Calling all roving sailors - your chance to help a marine survey

Just lower it into the water until it disappears, and measure the depth - called the ’Secchi Depth’
Richard Kirby
Here is your unique chance to make a difference in the marine scientific world, just because you are a sailor with a smart phone, and especially if you are sailing somewhere remote, helping with a plankton survey. The process is simple and fun and it's vital to our knowledge of the oceans and climate change.

This month the Secchi Disk study and the Secchi App project is just a year old, and Ocean Cruising Club members have been making their own difference by joining in as citizen scientists... but YOU don't have to be an OCC member, just keen to help the study of climate change.

What is the Secchi Disk study and the Secchi App project? It is the global Citizen Study by seafarers to study the marine phytoplankton and to help track the effects of climate change. (See Sail-World story.) The Ocean Cruising Club were one of the first organisations to promote the study.

Secchi disk - simple to make at home. Watch the video below for explanation
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If you didn't find out about it the first time, read on to find how you can help while out sailing. After a year, and although it is still early days in terms of a long-term study, the project organisers are already excited by the extent of the data collected. Dr Richard Kirby, the project's leader, told Daria Blackwell of the Ocean Cruising Club, 'We hope to soon be able to start some analyses on the role of Citizen Science in marine biology, which will hopefully lead to a publication to acknowledge all your efforts so far. The project is a long-term study however, and the database improves continuously as ocean coverage increases and successive years of Secchi depth data accumulate.'

It was all started when a study by a team of Canadian marine biologists 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.

However, other scientists didn't agree and the problem was 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.

The Citizen Science project relies upon sailors and other seafarers, anglers and divers, knowing about its existence and taking part. They are especially keen to reach out to sailors cruising in the remoter Southern Hemisphere.

Secchi free app for iPhone or Android
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Finally, as the project team anticipated at the start, sailors have been remarkably ingenious with the variety of materials they have used to make their 30 cm white Secchi Disk. The more unusual materials include a Vinyl LP, an aluminium road sign, a Frisbee, and a disk cut from a ship's toilet seat.

So what is a Secchi Disk and how do you make it?

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.

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.

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 the scientific team to understand the Ocean's biology much better. It is planned for the Secchi Disk study to run for many years to come to create the world's biggest plankton survey.

In order to take part in the project you need to make the very simple DIY Secchi Disk and download the free Secchi app to your smartphone or tablet - you 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.

For more information go to the website

Sail-World Cruising would like to thank the world-wide www.oceancruisingclub.org!Ocean_Cruising_Club for their contributions to this article.
http://www.sail-world.com/119526