Abundance and night-time habitat use patterns of Ponto-Caspian gobiid species (Pisces, Gobiidae) in the littoral zone of the River Danube, Hungary

Abstract

We examined the abundance and meso-habitat use of gobiid species during both day and night along 43 stretches (500-m long) of the littoral zone at five locations of the Middle Danube, Hungary, in spring and in summer 2004. Electro-fishing catch per unit effort sampling revealed significantly higher relative densities at night than during the day. Gobiids occupied all the available habitats encountered during sampling. Habitat-abundance relationships from night-time samples revealed that the two most abundant species, round goby Neogobius melanostomus and bighead goby Neogobius kessleri, were found in highest relative density along gravel beach and artificial rip-rap habitats; these species were in relatively low density in sandy areas. Monkey goby Neogobius fluviatilis was more abundant in natural shorelines than in rip-rap habitats and dispersed more consistently between sandy and gravel beaches. Tubenose goby Proterorhinus marmoratus demonstrated great plasticity in meso-habitat use. In conclusion, Ponto-Caspian gobies occurred rather consistently along the Hungarian section of the Danube, occupying all available habitats examined. Abundance-habitat relations suggest plasticity in meso-habitat use but partial segregation between species. Further studies are required at multiple spatial scales to assess how micro- and meso-habitat use varies with fluctuating population densities.