Author(s): Suiliang Huang, Min Wu, Changjuan Zang, Shenglan Du, Wenwen Kong, Joseph Domagalski, Magdalena Gajewska, Adam Szymkiewicz, Romuald Szymkiewicz
Linked Author(s): Suiliang Huang
Keywords: Fish food, bighead carp, common carp, nitrogen flux, enclosure experiment.
Abstract: Fish culturing in inland freshwater has a potential impact on water quality, especially for drinking water sources. In this paper, nitrogen dynamics were investigated under the condition of culturing bighead carp and common carp with added fish food (Phosphorus dynamics will be discussed elsewhere because its behavior is different from nitrogen). Nearly fifty days of observation indicated that the reservoir water was typically �nitrogen-rich� water, and nitrate -nitrogen (NO3--N) was the main nitrogenous form and accounted for 70 percent of measured total nitrogen (TN). TN, dissolved total nitrogen (DTN) and NO3--N concentrations in the enclosures with the addition of fish food were significantly lower than those in the control enclosure without fish food and the reservoir water. However, presence of fish food greatly increased ammonia-nitrogen (NH4+-N) and particulate total nitrogen (PTN) concentrations (p<>0. 05) when compared to the reservoir water. Culturing bighead carp and common carp showed insignificant contributions to TN, NH4+-N and NO3--N concentrations. Harvesting fish can remove 3. 22%, 29. 21% and 20. 66% of nitrogen in enclosures with culturing bighead carp, common carp and mixed bighead carp and common carp, respectively. Though TN concentrations in the fish culturing enclosures were somewhat lower than those in the surrounding reservoir water, contributions from long-term nutrient release of uneaten food, senescent algae, fish feces and polluted sediment to the algae growth and nutrient dynamics should be taken into fully consideration, which may be helpful to the reservoir management and safety of the water supply
Year: 2017