Abstract: A 4-factorial (water temperature, salinity, nitrogen, and phosphorus) experiment was designed to study the niche characteristics of four common micro algae communities in prawn-aquaculture pond. The results showed that the niche breadth was the greatest for Cryptomonas erosa in temperature and salinity r esources (0980 and 0988, respectively) and for Niztzschia closterium in nitr ogen and phosphorus resources (0990), but the smallest for Chlorella pyrenoidosa in all test resources, with an average value of 0926. As for niche overlap, it was the smallest for C. erosa and C. pyrenoidosa in temperature and sa linity resources (0809 and 0702, respectively) and for C. erosa and N. closterium in nitrogen and phosphorus resources (0829), but the greatest fo〖HJ*3〗 r C. pyrenoidosa and Nannichloropsis oculata in temperature, salinity, and nitro gen and phosphorus resources, with the values being 0986, 0974 and 0989, r espectively. All of these suggested that in prawn-aquaculture pond, C. erosa co uld be bred with any other three of the microalgae communities, while N. oculata and C. pyrenoidosa should not be bred together for their obvious competition on the resources.

Key words: humidity and temperature variation, net ecosystem carbon exchange, eddy covariance., mobile dune