Similar can occur and in freshwater
Outbreak of algal blooms off the coast of California in 2015, has made fish and shellfish inedible due to their toxicity “zombie”-acid, arose from the discharge of fertilisers into the sea, scientists have found, published an article in the journal Geophysical Research Letters.
“Studying similar episodes, it is necessary to consider not only physical and chemical factors for the prediction of their consequences. In this case, silicon has been a key factor in the growth of these algae. On the other hand, you need to take into account the fact that other nutrients, including urea in waste water can influence the toxicity of the algae,” said John Ryan (John Ryan) from the Monterey Institute in moss Landing (USA).
Algal blooms cause brown or blue-green algae that live in freshwater lakes and reservoirs and sea water. With the explosive growth in the number of cyanobacteria and brown algae in the water occur extensive spots that may pose a threat to human health and animals because of the toxins that the algae produce water, clearing his “living space”.
Spring and winter 2015 West coast USA was struck by a kind of “zombie epidemic” is an outbreak of growth of algae species Pseudo-nitzschia australis, whose cells during flowering produce large quantities of the neurotoxin DA, the so-called “acid zombie”. The molecules of this substance are easy to accumulate in body tissues of fish and shellfish, and eating mammals, birds or humans it causes hallucinations, cramps, and death.
As Ryan says, scientists have long believed that the main reason for this outbreak of algal bloom was abnormally high activity of the climatic phenomenon El niño, which made the waters off the coast of California is warmer than usual, and allowed them to multiply uncontrollably.
However, in subsequent seasons, despite a similar as El niño, outbreaks of water poisoning have occurred much less frequently, which forced scientists to seek other explanations for this unusual incident. In addition, the analysis of climate data over the past decade showed that a similar rise in water temperature did not lead to algae bloom.
For uncovering the roots of this anomaly Ryan and his colleagues analyzed the chemical composition of water samples collected off the coast of California before and after algal blooms, and tried to determine what changes in its mineral and chemical composition could make Pseudo-nitzschia australis to multiply rapidly.
As shown by this analysis, the cause of the reproduction of the algae was two things – a strong wind blowing at the time in the North-West and shonassie coastal waters towards the ocean, and a large number of nitrogen compounds in them, got there due to the extensive use of fertilizers in the fields of California.
Nitrogen, as the scientists explain, is not the only limit the growth of Pseudo-nitzschia australi. As with other diatoms, for their reproduction need another trace element silicon, the atoms which forms the carapace of the plankton.
If silicon is not enough, then what happens is the algae cease to divide but continue to develop Domovoy acid, making themselves more toxic to consumers of the plankton. That is why, scientists believe the algae bloom in 2015 was so deadly and dangerous to other inhabitants of the sea and people.
Similar processes, as scientists believe, can occur in freshwater ponds and in other parts of the world ocean. For this reason, ecologists in predicting the effects of algal blooms should take into account not only climatic factors, but that falls into the water due to human activity.
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