Pond Boss Forums INTRO Questions & Observations Zooplankton Calculations

I keep reading about the importance of zooplankton and fish growth. And have no idea where my ponds stand in terms of these creatures. Is it possible to caculate the amount of zooplankton in a body of water at least for a particular moment in time? If so, how? Is there a number that would indicate "rich or poor" in zooplankton?

Bill Cody is the man you want. He does this for a living. He should be along shortly.

Personally I am not concerned with zooplankton levels, except in my production ponds, where my fry need them -- after they use up their yolk sacs -- before taking artificial feed.

See this thread

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=268052&page=1

Most of the pictures in the link are phytoplankton. A couple rotifers are present Keratella and Polyarthra, both smaller sized individuals belonging to genera of normal zooplankton communities. What mnfish is referring to is a quantitative analysis that determines the biomass or volume of animals in a specific volume of water. Keep in mind that zooplankton really includes all sizes of invertebrate animals in the water column - protozoa, rotifers, and crustaceans. Most often quanitative detailed estimates are not done for normal situations due to the amount of effort envolved, but it can be done and is done where quantitative estimates are needed.

Normally what is often done, easiest, and simplest but not real accurate is measure the water clarity with a secchi disk as shown in the link above. This measurement assumes the cloudiness in the water is due mostly to phyto and zooplankton which is not always correct, often yes; always no. Generally the more phytoplankton in the water, the more zooplankton that will be present to graze on the phytoplankton. As phytoplankton increase zooplankton increase, as phyto decreases so goes the zooplankton. Thus if one has abundant or common phytoplankton one can assume the zooplankton will also be relatively abundant. Obviously if suspended silt or clay is causing a low secchi disk reading, the wrong assumption can be made. Green hue to the water generally indicates phytoplankton. Grey, brown, and soil colored water usually indicates silt and/or clay.

There are various methods to specifically sample for zooplankton. Methods vary depending on which component of zooplankton one is interested in - protozoa, rotifers, and/or crustacea. Each requires a slightly different method due to the different general size category of each group.

Generally plankton density is on a continuum scale of very low to very high and all densities in between based on nutrient concentrations. Plankton is dynanmic always changing waxing and waning in density and species composition.

Thank you very much for the information Bill. My water is very clear and stained to a dark brown/black color. I'm guessing, due in large part from the iron in the soil. (I have taken a 5 gallon bucket of water and added bleach to percipitate the iron out) My pond is only 6.5' in the deepest hole and have never dropped a disk down. I can see down 24", as observed while swiming, into the pond and without the staining I would bet I could see much further. This clarity remains for the entire season.

So, with clear water am I to assume zooplankton have little to feed on and thus don't exist in large quantities?

I have made some observations over the past few winters and wonder if they tie in here. In the winter, when I drop down my underwater camera and turn on the IR light, I notice these little "white dots". They look like they are bouncing in the water. As the winter goes on, these bouncing balls become very concentrated. So much so, that when a fish swims by the camera a swirling cloud occurs. I know this is a type of life because of the pulsing movement. Could this be a type of zooplankton?

And for the record, I made these observations before the Coor's Lite came out and I wasn't delirious from hypothermia!

All ponds have zooplankton in different amounts based on fertility. The 'white dots' are very likely a collection or grouping of zooplankton since they are attracted to light in the darkness. Zooplankton groupings attract fish. Thus the rationale of the 'crappie light'.
The brown color of your water may not be dissolved iron but it could be due to tannin stain in the water. The bleach may change the color of the water. Did the water sample have a rusty precipitate from the iron after it was 'bleached'? Often high iron content in the water will form a reddish precipitate (yellow dog) after the water is exposed to air/oxygen and the pH is increased. If there was no precipitate the brown color was likely tannin (plant stains) in the water.

http://windowoutdoors.com/WindowOutdoors/Iron%20in%20Springs%20and%20Seeps.html

http://en.wikipedia.org/wiki/Acid_mine_drainage

The water percipitated out the same colors as in those linked pic's. But I bet your right about the stained water. My ponds were dug thru varing thickness of peat (1' to 5' deep). High organic matter for such. This water gives my YP an almost black gold coloration instead of the yellow green. I will catch some and take pic's to post. Hopefully the camera will capture the colors. Thanks again for sharing your hard earned knowledge.