Watch the video
Full instructions in the Secchi app
Join our seafaring Ambassador Susie Goodall in Secchi Disk science
What people are saying about the Secchi Disk study
Show others you are taking part
Fly a flag
A 90cm pennant, fully sewn on woven polyester with header webbing. Superb.
Double-sided £64.00 (+p&p).
Wear a polo shirt
Navy Polo shirt with the study website and a Secchi Disk.
Ultimate, 100% cotton £13.15, lightweight cotton or poly/cotton £10.25 (+p&p).
Keep warm with a Beanie
Navy Beanie hat with the study website and a Secchi Disk.
100% Acrylic, £7.00 (+p&p).
Clicking on 'Buy Now' will let you send an e-mail to order directly from our suppliers
The Secchi Disk study in the news
Sponsor the Secchi Disk study
The Secchi Disk study is funded 100% by donations to The Secchi Disk Foundation. Sponsor or make a donation and you will help to engage people of all ages in marine science to help understand the oceans' phytoplankton.
ABOUT THE STUDY
The phytoplankton in the sea account for over 50% of all photosynthesis on Earth and, through the food web they support, they underpin the marine food chain.
Living at the surface of the sea the phytoplankton are particularly sensitive to changes in sea surface temperature. A recent study of global phytoplankton abundance over the last century suggested that global phytoplankton concentrations had declined by 40% over the last 50 years due to rising sea surface temperatures as a consequence of current climate change.
We need to know much more about these changes and you can help by making a simple piece of scientific equipment called a Secchi Disk and using the free Secchi app.
Full instructions for the project are included in the Secchi app.
Read the Nature paper that provoked us to create the Secchi Disk study. You can download it as a PDF from the laboratory of Dr Boris Worm, Dalhousie University using the button below.
HOW IT WORKS
The Secchi Disk is a
30cm diameter, plain white disk that is attached to a tape measure
and weighted from below with enough weight to make the disk sink
vertically. It is one of the oldest and simplest marine scientific
tools. You can make a Secchi Disk from any material e.g. a white
bucket lid. A good material is 3mm or 5mm Foamex as it is easy to
cut and you can often obtain remnants from printing/display
When a Secchi Disk is lowered vertically into the water the depth below the surface at which it just disappears from sight is called the Secchi Depth. The Secchi Depth measures the clarity of the seawater, which away from estuaries and coasts indicates the amount of phytoplankton at the sea surface.
By measuring the Secchi Depth you can therefore help map the ocean's phytoplankton. You can record Secchi Depths on your travels or perhaps, repeatedly from a local sampling site you establish.
The Secchi Disk study is a long-term program that began on February 22nd 2013. The study has no end date or geographic boundaries in the sea.
success of the Secchi Disk study relies upon it being known to
seafarers. If you would like to
help publicise the study by writing about it, or by placing a poster at your marina or yacht
club, you can obtain free resources at the following