Research On Effects Of Temperature,Feeding Level And Salinity On Rates Of Ammonia Excretion And Phosphate Excretion Of Sebastes Schlegeli Under Farm-like Conditions

Black stock fish Sebastes schlegeli is a fine species for the cage culture in Yellow Sea and Bohai Sea region.There are important economic and social benefits for artificial production- increasing cultivation of Sebastes schlegeli in the coastal areas.But now there are only 15% -30% nitrogen total input and 10% -15% phosphorus total input to be used by the fish.And the rests enter into the environment in different ways.It not only is a great waste of resources, and will pollute the water environment and affect the sustainable development of the industry if these nutrients are not rational used.In order to solve these problems, we must understand the effect of temperature,feeding level and salinity on ammonia nitrogen and phosphate excretion of Sebastes schlegeli.We simulate cage culture under farm-like conditions to measure the rate of the ammonia nitrogen and phosphate excretion after feeding normally and starvation 24h during the day under different temperatures and different feeding levels.And study the relationship between them.Meanwhile we research the influences of irregular salinity pulse effecting on rates of ammonia excretion and phosphate excretion of black stock fish.The main results are summarized as follows.(1)Effects of feeding level on ammonia nitrogen and phosphate excretion rate The results show that the rate of the ammonia nitrogen and phosphate excretion rise with the feeding level increasing in 10 hours after feeding normally.And this trend slows gradually after 10 hours.The maximum is at high feeding level of 10%, and the minimum is at low feeding level of 1% and 2%.The ANOVA analysis show that there aren't significant difference(sP>0.05)to the rate of ammonia nitrogen excretion during the whole experiment at different feeding levels but there are significant difference(P<0.05)to the rate of phosphate excretion during the whole experiment .And the rate of the ammonia nitrogen and phosphate excretion during the whole experiment is higher significant after feeding normally than starvation 24h.(2)Effects of temperature on ammonia nitrogen and phosphate excretion rate The ANOVA analysis show that are significant differences(P>0.05) both to the rate of ammonia nitrogen excretion and to the rate of phosphate excretion at different temperatures.Rates of ammonia nitrogen excretion first reduce then increase as temperature increasing at feeding level of 2%,4% and 10%, but there are opposite trend at feeding level of 1% and all feeding levels after starvation 24h.Basically, rates of phosphate excretion first reduce then increase as temperature increasing.(3)Effects of salinity on ammonia nitrogen and phosphate excretion rate The ANOVA analysis show that there are significant differences(P<0.05)to the rate of ammonia nitrogen excretion at different salinity pulse levels but it's no to the body weight ; however, there are significant difference(P<0.05)to the rate of phosphate excretion at different body weight levels but it's no to the salinity pulse.In conclusion of the study ,we reveal the effect of salinity,temperature and feeding level on ammonia nitrogen and phosphate excretion of Sebastes schlegeli,add important information on Physiological Ecology of the species,provide a theoretical basis for the artificial cultivation of the species,at the same time provide new information for building a bioenergetics model of energy metabolism.It is very important for using the nutrient coming from the waste output of cage culture effectively,improving the comprehensive efficiency of aquaculture,promoting the sustainable development of industry,and protecting the marine environment.