Growth responses of the submerged macrophyte sago pondweed (Potamogeton Pectinatus) to disturbance by three omnivorous fishes

Abstract

In China, the distribution area and ecological function of Potamogeton pectinatus have been adversely affected by aquaculture. To evaluate the effects of omnivorous fishes on submerged plant recovery in cultured lakes, growth responses of Potamogeton pectinatus to disturbance by three such fishes (gold fish (Carassius auratus), common carp (Cyprinus carpio), and yellow catfish (Pelteobagrus fulvidraco)) were analyzed. Three stocking densities (low, medium, and high) were selected for each fish species. Fish stocking obviously increased total nitrogen, total phosphorus, conductivity, and total dissolved solids and decreased dissolved oxygen and pH of the water. Fish species had significant effects on plant height, root length, root dry weight, and aboveground dry weight, which were the lowest after Cyprinus carpio treatment. Stocking density had significant effects only on root length, root dry weight, and aboveground dry weight. The fish species, stocking density, and their interaction had significant effects on total dry weight and biomass allocation. The total dry weight and root:aboveground part values were significantly lower after Cyprinus carpio treatment than after the other treatments. Therefore, the dominant fish species should be scientifically assessed before restoring submerged vegetation, and fish stocking density needs to be controlled to promote submerged macrophyte establishment in cultured lakes.