Why is plankton so important to have in your aquarium?
Plankton: It is not a species or type of plant or animal. Plankton is the term used to describe all free floating organisms in open water both marine and freshwater. Although we may usually think of plankton as being a microscopic species, many can be seen by the naked eye (such as some copepods) or can even be quite large organisms (like some species of jellyfish). Plankton float with the ocean’s current and will even fall to the extreme depths of the ocean, (the benthic zone) in the form of “marine or reef snow” a zombie variety is available in a bottle sold at your LFS.
The water found at corals reefs, and in your home aquarium, should always have a healthy population of plankton. Plankton is important for a variety of reasons. To begin, it makes a terrific natural food source. Fish rely on plankton as a major food source as some point in their life cycle, most significantly in their larval stage. Additionally, many corals will capture zooplankton and bacterioplankton as food, despite their reliance on zooxanthellae (dinoflagellate algae) for nutrition via photosynthesis. In addition to their position as a food source, many forms of plankton contribute greatly to the breakdown of organic matter in the system. Many, such as amphipods, are scavengers, and will feed on the detritus and waste material (or alternatively, become the detritus after death) found in your small, closed system of a home aquarium. In this way, they contribute to the carbon cycle of the marine aquarium.
There are a variety of methods to both encourage and discourage the growth of plankton in your aquarium. The use of skimmers and filters will commonly remove free floating organic matter from the aquarium. This will remove plankton directly or remove their source of food. Most corals, clams, oysters, mussels, tube worms, larval fish, anemone’s, to name a few will thrive in your aquarium in the absence of a skimmer specifically because they will feed on the plankton that would normally be removed in the traditional filtration process.
The increased use of sumps as refugiums actually encourages the growth of plankton in your home system. Zooplankton and phytoplankton can live in the refugium without being over harvested by the fish, corals, and other invertebrates found in the display tank. On a regular basis, some of that plankton will be washed through the display tank and contribute food. As waste and detritus is washed into the sumps, the plankton will feed on it, breaking down the organic matter. Many aquarists intentionally add macroalgae to the sump to aid in sheltering the zooplankton.
Plankton in your aquarium will provide food for all of your filter feeders, the Australian freshwater mussels which there are 50+ varieties, marine mussels, clams, cockles, scallop, rock oysters, pipis, corals, tube worms, many anemone’s any larval fish, zooplankton etc.