Evaluation of a combined macrophyte–epiphyte bioassay for assessing nutrient enrichment in the Portneuf River, Idaho, USA

摘要: We describe and evaluate a laboratory bioassay that uses Lemna minor L. attached epiphytes to characterize the status of ambient nutrient-enriched water from Portneuf River, Idaho. Specifically, we measured morphological (number fronds, longest surface axis, root length) population-level plants dry mass) responses community-level (ash-free mass [AFDM] chlorophyll [Chl a]) nutrient enrichment. Overall, measures macrophyte biomass abundance increased with increasing concentrations dissolved phosphorus (P) responded more predictably enrichment than measures. Epiphyte AFDM Chl were also greatest in P-enriched water; enrichments N alone produced no measurable epiphytic response. The epiphyte response did not directly mirror responses, illustrating value combined macrophyte–epiphyte assay fully management strategies. Finally, most waters only supported greater standing stocks but had significantly higher column oxygen organic carbon lower pH. Advantages this over traditional single-species assays include use realistic level biological organization, relatively short schedule (~10 days), inclusion multiple water-quality