Zoological Studies

Vol. 47 No. 3, 2008

Spatial and Seasonal Variations in Chaetognath Assemblages in Two Subtropical Marine Inlets with Different Hydrographical Characteristics

Pan Tse1, Sami Souissi2, Jiang-Shiou Hwang3, Qing-Chao Chen4, and Chong Kim Wong1,*

1Department of Biology, The Chinese University of Hong Kong, Shatin, Hong Kong, China
2Universite Des Sciences Et Technologies De Lille-Lille 1. Cnrs-Fre 2816 Elico, Station Marine, 28 Avenue Foch, 62930 Wimereux, France
3Institute of Marine Biology, National Taiwan Ocean University, Keelung 202, Taiwan
4South China Sea Institute of Oceanology, No. 164, Xingangxi Rd., Haizhu District, Guangzhou 510301, China

Pan Tse, Sami Souissi, Jiang-Shiou Hwang, Qing-Chao Chen, and Chong Kim Wong (2008) The seasonal and spatial occurrences of Chaetognatha were studied in 2 subtropical marine inlets with different hydrographical characteristics.  Tolo Harbour and Mirs Bay are marine bays in the northeastern corner of Hong Kong.  Tolo Harbour is a semi-enclosed bay with poor water circulation.  It opens into Mirs Bay which is fully exposed to water currents from the South China Sea.  Chaetognath species were grouped by hierarchical classification of samples using the BrayCurtis similarity coefficient and a clustering strategy with flexible links.  Indicator species for each group were used to characterize species assemblages.  Indigenous species, including Flaccisagitta enflata, Aidanosagitta neglecta, A. delicata, A. nagae, A. crassa, A. johorensis, and A. regularis, occurred in the entire study area, but their densities were higher in Tolo Harbour.  Non-indigenous species, including A. bedfordii, Krohnitta pacifica, Pterosagitta draco, Decipisagitta decipiens, Ferosagitta ferox, Fer. robusta, Fer. tokiokai, Mesosagitta minima, Sagitta bipunctata, Serratosagitta pacifica, Zonosagitta bedoti, Z. bruuni, and Z. pulchra were carried into Mirs Bay by ocean currents from the South China Sea and were rarely found in Tolo Harbour.

Key words: Chaetognaths, Spatial-seasonal distribution, Subtropical marine inlet, Indicator species.

*Correspondence: Fax: 852-26035391.  E-mail:chongkimwong@cuhk.edu.hk