Food web structure of a subtropical headwater stream
I-Yu Huang A , Yao-Sung Lin A , Chang-Po Chen B and Hwey-Lian Hsieh B CA Department of Life Science, National Taiwan University, Taipei, Taiwan 106, ROC.
B Research Center for Biodiversity, Academia Sinica, Nankang, Taipei, Taiwan 115, ROC.
C Corresponding author. Email: zohl@gate.sinica.edu.tw
Marine and Freshwater Research 58(7) 596-607 https://doi.org/10.1071/MF06127
Submitted: 18 July 2006 Accepted: 11 April 2007 Published: 26 July 2007
Abstract
The food web structure of a headwater stream (Hapen Creek) in subtropical northern Taiwan, which is subject to regular typhoon disturbances, was characterised using stable isotope techniques. δ13C and δ15N signatures were used to examine (i) the relative contributions of allochthonous versus. autochthonous sources to the web, and (ii) the trophic organisation of the community including the predominant feeding guilds and the most prevalent feeding mode. This study presents food web attributes for one of the very few food webs studied to date in a subtropical region. Consumers utilised allochthonous and autochthonous carbon sources differently depending on their trophic positions. The majority of consumers exploited more autochthonous carbon sources. Consumers at higher trophic positions in the food web had more direct and greater association with benthic algae. Higher-order consumers also consumed allochthonous carbon in an indirect manner by assimilating lower-order insects. The results reveal the importance of invertebrate consumer snails and aquatic insects in the transfer of organic matter. Omnivores predominated in the food web; this may reflect an opportunistic foraging strategy that enables them to adapt to hydrological disturbances and a fluctuating food supply.
Additional keywords: allochthonous v. autochthonous flows, δ13C, δ15N trophic interactions.
Acknowledgements
The authors thank Ling-Chuan Chuang and Chi-Chang Liu for their assistance in field collections and Sen-Her Shieh and Chorng-Bin Hsu for aquatic insect collection and identification. We also thank Drs. Jacques C. Finlay and Shuh-Ji Kao and the abovementioned colleagues for valuable discussions on stream dynamics. We are grateful to two anonymous referees for valuable comments on the manuscript. This research was supported by a grant (NSC90–2621-B-002–007) from the National Science Council of Taiwan to YSL. The study complies with the current laws of the country in which it was performed.
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