Investigating the ecological recovery and the restoration of aquatic ecosystem integrity post successful biological control of alien aquatic weeds

Investigating the ecological recovery and the restoration of aquatic ecosystem integrity post successful biological control of alien aquatic weeds
Samuel N. MOTITSOE, Jaclyn M. Hill, Martin P. Hill, Julie A. Coetzee
Biological Control Research Group, Department of Zoology and Entomology, Rhodes University, Grahamstown, South Africa

The establishment of aquatic alien species has recently been recognized as the second major contributor to loss of ecosystem biodiversity after habitat loss. Reversing the impact of alien aquatic weeds would be of major benefit to the ecosystem following the recovery of indigenous biodiversity. In South Africa, studies have shown that biological control programme against floating water weeds has been largely successful, with effective control (where no other intervention is necessary) of water lettuce (Pistia stratiotes), red water fern (Azolla filiculoides) and Kariba weed (Salvinia molesta). However, despite successful host specificity testing, release and establishment of biological control agents and eventual effective control of multiple invasive aquatic plants, the indirect and long-term aquatic ecosystem effects of biological control are currently poorly understood. Therefore, this study is aimed at investigating the long-term ecological contribution post successful biological control of alien aquatic weeds. It is anticipated that this research will resolve some of the major uncertainties associated with biological control of aquatic weeds e.g. does successful biological control result in long-term (1) enhancement in aquatic biodiversity and/or changes in food webs (2) ecosystem recovery (i.e. healthier habitat and better water quality) and (3) promotion of ecosystem ecological benefits? Addressing the above-mentioned ecological concerns in a series of mesocosm experiments (invaded, controlled and reference study sites) with main focus on aquatic ecosystem biological components, this study will investigate the role and effectiveness of biological control in ecosystem integrity recovery, restoration and ultimately the provisioning of freshwater ecosystem services

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