What strikes me as harsh are all the animals that were killed because reef hobbyests were given a misrepresentation of phosphorus in reef ecosystems.
Back in the early 90's I bought into the notion PO4 needed to be low. But my experiences working at a LFS, for an aquarium maintenance company then starting my own business and what I read moderated what I believed. With PO4 among the authors I read varying from no recommendation to 0.0 mg/l to .5 mg/l and seeing nice systems with "unacceptable" PO4 and algae ridden systems with "ideal" PO4 I stopped worrying about it. Using test kits that read from 0.0 to .08 or 1.0 as long as PO4 was in the middlin to lower part of the range I didn't try lower it.*
Getting active on the forums in 2009 I was puzzled by the low recommendations and started looking to see what reef scientists where saying. Veron's observations, published in 1993, noting ocean circulation and upwelling, with as much as .3 mg/l PO4, was an important supply of nutrients for reefs.
"Imported nutrients are usually transported to reefs from rivers; but if there are no rivers, as with reefs remote from land masses, nutrients can only come from surface ocean circulation. Often this supply is poor, and thus the vast ocean expanses have been refered to as "nutrient deserts". The Indo-Pacific has many huge atolls in these supposed deserts which testify to the resilience of reefs, but the corals themselves may lack the lush appearance of those of more fertile waters. Many reefs have another major supply of inorganic nutrients as, under certain conditions, surface currents moving against a reef face may cause deep ocean water to be drawn to the surface. This "upwelled" water is often rich in phosphorus and other essential chemicals." J. E. N. Veron "Corals of Austrailia and the Indo-Pacific" pg 30
Adding Veron's observations to
Conkright's paper on ocean surface PO4 levels and
Kleypas look at values on reef systems and a very different picture appears. Instead of corals living in their corner of the ocean in low nutrient waters you have a gradient from .3 mg/l PO4 in deeper waters to ~.02 - ~.04 mg/l PO4 in surface waters away from reefs to very low around reefs. Along with other papers showing a high demand for phosphorus in it's various forms it seemed obvious the low PO4 numbers around corals is because they're sucking it up and maybe the assumption to keep it low in our reefs wasn't the best idea.
Seeing your
reference to ENCORE I looked it up on google scholar.
Szmant's paper in 2002 is one that popped up. In the abstract referencing nutrient over-enrichment as a cause of coral decline she said "Support for such claims is equivical at best." She goes on to discuss various problems with ENCORE. (One that seems egregious to me was using data from colonies of species transplanted to locations those species did not occur naturally.) I had never heard of bisphosphonate in
Yamashiro's paper referenced in your article looked into it and found
Marshall & Clode (2002) looked at bisphosphonate's effect on calcification also and found it's effect "potentially illusory". So it looks like you used some questionable papers.
You're right Dr. Holmes-Farley, a lot of people assumed corals needed low PO4 numbers. But it doesn't look to me like many of the reef aquarist gurus did much research to verify their assumptions or just looked until they found what confirmed their assumptions. Look at your refferences in your post, you're still using ENCORE 22 years after Szmant's paper pointed out serious flaws in it. You say you were not aware of other research. How hard did you look for other research? I have to wonder because Szmant certainly found contradictory research. Were you even aware of Szmant's paper before now?
*For the record, for those not familiar with my posting current research, what I've been posting for years is .03 to .3 mg/l for PO4. The research by Rosset, deAngelo and Weidenman at the University of Southampton done with corals maintained in a closed reef system found phosphate deficiency in corals impacts their photobiology. They've identified a minimum level of .03 mg/l. Coupled with Veron's observations of upwelling potentially providing .3 mg/l gives what seems a reasonable range of .03 to .3 mg/l for PO4 for reef ecosystems. See
my post here for some other PO4 numbers corals have been successfully spawned and raised in.
