ◽  
North Eastern ◽  
Eastern Aegean Sea

The demersal fish assemblages of the south-western Sea of Marmara and the north-eastern Aegean Sea were examined in relation to their biogeographical and environmental conditions. Sampling was carried out during bottom trawl surveys conducted during five periods between June 2006 and August 2007. A total of 40 hauls were processed, including 16 in the Sea of Marmara (38–74 m deep) and 24 in the north-eastern Aegean Sea (63–401 m deep). A total of 47,940 individuals, from 91 species and 47 families were collected. Cluster analysis of catch data indicated that there were three assemblages, one in the shelf of the Sea of Marmara and two in the Aegean Sea (<100 and >200 m depth). The numerical abundance and biomass of fish, mean fish weight, mean species richness, diversity and evenness were compared between these assemblages. Multivariate analysis was used to test differences in environmental conditions between areas, and relationships between species and environmental variables were explored by using redundancy analysis. In addition to bathymetric differences, differences in both diversity and species composition were observed between shelf assemblages in the two nearby areas. The distinct biogeographical, environmental characteristics (depth, dissolved oxygen and temperature) and fishing pressure are discussed as the main factors which could explain the differences detected.

scholarly journals Tracers confirm downward mixing of Tyrrhenian Sea upper waters associated with the Eastern Mediterranean Transient

Ocean Science ◽  
2011 ◽  
Vol 7 (1) ◽  
pp. 91-99 ◽  
Author(s):  
W. Roether ◽  
J. E. Lupton
Keyword(s):  
Deep Water ◽  
Time Scale ◽  
Eastern Mediterranean ◽  
Vertical Mixing ◽  
Western Mediterranean ◽  
The Other ◽  
Tyrrhenian Sea ◽  
Deep Waters ◽  
Major Process ◽  
Gibraltar Strait

Abstract. Observations of tritium and 3He in the Tyrrhenian Sea, 1987–2009, confirm the enhanced vertical mixing of intermediate waters into the deep waters that has been noted and associated with the Eastern Mediterranean Transient in previous studies. Our evidence for the mixing rests on increasing tracer concentrations in the Tyrrhenian deep waters, accompanied by decreases in the upper waters, which are supplied from the Eastern Mediterranean. The downward transfer is particularly evident between 1987 and 1997. Later on, information partly rests on increasing tritium-3He ages; here we correct the observed 3He for contributions released from the ocean floor. The Tyrrhenian tracer distributions are fully compatible with data upstream of the Sicily Strait and in the Western Mediterranean. The tracer data show that mixing reached to the bottom and confirm a cyclonic nature of the deep water circulation in the Tyrrhenian. They furthermore indicate that horizontal homogenization of the deep waters occurs on a time scale of roughly 5 years. Various features point to a reduced impact of Western Mediterranean Deep Water (WMDW) in the Tyrrhenian during the enhanced-mixing period. This is an important finding because it implies less upward mixing of WMDW, which has been named a major process to enable the WMDW to leave the Mediterranean via the Gibraltar Strait. On the other hand, the TDW outflow for several years represented a major influx of enhanced salinity and density waters into the deep-water range of the Western Mediterranean.

Westward Palaearctic range expansion of Papilio demoleus Linnaeus, 1758 (Lepidoptera: Papilionidae) and its arrival at Mediterranean coastal regions of Turkey and Syria

2020 ◽  
Vol 71 (4) ◽  
pp. 257-272
Author(s):  
Onat Başbay ◽  
Mudar Salimeh ◽  
Eddie John
Keyword(s):  
Eastern Mediterranean ◽  
Economic Importance ◽  
Invasive Pest ◽  
Pest Species ◽  
Coastal Regions ◽  
The North ◽  
North Eastern ◽  
The World ◽  
Invasive Pest Species ◽  
Papilio Demoleus

We review the continuing and extensive spread of Papilio demoleus in south-eastern Turkey and in regions of Turkey and Syria adjacent to the north-eastern Mediterranean. Since the authors documented the arrival of this attractive but potentially destructive papilionid species at coastal areas of Syria in 2019, regular monitoring has confirmed successful overwintering there, as well as in Turkey. As previously indicated, P. demoleus is widely recognized as an invasive pest species in Citrus-growing areas of the world and hence its arrival is of potential economic importance to a region in which citrus is widely grown.

Coastal inundation in the north-eastern mediterranean coastal zone due to storm surge events

2010 ◽  
Vol 15 (3) ◽  
pp. 353-368 ◽  
Author(s):  
Yannis N. Krestenitis ◽  
Yannis S. Androulidakis ◽  
Yannis N. Kontos ◽  
George Georgakopoulos
Keyword(s):  
Storm Surge ◽  
Coastal Zone ◽  
Eastern Mediterranean ◽  
Coastal Inundation ◽  
The North ◽  
North Eastern

scholarly journals Hydrography and Circulation West of Sardinia in June 2014

2017 ◽  
Author(s):  
Michaela Knoll ◽  
Ines Borrione ◽  
Heinz-Volker Fiekas ◽  
Andreas Funk ◽  
Michael P. Hemming ◽  
...  
Keyword(s):  
Eastern Mediterranean ◽  
Potential Temperature ◽  
Atlantic Water ◽  
Western Mediterranean ◽  
Anticyclonic Eddy ◽  
Intermediate Water ◽  
Potential Density ◽  
Sea Trial ◽  
The North

Abstract. In the mainframe of the REP14-MED sea trial in June 2014, the hydrography and circulation west of Sardinia, observed by means of gliders, shipborne CTD instruments, towed devices, and vessel-mounted ADCPs, are presented and compared with previous knowledge. So far, the circulation is not well known in this area, and the hydrography is subject to long-term changes. Potential temperature, salinity, and potential density ranges, as well as core values of the observed water masses were determined. Modified Atlantic Water (MAW), with potential density anomalies below 28.72 kg m−3, showed a salinity minimum of 37.93 at 50 dbar. Levantine Intermediate Water (LIW), with a salinity maximum of about 38.70 at 400 dbar, was observed within a range of 28.72 < σΘ [kg m−3] < 29.10. MAW and LIW showed slightly higher salinities than previous investigations. During the trial, LIW covered the whole area from the Sardinian shelf to 7°15' E. Only north of 40° N was it tied to the continental slope. Within the MAW, a cold and saline anticyclonic eddy was observed in the southern trial area. The strongest variability in temperature and salinity appeared around this eddy, and in the southwestern part of the domain, where unusually low saline surface water entered the area towards the end of the experiment. An anticyclonic eddy of Winter Intermediate Water was recorded moving northward at 0.014 m s−1. Geostrophic currents and water mass transports calculated across zonal and meridional transects showed a good agreement with vessel-mounted ADCP measurements. Within the MAW, northward currents were observed over the shelf and offshore, while a southward transport of about 1.5 Sv occurred over the slope. A net northward transport of 0.38 Sv across the southern transect decreased to zero in the north. Within the LIW, northward transport of 0.6 Sv across the southern transects were mainly observed offshore, and decreased to 0.3 Sv in the north where they were primarily located over the slope. This presentation of the REP14-MED observations helps to further understand the long-term evolution of hydrography and circulation in the Western Mediterranean, where considerable changes occurred after the Eastern Mediterranean Transient and the Western Mediterranean Transition.

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