Protecting the Seas from an Invisible Killer: HABS, Also Known as Red Tides

Published Date: 16 September 2011

© IAEA IAEA helps provide protection from an invisible killer - Harmful Algal Blooms, also known as Red Tides. One of the problems facing coastal waters around the world is the occurrence of harmful microalgae. This phenomenon is commonly known as 'red tides', scientifically called Harmful Algal Blooms (HABs), which can be red, blue, pink or invisible to the eye. HABs lead to the contamination of fishes and shellfish with toxins, which, if eaten by humans, can cause anything from severe diarrhoea, to paralysis, amnesia or death. HAB events have become a common problem both in developed and developing countries, affecting public health and the shellfish and fish farming industry. HABs are a problem from Chile to Mexico, South Africa to Tunisia and the Philippines to Thailand. Most species of microalgae are not harmful but vital to the food chain, sustaining a host of marine life such as oysters and clams. Sometimes when changes occur in their environment, the microalgae grow extremely fast or 'bloom' into thick patches near the surface of the water or on the bottom of the sea. But a small number of species produce potent poisons called saxitoxins. When they 'bloom' the results can be deadly. Shellfish, which filter seawater to feed on microalgae, can accumulate some of their toxins. If humans eat the contaminated seafood, the flow of sodium through nerves is blocked. Symptoms range from mild discomfort and vomiting, to paralysis, seizures and even death from cardiac and respiratory failure. Using nuclear technology in combination with other techniques, toxin levels in marine organisms can be determined quickly and accurately. This information can be used to provide early warnings to local fishers about the toxicity levels of algae blooms, thus reducing the risk to food safety and ensuring that toxic seafood does not make its way into the human food chain. While the bloom itself cannot be stopped, its effects on people can be. Scientists used to test for toxins by extracting them from the shellfish and injecting the harmful substances into live mice to measure how long it took for the mice to die. This process took days. A faster, more accurate gauge of toxicity was needed. As such, the nuclear-based technique — Receptor Binding Assay (RBA) — was developed and is being increasingly used worldwide to complement or replace the mouse bioassay. The IAEA's Department of Technical Cooperation, together with international and national organisations around the world, works with national marine institutes and governments to tackle the issue. One such marine institute is the Laboratory of Marine Toxins of the University of El Salvador (LABTOX-UES). The IAEA equipped the laboratory and provided training on specialized detection equipment that is used to monitor HABs. The government relies on the facility to detect toxicity in HABs for its early warning system, which is used to alert fisherman and locals as soon as there is a dangerous concentration of toxins in the water. This system depends on a network of monitoring stations located in the fishing parks. Samples from the monitoring station are brought to the facility for analysis. There are similar systems around the world. The Philippine Nuclear Research Institute, which is the only IAEA collaborating centre on Harmful Algal Blooms (HABs) in the world, does research with the IAEA Environment Laboratories in Monaco to track the impact and fate of biotoxins in the marine food-chain. Through the Technical Cooperation programme, 14 marine laboratories were established in Africa, Asia and in Central and Latin America. Through an on-going project in the Caribbean and Latin America, the IAEA will be establishing three more laboratories by 2013 and will develop the capabilities of eight other countries to detect HABs. Also, a new regional project in Asia will enhance capacity to monitor the impact of toxic algae by addressing ciguatera (a disease contracted when one eats fish contaminated by toxins). These facilities are prime examples of the benefits of cooperation between the IAEA and Member States to protect national food security, public health and the economy. They contribute to the sustainable management of fishery products and the coastal economy, increase food security and are a resource for faculty, students and the government: all benefits that will last long into the future.