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Clove Oil: An Anesthetic to Knock Out Zooplankton?

Everyone has been frustrated by having a particular specimen swim out of the field of view or by having another specimen knock the one of interest. Often simple chilling of samples will slow zooplankton sufficiently to allow a good look. If this fails, a variety of anesthetics are variously effective on specific taxa. Unfortunately, many are expensive, difficult to find, or have significant safety concerns. A recent discussion on the crustacean list serve noted a variety of possible anesthetics. It appears that clove oil (toothache drops) is becoming increasingly popular as an anesthetic for both fishes and crustaceans. We have NOT tested it yet with a mixed zooplankton sample to see how different taxa respond. Hopefully, a number of you will try this method and then share your impressions with us to include on this web site.

Recommended doses for larger animals (fish and large decapods) range from 30-125 ppm. Addition of a little ethanol seems to aid mixing. If ethanol is not available, try isopropyl “rubbing alcohol”.

OR- for a rapid method-

Try adding 5 ml of ethanol per liter of seawater and then 5 drops of clove oil.

Clove oil or clove oil found in “toothache drops” may be available at local or on-line pharmacies and is relatively inexpensive. The amount used may need to be increased depending on the concentration of clove oil found as an active ingredient in the medication. Also, eugenol, the active ingredient in clove oil (80-90%), may be purchased from chemical suppliers

SAFETY NOTE. May cause skin irritation or irritate eyes. Use standard lab safety precautions.

Submitted by: Bill Johnson, Goucher College, Towson, MD. June 2, 2005

Mighty Fine Dissecting Needles—Make ‘em yourself

When standard dissecting needles and even fine forcepts are often too big, ”Minutien” pins mounted on balsa wood handles provide an inexpensive way to make finer needles for manipulating zooplankton.

Materials:

Minutien pins. Small stainless steel Minutien Pins are used by entomologists for mounting fine specimens and are available from Carolina Biological Balsa Sticks: Available in local hobby shops that carry supplies for model airplane construction. Carolina

Assembly:

Use pliers to push the blunt end of the pins into 4-6” lengths of 1/8” square balsa wood sticks. Gluing is optional.