Secchi Disk study

If you have difficulty getting a GPS fix using the Secchi app on iOS or Android please read the following: On Android, it could be a problem with your device's AGPS. Read THIS ARTICLE for a fix. First, set your device's Location Mode to High Accuracy (Settings > Location > Mode > High Accuracy). Then, install and open the GPS Test app, tap the menu icon in the upper right corner and then tap CLEAR AGPS. Next, tap the menu icon again and this time tap UPDATE AGPS. On iOS you can check your device is working properly using the MAPS app (read THIS ARTICLE) or or you can see the number of satellites acquired using the paid for GPS Diagnostic app. Because of the positions the GPS satellites orbit the Earth it can take longer to obtain a GPS location towards the poles.

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.

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 companies.

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.

Climate change is threatening the phytoplankton that underpins the marine food chain. We must understand why before it's too late. Help collect essential data by taking part in this vital citizen science study.

Latest Research Article

Make your Secchi Disk

Full instructions in the Secchi app

Join our ambassador Susie Goodall in Secchi Disk science

See your Secchi Disk data

Don't want to DIY?

Common questions

What people are saying about the Secchi Disk study

Secchi Disk study in the press

The Secchi Disk study is used as a citizen participation on collecting ocean data in the European IFADO project (Innovation in the Framework of the Atlantic Deep Ocean).

Sponsor the Secchi Disk study

ABOUT THE STUDY

HOW IT WORKS

MEDIA RESOURCES

Project leader

Dr Richard R Kirby

Data Manager

Dr Sam Lavender