AB 12:291-298 (2011)  -  DOI: https://doi.org/10.3354/ab00344

ABSTRACT: Carbon and nitrogen stable isotope analyses were used to determine how a trichopteran filter feeder Stenopsyche marmorata Navas (Stenopsychidae) reflects shifts in food sources (suspended particulate organic matter [SPOM], benthic particulate organic matter [BPOM], and periphyton) in response to channel drying in the alluvial soils of the Inukami River in Japan. The δ¹³C and δ¹⁵N values of consumers shifted to a pattern similar to that of BPOM in an intermittent river, which suggests that particulate organic matter at each station may play an important role as a food source. Moreover, analysis of the upper reaches of the dry channel revealed that both consumers and food sources have enriched δ¹³C values due to physicochemical characteristics in the channel such as a high water temperatures and stagnant water. Conversely, the lower reaches showed more negative δ¹³C values, suggesting either a lack of carbon or a reduced supply of terrestrial dissolved carbon, both caused by channel drying, and higher δ¹⁵N values, suggesting a high dissolved inorganic nitrogen concentration in groundwater. Our study showed that a dry channel may influence the flow of energy between ­consumers and their food sources and the flow of nutrients from the upper to the lower reaches.

KEY WORDS: Trichopteran filter feeder · δ¹³C · δ¹⁵N · Channel desiccation · Inukami River