Phytoplankton diversity in Futian mangrove wetland of Shenzhen: Composition and distribution

Based on the field survey in 2005-2006, the composition and spatiotemporal distribu-tion of phytoplankton diversity in Futian mangrove wetland of Shenzhen were studied, and the wa-ter body' s trophic state of the wetland was assessed by using Shannon-Wiener diversity index, Pielou evenness index, Margalef abundance index, and dominance index. A total of 51 species (including 1 variety and 9 unidentified species) belonging to 28 genera in 5 phyta were identi-fied. The phytoplankton density in each season all reached 10 ind · L ^-1 or more. In terms of species number and quantity, diatom was dominant in the phytoplankton community. Cyclotella caspia and Thalassiosira nordenskiöldi were the dominant species, while the other pollution-toler-ance species such as Oscillatoria minima and Euglena pisciformis· became dominant in some sta-tions in summer and autumn. In contrast to the remarkable spatiotemporal variation of species composition, a greater spatial but little temporal variation of phytoplankton quantity was ob-served. Dominant species had remarkable spatiotemporal variation, but the simplicity was obvi-ous. The four diversity indices presented more spatial variation, and the assessment with these indices showed that the water body' s trophic state of the wetland was at meso-eutrophic, and ten-ded to be eutrophicated. It was necessary to strictly control the wastewater discharging and inland runoff into the mangrove wetland.