A National Ocean Service/National Center for Coastal Ocean Science Program
Phytoplankton Monitoring Network
Promoting a better understanding of harmful algal blooms by way of volunteer monitoring
Frequently Asked Questions
Sampling
- How is a phytoplankton sample taken?
- How often will samples need to be taken/identified and results sent to PMN?
- Where are samples collected?
- How are samples preserved for future use?
- How is Lugol's solution made?
- What is the time frame for identifying a sample?
- How many sites can a volunteer monitor?
- Does each individual phytoplankter need to be counted?
How is a phytoplankton sample taken?
Volunteers use a plankton net with a 3 point bridle, 20 micron mesh size with a 40 cm length and 15 cm ring diameter. Most volunteers sample off a floating dock or edge of a pond therefore the nets will be dipped into the water (horizontal plankton tow) instead of performing an actual tow behind a boat.
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How often will samples need to be taken/identified and results sent to PMN?
Volunteers are asked to make a weekly or biweekly commitment. Consistent sampling is key to strengthening the knowledge of the phytoplankton community.
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Where are samples collected?
Volunteers have the ability to choose a sampling site. There are two criteria: 1) no other PMN volunteer is sampling at or near the site and 2) the salinity of the site is greater than 15 ppt. The salinity of site can be tested with a refractometer. Feel free to contact PMN staff if the salinity of a sampling site is in question. The site should be convenient for ease of weekly sampling.
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How are samples preserved for future use?
Add about 0.5 mL of Lugol's solution to a 25 mL sample for preservation. You may have to occasionally add additional Lugol's solution over time to maintain the stain on your phytoplankton. The goal is to stain your sample with Lugol's solution so that it is tea-colored.
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How is Lugol's solution made?
Dissolve in 225mL of distilled water 25g KI (potassium iodide), then 0.5g I2 (iodine), and finally add 25mL glacial acetic acid. Store solution in a glass bottle, preferably in darkness at low temperature.
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What is the time frame for identifying a sample?
It is best to identify the sample on the same day it is collected. However, samples will last approximately 3 days. After the third day, phytoplankton will be visible but movement, a distinguishing characteristic, will have ceased. To keep samples healthy as long as possible, keep them at room temperature with the lid placed loosely on top. Do not twist the lid into place. By placing the lid loosely on top, oxygen can still enter the bottle.
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How many sites can a volunteer monitor?
It is recommended that beginners take on no more than 2 sampling sites at the start. As volunteers become more comfortable with phytoplankton identification, additional sites are welcomed.
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Does each individual phytoplankter need to be counted?
No. Volunteers will be trained to estimate the approximate abundance of each species using an abundance ratio chart. If levels of any species become so great that a bloom is recorded, the PMN will need to be contacted immediately in order to send a scientist to collect a sample. A cell count will be conducted at the NOAA laboratory.
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