Forest conversion to oil palm compresses food chain length in tropical streams.

Clare L Wilkinson,Victoria Kemp,Pavel Kratina,Arman Hadi Fikri,Darren C J Yeo,Jia H Liew,Roswitha Fiala,Robert M Ewers,Kenny W J Chua

doi:10.1002/ecy.3199

Abstract

In Southeast Asia, biodiversity-rich forests are being extensively logged and converted to oil palm monocultures. Although the impacts of these changes on biodiversity are largely well documented, we know addition to samples we collected in 201 little about how these large-scale impacts affect freshwater trophic ecology. We used stable isotope analyses (SIA) to determine the impacts of land-use changes on the relative contribution of allochthonous and autochthonous basal resources in 19 stream food webs. We also applied compound-specific SIA and bulk-SIA to determine the trophic position of fish apex predators and meso-predators (invertivores and omnivores). There was no difference in the contribution of autochthonous resources in either consumer group (70-82%) among streams with different land-use type. There was no change in trophic position for meso-predators, but trophic position decreased significantly for apex predators in oil palm plantation streams compared to forest streams. This change in maximum food chain length was due to turnover in identity of the apex predator among land-use types. Disruption of aquatic trophic ecology, through reduction in food chain length and shift in basal resources, may cause significant changes in biodiversity as well as ecosystem functions and services. Understanding this change can help develop more focused priorities for mediating the negative impacts of human activities on freshwater ecosystems.

Highlights

Photo 1: Freshwater fieldwork at the SAFE project in Sabah, Malaysia
Study Description The study took place at the Stability of Altered Forest Ecosystems project, in the southeast of Sabah, Malaysia, which was set up to understand the impacts of deforestation and conversion of rainforest to oil palm plantations on biodiversity, ecosystem functioning and processing, at multiple spatial scales
This project used stable isotope analysis to explore how freshwater food webs in small streams were impacted across the land use gradient, including streams in primary forest, logged forest, and oil palm plantations

Summary

Introduction

Photo 1: Freshwater fieldwork at the SAFE project in Sabah, Malaysia. Researchers sampling a stream using electrofishing equipment to catch fish. J. Chua , Roswitha Fiala, Jia Huan Liew, Victoria Kemp, Arman Hadi Fikri, Robert M. Study Description The study took place at the Stability of Altered Forest Ecosystems project, in the southeast of Sabah, Malaysia, which was set up to understand the impacts of deforestation and conversion of rainforest to oil palm plantations on biodiversity, ecosystem functioning and processing, at multiple spatial scales.

Results

Conclusion