Long‐term changes in the fish assemblage structure of a shallow eutrophic reservoir (Lake Hídvégi, Hungary), with special reference to the exotic Carassius gibelio

Abstract

European reservoirs are considered to be well characterized from many aspects. However, the description of long‐term sequence of events in the fish fauna is restricted and mostly limited to deep, oligomictic reservoirs. Lake Hídvégi is a shallow hypertrophic reservoir (average depth = 1.14 m), which started to operate in 1985. The main function of this reservoir has been to retain nutrients carried by the River Zala in order to protect the water quality of Lake Balaton. The changes in the fish fauna of Lake Hídvégi was monitored in selected localities using standard method (electrofishing). Species composition and assemblage structure changed significantly during the study period, between 1986 and 2011. Following the inundation, the rapid expansion of gibel carp (Carassius gibelio BLOCH, 1782) occurred, but after a peak this tendency turned. Surprisingly, based on the among‐years variance of the relative abundances, most of the species were not affected seriously by the invasion. By the end of the studied period, the native generalist roach (Rutilus rutilus L. 1758) became the most abundant species, amounting to more than 50% of the stock. By analyzing functional guilds, we identified an increasing trend in omnivore abundance, in parallel with the disappearance of planktivores. Our results suggest that the fish assemblage structure can be considered as metastable, disturbance tolerant and is mostly composed of generalist cyprinid species still after 29 years of operation.

Desiccation frequency drives local invasions of non-native gibel carp (Carassius gibelio) in the catchment of a large, shallow lake (Lake Balaton, Hungary)

“…The dominance of C. gibelio at early successional stages was previously found in other habitats of the Balaton catchment (Ferincz et al, 2012;Paulovits et al, 2014). The drastic changes in the hydroperiod length of originally permanent waterbodies (Zlinszky and Tímár, 2013), can be interpreted as disturbances and fit well into the 'environmental change' type invasion scenario in the conceptual framework described by Facon et al (2006).…”

“…This reproductive characteristic seemed to be effective in the initial, colonization phase of reservoir fish community development. Later on, the stressful hyperthrophic environment and the increasing abundance of native competitors are possible drivers towards sexual reproduction and result in lower gibel carp abundance (see details in: Paulovits et al, 2014).…”

Remote sensing of macrophyte morphological traits: Implications for the management of shallow lakes

“…We must point out that the nutrient stock in T. natans meadows is likely to be an underestimation of the real nutrient uptake because we only considered above-water biomass (e.g., in July above and below water biomass of Tn were 60% and 40% of total biomass; Pinardi et al, 2011) and without leaf turnover during the whole vegetative period (e.g., by doubling the maximum standing stock; galanti and Topa esposito, 1996). if we assume that these values are generally representative of the allocation of biomass above and below water, and an equal allocation of nutrients for above and below water plant parts, then we estimate that the total nutrient storage in T. natans biomass is up to 11.7 n t and 1.3 P t. according to published works describing nutrient or chemical inflow and water discharge data over time, we calculate a total load for the growing season period (May-october) of 72-206 t n and 6-13 t P (szilagyi et al, 1990;Pomogyi, 1993;Tátrai et al, 2000;hatvani et al, 2011;horváth et al, 2013;Paulovits et al, 2014). The comparison of nutrient content in macrophyte beds derived from aPeX maps with nutrient load inflowing by the Zala river evidenced that about 6-16% and 10-21% of n and P, respectively, can be temporarily stored in T. natans biomass.…”

Native freshwater species get out of the way: Prussian carp (Carassius gibelio) impacts both fish and benthic invertebrate communities in North America

“…In particular, dense aquatic vegetation can be an indication of eutrophication, a product of anthropogenic activities such as agriculture [ 66 ]. Prussian carp are known to flourish in eutrophic environments and tend to colonize aquatic systems as the level of eutrophication increases [ 23 , 64 , 67 ]. As aquatic habitat integrity is often compromised in many habitats in western North America [ 27 , 62 ], this may also facilitate Prussian carp establishment as they have the ability to exploit a potentially undesirable niche space.…”