Consumer trophic positions respond variably to seasonally fluctuating environments. Issue 2 (18th January 2019)

• Record Type: Journal Article
• Authors: McMeans, Bailey C.; Kadoya, Taku; Pool, Thomas K.; Holtgrieve, Gordon W.; Lek, Sovan; Kong, Heng; Winemiller, Kirk; Elliott, Vittoria; Rooney, Neil; Laffaille, Pascal; McCann, Kevin S.
• Is Part Of: Ecology. Volume 100:Issue 2(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-01-18
• Subjects: aquatic -- environmental variation -- fishes -- food webs -- omnivory -- stable isotopes -- stomach contents -- tropical river–floodplain ecosystem; Ecology -- Periodicals; Ecology -- Periodicals; Écologie -- Périodiques; Ecologie; Écologie; Écologie animale; Écologie végétale; Ecology; Periodicals; 577.05
• DOI: 10.1002/ecy.2570
• Languages: English
• ISSNs: 0012-9658

Abstract

Abstract: The effects of environmental seasonality on food web structure have been notoriously understudied in empirical ecology. Here, we focus on seasonal changes in one key attribute of a food web, consumer trophic position. We ask whether fishes inhabiting tropical river–floodplain ecosystems behave as seasonal omnivores, by shifting their trophic positions in relation to the annual flood pulse, or whether they feed at the same trophic position all year, as much empirical work implicitly assumes. Using dietary data from the Tonle Sap Lake, Cambodia, and a literature review, we find evidence that some fishes, especially small piscivores, increased consumption of invertebrates and/or plant material during the wet season, as predicted. However, nitrogen stable isotope (δ 15 N) data for 26 Tonle Sap fishes, spanning a broader range of functional groups, uncovered high variation in seasonal trophic position responses among species (0 to ±0.52 trophic positions). Based on these findings, species respond to the flood pulse differently. Diverse behavioral responses to seasonality, underpinned by spatiotemporal variation at multiple scales, could be central for rerouting matter and energy flow in these dynamic ecosystems. Seasonally flexible foraging behaviors warrant further study given their potential influence on food web dynamics in a range of fluctuating environments.