Trophic isotopic carbon variation increases with pond\u2019s hydroperiod: Evidence from an Austral ephemeral ecosystem

Tatenda Dalu,Ryan J Wasserman,Olaf L F Weyl,P William Froneman

doi:10.1038/s41598-017-08026-6

Abstract

Trophic variation in food web structure occurs among and within ecosystems. The magnitude of variation, however, differs from system to system. In ephemeral pond ecosystems, temporal dynamics are relatively more important than in many systems given that hydroperiod is the ultimate factor determining the presence of an aquatic state. Here, using stable isotopes we tested for changes in trophic chain length and shape over time in these dynamic aquatic ecosystems. We found that lower and intermediate trophic level structure increased over time. We discuss these findings within the context of temporal environmental stability. The dynamic nature of these ephemeral systems seems to be conducive to greater levels of intermediate and lower trophic level diversity, with omnivorous traits likely being advantageous.

Highlights

Trophic variation in food web structure occurs among and within ecosystems
Much work on the dynamic nature of food webs has been conducted[1, 2, 5, 10, 11] and, it is well recognised that trophic variation occurs among and within ecosystems across spatial and temporal scales[5]
Temporal dynamics are important given that hydroperiod is the ultimate factor determining whether the aquatic state is even present

Summary

Introduction

Trophic variation in food web structure occurs among and within ecosystems. The magnitude of variation, differs from system to system. Temporal dynamics are relatively more important than in many systems given that hydroperiod is the ultimate factor determining the presence of an aquatic state. Much work on the dynamic nature of food webs has been conducted[1, 2, 5, 10, 11] and, it is well recognised that trophic variation occurs among and within ecosystems across spatial and temporal scales[5]. Temporal dynamics are important given that hydroperiod is the ultimate factor determining whether the aquatic state is even present. The relative importance of bottom-up and top-down pressures is likely to shift over time, and have significant implications for food web structure and trophic shape. These environments typically only exist as aquatic environments for limited periods and typically only hold water for a few www.nature.com/scientificreports/

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Conclusion