Potential influence of water level changes on energy flows in a lake food web

Abstract

Large seasonal water-level fluctuations may influence isotopic signatures of primary producers and the types and amounts of these potential food sources accessible to aquatic fauna of Poyang Lake, the largest freshwater lake in China. In this study, the isotopic signatures of primary producers and consumers were determined, stable carbon and nitrogen isotope analysis and mixing models were combined to investigate the influence of water levels on the diet and isotopic composition of Poyang Lake fish and invertebrates. Five potential food sources (seston, benthic organic matter, aquatic macrophytes, attached algae, and terrestrial plants), 4 species of invertebrates, and 10 species of fish were collected from the lake area during dry and wet seasons between January

Seasonal variability in baseline δ15N and usage as a nutrient indicator in Lake Poyang, China

“…As water-level fluctuates, the organic matter from terrestrial or macrophyte plants also may represent a large proportion of the basal food sources of floodplain lakes (Wantzen et al 2002;Wang et al 2011Wang et al , 2012. Major nitrogen cycling processes, such as nitrogen fixation, nitrification, and denitrification, which exert strong effects on isotopic fractionation during nitrogen transformation, also vary between dry and wet seasons (Hadas et al 2009).…”

“…It exhibits dramatic annual water-level fluctuations ranging from 8 to 14 m (Zhu and Zhang 1997) and the energy sources for the Lake Poyang food web vary with the seasons (Wang et al 2011;Wang et al 2012). In our study, we evaluated the variability of baseline isotopic signatures in this mesotrophic lake and explored the relationship between stable N isotope compositions of POM, SOM, mussels, snails, and seasonal ambient nutrient conditions in Lake Poyang.…”

Phytoplankton chlorophyllain Lake Poyang and its tributaries during dry, mid-dry and wet seasons: a 4-year study

“…This seasonality is related to differences in the water level during the dry, mid-dry and wet seasons. Although previous research has addressed the effect of the water level on energy flows in Lake Poyang (Wang et al, 2011), the patterns of variation in phytoplankton and the associated environmental factors during the dry, mid-dry and wet seasons remain unclear. Indeed, such studies will contribute to our knowledge of phytoplankton in river-connected and subtropical lakes.…”

Stable isotope analysis reveals relative influences of seasonal hydrologic variation and impoundment on assimilation of primary production sources by fish in the Upper Yesilırmak River, Turkey

“…In contrast, some studies report that algal production was the dominant energy source in large river food webs during high-flow pulses (Huryn et al, 2001;Herwig et al, 2007;Hladyz et al, 2012). Despite the potential for more terrestrial plant and animal material to enter the littoral zone during spring, autochthonous production sources seemed to support most fish biomass, a finding that contrasts those from other studies (Herwig et al, 2004;Wang et al, 2011).…”