Benefits of using AHFM to detect algal blooms
Algae blooms i.e. very high concentration of algae and/or cyanobacteria occur mainly in lakes and slow-moving rivers. Beneficial for their occurence are the presence of high levels of nutrients, together with warm, sunny and calm weather conditions. Algae blooms cause various nuisance effects such as foams and scums on the surface and a discoloration of the water, which might effect recreational activities. Most species forming algae blooms are not harmful, but there are certain species produce toxins, which are harmful for humans and other organisms and can causes losses in local economies. The elevated concentrations of organic material during and after a algae bloom also have detrimental effects in water works. AHFM can help to avoid negative impacts of algae blooms by enabling authorities to issue warnings to refrain from certain recreational water uses such as bathing or to make it possible for water managers to induce the necessary changes in the water treatment process.
Direct human health effects of freshwater-lake HABs include gastrointestinal effects such as diarrhoea and nausea, dermatologic effects as skin irritation, neurologic effects, respiratory problems, as well as general fatigue, fever, dizziness, headache. Data from outbreaks in the US showed that only 3% of reported illnesses after contact with HABs required treament. In Kansas, hospitalization for three days for supportive care in cases of pneumonia and cyanobacteria toxicosis after recreational activities in direct contact with freshwater under an algae bloom was reported. In addition to the medical treatment costs, also the costs of lost productivity must be considered.
Indirect health effects might occur, when the algae bloom remains undetected and increased concentrations of organic material from the algae disturb water treatment processes and lead e.g. to the formation of disinfection-by-products.
Impact on recreation & aesthetics
Algae blooms (harmful or not) can decrease the recreational and aesthetic enjoyment related to water bodies. Certain activities like swimming should be forbidden during HABs.
Drinking Water Treatment
During and after algae blooms there are elevated concentrations of organic materials in the water, which can cause problems for water treatment if they are not detected. They will cause filters to clog faster and might lead to the formation of disinfection-by-products, which can have negative health effects. For the removal of cyanotoxins additional treatment steps must be taken otherwise low concentrations of cyanotoxins can remain in the drinking water also causing detrimental health effects.
HABs can also have negative effects on local businesses. Cyanotoxins can accumulate in aquatic organisms grown in aquaculture, so they cannot be sold anymore. If water contaminated with cyanotoxins is used for irrigation of agricultural products, there might also be a risk that those cannot be sold anymore.
Benefits of AHFM for the detection of elevated DOM concentrations
In many water bodies, dissolved organic matter (DOM) is the main reason for the brownish color of the water. DOM is leached out from soils and with more erratic weather patterns in the future (i.e. more dry and wet spells) it can be expected that DOM concentrations will increase in general, but that there will also be more episodes with rapid changes in DOM concentrations. DOM consists of a mixture of substances and can cause detrimental effects in drinking water treatment plants. More worrisome than long term increases of DOM concentrations, which will require water works to adjust their treatment practices, are rapid changes in DOM concentrations. Rapid DOM changes will, for example, cause filter units to clog faster and thus the treatment capacity will be reduced or DOM will not be sufficiently removed in the treatment process. If DOM remains until the disinfection step, disinfection-by-products may be formed, which have negative impacts on human health.