Harmful algae blooms are a global problem, causing health issues, fish deaths, and taste and odor problems when blooming in lakes or water reservoirs. LG Sonic has developed a novel method to predict algal blooms in freshwater and seawater.
Algae and harmful algal blooms
Algae is a natural part of the aquatic ecosystem and most species are safe or non-toxic. However, some algae can produce toxins harmful to humans, domestic animals, livestock, and organisms that drink, come in contact with, or live in the water. These algae can be found in freshwater, marine and estuarine waters. A rapid growth and build-up of algae on the water’s surface is called algal bloom. These blooms are typically triggered by increased water temperature and soluble nutrients as well as high light availability and water stagnation. Algal blooms that release toxins are officially termed harmful algal blooms and can have considerable impacts on ecosystems, public health, and the economy by affecting water supplies, aquaculture, and recreational waters. Harmful algal blooms also deplete oxygen as they decompose, creating oxygen poor waterbodies and suffocating masses of aquatic life.
The most notorious algal species, which can form toxic blooms in both freshwater and marine environments, are cyanobacteria. These species have exhibited remarkable ecophysiological adaptations to global change and produce a wide range of toxins, odors and noxious compounds. Their massive proliferation is a worldwide environmental problem. Numerous examples of human exposure to cyanobacteria blooms and toxins have been associated with health outcomes in scientific papers and publications since the 1930s.
Every year, hundred miles of marine system coastline are affected for weeks or months by harmful algal blooms with a distinct red colour, called red tides. This phenomenon is the result of the algal blooms of a certain species, such as Dinoflagellates. In a red-tide bloom, millions of these tiny organisms produce a paralyzing neurotoxin that prevents fish and marine life from respirating; the toxin is also mildly dangerous for humans. Toxins can accumulate in filter-feeding shellfish (oysters, clams) tissue and can, if ingested by humans, cause Neurotoxic Shellfish Poisoning. The toxin can also go airborne and be dangerous for those with respiratory sensitivities. The longest red tide on record lasted 30 months in the mid-1990s (South Florida, USA). The economic loss caused by red tides in many areas worldwide is enormous. Commercial fisheries have been severely damaged due to fish kills, desalinization plants have had to increase chemical consumption or even shut down, and tourism activities near the sea have been prohibited.
With increasing knowledge and understanding of algal bloom dynamics and ecology, the need for effective monitoring is increasing. It is important to provide quick answers detailing where the presence of such blooms is suspected. The continuous monitoring of algal growth on surface waters is key to the early detection of harmful algal blooms and initiation of preventative measures.
Real-time algae monitoring as an early warning system
Algae have a remarkable range of strategies to grow and survive, and this makes predicting when blooms will occur difficult. In order to manage the risk algal blooms pose to water supplies, humans and the environment, it is necessary to provide real-time measurements which detect the growth of various types of algae.
The LG Sonic Algae Alert system is a robust device for online detection and the continuous monitoring of photosynthetic microorganisms in both freshwater and marine waterbodies. The system provides real-time display of key chlorophyll parameters crucial to algal growth monitoring. Powered by a steady solar-powered platform, the system uses submersible fluorometers that can monitor chlorophyll-a, phycocyanin (for measurements of cyanobacteria growth in freshwater systems) or phycoerythrin (for measurements of cyanobacteria and red algae growth in marine and estuarine systems).
Phycocyanin and phycoerythrin pigments, which have strong fluorescent signatures, do not interfere with the fluorescence of chlorophyll. This allows for the in vivo detection of cyanobacteria and red algae without interference from other algal groups. To combat algal species that are vigorous swimmers (such flagellate species) and can migrate vertically on a daily basis, the system can perform real-time measurements at different depths within large waterbodies in order to measure the growth of algae across deep euphotic zones (marine systems). In this case, multiple sensors are integrated as part of the Algae Alert system over a range of discrete depths.
In addition to chlorophyll sensors, which directly indicate the growth of various types of algae, the Algae Alert system also employs relevant water-quality parameters to evaluate conditions proven to synergistically promote algal bloom episodes and affect water quality. Advanced sensing technology is used for the real-time monitoring of Turbidity, Total Suspended Solids, pH, dissolved oxygen, temperature, conductivity (for freshwater systems) and salinity (for marine environments). The sensors consume little power and are specially coated for fouling protection. Sensors’ sampling rates and dynamic ranges are adjustable. A mechanical wiper technology is incorporated in the sensor set to reduce biological fouling.
Monitoring data-sets are collected and delivered in real-time via radio, GPRS, and 3G to the web-based software MPC-View. This software can generate a complete overview of the water quality of one or more water bodies and provides real-time insight into water quality. Warning alarms and alerts can be set within the software to provide timely detection in changing water conditions and ensure an effective algal bloom monitoring. Alarms and reminders for maintenance activities can also be set. This way, customers and employees of LG Sonic can remotely monitor and confirm that devices are working properly. Generated reports can be exported to Excel or converted to PDF to be shared or published.
Eye in the sky: tracking algal blooms from space
Massive algal blooms, glowing green in the water, are visible from space. Several parts of the world suffer massive annual algal blooms, such as Lake Apopka (Florida), Lake Erie (Ohio) or the Baltic Sea (Europe). True-color satellite images like those pictured below capture the biomass of these algal blooms. LG Sonic uses Satellite Remote Sensing Technology to accurately retrieve water quality parameters.
Satellite remote sensing, in combination with In-Situ water quality data from the Algae Alert system, allows for the quality detection and monitoring of larger surface waterbodies with greater spatial and temporal coverage. In this way algal bloom dynamics can be effectively monitored. In addition, satellite remote sensing technology enables the collection of other water quality parameters, such as water temperature, suspended particulate matter, and colored dissolved organic matter. This technique saves time and effort by allowing information to be quickly gathered across large areas. The combination of earth observations with rapid field monitoring can provide information on the location, intensity, spatial extent, and surface transport of algal blooms and other types of discolored waters. This existing and historical data can then be used to best predict how algal blooms may grow and affect different regions.
About the author
Valentini Maliaka is the R&D Manager of LG Sonic B.V in the Netherlands. She graduated from Wageningen University with an MSc Degree in Water Quality Management and Aquatic Ecology and she is a PhD(c) of Radboud University in Nijmegen. She has done applied research on the biogeochemical processes of eutrophic lake systems and developed restoration methods which aim to improve their water quality.