scholarly journals The Influence of Parasitic Infection on the Black Sea Whiting, Merlangius merlangus euxinus (Gadidae), Morphophysiological and Biochemical Parameters

2013 ◽  
Vol 47 (4) ◽  
pp. 309-317 ◽  
Author(s):  
E. N. Skuratovskaya ◽  
V. M. Yurakhno ◽  
A. V. Zavyalov

Abstract Complex influence of infection by myxosporeans Myxidium gadi Georgevitsch, 1916; Ceratomyxa merlangi Zaika, 1966 and nematode Hysterothylacium aduncum (Rudolphi, 1802) on the morphophysiological and biochemical parameters of the Black sea whiting Merlangius merlangus euxinus (Nordmann, 1840) were studied. Significant decrease of spleenosomatic index and increase of hepatosomatic index in fish with average and high intensity of infection were found. The dependence of hepatic antioxidant enzyme activities on intensity of infection was observed. Increase of superoxidismutase, catalase, glutation-S-transferase activities in fish with average and high intensity of infection and decrease of peroxidase activity in specimens with average intensity of infection were shown.

2019 ◽  
Vol 9 (4) ◽  
pp. 700-709
Author(s):  
Ekaterina Skuratovskaya ◽  
Ekaterina Skuratovskaya ◽  
Andrey Zav'yalov ◽  
Irina Rudneva

Biometrical and biochemical parameters in healthy and parasitized by nematode Hysterothylacium aduncum Black Sea whiting Merlangius merlangus euxinus were studied. The increase of hepatosomatic index and decrease of spleen index in infected fish were found, while condition factor was similar in both groups. Antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), peroxidase (PER), glutathione reductase (GR) and glutathione-S-transferase (GST)) were higher in red blood cells in the parasitized fish as compared with the healthy animals. In the liver, the antioxidant response was not uniform: activities of SOD and GST decreased and activities of PER, GR and CAT increased in the infected individuals. The obtained results reflect host defense against oxidative stress caused parasitic infection. The tissue specific fluctuations of antioxidant response in parasitized and healthy fish are discussed. Data in this study can be used for understanding the defense mechanisms of fish against parasites.


2011 ◽  
Vol 11 (3) ◽  
pp. 945-963 ◽  
Author(s):  
G. A. Papadopoulos ◽  
G. Diakogianni ◽  
A. Fokaefs ◽  
B. Ranguelov

Abstract. Data on tsunamis occurring in the Black Sea and the Azov Sea from antiquity up to the present were updated, critically evaluated and compiled in the standard format developed since the 90's for the New European Tsunami Catalogue. Twenty nine events were examined but three of them, supposedly occurring in 557 AD, 815 AD and 1341 or 1343, were very likely falsely reported. Most of the remaining 26 events were generated in Crimea, offshore Bulgaria as well as offshore North Anatolia. For each of the 26 events examined, 22 events were classified as reliable ones receiving a score of 3 or 4 on a 4-grade reliability scale. Most of them were caused by earthquakes, such as the key event 544/545 of offshore Varna, but a few others were attributed either to aseismic earth slumps or to unknown causes. The tsunami intensity was estimated using the traditional 6-grade scale and the new 12-grade scale introduced by Papadopoulos and Imamura (2001). From 544/545 up to now, only two reliable events of high intensity K ≥ 7 have been reported, which very roughly indicates that the mean repeat time is ∼ 750 years. Five reliable tsunamis of moderate intensity 4 ≤ K < 7 have been observed from 1650 up to the present, which implies a recurrence of 72 years on the average. Although these calculations were based on a very small statistical sample of tsunami events, the repeat times found are consistent with the theoretical expectations from size-frequency relations. However, in the Black Sea there is no evidence of tsunamis of very high intensity (K ∼ 10) such as the AD 365, 1303 and 1956 ones associated with large earthquakes occurring along the Hellenic arc and trench, Greece, or the 1908 one in Messina strait, Italy. This observation, along with the relatively low tsunami frequency, indicates that the tsunami hazard in the Black Sea is low to moderate but not negligible. The tsunami hazard in the Azov Sea is very low because of the very low seismicity but also because of the shallow water prevailing there. In fact, only three possible tsunami events have been reported in the Azov Sea.


2015 ◽  
Vol 90 (3) ◽  
pp. 347-352 ◽  
Author(s):  
A. Özer ◽  
Y. Kornyychuk ◽  
T. Öztürk ◽  
V. Yurakhno

AbstractGyrodactylus alviga is a generalist species reported in many Black Sea fish species, but whiting is known to be its main host. It is the only monogenean parasite that has been reported so far on the skin, fins and gills of whiting Merlangius merlangus in the Black Sea. A total of 690 fish from Turkey and 423 fish from Russia were examined to detect parasites. Infection indices of prevalence, mean intensity and mean abundance values were calculated for length classes and sex of fish, as well as for the seasons. There is a gradual increase in infection indices in relation with increasing host length classes and there are higher infection indices on female fish. Furthermore, despite lower prevalence indices in spring and winter, higher parasite intensity values were determined in these seasons. It is concluded that larger fish provided more space and food for G. alviga, and female fish were more parasitized as they were more active in searching for food, which enables the parasite to switch between hosts. In addition, winter and spring were more appropriate for reproduction of G. alviga.


2008 ◽  
Vol 265 (3-4) ◽  
pp. 396-409 ◽  
Author(s):  
C.P. Holzner ◽  
D.F. McGinnis ◽  
C.J. Schubert ◽  
R. Kipfer ◽  
D.M. Imboden

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