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Harvard Forest REU Symposium Abstract 2012

  • Title: Identifying indicators of tipping points within the aquatic micro-ecosystem of the pitcher plant, Sarracenia purpurea
  • Author: Jennie I Sirota (North Dakota State University)
  • Abstract:

    A gradual or rapid disruption to a natural system can lead to a tipping point, after which the system undergoes a potentially irreversible and undesirable state change. State changes are challenging to predict but hold great importance in the management of ecosystems and maintenance of biodiversity. Tipping points are often observed in aquatic ecosystems in which an overabundance of nutrients can push the system from an aerobic state to an anaerobic one, greatly altering community composition and structure. Here, we aim to determine if tipping points can occur within the aquatic micro-ecosystem of the carnivorous pitcher plant, Sarracenia purpurea, and to identify nutrient concentrations that drive the system to shift states from aerobic to anaerobic. Six replicate greenhouse experiments were conducted; each consisted of five treatments that included one control and four levels of nutrient enrichment (prey addition). One leaf on each plant was filled with filtered pitcher fluid containing only bacteria and introduced daily aliquots of ground dried vespid wasp to test state change dynamics. In addition, five individuals of the pitcher plant mosquito, Wyeomyia smithii, were placed into three of the replicates to test the influence of oxygen levels on the top predator in this aquatic food web. Dissolved oxygen and temperature were measured in each pitcher, and photosynthetically active radiation (PAR) was measured at the level of the pitcher plant leaves. The addition of 0.5-1.0 mg ml-1d-1 of prey (ground wasps) shifted the Sarracenia micro-ecosystem from aerobic to anaerobic within five days. The pitcher plant mosquito showed no difference in a range of oxygen levels, suggesting that the top predator isn’t immediately affected by a state change. By having a clearer understanding of tipping points in the Sarracenia ecosystem, we can learn more about predicting and managing state changes in a variety of other systems.

  • Research Category: Conservation and Management; Physiological Ecology, Population Dynamics, and Species Interactions

  • Figures:
  • Runs123456_decycledmean.pdf
    RUN2_ColorPAR.pdf