The causes and effects of harmful algal blooms have only been studied recently, as damage to the global aquaculture industry mounts.
Prof. Boyd provides additional insights into fertilization of aquaculture ponds, discussing phytoplankton requirements, organic and inorganic fertilizers, and other relevant aspects of pond management.
Dissolved oxygen management is the most important requirement of aquaculture pond water quality. DO concentration below 3 mg/L is stressful to shrimp.
Intensification of pond aquaculture involves the use of commercial fertilizers such as urea and triple superphosphate to stimulate phytoplankton blooms. There is no objective way of determining the ideal fertilization rate for an individual pond.
Commercial nitrogen and phosphorus fertilizers are widely used in aquaculture production systems to stimulate phytoplankton growth and the food web that provides natural food organisms beneficial to stocked fish fry and shrimp postlarvae.
Changes in atmospheric carbon dioxide concentration should have little effect on rising alkalinity concentration in aquaculture systems. Climate change is of greater concern in freshwater aquaculture than is an increase in alkalinity.
Phytoplankton has several important effects on water quality, including removing ammonia nitrogen from water and absorbing nutrients from the water for its growth. Abundance of blue-green algae tends to increase as nutrient inputs in aquafeeds or fertilizers increase.
A vigorous phytoplankton bloom will support a healthy benthic community and will contribute significantly to stabilising and maintaining adequate pond water and bottom quality.
Manufactured aquafeeds, if improperly managed, can result in undesirable oxygen demand that can reduce dissolved oxygen levels and pollution through effluents, and stress cultured animals.