ELUCIDATING NUTRIENT LOADS AND BIOAVAILABILITY TO CYANOBACTERIA IN CATFISH PONDS FOR SUSTAINABLE AQUACULTURE

An actionable understanding of nutrients--phosphorus (P) and nitrogen (N)--load and bioavailability to cyanobacteria in freshwater systems is vital for water quality management and harmful algal bloom (HAB) mitigation, especially under global warming pressures. The goal of this project is to accurately reevaluate the 'real contribution' of different size fractions of particles on nutrients (P and N) load and bioavailability to cyanobacteria in economically important catfish production ponds in Alabama. This project has four main objectives:Objective 1: Collect bimonthly water samples from 21 catfish aquaculture ponds in Alabama and physically separate the collected water samples into six-size fractions, with two Tasks:Task 1: Bimonthly water sampling of 21 catfish aquaculture ponds in AlabamaTask 2: New particle size separation using sequential centrifugation and ultrafiltrationObjective 2: Chemically quantify nutrients (P & N) concentration and speciation, along with key algal-related water quality parameters (algal pigments, algal toxins, and off-flavors and odors) in the six size fractions to relate with water temperature (i.e., seasonal change), with two Tasks:Task 3: Re-analyzing concentrations of nutrients and algal parameters in different size fractionsTask 4: Re-analyzing relationships of nutrients with algal parameters in different size fractionsObjective 3: Biologically test the bioavailability of nutrients in the six size fractions under different temperatures (mimic climate change) to three cyanobacteria (Microcystis, Cylindrospermopsis, and Dolichospermum) isolated from aquaculture ponds, with three Tasks:Task 5: Colloidal stability, aggregation, and sedimentation of particles in different size fractionsTask 6: Bioavailability tests to three cyanobacteria grown individually in a warmer climateTask 7: Bioavailability tests to three mixed cyanobacteria in a warmer climateObjective 4: Develop and implement cost-effective solutions (e.g., engineered biochars) for water quality management and HAB mitigation in aquaculture ponds for sustainable aquaculture, with one Task:Task 8: Cost-effective biochars for nutrient control and HAB mitigation in aquaculture ponds.The findings will enable USDA, regulatory agencies, and aquaculture stakeholders to adopt best management practices (BMPs) and implement cost-effective solutions (e.g., engineered biochars) for the mitigation of HABs, contributing toward more sustainable aquaculture productivity and profitability for a growing world population.