Effects Of Liza Haematocheila T. & S On Nutritional Elements Cycle And The Fisheries Resources In The Yangtze Estuary

Detritivorous fishes can transport nutrients into ecosystem from sediments through feeding on detritus, and this course is concerned of inflow and outflow of nutritional elements and energy in aquatic ecosystem. This research selected redlip mullet (Liza haematocheila T.& S. (body weight from 1.92 to 5.60g) as object, and carbon (C),nitrogen (N),phosphorus (P) and energy were regarded as the indicators, based on physiological and nutritional methods, to study the utilization and regeneration of the nutritional elements and energy in the aquatic ecosystem. Three factors were set up: temperature, feeding levels, and kinds of diet. Moreover, the scavenging abilities of nutritional elements were measured and the detailed energy budgets were constructed.The results showed:1).Temperature did significant effects on the scavenging abilities of redlip mullet. Under a certain temperature, there were positive relationships between scavenging abilities and body weight. The relationships between temperature,body weight and scavenging abilities could be described as:: Carbon:z = 1.3951x^0.8044(1.7135y²-55.5007y+952.0986); Nitrogen:z = 0.7172x^0.8158(0.8814y²â€”29.4593y+438.2633); Phosphorus:z = 0.2355x^0.7558(0.1300y²â€”4.4501y+66.4795); (where z is scavenging ability, the same as the difference between intake and faecal matter, y is temperature and x is body weight).In the budget, temperature and body weight did significant effects on intake parts (IC,IN,IP), showing positive relationships. Percentages of parts allocated into growth (GC,GN,GP) were positively related with temperature, while non-faecal loss (NFLC,NFLN,NFLP) percentage decreased with increasing temperature. Percentages of faecal carbon (FC),nitrogen (FN) but phosphorus (FP) increased with growing temperature. Loss of intake carbon and nitrogen were mainly in non-faaecal...