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https://www.climate.gov/news-features/event-tracker/record-setting-bloom-toxic-algae-north-pacific
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Over
the past few years, algal blooms have become a serious issue that affects
humans and aquatic organisms. They occur when the temperatures and nutrient
inputs, such as phosphorous, are high (Townhall). These conditions are favorable for algal blooms because it
allows for fast growth (Townhall). Algal blooms find their way into aquatic organisms from being
consumed by zooplankton, clams, mussels, and shellfish and then they move up
the food web when those organisms are consumed (Townhall). Algal blooms can also create dangerous toxins that can have
huge impacts on the organisms that consume them. Two of the toxins that have
been found in marine systems are domoic acid, which is produced by an alga
called Pseudo-nitzschia (shown above), and saxitoxin, produced by
dinoflagellates (nwfsc). Domoic acid causes brain damage in affected organisms which can
lead to deficits in spatial memory (Townhall). It also causes seizures in sea lions (nwfsc). This toxin increases the likelihood of death due to not
remembering how to forage, avoid ship strikes, or migrate (Townhall). Saxitoxin causes PSP (paralytic seafood poisoning) in clams (Townhall).
Recently, both
these toxins were found in marine mammals in Alaskan waters which is very
unusual since the waters are normally too cold for blooms to occur (nwfsc). Samples from 900 marine mammals of 13 different species, including
whales, walruses, sea lions, seals, porpoises and sea otters were found to contain
these toxins and from all regions of Alaska (nwfsc). As of now, warming trends seem to be the cause of the blooms
that contain these toxins (Townhall). Alaska is not the only place to experience these blooms and
toxins. Last year, a record-breaking algal bloom off the Pacific coast occurred
where domoic acid concentrations were 10 to 30 times higher than a normal bloom
(cbsnews). Because these blooms occur from May through October, California
and other neighboring states temporarily executed a freeze on shellfish
harvesting (Climate.gov). This particular bloom caused fisheries to close for a while
because toxin levels were so high (Climate.gov). Normally the levels of domoic acid are not enough to cause
harm to humans while swimming, but it can be harmful when eating seafood that
contains large quantities of domoic acid (cbsnews). However, there are forms of algae that can cause human harm if
there is major contact. This type of algae was found in Lake Erie last year due
to high concentrations of phosphorous from runoff from all the precipitation
that occurred during the summer (Time).
Scientists confirmed that it was toxic cyanobacteria and that if any human were
to go swimming in it, they risk intestinal distress, liver damage, or
dermatitis (Time). Because
Lake Erie a source of freshwater for many people, there was discussion of
treating the water to get rid of this harmful toxin to prevent it from
polluting drinking sources. However it is more expensive for water treatment
when there are algal blooms and it takes a great amount of effort to clean it
all up (Time).
These are
just a few examples of marine systems that are affected by algal blooms and the
resulting toxins. Humans need to decrease nutrient inputs in order for these
harmful toxins to stop being a problem and continue to reduce global warming
trends in order for real change to be observed.
References
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