LENGTH/WIDTH-WEIGHT RELATIONSHIPS OF THE MEDITERRANEAN GREEN CRAB Carcinus aestuarii NARDO, 1847 IN THE HOMA LAGOON, AEGEAN SEA TURKEY

Author(s):  
Tahir Ozcan
Author(s):  
Murat Özbek ◽  
Cengiz Koçak ◽  
Deniz Acarlı

AbstractThe Mediterranean green crab Carcinus aestuarii Nardo, 1847 (Crustacea, Brachyura, Portunidae) is a common inhabitant of the shallow waters of Homa Lagoon in Izmir Bay, Turkey, in the eastern Mediterranean. Monthly samples were collected in Homa Lagoon from June 2006 to May 2007 using trammel nets, fyke nets, beach seines and fence traps. In total, 608 males and 559 females of C. aestuarii were collected. The highest sex ratio (81–86% females) was recorded between October and December, and in August (58% females). Ovigerous females were obtained only from November to February with the highest ratio of ovigerous females (55%) observed in January 2007. The maturation curve presenting the carapace width showed that 50% of female crabs with the carapace width of 26.84 ±1.58 mm (r= 0.72) were physiologically mature. Regression analyses indicated that the number of eggs was positively correlated with carapace width and wet weight (P < 0.05, in both cases).


2013 ◽  
Vol 14 (1) ◽  
pp. 238 ◽  
Author(s):  
I. SIOKOU ◽  
A.S. ATES ◽  
D. AYAS ◽  
J. BEN SOUISSI ◽  
T. CHATTERJEE ◽  
...  

This paper concerns records of species that have extended their distribution in the Mediterranean Sea. The finding of the rare brackish angiosperm Althenia filiformis in the island of Cyprus is interesting since its insertion in the Red Data Book of the Flora of Cyprus is suggested. The following species enriched the flora or fauna lists of the relevant countries: the red alga Sebdenia dichotoma (Greece), the hydrachnid mite Pontarachna adriatica (Slovenia), and the thalassinid Gebiacantha talismani (Turkey). Several alien species were recorded in new Mediterranean localities. The record of the burrowing goby Trypauchen vagina in the North Levantine Sea (Turkish coast), suggests the start of spreading of this Lessepsian immigrant in the Mediterranean Sea. The findings of the following species indicate the extension of their occurrence in the Mediterranean Sea: the foraminifer Amphistegina lobifera (island of Zakynthos, Greece), the medusa Cassiopea andromeda (Syria), the copepod Centropages furcatus (Aegean Sea), the decapod shrimp Melicertus hathor (island of Kastellorizo, Greece), the crab Menoethius monoceros (Gulf of Tunis), the barnacles Balanus trigonus, Megabalanus tintinnabulum, Megabalanus coccopoma and the bivalves Chama asperella, Cucurbitula cymbium (Saronikos Gulf, Greece).


2021 ◽  
Author(s):  
Marilia Gogou ◽  
Ioanna Triantafyllou ◽  
Spyridon Mavroulis ◽  
Efthimis Lekkas ◽  
Gerassimos A. Papadopoulos

&lt;p&gt;On October 30, 2020, an Mw=7.0 earthquake occurred offshore northern Samos Island (Eastern Aegean, Greece). It was felt over a large area extending from Samos to Peloponnese in Greece and from Izmir to Istanbul in Turkey. It triggered many earthquake environmental effects and damage to buildings resulting in 119 fatalities in both countries. Among the triggered phenomena, tsunami waves with maximum height ~3.35 m struck mainly the northern coastal part of Samos Island and then other islands in the Aegean Sea including Chios, Andros, Ikaria Islands, and the western coast of Turkey.&lt;/p&gt;&lt;p&gt;In order to assess the tsunami intensity in Samos Island, the Integrated Tsunami Intensity Scale (ITIS 2012) was applied. ITIS 2012 is a recently introduced 12-grade scale ranging from I (not felt) to XII (completely devastating) and it is based on the assessment of a large number of objective criteria, grouped in six categories (physical quantities, impact on humans, impact on mobile objects, impacts on infrastructure, environmental effects and impact on structures).&lt;/p&gt;&lt;p&gt;In this context, the above information and data were used for the October 30, 2020 tsunami in Samos. Observations and measurements during a field survey conducted in Samos shortly after the event by the authors were mainly used for assigning intensities. Moreover, other sources included eyewitness, photos and videos from locals capturing the type and the extent of the tsunami impact as well as reports on the qualitative and quantitative tsunami properties and impact on the natural and built coastal environment were also used. Based on the recorded data and information and the guidelines for applying ITIS 2012, tsunami quantities and impact on humans, mobile objects, coastal infrastructure, the natural environment and buildings were taken into account. All available data were added and edited in a database in Geographic Information Systems (GIS) environment, specially designed for the purpose of the study. Then, the respective tsunami intensities were assigned in the studied sites. Moreover, interpolation methods have been also used in order to obtain zones of different intensity in the inundated coastal areas. The results included an ITIS 2012 intensity map of Samos Island.&lt;/p&gt;&lt;p&gt;Based on the assigned intensities, the October 30, 2020 tsunami is characterized as a moderate to strong event with considerable impact on all ITIS 2012 categories. The spatial distribution and the amount of the tsunami effects along the coastal area of Samos enabled the compilation of an intensity map with high resolution indicating that this scale works well for modern events with large amounts of effects and related information. Moreover, the individual criteria of the ITIS 2012 successfully complemented each other resulting in a detailed, concise and precise intensity map.&lt;/p&gt;&lt;p&gt;This is the first time that the ITIS 2012 is applied for a modern tsunami with large amounts of effects in the Mediterranean Region and especially the Aegean Sea. The results could be used for a more effective disaster risk management and risk mitigation strategies for tsunami in the Mediterranean Sea.&lt;/p&gt;


Author(s):  
Gerassimos Papadopoulos

According to Imamura (1937: 123), the term tunami or tsunami is a combination of the Japanese word tu (meaning a port) and nami (a long wave), hence long wave in a harbour. He goes on to say that the meaning might also be defined as a seismic sea-wave since most tsunamis are produced by a sudden dip-slip motion along faults during major earthquakes. Other submarine or coastal phenomena, however, such as volcanic eruptions, landslides, and gas escapes, are also known to cause tsunamis. According to Van Dorn (1968), ‘tsunami’ is the Japanese name for the gravity wave system formed in the sea following any large-scale, short-duration disturbance of the free surface. Tsunamis fall under the general classification of long waves. The length of the waves is of the order of several tens or hundreds of kilometres and tsunamis usually consist of a series of waves that approach the coast with periods ranging from 5 to 90 minutes (Murty 1977). Some commonly used terms that describe tsunami wave propagation and inundation are illustrated in Figure 17.2. Because of the active lithospheric plate convergence, the Mediterranean area is geodynamically characterized by significant volcanism and high seismicity as discussed in Chapters 15 and 16 respectively. Furthermore, coastal and submarine landslides are quite frequent and this is partly in response to the steep terrain of much of the basin (Papadopoulos et al. 2007a). Tsunamis are among the most remarkable phenomena associated with earthquakes, volcanic eruptions, and landslides in the Mediterranean basin. Until recently, however, it was widely believed that tsunamis either did not occur in the Mediterranean Sea, or they were so rare that they did not pose a threat to coastal communities. Catastrophic tsunamis are more frequent on Pacific Ocean coasts where both local and transoceanic tsunamis have been documented (Soloviev 1970). In contrast, large tsunami recurrence in the Mediterranean is of the order of several decades and the memory of tsunamis is short-lived. Most people are only aware of the extreme Late Bronge Age tsunami that has been linked to the powerful eruption of Thera volcano in the south Aegean Sea (Marinatos 1939; Chapter 15).


2020 ◽  
Vol 32 (2) ◽  
pp. 337-353
Author(s):  
Maïa Fourt ◽  
Daniel Faget ◽  
Thierry Pérez

In the first half of the nineteenth century, industrialization increased the demand for sponges extracted by the sponge fishermen of the Dodecanese Archipelago in the Aegean Sea. This had widespread repercussions, leading to increasing numbers of sponge fishermen, the geographical expansion of fishing zones and the evolution and diversification of fishing techniques. In this context, foreign sponge traders imposed the hard-hat diving suit, which enabled divers to remain underwater for several hours without surfacing. It was therefore perceived as being more efficient than traditional skin-diving. But this equipment greatly exacerbated the physical risks faced by the divers, with injuries and fatalities increasing markedly. It also required heavy financial investments that compounded the losses of fishermen and their families. With hindsight, these investments were catalysts of the major socio-economic upheaval that followed. As well as provoking mass revolt among the islanders of the Dodecanese, this entailed modifications in crews and community structure as a nascent model of capitalist organization marked the development of the sponge fishery.


1991 ◽  
Vol 61 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Eleni Voultsiadou-Koukoura ◽  
R.W.M. van Soest

A representative of the genus Hemiasterella Carter, 1879 was found for the first time in the Mediterranean Sea during sampling in the shallow waters of the northern Aegean Sea. The new species, H. aristoteliana, is compared with Atlantic Hemiasterella elongata Topsent, 1928. The status of the family Hemiasterellidae is discussed.


2020 ◽  
Author(s):  
Valentina Turk ◽  
Nina Bednarsek ◽  
Jadran Faganeli ◽  
Blaženka Gasparovic ◽  
Michele Giani ◽  
...  

&lt;p&gt;Although the marginal seas represent only 7% of the total ocean area, the CO&lt;sub&gt;2&lt;/sub&gt; fluxes are intensive and important for the carbon budget, exposing to an intense process of anthropogenic ocean acidification (OA). A decline in pH, especially in the estuarine waters, results also from the eutrophication-induced acidification. The Adriatic Sea is currently a CO&lt;sub&gt;2 &lt;/sub&gt;sink with an annual flux of approximately -1.2 to -3 mol C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt; which is twice as low compared to the net sink rates in the NW Mediterranean (-4 to -5 mol C m&lt;sup&gt;-2&lt;/sup&gt; yr&lt;sup&gt;-1&lt;/sup&gt;). Based on the comparison of two winter cruises carried out in in the 25-year interval between 1983 and 2008, acidification rate of 0.003 pH&lt;sub&gt;T&lt;/sub&gt; units yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt; was estimated in the northern Adriatic which is similar to the Mediterranean open waters (with recent estimations of &amp;#8722;0.0028 &amp;#177; 0.0003 units pH&lt;sub&gt;T&lt;/sub&gt; yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;) and the surface coastal waters (-0.003 &amp;#177; 0.001 and -0.0044 &amp;#177; 0.00006 pH&lt;sub&gt;T&lt;/sub&gt; units yr&lt;sup&gt;&amp;#8722;1&lt;/sup&gt;). The computed Revelle factor for the Adriatic Sea, with the value of about 10, indicates that the buffer capacity is rather high and that the waters should not be particularly exposed to acidification. Total alkalinity (TA) in the Adriatic (2.6-2.7 mM) is in the upper range of TA measured in the Mediterranean Sea because riverine inputs transport carbonates dissolved from the Alpine dolomites and karstic watersheds. The Adriatic Sea is the second sub-basin (319 Gmol yr&lt;sup&gt;-1&lt;/sup&gt;), following the Aegean Sea (which receives the TA contribution from the Black Sea), that contribute to the riverine TA discharges into the Mediterranean Sea. About 60% of the TA inflow into the Adriatic Sea is attributed to the Po river discharge with TA of ~3 mM and TA decreases with increasing salinity. Saturation state indicates that the waters of the Adriatic are supersaturated with respect to calcite (&amp;#937;&lt;sub&gt;Ca&lt;/sub&gt;) and aragonite (&amp;#937;&lt;sub&gt;Ar&lt;/sub&gt;) throughout the year. However, saturation states are considerably lower in the bottom water layers, due to the prevalence of benthic remineralization processes in the stratification period. The seasonal changes of the chemical and environmental conditions and relatively small size of the Adriatic Sea area the microbial community composition, function (growth, enzymatic activity) and carbon and nitrogen biogeochemical cycles. Significant effects on calcifying organisms and phytoplankton are expected while the effects of possible OA on microbially-driven processes are not known yet.&lt;/p&gt;


2020 ◽  
Author(s):  
Paul Meijer

&lt;p&gt;While the Mediterranean Sea is, since the Middle Miocene, a nearly completely land-locked basin indeed, it is itself comprised of several smaller semi-enclosed seas. What the Mediterranean Sea as a whole is to the Atlantic Ocean, are the Adriatic Sea or Aegean Sea to the Ionian-Levantine basin, for example. In the discussions regarding the Messinian salinity crisis the marginal basins of the Mediterranean play a prominent role because it is from these parts that the sedimentary record has been uplifted and become exposed.&lt;/p&gt;&lt;p&gt;In view of this and with an aim to contribute insight from the field of modelling, we focus on the basic element: a single marginal basin, subject to atmospheric forcing and exchanging water through a seaway with an adjacent larger basin. The equations are derived in dimensionless form and a universal, scale-independent, solution for basin salinity obtained. The analysis yields two dimensionless ratios which control basin behaviour in terms of salinity and response time.&amp;#160;&lt;/p&gt;&lt;p&gt;Application of the theoretical model to the Messinian salinity crisis sheds new light on the formation of gypsum in marginal basins that were separated from the main Mediterranean by a sill, gives insight about the role of atmospheric heat exchange, and underlines the previous finding that, at elevated salinity, marginal basins respond to periodic climate variation (e.g. due to precession) with a significant lag.&lt;/p&gt;


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