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Old 09-09-2020, 07:51 PM
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Default Interesting recent-ish study on SLS

I bumped into this, and thought I'd share.

https://www.researchgate.net/publica...s_Atelopus_spp


Abstract
Spindly Leg Syndrome (SLS) is a persistent animal welfare issue associated with the rearing of amphibians in captivity. We conducted two experiments to investigate the effects of diet, water composition and overfeeding on prevalence of SLS in newly metamorphosed harle- quin frogs (Atelopus spp.). In our first experiment, we offered 400 full-sibling tadpoles of Atelopus certus isocaloric diets in treatments of 31%, 37%, 42% and 48% crude protein respectively. Tadpoles fed higher protein diets metamorphosed faster, but the incidence of SLS exceeded 80% in all treatments leading to the conclusion that variation in dietary pro- tein was not responsible for causing SLS. We used 720 full-sibling Atelopus glyphus tad- poles in a second experiment to examine the effects of diet type, water composition and diet ration on SLS. We found that an overall incidence of 58% spindly leg in tadpoles reared in tap water, but reduced to about 10% in water treated by reverse osmosis and then reconsti- tuted. It is possible that the reverse osmosis treatment removed some factor that caused the SLS, or that the reconstitution may have added a mineral lacking in the original tap water. Within tap water treatments, overfeeding tadpoles in tanks increased the incidence of SLS. We recommend further experimental research into this condition to identify the causative factors in the water. Additional research into the nutritional composition of food available to wild tadpoles would be useful in formulating captive diets, that have to date been solely based on surrogate species.
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Old 09-09-2020, 10:05 PM
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Default Re: Interesting recent-ish study on SLS

This is pretty spiffy!! Thank you for sharing this!

I love scientific studies even when they don't find a lot because it at least eliminates possibilities. Here the lesson was don't overfeed and you are much better off using a commercial tadpole food then making your own. Plus if you have crazy soft water you need to add supplements to harden it back up. Also UVB for tadpoles is rather pointless. Or at least that was the takeaways I got.
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Old 09-10-2020, 01:41 AM
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Default Re: Interesting recent-ish study on SLS

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Originally Posted by minorhero View Post
Plus if you have crazy soft water you need to add supplements to harden it back up.
I think the finding here was that reconstituted RO water (using a crummy CTA membrane, judging from the Cl residual) was less likely to contribute to SLS than (their unique) tap water. I would have loved to see a pure RO experimental group.
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Old 09-10-2020, 01:56 AM
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Default Re: Interesting recent-ish study on SLS

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I think the finding here was that reconstituted RO water (using a crummy CTA membrane, judging from the Cl residual) was less likely to contribute to SLS than (their unique) tap water. I would have loved to see a pure RO experimental group.
They don't mention if they were using a commercial product or not but their 'reconstituted' process is what in the aquarium world is called remineralized. The end result was that they had greater TDS in their 'reconstituted' RO then their tap water. Hence my comment regarding needing to harden really soft water. But ultimately these guys did some weird stuff that messed up their experiment. They mentioned that they believed all of their diets were over feeding and that they water quality led to a high mortality rate. I believe it because instead of feeding a commercial food normally, they decided to ground up food (they don't mention if it's a commercial food or not) then make a paste out of it and then put the paste on a glass slide they add to the aquarium. This didn't sound like a good idea to me when I first read it and now knowing how it turned out it sounds even worse. I think they would have had different outcomes if they just added a commercial food as flakes/pellets in an appropriately small amount. Just my read on it.
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Old 09-10-2020, 02:05 AM
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Default Re: Interesting recent-ish study on SLS

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They don't mention if they were using a commercial product or not
Page 5:

"We prepared RO water in 90L reservoirs using a non-commer- cial 100G gallon per day Reverse Osmosis System and reconstituted the RO water by dissolving 0.0395g calcium chloride, 0.0465g magnesium sulfate, 0.0358g potassium bicarbonate and 0.0298g sodium bicarbonate per liter of RO water."

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The end result was that they had greater TDS in their 'reconstituted' RO then their tap water.
Page 6:

"Conductivity μS/cm -- Tap: 486.5, RO + salts: 277.2" ( ppm TDS: Tap 316/Recon RO 183)
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Old 09-10-2020, 11:17 AM
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Default Re: Interesting recent-ish study on SLS

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Page 5:

"We prepared RO water in 90L reservoirs using a non-commer- cial 100G gallon per day Reverse Osmosis System and reconstituted the RO water by dissolving 0.0395g calcium chloride, 0.0465g magnesium sulfate, 0.0358g potassium bicarbonate and 0.0298g sodium bicarbonate per liter of RO water."



Page 6:

"Conductivity μS/cm -- Tap: 486.5, RO + salts: 277.2" ( ppm TDS: Tap 316/Recon RO 183)
Their RO system was custom made but what did they use to 'reconstitute' was that commercial or did they just add the salts themselves? Thats what I was talking about.

As for the TDS, that table is their starting parameters they were aiming for but if you look at Table 7 you will see all of the RO systems had much higher TDS then the tap water at the time of water changes. They also note:

"According to the U.S. Geological Survey, soft waters are less than 60 mg/l hardness, while very hard water exceeds 251 mg/l on the water hardness scale. Our Gamboa experimental water is on the lower end of the scale with Ca hardness values of 26 mg/l in tap water 56 mg/l in reconstituted water" page 11

Edit: Also I couldn't find this one way or another, but what did they use for food to make their horrible paste? They mention at the start

"The second hypothesis is that some unknown nutritional factor in our experimental diet may cause SLS based on reports from the Maryland Zoo that they did not observe any SLS in Atelopus tadpoles fed exclusively on a commercial food recommended by the Species Survival Program (K. Barrett, pers. comm). Page 2

I've looked quite a bit trying to figure out what that food was since that seems to be a pretty useful takeaway (anecdotal?) but couldn't find it. I'm hoping someone either knows what it was or that I just missed it and someone can point it out.

Last edited by minorhero; 09-10-2020 at 11:30 AM. Reason: edit
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Old 09-10-2020, 12:18 PM
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Default Re: Interesting recent-ish study on SLS

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Their RO system was custom made but what did they use to 'reconstitute' was that commercial or did they just add the salts themselves? Thats what I was talking about.
Typically when a retail product is used, it is named. It seems clear that they added the salts themselves, since that is what they claimed to do.


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As for the TDS, that table is their starting parameters they were aiming for but if you look at Table 7 you will see all of the RO systems had much higher TDS then the tap water at the time of water changes.
This was distinctly not part of the tested hypotheses, but rather an unexplained phenomenon. Page 8:

"Multiple measurements of a more limited set of parameters in the actual tanks revealed that dissolved solids, ammonia and ammonium were consistently higher in RO treatments than tap water (Table 7). This pattern was not evident in the starting concentrations of the water provided (Tables 3 & 4), indicating that some differential biological processes may be occurring in the different water treatment groups."

Further, that quote doesn't lead to this conclusion:

Quote:
Originally Posted by minorhero View Post
if you have crazy soft water you need to add supplements to harden it back up.
since that is not what they did. Their conclusions relate RO to tap water, not lower TDS to higher.
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Old 09-10-2020, 01:27 PM
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Default Re: Interesting recent-ish study on SLS

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since that is not what they did. Their conclusions relate RO to tap water, not lower TDS to higher.
Honestly their conclusions were that they didn't know what happened and they need more research. Personally looking at their experiment I find this pretty significant:

"Our Gamboa experimental water is on the lower end of the scale with Ca hardness values of 26 mg/l in tap water 56 mg/l in reconstituted water" page 11

Their tap water had crazy low calcium and they ended up with a huge number of froglets with SLS. So yeah, if your water is super low in calcium you need to add it back in and a big part of TDS is... calcium. Sooo yeah like I said if you have crazy soft water you will want to add something back into it. Personally I use seachem equilibrium with some of my aquariums when I have a huge snail/shrimp population and start to notice deficiencies in the snail shells. It solves the problem every time. They didn't formally conclude this of course but I mean... I feel like a study showing that calcium is helpful for froglet development falls into the realm of studies where you hear the conclusion and the response is like 'wow someone really wanted to pluck some low hanging fruit for a grant'. (if that makes sense)
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Old 09-10-2020, 03:18 PM
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Default Re: Interesting recent-ish study on SLS

The authors describe the hypotheses the study is designed to test, none of which involve calcium, and all of which are relatively unstudied, AFAIK. Presumably they set some grad students out on a lit review before proceeding.

"We conducted two controlled captive-rearing experiments designed to improve our under- standing of the occurrence of SLS in captive harlequin frogs of the genus Atelopus. In the first experiment, we tested the hypothesis that lack of dietary protein in Atelopus tadpoles caused SLS. The hypothesis is from anecdotal observations that increasing animal protein in Mantella aurantiaca tadpole diets reduced SLS incidents at the National Zoo (L. Augustine, pers. comm).
We tested three hypotheses in the second experiment. The first hypothesis is reducing quantity of food offered might reduce SLS based on anecdotal observations by JG that Atelopus tadpoles from the same clutch that were fed lower food quantities, took longer to metamor- phose and had a lower SLS incidence. The second hypothesis is that some unknown nutritional factor in our experimental diet may cause SLS based on reports from the Maryland Zoo that they did not observe any SLS in Atelopus tadpoles fed exclusively on a commercial food recom- mended by the Species Survival Program (K. Barrett, pers. comm). The third hypothesis is that reverse-osmosis (RO) treatment of tap water will reduce SLS incidence based on observations that SLS disappeared from the collection following a transition from well water to reconsti- tuted reverse osmosis-treated water at the PARC Project facility at the Nispero Zoo in El Valle de Anton (HR pers. obs)."

Yes, the calcium correlation is interesting (and the authors cite a number of relevant studies in the discussion), and there are many, many other interesting tidbits that can be dug out of the data, but simply "adding something to harden up" soft water isn't supported by the study, and could be taken all sorts of wrong ways by novices.

A very interesting thing about this study is that it simply ignores the assumption (in the hobby, anyway) that Vit A is a central player in SLS.
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Old 09-10-2020, 04:37 PM
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Default Re: Interesting recent-ish study on SLS

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A very interesting thing about this study is that it simply ignores the assumption (in the hobby, anyway) that Vit A is a central player in SLS.
Considering how many of us supplement Vit A in a form combined with calcium, calcium could still be playing a role. I take the proper baseline assumption to be that no single factor/nutrient controls or prevents SLS - so I imagine both could be a factor.
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