Sean Thackeray, Jackie M. Hill, Grant Martin-Department of Zoology and Entomology, Rhodes University

Increased nutrient loading is regarded as one of the primary mechanisms in driving invasions of freshwater weeds.

Highly eutrophic ecosystems are not only susceptible to invaders, but in the case of established water weeds, high plant fitness associated with high nutrient availability often renders the biological control of these weeds ineffective.

To understand the interactions of control agents and their associated target plants at different nutrient levels, researchers often need to perform laboratory experiments and it is common practice to obtain different nutrient concentrations with the use of controlled slow release fertilizers.

Very little is known about the nutrient release dynamics of controlled slow release fertilizers within aquatic environments, which may change significantly over time thus altering nutrient availability and confounding results.

This project aims to quantify the release dynamics of slow release fertilizers in aquatic environments under a range of temperatures, nutrient levels and uptake conditions using a nitrogen mass balance approach.