Meiofaunal assemblages in relation to properties of fluid mud in river estuaries.pdfVIP

? by PSP Volume 22 – No 1. 2013 Fresenius Environmental Bulletin 67 MEIOFAUNAL ASSEMBLAGES IN RELATION TO PROPERTIES OF FLUID MUD IN RIVER ESTUARIES Bao-Zhu Pan1, Zhao-Yin Wang2,*, Chao Ying3, Meng-Zhen Xu2, Zhi-Wei Li2 and Guo-Bing Huang1 1 Changjiang River Scientific Research Institute, Wuhan 430010, China 2 State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China 3 Institute for Sedimentation River and Coastal Engineering, Tianjin University, Tianjin 300072, China ABSTRACT A systematic investigation of meiofauna in the fluid mud of river estuaries was carried out in December 2009 and May 2010. A total of 7 meiofaunal groups were iden- tified, and they were nematodes, rotifers, copepods, ostra- cods, bivalves, insects and arachnids. Meiofauna were mainly distributed in the depth of 0-10 cm, especially concentrated in 0-2 cm. Meiofaunal density in the New Ziya River estuary was up to 9051 ind 10 cm-2 in the depth of 0-2 cm, about 5 times that in the Jiyun River estuary. Comparison at the same vertical layer indicated that meiofaunal density in the New Ziya River was much higher than that in the Jiyun River. Pearson correlation analyses revealed that meiofaunal densities were signifi- cantly related to median grain size, water content, critical shear stress and bulk density. Activities of plenty of meio- faunal animals brought about intense disturbance to floc- culated masses. Existence of these animals can inhibit further sedimentation and compactification of suspended sediment. It is suggested that studies on relations among en- vironment, fluid mud and meiofauna should receive atten- tions from river managers. KEYWORDS: sediment, meiofauna, vertical distribution, river estuary 1 INTRODUCTION River estuary is a mixed zone of salt and fresh water, where nutrients are rich, bio-productivity is high, and ecological environment is changeable. Estuarine area has a special s