It is a non-cuantitative study about diversity at genera taxonomic level of planktonic green algae and cyanobacteria in two continental water bodies of 6084 and 4540 m2. I interested in know about of sampling design: techniques for site selection in the water bodies, number of sites and sample volumen.
Thanks.
Best regards,
Gustavo.
Dear Gustavo,
I don't know any specifics for ocean sampling, but at least I can add that you should be aware that the richness is a nonlinear function of sampling size. It s called a species-area curve (https://en.wikipedia.org/wiki/Species-area_curve), but could also be seen as taxon x sample size (area, volume or another unit). So in principle, you should sample until you reach an approximate asymptote (the number of genera does not change with addition of a few more samples). There are simple relations that could be used for a uniform distribution of sampling points in three dimensional space and time to account for those sources of variability, but perhaps someone more experienced with this kind of sampling can provide a better guide.
Dear, Mr. Castagna.
Thanks for the answer. Maybe I did not explain properly, the sampling design is for two freshwater bodies.
Really thanks again for the orientation.
Regards.
Thanks for the answer, Dear Mr. Kürten. Respect to different depths I think that can be composited samples with superficial, 50% radiation depth and non-photic/photic limit. Studies about trophic status and algae diversity aren´t avaliable, in this order of ideas I think in a sampling design with number of sample in function of area of lakes can be a good option (but I don´t have experience in this topic, for that is possible I can going wrong)
I interested in determine the number and localization of sample site.
Regards!
Independently of the sampling strategy you choose for water collection (surface vs composite samples), you can reach the 'plateau' of the species-area curve by either increasing the number of phytoplankton slides that you will identify/enumerate with your microscope or by concentrating your algal sample using a filtration technique + resuspension of the residue in order to catch the rarest species.
However, the volume of water to be filtered has to be determined and you may have to try several times or keep adding water while filtering until the filter turns green...not too much green because you may collect too much algal biomass and it will be very difficult to count cells.
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