Sailors for Citizen Science

Secchi Disk project Richard Kirby Secchi Disk project Richard Kirby

by Richard Kirby on 22 Apr 2013We launched the project on the 21st February and the idea came from a study by a team of Canadian marine biologists who reported that the phytoplankton in the oceans had declined by 40% since the 1950s due to climate change. The phytoplankton are microscopic plant-like cells that float at the surface of the sea from where they underpin the whole marine food chain. Knowing the amount of phytoplankton in the sea, and whether it is changing, is very important therefore, since their abundance determines the number of creatures at every step above them in the marine food web; this includes the amount of fish in the sea to the numbers of sharks, whales, penguins, and polar bears. The Canadian scientist's study provoked debate among many marine biologists however, as some thought they saw different results. Part of the controversy arises from the fact that the oceans are a vast place and there aren't enough marine biologists to study them, and so this is where you, by becoming a Citizen Scientist, can help.



In order to take part in the project we hope that sailors will make a simple piece of DIY scientific equipment called a Secchi Disk and download the free Secchi app to their smartphone or tablet - they will need a smartphone or tablet that can receive a GPS signal. You can follow the data you collect, along with that of others, on the project website.



Sailors can find out everything they need to know to take part on our website and also in the instructions included with the Secchi app, which describe how to make and use a Secchi Disk.







The Secchi Disk is a famous piece of equipment in marine science, and probably one of the simplest. The Secchi Disk was invented in 1865 by the Pope's Astronomer Pietro Angel Secchi and it is used to measure the transparency of the sea water. When the Secchi Disk is lowered vertically into the water from the side of a stationary boat, the depth below the surface at which it just disappears from sight is called the Secchi Depth. Away from estuaries, the Secchi Depth reflects the amount of phytoplankton in the water column.



A Secchi Disk apparatus is a weighted, 30 cm diameter white disk attached to a tape measure. The Secchi Disk can be made from fibreglass, plastic, metal or wood, the only restriction on its design is that it must be 30 cm in diameter and matt white.



The amount of phytoplankton in the water column will vary seasonally, from place to place and annually. You may choose to set up a sample site and measure the Secchi Depth twice or more a month, or you may choose to make recordings on your travels. In whatever way you decide to take part, your help will help us understand the OceanS biology much better. We plan for the Secchi Disk study to run for many years to come to create the world's biggest plankton survey.



Many of the datasets that scientists rely upon today to tell us about long-term changes are 'citizen science' studies that were begun a few decades ago. Often we look back and wish we had already started monitoring something about the natural world - 'if only we had started measuring 'x' ten years ago'. Well our view was there is no time like the present to start something for the future. This is why we created the Secchi App and this Citizen Science project, to try to encourage data collection on the plankton and make data submission simple.

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