We are working near of the headwater where the dominant substrate is limestone, and we are studying the biological responses of macroinvertebrates community and also, the biochemical response of a sentinel species. Despite the water quality is good, biochemical response of sentinel species is bad. Water quality analysis show that alkalinity, hardness and sulphates have high concentrations.
Hi,
it depends on what do you mean by high concentrations? Do you have data?
Sulphates in freshwater can be toxic for microinvertebrates (daphnia) since 1 g/L in long-term exposure. But it is well known that water hardness protect organisms from sulphates toxicity. For more information, see Soucek' studies on the effect of hardness on sulphate toxicity using daphnia and Hyalella.
Good luck!
Hi Karine, thank you for the hint to Soucek, important point when evaluating rivers with naturally elevated SO4. We have a few such rivers because they pass through gypsum formations.
Jacinto, this paper may also help: Elphick, James R., Martin Davies, Guy Gilron, Edmund C. Canaria, Bonnie Lo, and Howard C. Bailey. 2011. “An Aquatic Toxicological Evaluation of Sulfate: The Case for Considering Hardness as a Modifying Factor in Setting Water Quality Guidelines.” Environmental Toxicology and Chemistry 30 (1): 247–53. doi:10.1002/etc.363. (it is on RG)
What are your sentinel species? Response of species within an assemblage or community varies therefore sentinel species is such a broad term. You can run an indirect analysis (ordinations for instance) to isolate species correlating with high concentration of alkalinity, hardness and sulphates and then look for literature corresponding to level of which these species respond to a given concentration. This way even though you are taking a holistic approach but at the same time you isolate the cases in which response can be detected.
Great number of studies are done on Headwater Chalk streams (dating back to 70s) in England that are worth exploring.
Gerald, the paper of Elphick et al., (2011) has been a great help for us.
Thank you very much.
Dear Jacinto,
Sometimes the problem of the limestone substrate is the high concentrations of organic material, methane, and sulfuric. Also there are affections for the filters because of the particles.
I hope you have more clear idea after our contributions!
Good luck!
Doug Glazier wrote a paper on this several years back. Limestone springs in Pennsylvania.
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