Florida has been grappling with recurring red tide outbreaks for several years now, a situation caused by the algae Karenia brevis. The recent bloom might have escalated due to the discharge of polluted water into Tampa Bay from previous times.
The Phenomenon of Harmful Algal Blooms (HABs)
Harmful Algal Blooms (HABs) happen when colonies of algae become uncontrolled, leading to toxic or detrimental effects on humans, fish, shellfish, marine mammals, and birds. This phenomenon is often termed ‘red tides,’ however, the scientific community generally refers to it as a harmful algal bloom.
One of the most noted HABs in the US transpires nearly every summer along Florida’s Gulf Coast due to a species of dinoflagellate called Karenia brevis. Simultaneously, blooms in freshwater lakes and reservoirs are primarily initiated by blue-green algae (cyanobacteria), which are directly influenced by agricultural and urban runoff. An excess of nutrient pollution can stimulate the growth of cyanobacteria.
Triggers of Algal Blooms
Algal Blooms are caused by a variety of factors including Eutrophication (nutrient enrichment) of waterways, which supports the growth of algae and Cyanobacteria and is regarded as a crucial factor. Additionally, blooms are more likely to occur during the summer or fall but can manifest at any time of the year. Turbidity, or the amount of suspended particles and organic matter in the water column, can also influence blooms. When turbidity is low, more light can penetrate the water, creating ideal conditions for algal proliferation.
Consequences of Algal Bloom
Algal Blooms can have serious impacts. They generate extremely hazardous toxins which can sicken or even kill people and animals. If fish contaminated with the algae are consumed by other organisms, including humans, it can be harmful. Algal blooms also disrupt aquaculture operations and have resulted in reported cases of respiratory distress in humans due to red tide. Moreover, they starve aquatic organisms of sunlight and oxygen and negatively affect various species inhabiting the water. Algal blooms can also create ‘dead zones,’ commonly known areas of diminished oxygen levels in water, thereby escalating costs for drinking water treatment and damaging industries reliant on clean water.
Mitigating HAB Risks
Addressing the risks posed by HABs requires several measures. Simple treatment options tend to be ineffective; often, multiple stages are needed to remove algae toxins. Utilizing tertiary sewage treatment techniques to extract phosphate and nitrate before discharging effluent into rivers and lakes is essential.
Nitrogen testing & modelling is a technique for determining the optimum amount of fertilizer required for crop plants, thus reducing nitrogen loss to the surrounding area. Encouraging organic farming and minimizing fertilizer overuse can reduce runoff and be effective for curbing severe algal blooms. Other strategies include reducing nitrogen emissions from vehicles and power plants and lowering phosphate usage in detergents.
Tackling Algal Bloom in India
In India, measures such as the Algal Bloom Information Service (ABIS) have been put in place to provide timely updates on harmful algal blooms. ABIS plays a crucial role as these blooms pose a threat to coastal fisheries and water quality, and also induce respiratory complications in coastal populations over time. Additionally, ISRO’s Oceansat-2 satellite, launched in 2009, grants expansive coverage and delivers global ocean color data.
