An excerpt from a movie poster? Could be, but no. I am talking about the multitude of micro-organisms (plant and animal) that call your pond home. I briefly discussed those that live on the bottom or Benthic layer in a previous post. In this post I want to explore those that live in the water column. They are commonly referred to as Plankton.
Plankton is divided into two (2) groups-
-Phytoplankton which is microscopic plants (algae) and some species of bacteria. These are the primary producers in the aquatic food chain.
-Zooplankton consists predominately of crustaceans and rotifers. They are usually larger than phytoplankton. They are predators and feed on phytoplankton and other zooplankton.
As an example of the sheer magnitude of their numbers, in a fish culture pond it is not unusual for plankton (dry weight) to account for up to 50% of the total biomass (dry weight) of the pond (this includes the fish). That is a lot of little critters! But very important little critters! They comprise the bulk of any aquatic food chain and web. A pond’s biological balance would collapse without their existence in such great numbers
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Your Koi and/or Goldfish may be the Stars in your perception but, in biological terms, they are only bit players. They, because they are the top consumer in the food chain, are dispensable as far as maintaining biological balance. The lower an organism exists in the food chain, the more indispensable they become. This truly makes the existence of algae, for instance, more important than the fish. This is not to say that you can’t have too much algae. An overgrowth of algae can be problematic for the balance in a pond as can too many fish.
The USDA recently did away with the Food Pyramid in favor of a dinner plate diagram as a nutritional guide. I prefer the pyramid for it emphasizes the real importance of the food groups. Those most important and also in greatest numbers are at the bottom or base of the pyramid. The same applies to the food chain in a pond. Those organisms of greatest number and importance are at the bottom. Phyto-plankton.are part of this pyramid base.. Zooplankton are just one level higher in the pyramid.
All plankton serve as nutritional sources for organisms higher in the food chain. Insects, amphibians, annelids and some fish specie look to plankton as a food source.
Just observe all of the activity around your pond. It can be quite a pageant. A pageant that requires........... ‘a cast of thousands’.
