Year Established: 2017 Start Date: 2017-03-01 End Date: 2018-02-28
Total Federal Funds: $25,318 Total Non-Federal Funds: $50,487
Principal Investigators: Amit Sinha, William Green, Sixte Ntamatungiro
Abstract: Massive algal bloom formation in aquaculture ponds as a result of eutrophication (i.e., high nutrient loads typically phosphorus) is a major water quality issue worldwide. The majority of these blooms are formed by cyanobacteria (blue-green algae) which also produce toxins, thus, posing a serious threat to human and animal welfare. Manipulating phosphorus concentrations in order to limit its bioavailability to cyanobacteria is a key challenge for many of the water quality experts. Overwhelming research has been conducted to validate the best strategies at reducing the phosphorus burden from the fish ponds. These approaches include artificial mixing, flushing, dredging, and use of aluminum and copper salts. Each of these approaches has drawbacks as either they are not economically feasible at farm levels or are associated with the potential risk of ecotoxicity. In this proposed study, compounds possessing phosphorus-binding or fixative capacity, such as lanthanum (La) modified clays might represent a promising management tool that has been demonstrated to have no hazardous effects in several aquatic organisms including fishes. Moreover, lowering of phosphorus in waterbodies also shifts TN:TP ratios towards production of phytoplanktonic green algae, diatoms, and flagellates. Despite these advantages, few studies have investigated the potentiality of La-modified clay matrix to control algal blooms in aquaculture ponds. Alternate to the nutrient reduction strategy, the application of chemicals (e.g., metals, algaecides, herbicides, and plant extracts) are direct means of controlling harmful algal blooms by lysing cyanobacterial cells. However, these techniques induce massive release of cyanotoxins in rearing water, apparently deteriorating rather than resolving the water-quality issue. As a result, there is an urgent need for effective intervention techniques that can rapidly restrain the proliferation of cyanobacterial blooms without degrading the dynamics of overall water chemistry. Recent studies have verified that cyanobacteria are more sensitive to hydrogen peroxide (H2O2) than green algae or diatoms, as low concentrations of H2O2 can induce oxidative damage to photosynthetic pigments unique to cyanobacteria. Therefore, it is very likely that H2O2 can selectively eradicate cyanobacteria in mixed phytoplankton communities. Surprisingly, to date, the application of H2O2 to restrain cyanobacterial blooms in aquaculture ponds has not been extensively explored. Moreover, there is no consensus about the combination of nutrient manipulation (i.e., via phosphorus binding clay containing lanthanum) and H2O2 on the efficacy of the cyanobacteria control. Consequently, this proposal aims to investigate the inhibitory efficiency of nutrient manipulation and H2O2 exposure on cyanobacteria algal blooms in aquaculture ponds. These two factors will be evaluated in an experimental setting separately and in combination. In view of the increasing importance of aquaculture and the emerging problems of eutrophication and harmful algal blooms, the results of this work will add to the current knowledge and provide guidance for farmers, ecologists, and scientific community towards effective and safe techniques to successfully control harmful algal blooms.