Abstract
Context: In Australia's Murray-Darling Basin, the invasive common carp (Cyprinus carpio) poses a significant ecological threat. Efforts to manage their population include the potential use of cyprinid herpesvirus (CyHV-3) as a biological control agent. The environmental benefits of carp elimination could be substantial in the long term; our knowledge of the immediate ecological consequences resulting from large-scale fish die-offs remains limited. Aim: This study sought to investigate the effect of a large-scale fish-mortality event on water quality. Methods: Experiments of an increasing scale (bucket, mesocosm and whole wetland) were conducted to assess how decomposing carp carcasses alter dissolved oxygen and nutrient concentrations in water. Key results: In mesocosms, dead carp decayed more rapidly at 18 than 12°C, yielding oxygen demands of 1.022 ± 0.029 and 0.496 ± 0.239 mg kg-1 min-1 respectively. This carp decay released phosphorus, yielding 2121.1 ± 140.4 mg kg-1. In the wetland experiment, carp addition of 2400 kg ha-1 resulted in anoxic conditions over the following 2 weeks. The release of dissolved organic carbon and lipids led to a peak biological oxygen demand of 95.3 mg L-1. Conclusions: Carp decomposition considerably contributes to biological oxygen demand and algal growth through nutrient enrichment and is strongly influenced by carp density. Implications: The finding highlights key factors to consider before using biocontrol agents causing mass carp mortality, including hypoxia, anoxia and increased risk of harmful algal blooms.
| Original language | English |
|---|---|
| Article number | MF24183 |
| Journal | Marine and Freshwater Research |
| Volume | 76 |
| Issue | 2 |
| ISSN | 1323-1650 |
| DOIs | |
| Publication status | Published - Jan 2025 |
Keywords
- biogeochemistry
- CyHV-3
- Cyprinus carpio
- ecology
- eutrophication
- fish
- freshwater
- introduced species
- limnology
- Murray-Darling Basin