Virtual Poster Presentation - 3 minute narrated video presentation AFSS Conference 2020

Lake Sediment Bacterial Community Responses to Hydrogen Peroxide Exposure (#123)

Cody Woods 1
  1. Centre for Applied Water Science, Bruce, ACT, Australia

The increase of Cyanobacterial Harmful Algal Blooms (CyanoHABs) globally poses a serious threat to aquatic ecosystems. The primary driver of CyanoHABs is eutrophication (nutrient enrichment). In lacustrine ecosystems, nutrients from external sources and released through in-lake biogeochemical cycling, increase eutrophication and drive CyanoHABs. The application of hydrogen peroxide (H2O2) as a short-term control option for CyanoHABs, has been effective in reducing CyanoHABs in lakes. Studies show low concentrations (under ~4mg/L H2O2) selectively target prokaryotic cyanobacteria, leaving beneficial eukaryotic algae and higher organisms unharmed. Few studies have investigated the effects of H2O2 on non-target prokaryotes such as lake sediment bacteria but negative effects have been observed.

Lake sediment bacteria mediate biogeochemical cycling and in particular, nutrient cycling. Alterations to the lake sediment bacterial community (LSBC) structure have the potential to affect in-lake nutrient dynamics. Indirect effects on non-target prokaryotes caused by treating CyanoHABs with H2O2 could alter the LSBC and consequently, biogeochemical cycles. By altering biogeochemical cycles, H2O2 control could contribute to a longer-term negative feedback loop, increasing eutrophication and CyanoHABs. This brings into question the suggestion that H2O2 is a safe and effective short-term solution to CyanoHABs. To address this knowledge gap, a core incubation study is being undertaken to investigate the effect of 2, 4 and 8 mgL-1 H2O2 treatment on LSBC and nutrient cycling. Genetic marker analysis, plus total and dissolved nutrient concentrations will be used to determine if LSBC and nutrient cycling are affected by H2O2 treatment. Nutrient concentration and preliminary community structure results are expected by December. Final results are expected to increase understanding of the non-target effects of H2O2 in CyanoHAB management, allowing managers to make more informed decisions on H2O2 use.