Response of food organisms to inorganic nitrogen availability
AbstractInfluence of inorganic N2 forms on pond food organisms was investigated. Seven identified plankton taxa comprising four phytoplankton: Desmidiaceae (desmids), Bacillariophyceae (diatoms), Cyanophyceae (blue-green algae) and Chlorophyceae (green algae) and three zooplankton: Protozoa, Cladocera and Rotifera fluctuated in response to nutrient inputs. All recorded significant F-value across treatments. With exception of blue-green algae, other phytoplankton groups had comparable relative abundances in treatment with higher concentration of readily utilized Nitrate-Nitrogen (NO3-N) compared with control that recorded higher concentration of Ammonia-Nitrogen (NH3-N) and increased relative abundance of blue-green algae. Zooplankton exhibited same dominance pattern of Protozoa, Rotifera and Cladocera respectively, with treatment recording higher abundance in response to edible phytoplankton. N2 from zooplankton excretion influenced phytoplankton responses in the control. Ammonia-Nitrogen (NH3--N), Nitrate-Nitrogen (NO3-N) and Nitrite-Nitrogen (NO2-N) were observed to fluctuate along nutrient enrichment profile depending mostly on the concentrations of intermediate Nitrite-Nitrogen (NO2-N). All nutrient parameters except NH3-N recorded significant t and F statistic between and across treatments. Water quality parameter of pH and dissolved oxygen were favourable for most period of the experiment.
KEY WORDS: Nutrient, Plankton, Ammonia-Nitrogen, Nitrate-Nitrogen, Nitrite-Nitrogen.
Global Jnl Pure & Applied Sciences Vol.10(2) 2004: 243-248