Barbs and Backlashes


Bluegreen Algae by whitetips
July 7, 2010, 2:39 pm
Filed under: Fishing | Tags: ,

It is summer, the water is warming up and bluegreen algae blooms every year at this time, has been doing it for hundreds if not thousands of years.  Then folks start hearing some things about “health alerts” and there are A LOT of misconceptions out there.  So, I might as well dust off the bluegreen algae “speech” and post it again, here.

Bluegreen algae have become a phobia for some folks.  If you are one of those, you better sit down because there is not a body of water in Nebraska that does not have bluegreen algae!  You cannot go anywhere where bluegreen algae is not going to get you.  Bluegreen algae have been present in Nebraska waters forever and they will forever be present.

Bluegreen algae or cyanobacteria are one of the simplest “plants”.  Actually “bluegreen algae” and “cyanobacteria” are two different names used to describe the same group of organisms.  The cellular structure of bluegreen algae resembles bacteria except that these bacteria have chlorophyll.  So, do not think anything of the name “cyanobacteria”, it is just another name for bluegreen algae.  The “cyano-”  part of cyanobacteria refers to the bluegreen color (it has nothing to do with “cyanide”).

There are many species and types of algae.  Throughout the year different groups or families of algae will bloom and then die-off to be replaced by another type of algae.  There are algae blooms that even occur under the ice.  Bluegreen algae are just one group, one family of algae that tend to dominate during the warmest months of the year.  Depending on the body of water, you can see bluegreen algae blooms as soon as water temperatures begin to rise in late spring and early summer, but bluegreen algae blooms are more common in the middle of summer or late summer.  Blooms of bluegreen algae typically look like “pea‑green soup”, or they look like someone has spilled a can of John Deere‑green paint on the water.  Some species of bluegreen algae may look like grass clippings floating on the water.  If you see water that looks like that, typically along windblown shorelines where the algae is concentrated, then that might be water you and your pets want to avoid.  In the entire family of bluegreen algae, there are only a few species that can produce toxins called microcystins.  Even among the species that can produce the microcystins, those toxins are produced only under certain conditions.  The microcystins are released by the bluegreen algae while they are alive; they do not have to die to release the toxins, but microcystins can persist for some time, usually days, until they breakdown, after the algae die.

Bluegreen algae thrive in fertile waters.  Guess what?  There is not a body of water in Nebraska that could be considered infertile.  Bluegreen algae typically bloom and dominate when nutrient levels, particularly the level of phosphorus, is elevated.  In Nebraska waters elevated levels of phosphorus can be a particular problem due to years of silt and sediment accumulation (nutrients are carried on those sediments).  In the case of housing developments around water bodies, fertilizers from lawns and nutrients leaching from septic systems can also add nutrients to the aquatic ecosystem and eventually fuel bluegreen algae blooms.

A lot of factors can influence the formation of algae blooms.  Blooms may form earlier or be worse in some years than others.  Beside nutrient levels, water temperature and sunlight are factors that influence the formation of bluegreen algae blooms, but in many cases nobody knows exactly all the factors that trigger blooms.  It can be difficult to predict the timing, occurrence, or severity of bluegreen algae blooms from year to year.

Bluegreen algae blooms have been present in Nebraska waters forever.  Nobody ever worried about them until a few years ago, because nobody tested for the bluegreen algae toxins.  In recent years technology has made the tests easier and less expensive.  In addition a few years ago there were some pets that died in the vicinity of a private sandpit in Nebraska and testing done on those dead pets attributed their deaths to microcystins.  Following that incident, Nebraska’s Department of Environmental Quality (NDEQ) began testing waters around the state for microcystins.  Testing is done weekly and you can see the results and any health alerts that have been issued here,  http://www.deq.state.ne.us/ .  (There is a bunch of additional useful information on that website, look it over)

When NDEQ tests the water, they test it for the presence of microcystins.  It would be senseless to test for bluegreen algae because bluegreen algae are everywhere and only certain species produce toxins under certain conditions.  It is possible to have bluegreen algae present without there being elevated levels of microcystins.  When the levels of microcystins exceed action levels, health alerts are issued.  NDEQ does NOT take samples all over a body of water; sampling is concentrated in areas of heavy use, especially swimming areas.  The testing procedures and guidelines are very conservative to ensure public safety.  For example, if the wind has been blowing for a few days into a swimming area where they collect samples for bluegreen algae toxins, they can find a high concentration in that area where the wind has “piled up” or concentrated the bluegreen algae while the rest of the water body has low concentrations of bluegreen algae and low concentrations of microcystins.

When microcystin levels exceed 20 ppb a health alert is issued by NDEQ.  The health alerts advise people and their pets to stay out of the water, to avoid bodily contact or ingestion.  Activities such as swimming and water skiing would not be recommended, but activities such as fishing need not be curtailed.  The bluegreen algae toxins do not persist in the flesh of fish, so even though there may be a bluegreen algae health alert, it does not mean you cannot consume fish from that body of water.  Once an alert has been issued, that body of water remains on the alert list for at least two weeks after microcystin levels decline below action levels.

I should also add that the bluegreen algae toxins do not cause fish kills; algae blooms can cause fish kills due to oxygen sags, but the microcystins do not cause fish kills.  Bluegreen algae blooms can be so thick that fish may be hard to catch in those areas or they may move to areas with clearer water, but the algae itself does not impact fish behavior (sorry guys, blaming your poor fishing on bluegreen algae blooms is probably just an excuse).

Be aware of what is out there and know how to react, but there is no need to panic once bluegreen algae health alerts begin to show up.  I hope this helps; please ask questions if you have any.

If you see water that looks like this, do NOT dive in!

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1 Comment so far
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Daryl, just read the artcle about Holmes Lake and the probleams with keeping bass and no permits. I am sick and tired of these people who think it is their God given right to fish and not follow the rules set for them. G and P is way too easy on these violators, I say write them all up!!! Hit them in the pocket book, they will remember.

Comment by Dave




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