Drought and nutrient pollution produce multiple interactive effects in stream ecosystems

PLoS One. 2022 Jul 14;17(7):e0269222. doi: 10.1371/journal.pone.0269222. eCollection 2022.

Abstract

Drought and nutrient pollution can affect the dynamics of stream ecosystems in diverse ways. While the individual effects of both stressors are broadly examined in the literature, we still know relatively little about if and how these stressors interact. Here, we performed a mesocosm experiment that explores the compounded effects of seasonal drought via water withdrawals and nutrient pollution (1.0 mg/L of N and 0.1 mg/L of P) on a subset of Ozark stream community fauna and ecosystem processes. We observed biological responses to individual stressors as well as both synergistic and antagonistic stressor interactions. We found that drying negatively affected periphyton assemblages, macroinvertebrate colonization, and leaf litter decomposition in shallow habitats. However, in deep habitats, drought-based increases in fish density caused trophic cascades that released algal communities from grazing pressures; while nutrient enrichment caused bottom-up cascades that influenced periphyton variables and crayfish growth rates. Finally, the combined effects of drought and nutrient enrichment interacted antagonistically to increase survival in longear sunfish; and stressors acted synergistically on grazers causing a trophic cascade that increased periphyton variables. Because stressors can directly and indirectly impact biota-and that the same stressor pairing can act differentially on various portions of the community simultaneously-our broad understanding of individual stressors might not adequately inform our knowledge of multi-stressor systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Droughts
  • Ecosystem
  • Nutrients / analysis
  • Periphyton*
  • Rivers*

Grants and funding

All funding for this experiment was provided by the Arkansas Game and Fish Commission and United States Geological Survey. The funding was non-specific and given to DDM as base funds. There was no additional external funding received for this study.