Fe & PO4 toxicity - Scientific research

[GillesF]

Hi guys

I stumbled upon these two research articles on another forum:

Fe : http://www.env.gov.bc.ca/wat/wq/BCguidelines/iron/iron_overview.pdf

To protect freshwater aquatic life guideline for iron is 1 mg/L for total iron and 0.35
mg/L for dissolved iron

PO4: http://ceqg-rcqe.ccme.ca/download/en/205

These phosphorus limits allow management to
define where their water bodies lie, and define a trigger
range for that water body.

Table 1. Total phosphorus trigger ranges for Canadian
lakes and rivers.
Canadian Trigger Ranges
Trophic Status Total phosphorus (μg·L-1)
Ultra-oligotrophic < 4
Oligotrophic 4-10
Mesotrophic 10-20
Meso-eutrophic 20-35
Eutrophic 35-100
Hyper-eutrophic > 100

Isn't this much lower most of us use?

 

[Tom Barr]

These systems typically lack Extremely high plants biomass........and algae causes problems for the food chains.
Minign runoff leaches metals other than just Fe, and many lakes are Fe limited algae wise.

So adding this changes the dynamics and food chain greatly.

Trout Fry and cold water fish are also about 100-1000X more sensitive to metals and NO3 etc.

 

[GillesF]

These systems typically lack Extremely high plants biomass........and algae causes problems for the food chains.
Minign runoff leaches metals other than just Fe, and many lakes are Fe limited algae wise.

So adding this changes the dynamics and food chain greatly.

Trout Fry and cold water fish are also about 100-1000X more sensitive to metals and NO3 etc.

Could you explain the text in bold? I'm not following ...

 

[Tom Barr]

Fe is sometimes a proxy for other metals, Fe is often limiting in many northern nutrient poor lakes.

This is mostly about the phytoplankton and larger deep lakes lacking plants, not littoral planted shallow lakes.

 

[dutchy]

The problem is that some people conclude these reports are representative for all fish, so certain levels of nutrients used with EI are potentially harmful.

They make a hypothesis but fail to validate it, because there is no proof these values are representative for the fish we keep, nor have they done tests to confirm. Yet they feel confident enough to make it look like a fact.

 

[Tom Barr]

Probably a better article is this one:

http://www.msbrownscience.com/uploads/4/8/7/2/4872895/nitrate_toxicity_to_aquatic_animals.pdf

The only real warmer water fish is the guppy, which is pretty tough, but this is for NO3, not Fe or PO4, PO4 you will not find upper levels for since it only becomes an issue when osomotic shock and salinity are high enough with say Kh2PO4salt.........

As a water wildlife manager, you are faced with many decisions and how to use this information:
1. You have MANY species, so you chose the most sensitive to see and test toxicity, or one that is not quite so rare and patchy, rather, one that is still common but sensitive to environmental change.
2. You cannot test for every species, it's not practical
3. You cannot test for every different habitat
4. You need some guideline, better safe than sorry.

 

[dutchy]

I understand the water wildlife manager, but I don't understand the aquarists who extrapolate these specific values on their tanks and claim EI is detrimental to fish health. I agree with them not to use exorbitant high levels of nutrients if it's not needed. But to spread the opinion that more than 0,5 ppm Fe is dangerous to fish in general, is based on assumptions.

The reference articles posted by GillesF were used on a Dutch forum to validate their opinion.

 

[Tom Barr]

I understand the water wildlife manager, but I don't understand the aquarists who extrapolate these specific values on their tanks and claim EI is detrimental to fish health. I agree with them not to use exorbitant high levels of nutrients if it's not needed. But to spread the opinion that more than 0,5 ppm Fe is dangerous to fish in general, is based on assumptions.

The reference articles posted by GillesF were used on a Dutch forum to validate their opinion.

Yes, misapplied research foir support........is a common problem, even within the field's research

Our glass boxes are radically different and most of the plants and fish species we keep have NEVER been studied, so they are not specific.
As far as lake studies, the University of Florida has ample lakes that are shallow, warm and full of plants........subtropical lake studies.........but Canada or northern Europe? It;s a big stetch, but if it's all you have, it's somewhere to start, then you test and see if it's true or not.

I think EI pretty much illustrates that it's much easier to falsify many hyphtesis about Fe, NO3, PO4, etc, than to demonstrate the cause for algae or poor growth in planted tanks etc.
In fact, for most plant growth studies EVERYWHERE and almost any Plant Science field, a non limiting reference is used for comparing growth is used(often like EI, a modified Hoagland's solution). Then a DI water sample is used for the most limiting. EVERYTHING ELSE...falls somewhere between those two.
Gerloff 1966 is a good paper on dosing P and N for plants in aquariums.

I bred Sturisoma panamense every 2 weeks for about 1 year using that dosing of Fe done 3x a week.
Cardinals got fat, other fish did as well.

 

[GillesF]

Tom & Dutchy, thanks for the info, very interesting discussion.

I've been dosing heavily too and never got any problems with fish so I was a little puzzled by this. Dutchy, do you mind me sharing this topic on the Dutch forum?

 

[dutchy]

I don't mind, maybe they even want to bring the discussion here

 

[Tom Barr]

I don't mind, maybe they even want to bring the discussion here

Well, they can see the pictures of Sturisoma and the CRS's and the Fire shrimp all breeding, Also some red dwarf farowellas, even Malawi cichlids recently.

 

[dutchy]

I also have some fry from wild caught Hemiloricaria parva. These are fish from the Mato Grosso. Even found some of them in the filter after four weeks and still survived. Already around 1,5 inch now.

Not bad results with "dangerously high Fe levels"