A free mobile phone app is behind the public science project

A mobile phone app called Secchi has been launched to allow

thousands of seafarers around the world to take part in a global study of


The unique public science project will measure the amount of

phytoplankton – the minute organisms that are at the very start of the ocean’s

complex food chain.

Scientists fear the population of the microscopic beings is

in decline due to rising sea temperatures.

If true, a lack of phytoplankton could have consequences for

every aspect of marine life as there would be less food around to support the

marine food chain.

To check the levels of phytoplankton in our oceans, marine

experts have developed a smart phone app for sailors and fishermen around the

world to use.

Because the phytoplankton – that are each thinner than a

strand of human hair – exist at the sunlit sea surface, mariners will need to

carry out a simple experiment using an easy to make, 30cm diameter, white disk

known as a Secchi Disk.

Attached to a measuring tape, the Secchi Disk is lowered

over the side of a boat and the depth at which it disappears from sight

estimates the amount of phytoplankton in the sea.

This depth is then uploaded to a database using the Secchi


The scientists, based at Plymouth University, hope to build

up a map of the oceans that charts the seasonal and annual changes of

phytoplankton from now and into the future.

The free app is called Secchi after Father Pietro Angelo

Secchi, an astronomer who invented the disk device in 1865 to measure water

turbidity in the Mediterranean.

The project is being led by Dr Richard Kirby, a plankton

biologist at the Plymouth University’s Marine Institute.

He said: ‘As the phytoplankton live at the surface of

the sea they are being affected by rising sea temperatures due to climate


‘A scientific paper published last year suggested that

since the industrial revolution the ocean’s plankton population had declined by

as much as 40 percent since 1950.

‘We need to know more about how the phytoplankton are

changing in order to understand the effects on the ocean’s biology.

‘Phytoplankton underpins the marine food chain, without

it the seas would be a barren wilderness.

‘Like all marine creatures, phytoplankton have a

preferred optimum sea temperature no matter where they are in the world and

therefore they will either move to different areas or decrease in number if the

sea temperature changes.

‘The Secchi Disks are still used by marine scientists

to study phytoplankton but there are too few scientists to survey the world’s

oceans as well as we would wish.’

He added:’This app enables seafarers around the world to take

part in a science project.

‘If we can just get a small percentage of the global

population of sailors involved we can generate a database that will help us

understand how life in the oceans is changing.

‘It would help us learn much more about these important

organisms at a crucial time when their habitat is altering due to climate


Sailors are encouraged to take a Secchi Depth reading

whenever and wherever they can.

Professor Sam Lavender, whose company Pixalytics Ltd is

maintaining the Secchi Disk database, said: ‘We hope that all seafarers,

whether a sailor or angler, will enjoy taking part and will see how easily they

can help create a truly unique and important scientific database for future


Over time, the interactive data set will be linked with

satellite remote sensing data of ocean colour to create a resource for both the

general public and scientists alike.

Dr Nicholas Outram, developer of the iOS smartphone app

said: ‘Our goal was to make the Secchi app as simple to use as possible

when at sea.

‘It will upload the data you collect automatically to

the Secchi Disk database when you reach port and get a network


Find out more at www.secchidisk.org or visit the Facebook page.