As I said UF is doing what a researcher does and he does it well.
I rely on my histories successes and failures to guide me and I share those. I'm sure there are those that totally disagree with me. I look to see the fruits of their endeavors and judge them by that.
As a marine Bio major ( didn't t finish,) you wouldn't believe the crap science had to offer and so much of hard science has been modified or rejected altogether. Do I ignore science of courses not, but I don't blindly accept it either.
and that's been my point.. the "science" of ap is just too new.. experience and results are leading the way... science tries to prove or disprove those results
I have to disagree with Urbanfarmer on the subject of nitrates. There have been numerous studies on nitrate levels and how they impact fish. I actually remembered this from my biology classes as an undergrad, but I did a quick google search and came up with the following from several studies:
- Elevated nitrates above 100 ppm appear to substantially reduce antibody response in fish.
- Elevated nitrates above 200 ppm appear to cause damage to internal organs and particularly kidneys.
- Elevated nitrates above 100 ppm appear to negatively impact growth rate.
- Elevated nitrates at 200 ppm for 7 weeks tends to be fatal to fish.
- Elevated nitrates (no ppm given) tend to hamper oxygen absorption in fish.
I have to disagree with Urbanfarmer on the subject of nitrates. There have been numerous studies on nitrate levels and how they impact fish. I actually remembered this from my biology classes as an undergrad, but I did a quick google search and came up with the following from several studies:
- Elevated nitrates above 100 ppm appear to substantially reduce antibody response in fish.
- Elevated nitrates above 200 ppm appear to cause damage to internal organs and particularly kidneys.
- Elevated nitrates above 100 ppm appear to negatively impact growth rate.
- Elevated nitrates at 200 ppm for 7 weeks or more tends to be fatal to fish.
- Elevated nitrates (no ppm given) tend to hamper oxygen absorption in fish.
I am pursuing a Masters of Science in Environmental Science, with a major in Soil and Water, and 2 minors, Aquaculture, and Botany. I have not yet reached curriculum discussing water chemistry as it applies to fish nor fish biology (a course I am very much looking forward to). Yes, my very own custom tailored Aquaponics degree.
With that said, understand I have been left to my own devices until the time comes that I have the above stated education in a state-of-the-art manner. Now, please state any specific research or references otherwise so we can all act as peers reviewing said literature. From the posts in this thread I just reviewed research discussing 200 ppm nitrate on fish. So, please explain... If it is scientific fact that more than 7 weeks at 200 ppm nitrate levels is fatal to all fish in all stages in their life cycle, then how does one researcher state that he observed and studied fish in a commercial operation that consistently had over 200 ppm of nitrate? You would imagine this guy would be out of business with all the fish he has left?
I have yet to see evidence to conclude nitrate is toxic to fish, especially as it applies to Aquaponics.
I don't think it's safe to assume 200 ppm nitrate is toxic or even fatal to fish in any adult stage of their life cycle and sensitivity to nitrate is variably dependent on species and strain for pre-adult stages in their life cycle. FOR EXAMPLE, TILAPIA ARE SUPER FISH.
Anywhooooo, I wanted to thank you from the bottom of my heart for joining the discussion. I think we need more people interested in all our lively debates. With more of us searching out information and presenting it in a forum manner for discussion, I think we can all advance our learning faster and deeper than without each other.
P.S. Was your undergrad in biology or the like? Just curious how much I need to pick your brain.
Abstract
It has been proposed that transgenic zebrafish could be designed to detect low levels of chemical contaminants that cause oxidative stress in aquatic environments, such as heavy metals or pesticides. In this paper, we describe such a transgenic zebrafish that produces a luciferase–green fluorescent protein (LUC–GFP) fusion protein under conditions of oxidative stress. The reporter gene expression is under the regulation of the electrophile responsive element (EPRE), which activates gene expression in response to oxidative stressors. The GFP component of this fusion protein allows us to visually detect reporter gene activity in live animals to determine if activity is localized to a particular tissue. The luciferase component is capable of returning a quantitative assessment of reporter gene activity that allows us to determine if reporter gene activity is directly correlated to the concentration of the chemical inducer. We have tested this reporter construct in both transient and stable transgenic fish after exposure to a range of HgCl2 concentrations. GFP expression from the EPRE–LUC–GFP construct was inducible in transient assays but was below the limit of detection in stable lines. In contrast, we observed inducible luciferase activity in both transient assays and stable lines treated with HgCl2. We conclude that the EPRE is capable of driving reporter gene expression in a whole animal assay under conditions of oxidative stress. Furthermore, expression was induced at HgCl2 concentrations that do not result in obvious morphological defects, making this approach useful for the detection of low levels of oxidative contaminants in aquatic environments.
Oliver, I can't thank you enough for taking the time to make these posts (and thanks to JCO for setting up this section of the forum). As a newbie, this information is pure gold!
I'm done reading the first article, and am now onto the rest of this fabulous series.