Abstract: Taking Sanjiang Plain marsh as a study unit, the morphological image processing was applied to classify the spatial patterns of marshes at pixel level on binary marsh maps, and the morphological module and classification statistic module were used to analyze the spatiotemporal patterns of marsh landscape fragmentation in 1980-2000. The results showed that within the 20 years, the overall change tendency of the marsh area in Sanjiang Plain was first decreased rapidly, and then decreased slowly. The area of core marshes was decreased rapidly, from a dispersible spatial pattern to a gradually centralized pattern in the basins of Bielahong and Naoli rivers in northeastern Sanjiang Plain. The perforated marsh area decreased largely and disappeared gradually, and transferred from the original heterogeneous landscape into homogeneous landscape. Most core and perforated marshes were transferred into patch marshes, which were situated in the northwest, central, and south parts of Sanjiang Plain, and had a trend to gradually replace the core marshes in the northeast part of the Plain. The annual growth of edge marshes was the fastest, and the edge pixel became wider and wider. The core marshes in the west, south, and east parts of Sanjiang Plain were substituted by edge marshes, easily resulting in edge effects and intense interspecies competition.

Key words: Microzooplankton, Phytoplankton, Carbon-to-chlorophyll a ratio, Grazing rate, Grazing pressure, Jiaozhou Bay