Freshwater Macrophyte Communities of the Macleay River
Egeria is recognised as one of the world’s worst aquatic weeds. Outside of its natural range in South America, Egeria has naturalised throughout many countries on all continents except Antarctica, mainly as a result of the aquarium trade and anthropogenic disturbance.
With the ability to reproduce asexually, Egeria is able to rapidly expand its range in aquatic systems once established. Egeria growth is promoted by favourable biotic and abiotic factors such as high nutrient inputs, high disturbance rates, high plasticity, reduced or removed natural herbivores and pathogens and efficient dispersal mechanisms.
The impacts caused by Egeria are many, and include direct ecological loses such as reducing or replacing native aquatic flora, reducing light density and altering habitat conditions, and also economic losses by increasing siltation, reducing water flow, choking irrigation channels, reducing navigation in waterways and impeding commercial and recreational fishing activities.
Control options are currently limited to chemical and physical control and these have their own negative environmental impacts. Ongoing research into biological controls is producing promising results. Long-term management of Egeria densa is likely to involve a combination of the control options discussed, in addition to a reduction in nutrient loading and anthropogenic disturbance, improved land management practices and restoration of riparian vegetation.