COMPETITIVE REDUCTION OF NOXIOUS LYNGBYA-WOLLEI MATS BY ROOTED AQUATIC PLANTS

Establishment of native emergent or floating-leaved plants appears to offer natural and effective means to minimize the nuisance impacts of the mat-forming cyanobacterium Lyngbya wollei. This research has ident ified two species (Pontederia cordata and Potamogeton nodosus) which o ffer the potential for long-term competitive control of nuisance L. wo llei mats in shallow waters. Both species significantly impacted the d istribution and total mass of L. wollei mats within planted experiment al plots compared to adjacent unplanted control plots. The established plants forced a redistribution of the L. wollei biomass within the wa ter column, preventing the formation of the characteristic summertime floating mats, the most objectionable of the many nuisance aspects of this species. In addition, the L. wollei biomass was reduced by more t han 50% in planted plots. This reduction in mass may have been related to reduced light and nutrient availability within the vegetated plots . In addition, oxygenation and acidification of the benthic region may have promoted the decomposition and remineralization of the nuisance mat. Published by Elsevier Science B.V.