The Phormidium Case - Part II

I went back into the field for the Phormidium experiment. I was asked to take field photographs and get some extra samples. Analyzing the samples with the microscope revealed that the Phormidium patches of the experiment belonged to the autumnale group. This particular group of Phormidium is known to be an anatoxin-a (ATX) and homoanatoxin-a (HTX) producing group, when conditions are favourable.

A Phormidium patch gets a grip on underwater plants

A recently published article from New Zealand states that "our Phormidium autumnale isolates showed a large radiation of subspecies, and it seems likely that mats are comprised of a mixture of strains, only some of which have the ability to produce anatoxins. Therefore, the likelihood of obtaining an anatoxin-producing strain is dependent on the filament isolated and its relative abundance in the mat." (Heath et al., 2010).

Though an anatoxin-a test might prove our case, the implication of the dominant filaments being Phormidium autumnale, the toxic group, was enough at this point to know that precautions had to be made (closing the location for visitors).

Working with the underwater telescope
Photographs by Wim Bolkenbaas


The same authors also state that the production of anatoxin-a by Phormidium is variable over time and space:

"The presence and concentration of ATX and/or HTX and their degradation products, dihydroanatoxin-a and dihydrohomoanatoxin-a, was highly variable across all sites and over time. Anatoxin-a and HTX occurrence was restricted to periods of warm water temperatures (above 13.4°C) and below average river flows" (Heath et al., 2011).


Pools on the beach in which Phormidium

is attached to the sandy bottom in microbial mats


This conclusion may be applicable on the experiment. How much do we know about the variations in anatoxin-a and homoanatoxin-a production, and the degradation products of the particular patches? What about water temperatures and flows, relating to the patches used for the experiment? In Spring we might repeat the experiment to learn more about the specific situation.

Detail of the microbial mat

 

Phormidium autumnale group - the long filaments
Aphanothece microscopica - the green egg shaped cells,
also a cyanobacterium.
Photograph taken with Olympus IX70 cellSens
Dimension, 600x immersion oil.

Literature

Edwards C, Beattie KA, Scrimgeour CM & Codd GA (1992), Identification of anatoxin-a in benthic cyanobacteria (blue-green algae) and in associated dog poisonings at Loch Insh, Scotland, Toxicon 30: 1165–1175.

Gugger M, Lenoir S, Berger C, Ledreux A, Druart JC, Humbert JF, Guette C & Bernard C (2005), First report in a river in France of the benthic cyanobacterium Phormidium favosum producing anatoxin-a associated with dog neurotoxicosis, Toxicon 45: 919–928.

Heath MW, Wood SA, Ryan KG (2010), Polyphasic assessment of fresh-water benthic mat-forming cyanobacteria isolated from New Zealand, FEMS Microbiology Ecology, 73: 95–109.

Heath MW, Wood SA, Ryan KG (2011) ABSTRACT, Spatial and temporal variability in Phormidium mats and associated anatoxin-a and homoanatoxin-a in two New Zealand rivers, Aquat Microb Ecol 64:69-79.

Komarek J & Anagnostidis K (2005), Cyanoprokaryota -2. Teil/2nd Part: Oscillatoriales. Süsswasserflora von Mitteleuropa 19/2, (BüdelB, KrienitzL, GärtnerG & SchagerlM, eds). Elsevier/Spektrum, Heidelberg.