Re: Diatom Bloom

["Yvan Alleau" <yalleau@OCE.ORST.EDU>]

hi,
i've just read my mail so sorry if someone already answered that question.
Diatoms are phytoplankton which can be found in rivers, lakes, marine
environments (different species so). They have the particularity to used
silica (biogenic element) in the formation of their tests. In the natural
environment they typically bloom one or twice a year (often summer period)
in an amazing quantity when conditions are present. They are: good light
intensity and duration, presence of all the nutrients (phosphate, nitrate,
iron, manganese....) in optimum quantity, temperature as well. Nevertheless
Silica is a limiting parameter to their bloom.
I'm not quiet sure if its 100% bad for a tank since it will tend to reduce a
surplus of dissolved elements that may have built up but they may also
impact the amount of dissolved oxygen available.
Concerning the "blue-green algae " and the info that Ron enlighted :"The
important difference is that blue-green algae produce poisons (known as
cyanotoxins) that can and will kill fish and other aquatic life", i have to
say that each time i have been exposed to it in friends tanks i had a strong
allergic reaction (by touching or smelling them).

Hope that helps,
take care

                        FLI USA

Yvan Alleau
712 Kings boulevard
97330 Corvallis, Oregon
home # 738-0606
College of Oceanic and Atmospheric Sciences
Oregon State University
office (Burt 222) # 737-3649, to be used wisely !
yalleau@oce.orst.edu

"When you're far from everything, you're getting closer to the essential"


----- Original Message -----
From: "Ron West" <nfn09322@naples.net>
To: <apisto@listbox.com>
Sent: Thursday, March 01, 2001 7:53 PM
Subject: Re: Diatom Bloom


> >very few types of algal blooms are harmful. Most of the famous algal
> >species that are harmful occur in the marine environment, on the open
> >oceans. I don't know of any examples of harmful algal species in aquaria.
>
>
> I don't disagree with anything Jonathan has said, but I do feel a word of
> caution is in order here, especially for the benefit of newer aquarists.
>
> Cyanobacteria are not algae, but they look and act much like some types of
> true green algae. They are commonly referred to as blue-green algae and
> sometimes as "slime" algae. They form a very dark-green (sometimes almost
> black) film that can spread out and blanket anything that doesn't get out
of
> its way.
>
> Like true green algae, cyanobacteria also bloom in response to heavy
> nutrient loads, and in thriving tend to remove these excess nutrients from
> solution. The important difference is that blue-green algae produce
poisons
> (known as cyanotoxins) that can and will kill fish and other aquatic life.
> Not to cause a panic, as physical removal of the cyanobacteria mats and
> regular water changes will protect most fish even in the face of an
ongoing
> bloom ("infection"). However, left unchecked, the poisons will accumulate
> and the fish will eventually get sick and die.
>
> I'm not sure whether the fish die as a direct result of the toxins, or
> indirectly as a result of opportunistic infections attacking weakened
fish.
> Probably either, depending on the age, species, and overall health of the
> fish in question. I do know that fish, clearly heavily stressed and "sick"
> in the presence of a heavy blue-green algae bloom, can make quite quick
and
> dramatic recoveries when the bulk of the algae is removed and the water is
> 50-80% changed.
>
> One reason I felt I needed to speak up here was Bonny's statement that her
> tank is brightly lit. When I think of diatoms, I think of the brown film
> ("brown algae") that tends to grow in the back corners and other low light
> situations rather than under bright light. I may be wrong here. Others
with
> more knowledge feel free to correct me.
>
> I do know that cyanobacteria can grow under fairly modest light, but can
> also thrive in bright light, even full, direct sunlight.
>
> ><  º>            <º  ><
>
> Ron
> Naples, FL
>
>
>
>
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