Fall Plankton Cycles     In recent weeks, has your pond lost its appealing green color?  Have you noticed water clearing and increased visibility?  No concern.  It’s a fall decline in plankton growth.

Plankton is active in water temperatures above 60-65 degrees.  Like other pond life, it begins winter slumber below that range.  Since plankton is active in upper zones of the water column, as the density of growth diminishes, water clears.

Plankton is a microscopic organism that plays a valuable role in successful pond management.  It provides critical food to newly hatched fish.  Fry are spawned with a small yoke sack to nourish them through first days.  Once the yoke is absorbed, plankton becomes their primary food chain. If plankton is not present, fry survival rates decline significantly. By maintaining healthy plankton levels, you can double and even triple fishery productivity. In depths over three-feet, plankton also inhibits sunlight from reaching the bottom and promoting vegetation growth.

Plankton is grown by nutrients in the water.  Nutrients may enter with runoff from adjacent agriculture fields.  Other sources are intensely landscaped lawns or waste from fed fish.  If nutrients aren’t present, pond managers apply fertilizers with high phosphorus ratings like 12-61-0. If your pond doesn’t develop plankton naturally, it may not have adequate alkalinity levels plankton requires to thrive. Conduct a standard water analysis.  If alkalinity is low, we can add lime to restore normal readings.  Spring fed ponds may experience continual spillway discharge that limits plankton development.

Measure plankton regularly with a white disk mounted on the end of a wooden dowel or attached to a string.  The disk should disappear from sight at 18-24 inches.  Record readings.  If you observe fluctuations above or below this range, call us.  Lower readings may be a sign of deteriorating water quality.  Higher visibility may signal the need for adding slightly more fertilizer.  Either condition should be evaluated by a professional and corrected promptly.

It seems we just stocked tilapia, threadfin shad, crawfish, and other spring start-up projects.  Then we noticed this newsletter has tips on winterizing ponds and facilities.  What a year!  We’re field-testing a boatload of new products and procedures.  Staff is analyzing your program and preparing recommendations on how this improved science can take your management program to the next level in 2018.