Algae. 1997; 12(3): 215-228.
Phytoplankton Communities in Fertilized Fish Ponds: Effects of Different Nutrient Loadings
Jeong-Ha Kim, Larry M. O'Flaherty
Department of Biology, Sung Kyun Kwan University, Department of Biological Sciences, Western Illinois University
Outdoor plastic-lined ponds were used to examine the effect of different regimes of fertilization on phytoplankton community to enhance fish production at the Jake Wolf Memorial Fish Hatchery, Mason County, Illinois, USA. The combinations of organic (i.e. soybean meal, alfalfa pellets) and liquid inorganic (i.e.10-34-0 of N: P: K) fertilizers and yeast were applied to the four ponds which had initially been supplied by the same water source and treated with the same combination of fertilizers. Two sets of non-replicate comparison were made with two ponds for each case; High vs. Medium loadings of liquid inorganic fertilizers (LIF) and Low vs. Non-loading of LIF with the same amounts of organic fertilizer for each comparison in 1986 and 1987, respectively. The pond with the medium loading of LIF, dominated by Chlorophyta (51.6%) and Bacillariophyta (38.4%), had about five times greater density of phytoplankton than the other pond with two times the amount of LIF, dominated solely by Chlorophyta (73.6%). Levels of dissolved oxygen and pH were proportional to phytoplankton density; however, levels of ammonia and phosphate were much higher in the pond with the high LIF but with low abundance of phytoplankton. The pond which received the high amount of LIF seemed to be overfertilized and thus the increase of ammonia was correlated with the decrease of phytoplankton, particularly Chlorophyta. These two ponds exhibited different secondary succession of phytoplankton. The pond with the low LIF loadings had greater abundance, higher species diversity and evenness than the pond without LIF. The latter maintained oligotrophic characteristics of water indicated by lower levels of phosphate and the common occurrence of Haematococcus lacustris. The data suggested that the application of medium or small amounts of LIF to these ponds support a greater productivity of phytoplankton and higher diversity of algae which may enhance zooplankton abundance and fish production as well.
fertilizers, fertilizers, nutrient loading, phytoplankton community, secondary succession, species diversity