11/09/2017
Summer time in the Northern hemisphere! Time to go to the beach or a nearby lake to enjoy the water in the hot weather. Swimming, water-skiing, rafting, snorkeling, playing "fetch" with your dog - pleasurable ways to unwind.
Nutrient pollution of recreational waters is ruining holidays and poses a serious health risk
But danger lurks. You throw a stick into the lake. Your dog bounds after it and later dies. You inadvertently swallow water while swimming and get parasites. You eat seafood in a restaurant near the coast - and get sick. You head off for a swim in a lake only to find that is covered in green slime.
This is no horror movie. It’s a real-world problem, happening right now: Health warnings about dangerously polluted "fresh" or coastal waters are increasingly frequent. Pollution, mainly in the form of fertilizer run-off, livestock waste, and domestic and industrial wastewater discharges are the chief culprits.
A trawl of the Internet reveals a host of frightening reports about all the dangers and restrictions - things that were pretty much unheard of 50 years ago when our ecosystems were much more robust than they are today.
"Cyanobacteria (blue-green algae) now threaten the ecological well-being of some of the world's largest water bodies, including Lake Victoria in Africa, Lake Erie in the United States and Canada, Lake Taihu in China, the Baltic Sea in Northern Europe, and the Caspian Sea in West Asia. They've also been found in Lake Kokotel in Eastern Siberia, which is next to Lake Baikal, the world's largest, deepest and most ancient freshwater lake." (Article in Scientific American 2013)
USA, 2016 - "It’s as thick as guacamole, but you don’t want it near your chips. You don’t want it in your water, either, but that’s exactly where it is, a sprawling mat of toxic algae the size of Miami, spreading out across Florida’s storied Okeechobee lake and from there along major rivers to the state’s Atlantic and Gulf Coasts. Fish are dying. Beaches are closing. People are getting sick. Governor Rick Scott has declared a state of emergency in affected areas…".
USA, 2015 - "Sonoma County public health officials are weighing the extraordinary step of urging people and their pets to avoid the Russian River after a dog that died moments after swimming in the water preliminarily tested positive for a lethal toxin produced by blue-green algae…".
China, 2015 - "Every summer, the Yellow Sea turns green as a thick carpet of algae covers the beaches of Shangdong province, Eastern China. People living in Qingdao and nearby coastal towns have grown accustomed to their beaches looking more like verdant meadows every July… Partly as a result of the algae, Qingdao's beaches are home to a bizarre fashion trend: the Facekini. Many local women sunbathe and swim wearing masks to prevent sunburn and stop the algae getting tangled in their hair".
Australia, 2016 - "For much of this year, up to 1,700 km of the Murray river has been hit by a serious outbreak of potentially toxic blue-green algae, which has flourished in the hotter-than-average conditions… The past decade has seen four similar blooms on the Murray river: in 2007, 2009, 2010 and now".
Chile, 2016 - "An algal bloom in Chile that has killed up to 20 percent of the country's farmed salmon, causing higher prices globally, has started to recede along with fish deaths, the government said on Friday. Chile is the world's second largest producer of salmon and trout after Norway".
The apparent increase in the occurrence and frequency of harmful algal blooms (HABs) in freshwater and coastal aquatic ecosystems across the globe is being linked to the influence of ever-expanding human developments and the associated pollutant discharges where little is being done to adequately treat or divert nitrogen and phosphorus (two key nutrients often concentrated in these discharges) which are what nourishes algae in the water and causes algal blooms. The other worrying factor compounding the problem is climate change. With warming oceans, lakes and other aquatic ecosystems, as a result of warmer atmospheric temperatures, conditions become even more conducive for HABs to flourish in nutrient-enriched environments.
What can be done?
Governments could start by putting in place thresholds and standards for acceptable water quality in fresh and coastal water bodies. This in turn must be linked to the quality of farm (including livestock) runoff and waste discharges that are released from wastewater treatment plants and discharges from industrial sources. Best practices to encourage nutrient use efficiency (e.g. fertilizer application in crop production) and reduce harmful nutrient pollution discharges need to be implemented in agricultural and wastewater treatment systems.
The International Water Quality Guidelines for Ecosystems (IWQGES), published on 15th March 2016 as a draft for regional consultation, provides a framework and contains the most relevant information required to develop water quality guidelines for ecosystems, including approaches to identify indicators and set target and threshold values.
IWQGES is advisory. It is aimed at governments, but also sub-national and regional authorities. Guidelines cannot be developed and implemented without the involvement of regional authorities, water resources management authorities, stakeholders and technical and scientific services.
In September 2015, the United Nations General Assembly adopted the 17 Sustainable Development Goals (SDGs) with their inherent 169 targets, thus defining international aspirations, but also to a large extent the trajectory towards sustainability and development. The dedicated water goal (SDG 6): "Ensure availability and sustainable management of water and sanitation for all" with its eight targets, explicitly addresses the improvement of water quality and the health of freshwater ecosystems. In addition, SDG 14 "Conserve and sustainably use the oceans, seas and marine resources for sustainable development" targets prevention and reduction of marine pollution particularly from land-based activities, including nutrient pollution.
The tools and best practices for managing water bodies are available. Now, Governments, regional and local authorities need to take action to ensure your well-being. The cost of inaction will be greater than the cost of action.
Background facts
Eutrophication
Excess nutrient flows of phosphorus and nitrogen from farms and sewage into the aquatic system lead to algal blooms. Too much nitrogen and phosphorus in the water causes algae to grow faster than ecosystems can handle. As the algae dies, the oxygen in the water column is consumed. In extreme cases it can become completely deoxygenated, creating what is known as "hypoxic" conditions; such areas are termed "dead zones" Some algal blooms are harmful to humans because they produce elevated toxins and bacterial growth that can make people sick if they come into contact with polluted water, consume tainted fish or shellfish, or drink contaminated water. The primary sources of nutrient pollution are agriculture, storm water, domestic and industrial wastewater, soaps and detergents.
Toxicity
During a bloom, algae can produce nocive toxins that can render water unsafe and cause fish mortality, or can impact human health through the consumption of contaminated seafood, skin contact and swallow-water during recreational activities. Diatoms and dinoflagellates are involved in the production of toxins responsible for poisoning in humans. Toxins are usually released when an algal bloom dies off. Water or seafood contaminated with toxins are odourless and tasteless, and toxins cannot be destroyed by cooking or freezing.
Species
Diatoms are unicellular, photosynthetic eukaryotes and include about 100 species in marine and freshwater. Marine diatoms play a central role in the aquatic environment, contributing to 40% of primary productivity in marine ecosystems and 20% of global carbon fixation.
Dinoflagellates are microalgae which form a significant part of primary planktonic production in waterbodies and are largely responsible for HABs.
Cyanobacteria or "blue-green algae" comprise a diverse group of oxygenic photosynthetic bacteria with the ability to synthesize chlorophyll-a (a specific form of chlorophyll used in oxygenic photosynthesis) and other accessory pigments like phycobilin, phycocyanin and phycoerytrin proteins.
Đỗ Hoàng
(Source: Facts from EU 2016 - Algal bloom and its economic impact)
