It's Still in the Water!
- Thread starter cfockler
- Start date
When you gather some experience in the practical applications of this, we can discuss it further.
:lolspin:
Since I have extensive practical experience in binding metals with organic molecules (and you do not), you'd think the same would have applied to that discussion. Somehow you were able to comment on metal binding organics without any published practical experience, so why would you think Habib less able to participate in scientific discussions without having published sediment toxicity tests himself?
FWIW, all he did was point out a paper to you. If you've already read it, that's great. If you think it's nonsense, that's fine too, but it would be nice if you based your comments on the science of the paper in question and not the background of the person that pointed it out to you. That's what being an expert involves: people often, and hopefully frequently, point out things that you already know. It's not a reason to criticize them.
So, with your extensive background in sediment toxiciology, do you disagree with these conclusions in the abstract?
"while TIEs performed on interstitial waters from marine sediments have identified only ammonia and organics as toxicants, with metals playing a minor role. Preliminary evidence from whole sediment TIEs indicates that organic compounds play a major role in the toxicity of marine sediments, with almost no evidence for either metal or ammonia toxicity. "
:lolspin:
Since I have extensive practical experience in binding metals with organic molecules (and you do not), you'd think the same would have applied to that discussion. Somehow you were able to comment on metal binding organics without any published practical experience, so why would you think Habib less able to participate in scientific discussions without having published sediment toxicity tests himself?
FWIW, all he did was point out a paper to you. If you've already read it, that's great. If you think it's nonsense, that's fine too, but it would be nice if you based your comments on the science of the paper in question and not the background of the person that pointed it out to you. That's what being an expert involves: people often, and hopefully frequently, point out things that you already know. It's not a reason to criticize them.
So, with your extensive background in sediment toxiciology, do you disagree with these conclusions in the abstract?
"while TIEs performed on interstitial waters from marine sediments have identified only ammonia and organics as toxicants, with metals playing a minor role. Preliminary evidence from whole sediment TIEs indicates that organic compounds play a major role in the toxicity of marine sediments, with almost no evidence for either metal or ammonia toxicity. "
Something happened with your title, though...it seems to have some text missing. ;-)
Boy, I got sucked in with that one. I guess I'll have to be a little more skeptical of things you guys post.
Good one!
Boy, I got sucked in with that one. I guess I'll have to be a little more skeptical of things you guys post.
Good one!
Ron,
much of it has been the basis of TIE development in the areas considered.
So others did or try to do TIE's but not you?
If the tests show that levels of a certain metal kill animals, and if the tests show that the levels are above those levels, and animals do die then it is reasonable to suggest that the metal is responsible.
Is this a TIE?
When you gather some experience in the practical applications of this, we can discuss it further.
You mean reading and writing?
much of it has been the basis of TIE development in the areas considered.
So others did or try to do TIE's but not you?
If the tests show that levels of a certain metal kill animals, and if the tests show that the levels are above those levels, and animals do die then it is reasonable to suggest that the metal is responsible.
Is this a TIE?
When you gather some experience in the practical applications of this, we can discuss it further.
You mean reading and writing?
FWIW, Ron has initiated a new discussion of iron in my forum:
http://www.reefcentral.com/vbulletin/showthread.php?threadid=110366
Enjoy!
http://www.reefcentral.com/vbulletin/showthread.php?threadid=110366
Enjoy!
Also worth considering is the heavy metal speciation and pollution in Cleveland Bay (Australia) , the nearby coral reefs (a.o. magnetic island) and the advice not to dredge only around mass spawning periods.
In almost no cases that I know of are dredging restrictions based solely on the relevent scientific findings. Most of the time, in fact, the science takes a back seat to politics/economics. As an example, dredging may have to be done during certain periods due to tidal cycles (In the Puget Sound region of Washington, USA; it is most frequently done around the equinoxes as the tidal currents are far less). Dredge spoils may be stored for some periods, but generally are dumped soon after dredging occurs. This will happen whether or not it is advantageous for the adjacent fauna. I tried - several times - to regulate dredging times, but was only successful once or twice. Nobody argued with us that the dredging would damage the adjacent fauna, but that was simply considered "a cost" of the project.
So others did or try to do TIE's but not you?
TIEs were being developed during the 1990's when I did most of the work indicated, and presently have only begun to be investigated, and mostly on the eastern seaboard of the US, not on the west coast where I work. We did do pore water toxicity testing (which amounts to much the same thing - but it was not as standardized as the present TIEs), but it is/was difficult to do. In some sediments, it is effectively impossible to extract, particularly since it may have be to be done undewater by divers.
If the tests show that levels of a certain metal kill animals, and if the tests show that the levels are above those levels, and animals do die then it is reasonable to suggest that the metal is responsible.
Is this a TIE?
Yes, in part. There are several different types of tests, some involve direct toxicity to selected animals, others involve bacteriological testing.
Also, the TIEs have not been in use long enough or in enough cases to draw many conclusions from them. In most of the areas where they have been developed and used, the metals concentrations are relatively low compared to the organics, for example. In a lot of the areas where I worked, the situation was reversed.
We typically found free metal concentrations in oxygenated pore water to be low - probably due to organic complexing, or to binding with iron. These waters were toxic, but not as much as was expected. We attributed the toxicity to the organo-metal complexes, rather than the metals themselves. Directly above the sediments, the metals concentrations in the water were far lower, and the toxicities were correspondingly lower. The animal density in the upper (1-3 cm) layers of these sediments was often really quite high, but the animals present were largely those that could ventilate their burrows with the overlying waters.
As one went deeper into the sediments (4-6 cm), and the sediments became anaerobic, the metals concentrations in the waters rose dramatically, and the pore water became extremely toxic. However, as few organisms could tolerate this metallic tea, there was little water movement in these sediments and the metals were contained. If the sediments were disturbed, signficant, but transient mortalities were seen (sediment faunal kills, mass mortality of epifaunal animals).
I think you can see where I am going with this.
I think a comparable situation exists in our tanks, particularly after several years. The sediments build up a signficant load of chemicals that - if they become soluble - will be very toxic. Disturbances of the sediment will release toxins. Additionally, the salt water, as mixed, has higher concentations of copper and some other metals than we found in smelter slag. If the aquaria have highly "polished" water with low organic levels, this water will kill some organisms. If the water has the organics to bind the metals, these may form particulates which are eaten and in the acid phases of digestion they may become toxic. Additionally, the metals or metal/organic complexes in the water are very likely toxic to many animals. A lot of the mortality in aquaria attributed to incorrect acclimation is, I think due to incorrect acclimation alright, but to acclimation not to salinity or temperature but rather to heavy metals.
Earlier in this thread, Ron belittled the idea that marine organisms may release compounds to detoxify the marine environment. At the time, I could only supply data where it happens in freshwater systems. Here's a paper that suggests that it may happen in the ocean as well.
Check out this free online article:
http://neon.otago.ac.nz/chemistry/research/mfc/PUBS/REVIEWS/TEG97Review.pdf
It is titled "Has Trace Metal Marine Biogeochemistry Come of Age?"
I'd prefer people to read the article and not just my selection, but here's a section of special interest. In the section on copper speciation and toxicity, we find the following:
"The production of a strong Cu-binding ligand by cyanobacteria in the ocean may represent the result of selective evolutionary pressure to detoxify the environment by lowering the Ca++ activity."
Hence, the suggestion hat I made earlier that such might be happening in our tanks does not, apparently, seem far fetched to the scientific community.
Check out this free online article:
http://neon.otago.ac.nz/chemistry/research/mfc/PUBS/REVIEWS/TEG97Review.pdf
It is titled "Has Trace Metal Marine Biogeochemistry Come of Age?"
I'd prefer people to read the article and not just my selection, but here's a section of special interest. In the section on copper speciation and toxicity, we find the following:
"The production of a strong Cu-binding ligand by cyanobacteria in the ocean may represent the result of selective evolutionary pressure to detoxify the environment by lowering the Ca++ activity."
Hence, the suggestion hat I made earlier that such might be happening in our tanks does not, apparently, seem far fetched to the scientific community.
theearthling
Premium Member
Randy, Ron - you guys really need to get together and have a beer.
(invite me
)
-Simon
(invite me
)-Simon
