Rival at the gate: first record of the Asian clam Corbicula fluminea Müller, 1774 (Bivalvia: Corbiculidae) in Greece

This contribution presents the first record of the Asian clam Corbicula fluminea Müller, 1774 in Greece. The species was collected in Erythropotamos River (Reka Luda Луда река), one of the main tributaries of Evros River (classical name of the Maritsa river), thus being the southernmost record of this invasive bivalve in the Balkan Peninsula. The most likely entry source of C. fluminea in Greece is through active or passive downstream drift through the Bulgarian part of Erythropotamos River, which is shared between Bulgaria and Greece. Special attention is now required to assess the invasion extent of the Asian clam in the entire Evros basin and adjacent river basins of Bulgaria and the Aegean basins of Greece and Turkey.

The racer goby, Babka gymnotrachelus (Kessler, 1857) invades the Evros river: evidence of recent establishment in Greece

The discovery of the racer goby Babka gymnotrachelus in the transboundary Evros river basin, collected on September 10th 2018 at two locations very close to the Greek-Bulgarian and Greek-Turkish borderlines, is reported. This is a new addition to the non-native ichthyofauna of Greece and the Aegean Sea drainages, and it is the second non-native Ponto-Caspian goby to enter this river. Boat-based electrofishing sampling, following the EU Water Framework Directive monitoring program, provides first evidence of what is presumed to be a recently established population; most of the 13 collected specimens are juveniles and the species has not yet been located in the river's tributaries. Further study and international cooperation in monitoring and management of this and other alien species in the Evros are proposed.

Consideration of modern sendimentary processes of the Evros river delta front and prodelta, NE Aegean sea

Gravity cores data from the Evros River delta front and prodelta confirm the aspect that the Evros River deltaic deposits tend to west-northwest, along the main direction of the local hydrodynamic regime, preventing the construction of a symmetrical Holocene prism. In the delta front, the terrigenous sediment consists mostly of fine-grained material. Its vertical succession is monotonous with slight differences in grain size or colour, and lack of internal structure or current-produced laminae, indicating almost immutable sedimentary processes as well as long-term discharge fluctuations. The river-borne sand is limited because of its entrapment in the river mouth but sometimes, during extreme conditions (periods of high river discharge, short-lived catastrophic events etc.), can be transported seawards covering an extensive area of the Alexandroupolis Gulf. The negligible biogenic content and the absence of bioturbation effects are attributed to the high rates of deposition. Some bioturbated horizons are produced when sedimentation rates decrease temporarily. The prodelta sediment distribution patterns occur a distinctive zonation along an east-southeast to westnorthwest trend. In the central part, mud dominates, while on both sides of this area, the content of sand gradually increases and becomes the prevalent facies near the coast and in the outer plateau of the gulf. The vertical facies sequences of the upper sedimentary cover are complicated, with many variations in grain size, colour and biogenic content reflecting a complicated manner of deposition. The major feeder of this area is the Evros River providing great amounts of suspended load. Another remarkable source of sand is derived from the coastline, which during storm conditions provides coarse-grained material in the shoreface area. Finally, a sediment supplier of local importance, Loutros River, affects the eastern area of Alexandroupolis building up a small subaqueous fan. In the open sea, the consequences of the modern sedimentation are negligible. The sandy character of the surface and sub-surface sediments, the analysis of biogenic fragments, the long distance from the present-day terrigenous sources are some evidences which lead to the view that the upper sediment body of the southwestern part of the study area has a presumable relict origin. 210Pb profiles are, more of less, consistent showing a sedimentation rate more than 2 cm/yr in the delta front, which decreases to 0.2 cm/yr at about 8 km seaward.

Hybrid Fuzzy—Probabilistic Analysis and Classification of the Hydrological Drought

The consideration of a theoretical probability distribution regarding the annual cumulative discharge will provide a significant opportunity to characterize the intensity of the hydrological drought. However, the matching between the observed probabilities and the adopted theoretical probability distribution can not be identical. Hence, in this work this matching is achieved by using a fuzzy regression based methodology and the attributes of the log-normal distribution. Finally, an ascending procedure to classify the intensity of hydrological drought is proposed and it is applied in case of the Evros River.

Sheeppox in Evros. A 7-year (1994 - 2000) retrospective study

Sheeppox is a highly transmissible disease that caused the development of serious economical losses to the livestock of Evros County. From 1994 to 2000, following an absence of appearance in 1999, sheeppox has constantly occurred on a year basis. During the last sheepox epidemic in 1998, eradication measures have been implemented to control the disease. Stamping out of the animals from affected flocks and flock vaccination for the risk areas have been performed. Since 1994 and after, elimination procedures have been applied on affected and suspected flocks. In particular, (83), (677), (21.020), (8.838), (1512) and (507)animals were eliminated (stamping out) in 1994, 1995, 1996, 1997,1998 and 2000 respectively. The mode of transmission of pox disease must be differentiated from the Foot and Mouth disease and its expected incidence during an outbreak period. The compulsory by legislation 21-day isolation of pox-infected flocks shall be considered insufficient due to the virus resistance. Pox nodules, primarily seen on the parts of the body not covered by wool and skin lesions on the tail, are the most typical clinical signs. There is evidence to believe that pox virus was introduced into Greece from Turkey, because the disease is endemic in Turkey and our primary incursions have been detected close to Evros River, the borderline between the two countries. Area of epidemiological importance, where new outbreaks have yearly occurred (no reports in 1994), is Orestiada landscape, including Petrades village. The first confirmed cases of sheeppox, which were reported in fall 1994-95, 2000 (October- November) and summer 1996-98 (July). No cases were reported in winter. In this study, the sheep pox statistics, epizootiology, symptomatology, control measures and photo-images of the disease were reviewed based on cumulative experience.

The application of grain size trend analysis in the fine grained seabed sediment of Alexandroupolis Gulf.

Grain size trend analysis is a method that determines sediment transport direction, based on the relationship of grain size parameters (mean size, sorting, skewness). The application of the method in the seabed sediments of Alexandroupolis Gulf showed that there are three different sub areas of distinctive sediment movement of bottom sediments (water depths <40 m):(i) the eastern part, which is mainly influenced by the Evros river water/sediment influxes; (ii) the central part that is primarily controlled by the wave activity; and, (iii) the western part that is mainly influenced by the wind driven and/or thermo-saline coastal circulation.