L. Forró szerk.: Miscellanea Zoologica Hungarica 7. 1992 (Budapest, 1992)

Muskó, I. B.: Amphipoda species found in Lake Balaton since 1897

Amphipoda species found in Lake Balaton since 1897 by I. B. Muskó (Received January 29, 1992) Abstract: Since the first publication on Amphipoda in Lake Balaton (1897) altogether 8 species were found in different habitats of the lake. The species composition changed from time to time. In the 1980s 3 pontocaspian amphipods (Corophium curvispinum, Dikerogammarus haemobaphes and D. villosus) were found on the submerged macrophytes and on the stones of the littoral zone. We studied the life history and measured the biomass of C. curvispinum and D. haemobaphes on the submerged macrophyte Myriophyllum spicatum near Tihany peninsula. Both amphipods reproduce from May (C. cun'ispinum till October, D. haemobaphes till the middle of August). They produce two generations in a year. Biomass of C. curvispinum and D. haemobaphes was roughly 11 and 0.1 g animal dry wt per m. respectively, in an area covered by M spicatum in August 1986. Key words: Amphipoda, Lake Balaton, Corophium, Dikerogammarus, biomass Amphipods play an important role in water ecosystems as utilizers of organic matter and as food for fish. At the same time, they react sensitively to changes in the environment. The first data on the occurrence of amphipods in Lake Balaton are from the last century (Table 1). Information was published on one of the species (Gammants pulex) of the littoral zone. In the 1930s a pontocaspian species, Corophium curvispinum, appeared in the lake and rapidly invaded almost all of its habitats. This species might come from the Danube through the Sió canal, as they are building their tubes on the surface of water vessels (Sebestyén 1934, Entz 1943). In addition to this species, Gammarus roeseli appeared in the lake between the 1930s and 1950s. Species composition of amphipods of Lake Balaton changed considerably at the beginning of the 1950s, when Gammarus roeseli was replaced by pontocaspian Dikerogammarus species (D. haemobaphes and D. villosus). It is possible that the Dikerogammarus species came into the lake with Limnomysis benedeni, which was introduced into the lake as fish food (Woynárovich 1954). The Dikerogammarus species have been permanent elements of amphipod fauna in the lake. The spreading of pontocaspian amphipods in Lake Balaton was probably possible because of their ability to utilize the high detritus content of the lake water as filtering organisms (Entz 1943, 1949, Ponyi 1955, 1956a). Another reason for the presence of these species in Lake Balaton might be that D. villosus has a higher tolerance to high water temperature than does G. roeseli, which is basically a river inhabitant (Lukacsovics 1958). In addition to the above mentioned amphipods Synurella ambuláns and Niphargus mediodanubialis has been found in Lake Balaton (in the marshy zone of the reed belt, close to the shore) (Ponyi 1962). I should mention here that my description of the amphipod species follows the "Limnofauna Europaea" (Pinkster 1978), disregarding the description of subspecies.