I don't suppose anyone can elnighten me with some information regarding the environmental requirements of D. Geminata? Specifically, I'm looking for inforation regarding nutrient enrichment and blooming.
Being a diatom, it doesn't favor acidic water, and that one prefers water without much nutrient load in general, especially the warmer and slower eddies of otherwise cold, clear rivers or small lakes. It would probably flourish if you boosted the nitrogen or phosphorus a little bit in some place it was already growing, but it isn't found in eutrophic settings AFAIK. People only study those kinds of things when they cause problems - other than making fly fishermen slip on rocks in the northwestern US, I don't recall hearing of any problems with the stuff. You trying to grow it in an aquarium?
Nope. Looking at biota diversity reports at a location downstream of a municipal wastewater treatment plant.
It certainly doesn't require fertilization to flourish - it's been years since I was familiar, but IIRC it was one of our marker species for cold, low-nutrient (and higher pH, of course) water. I wouldn't guess, as a first assumption, that its mere presence was a consequence of effluent fertilization from a sewage treatment plant, in other words. Where are you?
It's not, and that's not what I'm trying to prove or ascertain. My recollection (I don't have the report open in front of me at this time) is that it is present both upstream and downstream of the effluent outfall, but it's more dominant downstream than upstream. The effluent is enriched in N&P, however typically basic (pH 7.5-8.5) and probably slightly warmer than the ambiant water temps (IIRC the river in question is primarily fed by snow meltwater, and glacial meltwater in it's higher reaches, and effluent tends to be warmer than its surroundings). The report asserts that this is probably because the biota sampling site is in the equivalent of a microclime (more or less) rather than any influence of the outfall, because D. Geminata prefers nutrient poor rather than nureint rich waters (hence specifically asking about nutrient enrichment, rather than eutrophication - even though they're not neccessarily unrelated).
That's beyond my familiarity. I have noticed, though, that some diatom pros think pH and - especially - conductivity, are more important than is generally realized. I knew one who used to carry a conductivity meter around with him, and he mentioned that it was a factor often overlooked. For what it's worth - -
No idea. Silica isn't something that local authorities are typically required to test for, and I have no idea if there might be tradewaste streams present in the effluent that might be silica enriched.
I think I meant silicates, which are quite different from silica (it's been a while). But higher silicate levels could explain the increased diatom presence in the downstream waters, since they use it for their shell-like structures.
Silica is a silicate (Quartz, among other things), bet yes, I understand your point, either way, I'm no aware of any indtrustrial tradewaste streams contributing to this discharge that could lead to an erichment of silicates in the wastewater plume.
