East Chongming salt marsh,located in the east of Changjiang Estuary, is a large wetland, which exhibits a variety of macrobenthos. Understanding the food sources and trophic level of macrofauna is a foundation to study the material and energy flux in the ecosystem. In this paper, stable carbon and nitrogen isotope ratios of organic matter sources and consumers were investigated in the summer of 2005 in the differents living environments of East Chongming salt marsh. It is found that the δ13C and δ15N values of surface sediments vary in different tidal levels, with δ13C from-21.3‰ to-24.2‰ and δ15N from 4.6‰ to 5.6‰. These stable isotope values suggest that sediments not only contain the extraneous materials but also are influenced by the autochthonous organic matter. Our data displays that the dominant macrophytes Scirpus mariqueter and Phragmites australis are the main allochthonous sources of sedimentary organic matter and the extraneous source is suspended particulate organic matter. The dominant macrophytes Scirpus mariqueter and Phragmites australis are C3 plants, and Spartina alterniflora is C4 plant. The stable isotopes are variable among different tissues of plants, especially of Phragmites australis, which suggests that care must be taken and the isotope value of leaves may not be used as that of the whole plant when estimating the food sources. The macrofauna shows a wide range of δ13C, with overall δ13C values between -23.6‰ and -14.7‰, which suggests significant difference of food sources. As a whole, sedimentary organic matter seems to be food base for macrofauna, while the dominant macrophytes of salt marsh appears to play a negligible trophic role. The nitrogen isotope can reflect the trophic level of macrobenthos. It is calculated that trophic level of macrofauna in East Chongming salt marsh is between 2.0 and 3.7, and thus the invertebrates are primary and secondary consumers.
YU Jie, LIU Min, HOU Li-jun, XU Shi-yuan, OU Dong-ni, CHENG Shu-bo
. Food Sources of Macrofaunal in East Chongming Salt Marsh as Traced by Stable Isotopes[J]. JOURNAL OF NATURAL RESOURCES, 2008
, 23(2)
: 319
-326
.
DOI: 10.11849/zrzyxb.2008.02.016
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