Abstract
The patterns of carbon flow in large rivers influenced by dams are still not well known. We hypothesized that spatial variation in fish assimilation of basal production sources would be affected by heterogeneity of landscape-scale hydrology within a watershed due to the impoundment. We used stable isotope analysis and Bayesian mixing models to estimate relative contributions of basal production sources to fish consumers in a tributary of the Three Gorges Reservoir (TGR) with remarkably heterogeneous habitats between the upper and lower reaches. Model estimates indicated that riparian C3 plants were the main basal food source irrespective of reaches or feeding groups. Autochthonous algae carbon also appeared to be important as secondary carbon sources. However, the major contributive aquatic algae in the upstream were benthic algae while planktonic algae were important in the downstream, and this difference was related to their distinct hydrological characteristics. The contribution from C4 plants was comparatively less important to all fish consumers. Our results highlighted the significance of the riparian C3 carbon source to fish consumers in the TGR tributary and that the difference in landscape-scale characteristics was not enough to influence the pattern, which may be attributed to abundant standing stock of the riparian plants as well as hydrologic regimes in this river.
Highlights
Deciphering the dominant carbon sources and energy pathways in riverine food webs is fundamental for understanding ecosystem function, with implications for future fluvial management and conservation
The sources and transport of carbon and energy in large river ecosystems have been conceptualized as several theoretical concepts, including the river continuum concept (RCC) [1], the flood pulse concept (FPC) [2] and the riverine productivity model (RPM) [3]
Each conceptual model has stressed the importance of organic matter originating from autochthonous or allochthonous sources [4]; such as the RCC stressing subsidy from upstream processing of terrestrial organic matter [1], the FPC emphasizing lateral river floodplain exchanges [2], and the RPM highlighting carbon derived from local in-stream production [5,6,7]
Summary
Deciphering the dominant carbon sources and energy pathways in riverine food webs is fundamental for understanding ecosystem function, with implications for future fluvial management and conservation. The sources and transport of carbon and energy in large river ecosystems have been conceptualized as several theoretical concepts, including the river continuum concept (RCC) [1], the flood pulse concept (FPC) [2] and the riverine productivity model (RPM) [3]. A more comprehensive concept, such as the Riverine Ecosystem Synthesis (RES), which regards rivers as arrangements of large hydrogeomorphic patches (functional process zones), is proposed to synthesize various river ecosystem concepts [10,11]. This new holistic and generalized concept has been developing recently in, for example, the river wave concept [12]. The most important carbon source supporting riverine food webs would vary depending on the temporal and spatial patterns of all kinds of environmental conditions [4,18,19]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
