Long Term Effect of Cyprinid Fishes on Phytoplankton and Zooplankton Communities in a Shallow Water Protection Reservoir

Abstract

The effects of fish kill and different fish stocks on the phytoplankton and zooplankton dynamics were studied in a shallow hypertrophic reservoir system. When fish stock was below 100 kg ha -1 , nutrient availability was not the main limiting factor for growth of phytoplankton. Consequently top-down forces controlled phytoplankton. In the years with high fish stock (>100 kg ha -1 ) the bottom-up forces dominated as nutrient availability was the main limiting factor for growth of phytoplankton. We can conclude that significant water quality improvement can be achieved in the reservoir system by decreasing fish stock below 100 kg ha -1 . Although clear-water phase could be stabilised temporary by macrophytes, stabilisation of good water quality requires continuous regulation of fish community.

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

“…These studies argued that the omnivore roach benefits from its plastic feeding and foraging strategy against the visual predator perch (P. fluviatilis L. 1758), mainly in younger (1þ, 2þ) age groups. In case of Lake Hídvégi, the mechanism might be similar, as young gibel carp feeds mostly on zooplankton (Specziár et al, 1997;Paulovits et al, 1998), which could be the limiting factor under cyanobacteria-dominated hypertrophic conditions (Jeppesen et al, 1998;Mátyás et al, 2004). It should be mentioned, however, that roach can switch to benthivorous strategy earlier (Lappalainen et al, 1975).…”

The consequences of mass mortality events for the structure and dynamics of biological communities

“…Although not specifically incorporated into our models, all studies suggested that some limiting nutrients increased following the MME-increasing NO 3 - (Nagdali and Gupta 2002), soluble P and NO 3 - (Vanni et al 1990), total and soluble reactive P (Mátyás et al 2004); however, the three studies showed various degrees of an initial fertilization effect, including no initial increase in resource abundance (Fig. 6a), a short-term positive impact on resource abundance (Fig.…”

“…Three studies, all from fish MMEs, presented time-series data that was sufficient to graphically visualize MME dynamics (Vanni et al 1990, Nagdali and Gupta 2002, Mátyás et al 2004. We extracted data from these studies using Image J ver.…”

“…Herbivore abundance increases when ε > 0, initial and middle stages 90% (n = 10 studies, ε not specified) Herbivore abundance decreases only when ε <<< 0, later stages, otherwise never 10% (n = 10 studies, ε not specified) (Vanni et al 1990) and (c) (Mátyás et al 2004). Dotted circles represent the start of the time series, solid circles represent the onset of the MME, and solid triangles represent the end of the time series.…”

Classification of the Oxbow Lakes of the Hármas-Körös River and Determination of Ways for Further Exploiting the Various Water Regions in the Light of the Water Framework Directive

“…In carp dominated the stocking, but still it was too small proportion accounted for predatory fish. In this way effect "bottom up" was reinforced and it was adjusted to the deterioration of water quality (Mátyás et al 2004). When planning stocking, the operation of bio manipulation were not used to improve water quality (Prejs 1978, Benndorf 1995, Tátrai et al 1998, Dawidowicz et al 2002.…”