罗非鱼对水质的影响

鱼类是影响水库等水质的重要因素,以我国南方主要养殖鱼类之一的罗非鱼为对象,通过广东大镜山水库原位围隔实验,研究了鱼类对水质的影响。结果表明,与对照组相比罗非鱼围隔中总氮,总磷和叶绿素a浓度分别升高了42%,129%和347%。罗非鱼的排泄增加了水体营养负荷,为浮游植物生长提供大量的营养盐,引起浮游植物生物量增加,水体透明度降低。罗非鱼通过营养盐释放所产生的上行效应明显大于由其牧食导致的下行效应。

The effect of tilapia on water quality

Fish can affect the quality of water in reservoirs. Tilapia is one of the main aquaculture fishes in southern China. This study evaluated the effect of tilapia on water quality using enclosure experiments in Dajingshan Reservoir. The results showed that fish increased the mean total nitrogen (N), total phosphorus (P) and chlorophyll a content by 42%, 129% and 347%, respectively. It was likely that fish excretion increased nutrient loading and enhanced phytoplankton growth. While phytoplankton biomass increase would lead to a decrease of water transparency. The results indicate that the bottom-up control on phytoplankton through fish excretion is stronger than the top-down effects through fish grazing.