Growing Native Marine Phytoplankton
The following is written by Glen Hemerick of Olalla, WA (Puget Sound, WA - USA) - Thank You!
- Collection site: Select a marine site having minimum exposure to ships, boats, residences, or industry. Collecting from a floating dock is convenient. On the beach there may be small tide pools with tiny fish, which eat edible zooplankton that eat edible phytoplankton.
- Materials: Phytoplankton can be collected using any kind of fabric bag, from window screen size mesh to fine fabric that holds water. I use the latter. Natural fiber fabrics are preferred, but a plankton net of synthetic fiber can be used if exposure is brief , and if the synthetic fiber is old, mended, and leached relatively free from plasticizer (phthallate).
- Containers: Containers should be non-plastic, non-metal, and chemically inert, such as glass, ceramic, glazed metal, enamelware, porcelain or porcelainized metal. Glass should be food-grade and used(not new).. Avoid laboratory glass, both used and new.
- Procedure: I add one gram or one-fourth teaspoon of any soluble garden fertilizer (which contains about 12 essential elements, except sulfur, magnesium and calcium)per gallon seawater. Those 3 elements are not added because there is plenty in seawater. I add half of the invisible plankton to the medium, usually in a 5-gallon glass bottle, but also in one-gallon jugs and jars. I aerate with aquarium air pumps, through old plastic tubing, ending at a glass tube (or pipette) in the water, bubbling. I illuminate at a window or with bulbs or fluorescent tubes. In mild weather I put the culture vessels inside an aquarium of fresh water for temperature measurement and control. In cold or stormy weather, I avoid aquaria because they may freeze. Today, I set up a 5-gallon bottle of phytoplankton culture inside a small, unheated greenhouse. The bottle is in a small wading pool of fresh water. The greenhouse also contains drums of water to store solar heat, and to prevent freezing.
- Viewing: The other half of collected plankton is carried in a jar inside an ice chest to a microscope, where they are videotaped. The videotape is reviewed, for counting and identification of plankton, and for still photos. The sample may contain copepods and tiny green edible phytoplankton.
- Harvest: I harvest phytoplankton by placing their growth vessel inside a refrigerator over night. Most of them settle. (In two nights nearly all settle to the bottom.) I use the same aeration tube to siphon off the medium into another growth vessel, leaving a green concentrate on the bottom of the first vessel. A syringe can be used to start the siphon. The clear medium usually contains a few cells, enough to start another batch, in the used medium. The phytoplankton concentrate is added to newly collected zooplankton in a jar, whose mouth is covered with fabric. The jar is tethered to the dock and the jar is submerged in deep seawater, to test food quality.
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