Cyanobacterial Blooms And Its Derivative Pollution Ecology Toxic Effect Of Silver Carps It Early Development Stage

With economic development, rapid progress in industrial and agricultural sectors in the recent years has resulted in the production of large quantity of eutrophic effluents. The occurrence of heavy cyanobacterial blooms in eutrophic freshwater is a worldwide ecological problem. Impairment of water quality due to eutrophication can lead to losses of ecological integrity, decreases in the transparency of water. Concomitant with the release of microcystins (MCs) during blooms degradation, cyanobacteria will produce many substances which are hamful to aquatic organism. In recent years, there have been increasing studies to evaluate MC contamination in aquatic vertebrates from natural water with cyanobacterial blooms, and we had some knowledges about the harmful of MCs. However, lots of studies foucs the harmful of cyanobacteial on juvenile fish, It is well known that early life stages are more sensitive to toxins than adult fish, because of the thinner epithelial layer combined with a relatively larger body surface to volume ratio, high metabolic rate, and limited mobility. The main purposes of this study were to assess the harmful of main dervants of cyanobacterial (MC-LR, NH3-N) on the carp larvae. Our goal was to use larvae and juvenile of sliver carp and bighead carp as the test organisms to determine the responses of growth and antioxidant systems to the toxicity of microcystin in combination with ammonia. The following is our study results:1The results of this research indicate that ammonia and microcystin can cause oxidative stress in silver carp(Hypophthalmichthys molitrix) larvae. The data suggest that these toxins have interactive effects on Catalase (CAT), Superoxide Dismutase (SOD), Glutathione (GSH), and Malonaldehyde (MDA) in silver carp larvae, especially in21-day-old larvae. SOD, GSH, and MDA, as biomarkers, are sensitive and effective in indicating ammonia and microcystin-induced oxidative stress in silver carp larvae, especially in21-day-old larvae. Therefore, SOD, GSH, and MDA, as sensitive biomarkers, are effective indicators of the oxidative stress and deleterious effects that multiple toxins released from senescence and lysis of cyanobacterial blooms have on aquatic organisms in lake environments.2The results of this research indicate that both MC-LR and NH3-N induced significant changes in oxidative stress biomarkers at the biochemical level of biehead carp (Hypophthalmichthys nobilis) larvae. Microcystin significantly decreased body length, while ammonia significantly increased body weight, specific growth rate (SGR), and condition factor (CF), but there was no significant interaction between ammonia and microcystin on them. The study firstly indicated ammonia could aggravate the harmful effect of MC-LR on larvae, because our results suggested ammonia combined with MC-LR resulted in oxidative damage to lipids and proteins and inhibition of antioxidant capacities. The more pronounced effects of NH3-N coupled with MC-LR compared to the MC-LR alone treatment show a synergic effect, this observation is of importance for further assessment studies:since the occurrence of eutrophic lakes is becoming more frequent, cyanobacterial blooms are increasingly causing important fish habitats to contain deleterious levels of MC-LR combined with ammonia. These results provide some evidences on understanding the impact of toxins derived from degradation of cyanobacterial blooms on early stages of fish.3The results of this research indicate that NH3-N induced significant changes in oxidative stress biomarkers at the protein and gene levels of juvenile bighead carp (Hypophthalmichthys nobilis). Low concentration ammonia increased body length, body weight, specific growth rate; while higher concentration could decreased ammonia increased body weight, specific growth rate, The study also indicated low concentration ammonia could significantly elevated the activity of SOD and increased MDA content. Higher concentration ammonia decreased SOD activity and MDA content. Besides, ammonia suppressed the expressions of SOD and CAT mRNA. Our results suggested ammonia resulted in oxidative damage to lipids and proteins and inhibition of antioxidant capacities. The more pronounced effects of NH3-N is that it suppress the expression of genes of antioxidant enzymes, this observation is of importance for further assessment studies:since eutrophic lakes is becoming more frequent, and eutrphic waters improved the concentration of ammonia in water. It is more harmful to the larvae bighead carp. These results provide some evidences on understanding the impact of toxins derived from degradation of cyanobacterial blooms on early stages of fish.4The results of this research indicate that the derivative of cyanobacterial bloom has caused serious harmful on juvenile bighead carp (Hypophthalmichthys nobilis). In our study, we test the effect of derivative of cyanobacterial bloom on the growth, antioxidant system, expression of mRNA, HSP70of juvenile bighead carp. The study indicated the derivative of cyanobacterial bloom have no significant effect on growth, SGR of juvenile bighead. However, it increased the activity of antioxidant enzymes and the expression of hot shock protein (HSP)70, the content of MDA has also been significant improved. Besides, the result also provides the derivative of cyanobacterial suppress the expression of mRNA of antioxidant enzymes. The results indicate the derivative of cyanobacterial cause severe harm to juvenile bighead, and damage gene of juvenile bighead. These results provide some evidences on understanding the impact of derived from cyanobacterial blooms on early stage of fish.