Differential sensitivity of a coccal green algal and a cyanobacterial species to dissolved natural organic matter (NOM)

作者：Prokhotskaya Valeria Yu; Steinberg Christian E W^*

来源：Environmental Science and Pollution Research, 2007, 14(1): 11-18.

DOI：10.1065/espr2007.01.379

• Chroococcus minutus
• Desmodesmus communis
• dissolved organic carbon (DOC)
• eutrophication
• growth promotion
• growth reduction
• humic substances
• natural organic matter

Background and Aim. In non-eutrophicated freshwaters, humic substances (HS) pose chemical stresses on aquatic organisms and, hence, separating sensitive from less sensitive or even tolerant species. One of the stresses, identified so far, is the reduction of photosynthetic oxygen production and reduction in growth in freshwater macrophytes and algae. In a previous paper, it has been shown that even closely related coccal green algae responded differently upon identical stress by HS, which is consistent with the hypothesis above. Due to their much simpler cellular ultrastructure, cyanobacteria are supposed to be more sensitive to HS exposure than eukaryote should be. One coccal green algal species (Desmodesmus communis) and one cyanobacterium (Chroococcus minutus) were exposed to four natural organic matter (NOM) isolates. One NOM has been isolated from a brown water lake (Schwarzer See) in Brandenburg State; three were obtained from a comprehensive Scandinavian NOM research project and originated from Norway (Birkenes), Finland (Hietajarvi), and Sweden (Svartberget). Methods. Cultures of D. communis and C. minutus were obtained from the Culture Collection of Algae, Gottingen, and maintained in a common medium. The cultures were nonaxenic. The algae and cyanobacteria were exposed under identical conditions to environmentally realistic NOM concentrations. Cell numbers were counted microscopically in Neugebauer cuvettes in triplicates. To avoid limitation by nutrient depletion, the experiments were terminated after 14 to 15 days. Until culture day 12, no growth limitation has been observed in the controls. Results. All NOM isolates modulated the growth of the algae and cyanobacteria. During the early culture days, there was a slight growth promotion with the coccal green alga and to a much lesser degree with the cyanobacterium. Yet, the major effect were significant reductions in cell yield in both primary producer cultures. C. minutus was much more affected than D. communis. This applies particularly to the three tested Scandinavian NOM isolates, which were effective at concentrations even below 1 mg L-1 DOC.

• 出版日期2007-5