Changes in fish production effectivity in eutrophic fishponds—impact of zooplankton structure

Abstract

Fishponds were and are purposeful water structures. Fish production is their main function and rational management is an inevitable condition for their existence. The present high level of fishpond eutrophication results in nutrients overloading. The effect of the high level of nutrients is emphasized by top-down control of zooplankton by high fish stock densities. Currently the zooplankton is represented by small species such as nauplii, small cyclopoid copepods, small species of Cladocera and rotifers that are not so effective filtrators. The high eutrophic level brings about high primary production (mostly with predominance of inedible Cyanophytes) which cannot be used by this type of zooplankton. The main consequences of high eutrophication are large fluctuations in basic environmental parameters and a decrease in production effectivity. It is expected that the utilization efficiency of the enormous primary production through zooplankton into fish production is low. Therefore, maintaining ecological stability and healthy, sound functioning of the ecosystem, meaning without considerable fluctuations, represents an important task in sustainable fishpond management.

Differential effects of age-structured common carp (Cyprinus carpio) stocks on pond invertebrate communities: implications for recreational and wildlife use of farm ponds

“…carp in spring. Summer zooplankton community composition in ponds with older-age carp was typical for fish planktivory, when mainly large-sized cladocerans are reduced, while copepods, which are better able to avoid fish predation, and small-sized species like Bosmina dominate (Lazzaro 1987;Potužák et al 2007). Daphnids have been suggested to be more important for phytoplankton control than collective zooplankton abundance (Brooks and Dodson 1965;Timms and Moss 1984).…”

“…Potužák et al 2007), at least until late summer, may be substantially important for visual effects of the pond landscape and for recreational use of ponds with 1? or 2?…”

“…Although carp diets, both in natural and aquaculture conditions, and the influence of carp on water quality have been widely studied (e.g. Matlak and Matlak 1976;Crivelli 1981;Vilizzi 1998;Rahman et al 2009), the consequences of carp impacts on the biotic and abiotic characteristics of aquacultural systems have received attention only with regard to the intensification of fish production (Pechar 2000;Potužák et al 2007) and pond suitability for viable polycultures with other fish species (reviewed in Kestemont 1995;Rahman et al 2009). Elucidation of the potential differences in age-structured carp effects on pond ecosystem properties, such as water turbidity, is crucial for understanding how to manage available pond resources so as to support functions other than fish production, e.g.…”

Water Quality After Application of Pig Slurry

“…L -1 till then 1990s. The impact of organic fertilization on increasing values of chlorophyll-a is well documented (Potužák et al, 2007). The application of organic fertilizer at regular intervals caused regular fluctuations of chlorophyll-a in the ponds.…”

The effect of different supplemental feed types in semi-intensive production of common carp fry (Cyprinus carpio) on the structure and dynamics of pond ecosystems

“…Njena vrednost zavisi od koliĉine rastvorenih materija i suspendovanih ĉestica u vodi meĊu kojima su i ţivi organizmi u vodenom stubu (fitoplankton i zooplankton). Upotreba mineralnih Ċubriva i stajnjaka sa ciljem podizanja produktivnosti ribnjaka zajedno sa prelaskom na sve gušći nasad riba dovela je do povećanog nivoa eutrofikacije i konaĉno hipertrofije šaranskih ribnjaka (Potuţák et al, 2007). Jedan od pokazatelja koji ilustruju ovakvo stanje je niska providnost vode (Pechar, 2000), ĉesto manja od 0,2 m (Potuţák et al, 2007).…”