Seasonal dynamics of macrobenthic functional groups and trophic levels in the bridge construction zone at the South Bank of Hangzhou Bay, China

摘要

A survey (May 2006 to February 2007) was carried out on the tidal flat near the Hangzhou Bay Sea-Crossing Bridge at the south bank, in order to assess the changes in habitat conditions of the tidal flat wetland resulting from differences in the zoobenthic community structure and function on different tidal flats and in different seasons. Macro-invertebrates were identified and counted. Based on the data collected from samplings near the bridge at the south bank of the Hangzhou Bay, we have categorized functional groups according to feeding types. 32 species were identified, and assigned to 5 distinct functional groups (planktophagous, phytophagous, carnivorous, omnivorous and detritivorous) and 4 trophic levels. The results showed that all the zoobenthic community’s diversity indices referred to in this paper were significantly different between the tidal flats, while only Margalef’s species richness indexes and the Shannon-Wiener diversity coefficient showed a significant difference between seasons. There was no significant difference between seasons for any of the diversity indices of functional group density, but a significant difference was found between the tidal flats (except for the planktophagous group). The number of species in the carnivorous group showed no significant difference between tidal flats, while a significant difference was found between seasons, as opposed to the other functional groups. There was no significant difference between seasons for any of trophic levels density, but a significant difference was found between the tidal flats. The number of species placed in the carnivorous group showed a significant seasonal difference, while no significant difference between tidal flats, as opposed to the other functional groups which placed in the second and third trophic levels. This study suggests that basic zoobenthic community parameters were reflected in the composition and diversity of the functional groups. Obtaining species diversity information from the analysis of the composition and diversity of functional groups helps us to understand changes in the ecological relationships underlying complicated community changes [ Acta Zoologica Sinica 53(6): 1011–1023, 2007].