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Satellite image of Lake Erie showing a mild harmful algal blom in the southwestern portion of the lake.
Harmful algal blooms (HABs) occur when colonies of algae—simple plants that live in the sea and freshwater—grow out of control while producing toxic or harmful effects on people, fish, shellfish, marine mammals, and birds.
While we know of many factors that may contribute to HABs, how these factors come together to create a 'bloom' of algae is not well understood.
Studies indicate that many algal species flourish when wind and water currents are favorable.
In other cases, HABs may be linked to 'overfeeding.' This occurs when nutrients (mainly phosphorus, nitrogen, and carbon) from sources such as lawns and farmlands flow downriver to the sea and build up at a rate that 'overfeeds' the algae that exist normally in the environment.
Some HABs have also been reported in the aftermath of natural phenomena like sluggish water circulation, unusually high water temperatures, and extreme weather events such as hurricanes, floods, and drought.
People often get sick by eating shellfish containing toxins produced by these algae. Airborne HAB toxins may also cause breathing problems and, in some cases, trigger asthma attacks in susceptible individuals.
HABs can also be costly in economic terms as well. At present, HABs cause about $82 million in economic losses to the seafood, restaurant, and tourism industries each year. HABs reduce tourism, close beaches and shellfish beds, and decrease the catch from both recreational and commercial fisheries.
NOAA scientists continue to monitor and study HABs to determine how to detect and forecast the location of the blooms. The goal is to give coastal communities advance warning, so they can adequately plan and deal with the adverse environmental and health effects associated with a harmful bloom.
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from enviro canterbury
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Algal blooms in lakes
Algal blooms. The algae that commonly grow in lakes are a free-floating form (phytoplankton). Some species are cyanobacteria that have the potential to grow rapidly to form a high density of cells (bloom) and produce cyanotoxins. In Canterbury, Lake Forsyth/Te Roto O Wairewa forms a bloom of the cyanobacteria Nodularia in most summers. This alga produces the toxin Nodularin, which has been known to kill stock and dogs that are in contact with lake water during a bloom.
[AS DOES LAKE ELLY] my add in:yaeh am not durnk:
Algal blooms in lakes or still waters are commonly blue-green in colouration, but can also be red or yellow. They typically form thick scums on the surface, and may also develop foams at the water's edge.
What causes cyanobacteria algal blooms?
Warning sign. The presence of extensive mats of cyanobacteria is linked with environmental conditions conducive to their growth. Favourable conditions include the right combination of warm temperatures, sunlight, low or stable river flows, and nutrients. The occurrence of mats or algal blooms is a natural phenomenon, but human activities, such as taking water from rivers or adding nutrients to waterways, can make things worse.
Are cyanobacteria always toxic?
No. There are several species of cyanobacteria, that may or may not be toxic, depending upon prevailing environmental conditions. However, if potentially toxic cyanobacteria are present in large numbers, you should presume that the water may be unsafe for contact recreation or consumption.
GEE YA FUCKIN THINK????:wtfsmilie:
Some algae have toxins in their cells, and can be harmful if they are consumed. Such algae present a risk to dogs which may eat algal mats, or ingest algae when they drink water from a watercourse. Other cyanobacteria may release toxins into the water surrounding them, which can affect those that contact or drink the water.
bit of a telling ommission from enviroment canterburys info .
