One common method for collecting a plankton sample is to tow the net horizontally using a low-speed boat. Before collecting the plankton, the net should be rinsed with the sample water. The user should ensure that the cod end is completely closed by turning the valve into a vertical position. Then the plankton net is then lowered horizontal to the water surface at the side of the slowly moving boat. Sampling is done for 1.5 minutes. After this time, the plankton sample is collected in a sample bottle by opening the cod end above it by turning the valve horizontally.
When the sample is collected it can be analysed using a microscope to identify the type of zooplankton or phytoplankton, or a cell count can be undertaken to determine the plankton cell density of the water source.
The second recorded use of a plankton net was by Charles Darwin on 10 January 1832, during the Beagle survey voyage. His diary included a sketch of the net, which appears to have been based on a trawl net described by John Coldstream in a letter to Darwin. It is possible that Thompson's idea had earlier been drawn to Darwin's attention by Robert Edmond Grant in Edinburgh. Darwin describes this "contrivance" as "a bag four feet deep, made of bunting, & attached to [a] semicircular bow this by lines is kept upright, & dragged behind the vessel".
The next day he remarked that "The number of animals that the net collects is very great & fully explains the manner so many animals of a large size live so far from land. — Many of these creatures so low in the scale of nature are most exquisite in their forms & rich colours. — It creates a feeling of wonder that so much beauty should be apparently created for such little purpose.
Sample collection is fairly simple, just trawl the net behind the yacht for a period of about 60 minutes, or for as long as it takes to collect at least 10ml of plankton. The yacht will need to be trravelling at under 2 knots during the trawl. Once the sample has been taken, remove the net from the water, allow the net to drain, and for the sample of the plankton to collect in the end cap. Once the net has drained, carefully decant the concents to the sample vial. Avoid touching the sample as this could transfer contamination from your hands. The wooden spatula provided with the kit may be used to help transfer the contents to the sample vial. Try to minimise the amount of water collected. Seal the tube firmly, the sample may now be stored for many weeks, however best to keep out of direct sunlight and if possible store in a cool dark place such as a fridge. The samples will not degrade becuase we are measuring metals, however way may conduct additional tests such as PCBs and PBDE on good samples.
Label the sample with the following information
The concentration of transition metals and heavy metals are much higher in the oceans that can be explained by the emissions from hydro-thermal vents, or air blown innoculation. Plastic also breaks down to nano-paticles and will sequester heavy metals as other priority chemicals. Below 20nm in size the particles can pass through cell walls, copepods and zooplankton then eat the algae and the toxins end up in the zooplankton. Very few research vessels have measured the pollutants, this is what makes it so important for plankton sampling and citizen science that is possible onboard yachts.
The sample containers are unfortunately in plastic, we tried to obtain glass vials with cork top, but they could not be certified meal free.
This sample vials comply with the following methods metal analysis.
|EPA 200.2||EPA 200.5||EPA 200.7|
|EPA 200.8||EPA 200.9||EPA 245.1|
|EPA 245.7||SM 3030||SM 3112|
|SM 3120||SM 3125||ISO 15202-2:2012|
|ISO 15587-1:2002||ISO 15587-2:2002||EPA 3050B|
Analysis is by ICP Atomic Emission Spectroscope, paper covering analytical principles . click here