两种不同株铜绿微囊藻培养液对大型溞的毒性效应研究

STUDIES ON THE TOXIC EFFECTS OF FILTERED CYANOBACTERIA CULTURE MED IA OF TWO DIFFERENT STRAINS(MICROCYSTIN-PRODUCING AND MICROCYSTIN-FREE)OF MICROCYSTIS AERUGINOSA ON DAPHNIAMAGNA

  • 摘要: 为了探讨铜绿微囊藻对浮游甲壳动物溞类的毒害效应,试验选取了两种不同株系(产毒和非产毒)的藻种,采取利用其培养液的方法,以研究铜绿微囊藻在生长过程中向水体中释放的毒素或类毒素物质对溞类的效应以及比较不同株系间效应的差异性。研究结果表明:(1)试验所选铜绿微囊藻产毒和非产毒株系的培养液均能对大型溞(Daphnia magna)的生长繁殖构成影响,表现为低剂量起促进效应,高剂量起抑制效应;(2)铜绿微囊藻产毒株较非产毒株更能影响大型溞的存活;(3)铜绿微囊藻产毒和非产毒株对大型溞的生长影响差异不大,但对其繁殖却存在明显不同,表现为株系942的抑制效应更强。可以初步推断,在以产毒株铜绿微囊藻为优势种形成"水华"的环境下,大型浮游甲壳动物溞类数量和生物量减少的主要原因可能是由于毒素对溞类较高的致死效应;而以非产毒株形成优势群体的水体里,其主要原因可能并非毒素的效应,而是由于其他原因,如藻类群体的形成阻碍摄食,缺乏必需脂肪酸等。

     

    Abstract: Negative effects of cyanobacteria on crustacean zooplankton Daphnia can be documented widely and severalm ainexplainary causes have been proposed (.i e. , toxicity, poor nutritional value, bad taste, and morphology ). But most of theprevious studies concentrated on the direct effects of cyanobacteria onDaphnia by add ingM icrocystis s. alone or inm ixtures( such as with Scenedesmus s.), inform at ion on the effects of culturem ed ia of M icrocystiss. on Daphnia was little. Th is paperw as to explore the harm ful effects of info-chem icals re leased by cyanobacterium M icrocystis aeruginosa during growtha nd to compare the differences in effects of different strains of M. aeruginosa on the crustacean zooplanktonDaphnia magna.Filtered cyanobacteria culturem edia of tw o different stra ins (m icrocystin-produc ing and m icrocystin- free) w ere used inthis study. The resultswere as fo llow:(1) Both of the culturem edia o f the two strains selected affected the grow th and productionofD. magna and the results showed that inhibitory effect occurred at high concentrations, wh ile stmi ulatory effectsw ere detected at low concentrat ions;(2) M icrocystin-producing strain affected the survival ofD. magna much more thanthe m icrocystin- free strain did;(3) No significant differences in grow th o fDaphnia were detected betw een the two strains,butm icrocystin-producing strain show ed stronger inhibitory effects on production than the m icrocystin-free stra in did.Therefore, it can be pred icted that, when cyanobacterial bloomsw ere dom inated bym icrocyst in-producing strainsM. aeruginosa,reduction in abundance and / or biomass of large filter- feeding cladocerans (such asDaphnia) could probab ly be explained by the high lethal effects ofm icrocystin; butwhen the phytoplankton commun ity was dom inated bym icrocystin- freestra ins, the foregoing phenomenon could not be explained by that, and then it should be attributed to other factors, such aslacking essential fatty acids, forming colony which can hamper ingestion or digestion, etc.

     

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