Experimental Study On Toxicity And Effect Of Several Water Environmental Physical-chemical Factors On Hatching, Growth And Development Of Lateolabrax Maculatus

1 The effects of salinity and ion composition on embryo and Newly hatched larvae of Lateolabrax maculatusThe objective of this section was to evaluate the effects of salinity and Ion composition on abnormal rate、hatching rate, ups and downs and survival activity index of the larvae of Lateolabrax maculatus. The results showed that eggs were sank below 23 and buoyant above 27, providing varying levels of suspension with salinities of 23.4-26 in the water column. The suitable salinities for hatching range from 15～30, the optimum salinities for hatching range from 20-30. The suitable salinities for newly hatched larvae range from 15-30, the optimum salinities for newly hatched larvae range from 20-30. When Ca2+ is less than or equal to 194.26mg/L, and Mg2+ is less than or equal to 556.67mg/L, the abnormal rate will be increase, the survival activity index of larvae will be reduced.2 Ontogeny of gill and swim bladder and ATPase activity of Lateolabrax maculatusThe objective of this section was to study the changes of ATPase of Lateolabrax maculatus from 0 to 2dph (day post hatching). Based on the histological and morphology observations under optical microscope, we studied the ontogeny of the gill and swim bladder of Lateolabrax maculatus from 0 to 45 dph. The results showed that the primordial gill was formed on 1dph, and the primordial lamellae were first formed in the pseudobranch on 15 dph. The primordial lamellae were formed in all giH arches on 25 dph. From 45dph forward, the filaments and lamellae of gills increased in number and length prominently and the gill of larvae was similar to that of fish. The primordial swim bladder was first observed on 1 dph, the swim bladder was dilated on 5 dph, and the swim bladder finished inflation on 11 dph. The specific activity of Na+, K+-ATPase and Ca2+、Mg2+ -ATPase have the same change tendency, reached the maximum (4.87±0.40U/g and 2.04±0.15 U/g) on 11 dph. The change of ATPase activity is closely related with the development of chloride cells.3 the effects Salinity acclimation on growth and development of larvae Lateolabrax maculatusThe objective of this section was to evaluate the effect of dilution gradient on distribution status, survival, growth, yolk and oil globule utilization, activity of ATPase, antioxidant enzymes of larvae of Lateolabrax maculatus. The results showed that newly hatched larvae and embryo have the same distribution of water, Larvae of low salinity groups go into a floating layer of water on the opening day of feeding. Larvae of groups of salinity below 18 were sank from 6 to 10 dph. Desalination affects the survival, growth, energy distribution, osmotic pressure and antioxidant system of larvae by osmotic pressure and density. The simple addition of Ca2+, Mg2+ ions affect the ion balance in larvae, resulting in increase of activity of ATPase and antioxidant enzymes.4 Acute toxicity of several conventional disinfectants on Juvenile Lateolabrax maculatusThe acute toxicity of five conventional disinfectants including chlorine dioxide, glutaraldehyde, benzalkonium bromide, three chloro isocyanuric acid, bromochlorohydantoin to juvenile Lateolabrax maculatus (weight 4.35±0.63 g) were studied at a salinity of 5, pH of 8.05-8.3, water temperature of 26～30, dissolved oxygen≥5.0mg/L. the results showed that the 24h LC50 values of chlorine dioxide, glutaraldehyde, benzalkonium bromide, three chloro isocyanuric acid, bromochlorohydantoin were 2.965,9.506,2.878,3.614,2.747mg/L; the 48h LC50 values were 2.625,7.319,2.391,3.359,2.218mg/L; the safe concentration values were 0.617,1.301,0.495,0.870,0.434mg/L. The susceptibility Lateolabrax maculatus of to the five drugs was in the order of bromochlorohydantoin> benzalkonium bromide>chlorine dioxide>three chloro isocyanuric acid (effective chlorine 30%)>glutaraldehyde.5 Acute toxicity of unionized ammonia and nitrite on Juvenile Lateolabrax maculatus according to the salinityThe acute toxicity of unionized ammonia and nitrite to juvenile Lateolabrax maculatus (weight 50.33±4.35 g) were studied at different salinity levels of 0,10,20. this section was also to evaluate the effects of salinity (0,10,20) and ammonia exposure (0,5,10,15,20mg/l) on oxygen consumption and ammonia excretion of Juvenile L. maculatus. The results showed that the safe concentration values of nitrite for L. maculatus at salinities of 0,10,20 were 16.357,52.540,58.622 mg/L. the safe concentration values of ammonia-N (unionized plus ionized ammonia as nitrogen) for L maculatus at salinities of 0,10,20 were 0.794,4.625,5.163 mg/L. the safe concentration values of ammonia-N (unionized plus ionized ammonia as nitrogen) for L. maculatus at salinities of 0,10,20 were 0.584,2.313,1.951 mg/L. the oxygen consumption and ammonia excretion of Juvenile L. maculatus were significantly affected by salinity, ammonia exposure, Temperature and salinity interaction.Oxygen consumption and ammonia excretion reached the minimum values at salinity of 10.