CULTURE AND USE OF Hoplias malabaricus
IN THE RESTORATION OF SHALLOW
EUTROPHIC AQUATIC SYSTEMS
Uruguay has a wide diversity of aquatic resources, and most quiet freshwater systems, whether natural or artificial, present shallow depths. Eutrophication is the main perturbation on these systems, being its first consequence the increase in phytoplankton and aquatic plant biomass. This response can directly interfere with several uses, such as tap water supply in the case of algal blooms (toxic or not), navigation given an excessive growth of macrophytes (for example, of water hyacinth), or decreasing the value of adjacent fields and houses due to bad odours, among the main consequences.
Restoration strategies of shallow eutrophic systems have evolved from solely control external nutrient supplies towards more ecosystemic approaches, combining nutrient load control with biomanipulation techniques. The combined application of these tools make easier to overcome the resilience to decrease algal biomass, even after nutrient supply has ceased, characteristic of shallow systems.
Biomanipulation seek to decrease phytoplankton biomass by the selective harvest of planktivorous fish and/or the increase of piscivorous fish biomass. The lack of native piscivorous fish production systems in our country prevents the application of these techniques to repopulate perturbed systems. The present proposal has the objective to implement the culture of juvenile Hoplias malabaricus (common name “tararira”), analysing experimentally the effects of this species introduction on water quality.