Massive BGA bloom in a local fishing lake

[Antoni]

Hi guys,

One of our local lakes has a massive outbreak of bga and the landlord has asked me, if can recommend a solution... now usually in a tank, I know how to fix it will increase nitrates, improve filtration, black out as a last reaort, but how you deal with it in a lake few acres in size
If anyone has experiense with such a problem, please share with us anything, that may be helpful.

Environmental Agency, contrary to what we all know, says that the bloom is caused by high nutrients levels and circulation , but the only measure they offer is to leave it on its own or in the worse case extraction of nutrients....

Is aeration going to change anything or introduction of some fast growing plants like elodea. ..?

 

[tam]

I think blooms in 'the wild' are often associated with excess nutrients e.g. agricultural fertilizer run off or sewage. Keep in mind a lake would also have a really long/high light photo period and might be lacking in CO2 - so not that different to algae in a tank.

No idea how you'd fix it on that scale though.

I guess aeration might help if there are fish and the O2 levels are dropping.

 

[Jose]

Maybe adding some floaters?like lemna minor or whatever is adapted to your climate. But youll need loads to start of with. So you need some plant found locally.

 

[Antoni]

Thanks mate, it is in the UK

 

[martin-green]

I don't think there is a simple / cheap answer, I would suggest installing a fountain to give aeration, you can get floating fountains for lakes

but they are very expensive

 

[dw1305]

Hi all,

Environmental Agency, contrary to what we all know, says that the bloom is caused by high nutrients levels

That is probably what caused it. There is a huge range of Cyanobacteria species in the plankton, and changes in the nutrient budget can cause them to bloom.

I think this should be available to every-one <"The rise of harmful cyanobacteria blooms: The potential roles of eutrophication and climate change">, but the bit you need is:

Of all of the potential environmental drivers behind harmful algal and cyanobacterial blooms, the one that has received the most attention among the global scientific community has been anthropogenic nutrient pollution. Research indicates that cultural eutrophication associated with the increased global human population has stimulated the occurrences of harmful algal blooms (Anderson, 1989, Hallegraeff, 1993,Burkholder, 1998, Anderson et al., 2002, Glibert et al., 2005, Glibert and Burkholder, 2006 and Heisler et al., 2008).

As bodies of freshwater become enriched in nutrients, especially phosphorus (P), there is often a shift in the phytoplankton community towards dominance by cyanobacteria (Smith, 1986, Trimbee and Prepas, 1987, Watson et al., 1997 and Paerl and Huisman, 2009). Examples of these changes are the dense blooms often found in newly eutrophied lakes, reservoirs, and rivers previously devoid of these events (Fogg, 1969, Reynolds and Walsby, 1975, Reynolds, 1987, Paerl, 1988 and Paerl, 1997). Empirical models predict that in temperate ecosystems, summer phytoplankton communities will be potentially dominated by cyanobacteria at total phosphorus (TP) concentrations of ∼100–1000 μg L−1 (Trimbee and Prepas, 1987, Jensen et al., 1994, Watson et al., 1997 and Downing et al., 2001).

One reason that P often controls the proliferation of freshwater ecosystems is that many cyanobacteria that bloom in warm waters have the ability to fix nitrogen (N; Paerl, 1988 and Paerl et al., 2001). Since many of the bloom forming cyanobacteria genera are not diazotrophic and the proliferation of some blooms may be limited by N (Gobler et al., 2007 and Davis et al., 2010), it has been hypothesized both N and P may control harmful cyanobacterial blooms (Paerl et al., 2008 and Paerl and Huisman, 2009). While research on cyanobacterial blooms has traditionally considered inorganic N and P pools as being accessed by cyanobacteria or total N and P pools for understanding the trophic state of ecosystems, recent research has demonstrated that organic N and P may be important nutrient sources for cyanobacteria.

I know often what they do in these situations is stop the use of ground-bait, but if you have stocking of carp etc. in the pond, their bottom feeding activities will continually replenish the available phosphate.

Phosphate is mainly bound to clay minerals in lakes, but it is estimated that if you stopped all additional input of PO4--- into the UK environment tomorrow it would take a 1000 years for the level to decline to the natural level.

Cheers Darrel

 

[Mick.Dk]

He he - our local "fire-pond" (don't know if you have those in GB) had constant algae-blooms................it's "fed" by runoff from surrounding, cultivated fields, ofcourse.
3 years ago the entire pond was emptied, literally tonnes of Crusian carp (Carassius carasius) was taken away, and other tonnes of mud was removed.
They decided to introduce pikes and perches - but I don't think it ever happened (I might do it myself, one late night ).
Since that "wipeout", the pond has been very clear.........

 

[Antoni]

Thanks for the input, guys! So nothing really can be done, they will come and go unless we scrape off the bottom of the lake
It is then very interesting why we add more no3 to fix the problem in our tanks...

 

[ian_m]

Yes sprinkle in aquatic chalk. Cleared lake near my work in a day or two.

Search internet thingie for aquatic chalk and what it does.

 

[dw1305]

Hi all,

3 years ago the entire pond was emptied, literally tonnes of Crusian carp (Carassius carasius) was taken away, and other tonnes of mud was removed.......... since that "wipeout", the pond has been very clear.........

With a fish like Carp it is a double whammy, the sediment they stir up continually replenishes the PO4--- in the water column, and both sediment and "green water" and filamentous algae block the light to submerged macrophytes, leading to more nutrients in the water column. As submerged macrophyte cover declines, the cover for zooplankton like Daphnia, that would feed on "green water" reduces and they are eaten by carp fry etc.

There are other approaches to algae control have a look at <"Ecological Stoichiometry & Algae">.

cheers Darrel

 

[dw1305]

Hi all,

Yes sprinkle in aquatic chalk. Cleared lake near my work in a day or two.

This can definitely work in the the short term. The chemical action is that the PO4--- forms insoluble calcium phosphate complexes and precipitates out.

In the longer term, if the water was low in calcium originally, it may also stimulate the growth of zooplankton and water filtering molluscs. Hopefully people have access to this one <"The potential for phosphorus pollution remediation by calcite precipitation in UK freshwaters">.

The down-side is that the phosphorus is still there and in alkaline water you often get blooms of filamentous green algae, so you may just swap "green water" for "blanket weed".

Looking at the effect of zooplankton, I think this one should be available to every-on <"An evaluation of the role of daphnids in controlling phytoplankton biomass in clear water versus turbid shallow lakes">.

On the Kennet and Avon canal they've had water clarity issues since they restored the <"Caen Hill"> lock flight. They've attempted to treat this by <"removing fish from the side ponds">, and making some of the ponds inaccessible to fish, to act as refuges for zooplankton and submerged macrophytes.

cheers Darrel