Effects of low salinity on corals?

[jsker]

I did a search on this topic and did not find this question of R2R

I started a auto water change on 4/15 and also recalibrated my conductivity probe about the same time. The reason for the recalibration was that for the past two years the probe was reading correctly and the last two month it has been creeping up ever so slightly. I cleaned the probe and did the calibration. I have a inexpensive refractometer and it has always read lower then than what my salinity really is so it was alway a mystery if my salinity was correct.

I will know for sure later this week, since I ordered a Hanna hi96822 digital.

My coral have been pailing but my arco's are going strong.

I am going to start raising my salinity slowly using the inexpensive refractometer and then use the new toy from now on for weekly checks.

Anyone else have this issue? please feel free to discuss this so the information will be here on R2R

 

[Crabs McJones]

How low do you suspect your salinity got?

 

[jsker]

How low do you suspect your salinity got?

I suspect down to 1.022?? I am not quite sure. That could also be the reason that I have the cutting back on my alk and Ca.

 

[Greenstreet.1]

I like [emoji1531] with a comment/question.
There’s a ratio to the 1.022 and other elements so I would say that something should happen. Good or bad I would say that depends on how fast that change happened.

What’s the ratio for the other elements at a salinity of 1.022 ?

 

[Randy Holmes-Farley]

It's a complex question without any data that I have seen whether lower than typical salinity while maintaining important elements at natural concentrations is a problem for corals or not. For example, if we lower sodium, sulfate and chloride to get to a low salinity, while maintaining everything else, is that a problem? It might be fine. It might even be better.

It becomes harder to maintain alk and calcium at lower salinity, but not impossibly so.

On the other hand, if you take NSW at a sg of 1.022, alk will be in the 5's of dKH. That would likely be an issue.

 

[jsker]

It's a complex question without any data that I have seen whether lower than typical salinity while maintaining important elements at natural concentrations is a problem for corals or not. For example, if we lower sodium, sulfate and chloride to get to a low salinity, while maintaining everything else, is that a problem? It might be fine. It might even be better.

It becomes harder to maintain alk and calcium at lower salinity, but not impossibly so.

On the other hand, if you take NSW at a sg of 1.022, alk will be in the 5's of dKH. That would likely be an issue.

Question, I your opinion would a higher dKh have a more adverse effect?

 

[jsker]

I like [emoji1531] with a comment/question.
There’s a ratio to the 1.022 and other elements so I would say that something should happen. Good or bad I would say that depends on how fast that change happened.

What’s the ratio for the other elements at a salinity of 1.022 ?

The decline has been really noticeable in the past two weeks, and in the last week more so the the last. I have been cutting back on the dosing of Ca, Mg, and alk for the past two weeks to bring the parameter back to where my reading have been for sometime at
was
Ca 420
Mg 1400
dKH 8.3
yesterday
Ca505
Mg 1470 was off the chart
8.9 declining from 10.5

 

[Randy Holmes-Farley]

Question, I your opinion would a higher dKh have a more adverse effect?

I don’t follow. Higher than what and worse than what?

 

[jsker]

I don’t follow. Higher than what and worse than what?

Sorry
A dkH at 1.022 at a 10.5 to a dKH at 1.025 10.5 is the effect the same?

 

[Randy Holmes-Farley]

Same with respect to calcification rates or excessive calcification in low nutrient environments? I’m not sure how alk uptake is altered by salinity changes.

 

[Flippers4pups]

Jeffrey, not to high jack your discussion, but have you checked the refractometer you have to some calibration fluid?

I don't think I would trust the probe and would check salinity weekly with a calibrated refractometer.

 

[jsker]

Jeffrey, not to high jack your discussion, but have you checked the refractometer you have to some calibration fluid?

I don't think I would trust the probe and would check salinity weekly with a calibrated refractometer.

Not at all, good question

Yes. The refractometer really never could be calibrated to where I could trust it.

Edit: hinch going digital. I need the New saltwater to match the system and it look like I can not relay on the conductivity probe that worked so well for the past 2 years. I dumped 600 grams of salt into the system this afternoon and the conductivity has not changed.

 

[Greenstreet.1]

Maybe just time for a new probe bud.

 

[Flippers4pups]

Not at all, good question

Yes. The refractometer really never could be calibrated to where I could trust it.

Edit: hinch going digital. I need the New saltwater to match the system and it look like I can not relay on the conductivity probe that worked so well for the past 2 years. I dumped 600 grams of salt into the system this afternoon and the conductivity has not changed.

I agree with a new probe. I'm just old school. Not knocking anything digital, but a good quality refractometer isn't a bad thing to have as a back up.

 

[Greenstreet.1]

I got that vital sine refractometer some years back when Randy recommended it must say it’s always on point also have one from brs must calibrate this one before use.

 

[jsker]

I got that vital sine refractometer some years back when Randy recommended it must say it’s always on point also have one from brs must calibrate this one before use.

That is a nice one also.

 

[Sarah24!]

Hello,

Call me crazy lol but I use a refactrometer also, but no apex or anything digital. I double check my water by using my hydrometer as well. If they are ever different, then I take a water sample to my lfs, and find out what it is. If it’s my refractometer, then I adjust it to the correct salinity. If it’s the hydro, I usually throw it away and buy a new one, and test it as well. I do this to make sure they are both within spec of each other.

Sincerely
Sarah

 

[Tony Thompson]

Hi @jsker , with regards your original question with reference to your title Effects of low salinity on corals?

Very interesting topic. One which triggered my own inquisitive nature. I had a browse through some research papers on the subject. The information I have read would suggest that low salinity (Hypo Osmosis) can indeed have a negative effect on corals and in some cases induce a bleaching effect. The data would suggest that, it is the symbiont relationship that is most affected. The observations appeared to show that the efficiency of the symbiants ability to photosynthesise and provide nutrition to its host is reduced by a significant factor.

However at least one paper, contrary to previous conclusions, suggest that the effects can be classed as sub lethal. (Experiments carried out in closed systems, salinity levels varied between 37ppt control and 33.5ppt - 15ppt to monitor response)

With regards my comments, I must include two significant caveats.

1. I am by no means academically qualified. Therefore my comprehension and any conclusions are based solely as a hobbyist.

2. My experience of comparing observations and conclusions from Oceanographers / Marine Biologists and Aquarists / Hobbyists would appear to show a number of conflicting views. For instance in the wild corals can be found to thrive in a wide range of temps and salinities. These can include tidal pools, lagoons and areas susceptible to wide variations in environmental conditions. Where as aquarists we would generally experience very high mortality if we maintained our aquaria under such extreme conditions.

I would therefore strongly suggest that anyone seriously interested in the topic should carefully read through the data before making any definite conclusions. For that reason I have included a link to the paper In question. If you have any academic association then the full paper should be available through your logon. For those without access, the full abstract should still be available to read.

https://www.researchgate.net/public...a_Nature_and_cause_of_'low-salinity_bleaching'

Note to admin please advise if posting links of this nature is not allowed. Thanks.

 

[Randy Holmes-Farley]

Hi @jsker , with regards your original question with reference to your title Effects of low salinity on corals?

Very interesting topic. One which triggered my own inquisitive nature. I had a browse through some research papers on the subject. The information I have read would suggest that low salinity (Hypo Osmosis) can indeed have a negative effect on corals and in some cases induce a bleaching effect. The data would suggest that, it is the symbiont relationship that is most affected. The observations appeared to show that the efficiency of the symbiants ability to photosynthesise and provide nutrition to its host is reduced by a significant factor.

However at least one paper, contrary to previous conclusions, suggest that the effects can be classed as sub lethal. (Experiments carried out in closed systems, salinity levels varied between 37ppt control and 33.5ppt - 15ppt to monitor response)

With regards my comments, I must include two significant caveats.

1. I am by no means academically qualified. Therefore my comprehension and any conclusions are based solely as a hobbyist.

2. My experience of comparing observations and conclusions from Oceanographers / Marine Biologists and Aquarists / Hobbyists would appear to show a number of conflicting views. For instance in the wild corals can be found to thrive in a wide range of temps and salinities. These can include tidal pools, lagoons and areas susceptible to wide variations in environmental conditions. Where as aquarists we would generally experience very high mortality if we maintained our aquaria under such extreme conditions.

I would therefore strongly suggest that anyone seriously interested in the topic should carefully read through the data before making any definite conclusions. For that reason I have included a link to the paper In question. If you have any academic association then the full paper should be available through your logon. For those without access, the full abstract should still be available to read.

https://www.researchgate.net/public...a_Nature_and_cause_of_'low-salinity_bleaching'

Note to admin please advise if posting links of this nature is not allowed. Thanks.

I would add two comments to that discussion of this paper:

1. They didn't do anything to slowly acclimate the corals to different salinities (or if they did, I missed it).

2. They lowered salinity by seawater dilution, so everything dropped similarly, and nothing was maintained at natural levels (calcum, alk, potassium, etc. ).

Doing 1 or 2 differently might have led to different results.

 

[jsker]

Hello,

Call me crazy lol but I use a refactrometer also, but no apex or anything digital. I double check my water by using my hydrometer as well. If they are ever different, then I take a water sample to my lfs, and find out what it is. If it’s my refractometer, then I adjust it to the correct salinity. If it’s the hydro, I usually throw it away and buy a new one, and test it as well. I do this to make sure they are both within spec of each other.

Sincerely
Sarah

Kind of why I ordered the digital refractometer is to check and see if I can really calibrate my refractometer. If I can not calibrate my refractometer the I will toss it and purchase a refractometer that was suggested and have both.