New patterns in Danubian distribution of Ponto-Caspian gobies – a result of global climatic change  and/or canalization?

 

Ákos Harka and Péter Bíró

 

1 Lajos Kossuth Secondary School, H-5350 Tiszafüred, Táncsics str. 1., Hungary; 2 Balaton Limnological Research Institute, Hungarian Academy of Sciences, H-8237 Tihany, Kuno Klebelsberg str. 3., Hungary,

Corresponding author:

2 P. Bíró, Balaton Limnological Research Institute, Hungarian Academy of Sciences, H-8237 Tihany, Kuno Klebelsberg str. 3., Hungary, Tel.: 36-87-448-244; Fax: 36-87-448-006; e-mail: biro@tres.blki.hu

 

Abstract: Since the 1970’s, dispersion of several Ponto-Caspian fish species in Central Europe, mainly along the Danube-valley, has been registered. Especially certain gobies have reached long distances, two of them (Proterorhinus marmoratus, Neogobius kessleri) have already been distributed in Germany. In parallel with this horizontal distribution, an upstream vertical migration can also be observed into the mountain zones of lowland and hilly country rivers. Horizontal and vertical expansions substancially do not differ from each other, because fish species in both cases have an upstream-oriented migration.

 Explanations concerning expansions cleared up only the modes of distribution. However, for widening of areas, the permanent settling of species is also required. In their acclimatiza­tion, some factor may play significant role. The first is probably the rising temperature of waters, the second is possibly the canalization resulting in a series of dammed river sections. As the local warming of certain river sections and construction of further reservoirs continue, the westward-migration of more warmwater fish species and further distribution of already present ones are highly probable.

 

Key words: Ponto-Caspian gobies, distribution, global climate change

 

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