Temporal shift in contribution of terrestrial organic matter to consumer production in a grassland river
| Autor: | Alexander D. Huryn, Kathi Peacock, Graeme Lyon, Chris J. Arbuckle, Roger G. Young, Ralph H. Riley |
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| Rok vydání: | 2001 |
| Předmět: |
Total organic carbon
chemistry.chemical_classification geography geography.geographical_feature_category Stable isotope ratio Ecology Seston chemistry.chemical_element Aquatic Science Carbon sequestration Plant litter Grassland chemistry Environmental chemistry Environmental science Organic matter Carbon |
| Zdroj: | Freshwater Biology. 46:213-226 |
| ISSN: | 0046-5070 |
| DOI: | 10.1046/j.1365-2427.2001.00648.x |
| Popis: | 1. We used stable isotopes to study the temporal (early summer versus autumn) pattern of use of terrestrial and aquatic sources of organic carbon by consumers in two bedrock-confined reaches of a grassland river in New Zealand. 2. The major sources of organic carbon available to primary consumers were expected to be terrestrial leaf-litter and biofilm from the stream channel. These putative carbon sources showed no significant change in mean δ 13 C between summer and autumn. Leaf litter (mean δ 13 C -19.92). 3. In contrast to leaf litter and biofilm, the δ 13 C of consumers changed over time, being enriched in 13 C in the autumn compared with early summer. Both the magnitude (> 5‰ in some cases) and rapidity of this shift (≤ 3 months) was surprising. 4. A two-source mixing model indicated that, during early summer, terrestrial carbon comprised > 50% of tissue carbon for 15 of the 17 taxa of aquatic consumers analysed. During autumn, terrestrial carbon comprised > 50% of the tissue carbon of only five of 25 taxa. Because the mean δ 13 C of putative food sources was consistent over time, the shift in δ 13 C values for consumers is attributed to a change in relative amounts of terrestrial and aquatic carbon available for consumption. 5. Because seston consists of a mixture of many particles of diverse origin, it may provide an integrated measure of catchment-wide sources of organic matter entering a stream channel. Like the tissues of most consumers, mean δ 13 C values for seston showed a significant shift toward 13 C enrichment. This indicated that the relative availability of terrestrial carbon decreased from summer to autumn. 6. The actual quantity of carbon contributed to the stream food-web by this potential terrestrial-aquatic link is unknown. Although terrestrial carbon may comprise a high proportion of the tissue carbon of consumers prior to summer, the majority of secondary production (and carbon sequestration) probably occurs during early summer as a consequence of rising temperature and high quality food in the form of biofilm. |
| Databáze: | OpenAIRE |
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