In response to the question of the ecological importance of
cyanobacteria (blue-gree algae) in Klamath lake.
The short answer is that no person can answer this question unless
there has been a thourough analysis of the lake, before and after the
harvesting started.
Since I have some interest in cyanobacterial ecology and have passed by Klamath
lake, your letter inspiried me to reply.
The cyanobacterial species in Klamath lake is called Aphanizomenon
flos-aquae. It belongs to the group of cyanobacteria that can fix
nitrogen from the air and convert it to a biologically more useful
form, like amino acids and proteins. Potentially this could give a
large input of nutrients to the, presumably, nutrient poor lake. The
question is whether there are any organisms present in the lake that
can use this biomass.
There are relatively few organisms known to feed directly on
cyanobacteria. This could be due to the fact that they sometimes
produce toxins, but no one has ever proven that these toxins give the
cyanobacteria an advantage. Some isolates of Aphanizomenon flos-aquae
are well known toxin producers.
The only pathogen I know of is a fungus that attacks the akinets
(cyanobacterial spores) of Aphanizomenon flos-aquae.
Bacteria could benefit from the primary production of cyanobacteria,
and these bacteria could either re-mineralise, or if they are eaten
up, move biomass further up in the nutrient chain.
It could also be the case that biomass is just falling to the bottom,
termed "snow". In which case the harvesting would have small or no
input on the ecosystem.
Hope you find this contribution useful
Sven Janson
Department of Botany
Stockholm University
Sweden
