Abstract Title

Tackling the global expansion of CyanoHABs along the freshwater to marine continuum: The need for a dual nutrient (N and P) control strategy

Start Date

24-5-2022 9:15 AM

End Date

24-5-2022 9:30 AM

Abstract

Anthropogenic nutrient over-enrichment, coupled with rising temperatures and an increased frequency of extreme hydrologic events, has promoted the expansion of harmful cyanobacterial blooms (CyanoHABs) along the interconnected freshwater-to-marine continuum. Pressures exist to reverse this trend in ecosystems to conserve drinking and irrigation, fishery, and recreational waters. Traditionally, reducing phosphorus (P) inputs are prescribed for freshwater systems, while nitrogen (N) inputs control estuarine/coastal CyanoHAB formation. However, microcosm to whole-lake nutrient-enrichment experiments increasingly indicate that CyanoHABs are stimulated by enrichment with both P and N or sometimes N alone. The accumulation of P “legacy” loads in water bodies supports effective internal P recycling, making it difficult to stem eutrophication with P-only external reductions. In most waterbodies, biological N2 fixation does not satisfy ecosystem N needs, while N can “escape” via denitrification, leading to perpetual N limitation. Therefore, dual N and P point and non-point reductions on watershed scales are needed to protect the continuum. In addition, a more climatically extreme world will augment watershed-based nutrient management challenges. In the short-term, physical, chemical or biological manipulative controls may improve immediate beneficial uses, but they are only temporary “fixes” that should be accompanied by long-term dual nutrient management for CyanoHAB control along the continuum.

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May 24th, 9:15 AM May 24th, 9:30 AM

Tackling the global expansion of CyanoHABs along the freshwater to marine continuum: The need for a dual nutrient (N and P) control strategy

Anthropogenic nutrient over-enrichment, coupled with rising temperatures and an increased frequency of extreme hydrologic events, has promoted the expansion of harmful cyanobacterial blooms (CyanoHABs) along the interconnected freshwater-to-marine continuum. Pressures exist to reverse this trend in ecosystems to conserve drinking and irrigation, fishery, and recreational waters. Traditionally, reducing phosphorus (P) inputs are prescribed for freshwater systems, while nitrogen (N) inputs control estuarine/coastal CyanoHAB formation. However, microcosm to whole-lake nutrient-enrichment experiments increasingly indicate that CyanoHABs are stimulated by enrichment with both P and N or sometimes N alone. The accumulation of P “legacy” loads in water bodies supports effective internal P recycling, making it difficult to stem eutrophication with P-only external reductions. In most waterbodies, biological N2 fixation does not satisfy ecosystem N needs, while N can “escape” via denitrification, leading to perpetual N limitation. Therefore, dual N and P point and non-point reductions on watershed scales are needed to protect the continuum. In addition, a more climatically extreme world will augment watershed-based nutrient management challenges. In the short-term, physical, chemical or biological manipulative controls may improve immediate beneficial uses, but they are only temporary “fixes” that should be accompanied by long-term dual nutrient management for CyanoHAB control along the continuum.