Please select your home edition
Edition
Melges 15

Sailors cruise ahead in a study of the oceans' phytoplankton

by Dr Richard Kirby 6 Dec 2017 19:00 GMT 6 December 2017
Richard Kirby, Secchi Disk Project Leader © Secchi Disk

Around the world, sailors and other seafarers are lowering round, 30 cm white disks into the sea from the side of their boats to study the oceans phytoplankton.

The disk the seafarers are using is called a Secchi Disk and it is named after the Pope's astronomer who invented it in 1865, and the seafarers are all citizen scientists taking part in the Secchi Disk study (www.secchidisk.org). The first data from this global study has just been published in The Public Library of Science ONE (PLOS ONE) (journals.plos.org/plosone/article?id=10.1371/journal.pone.0186092) and the Secchi Disk Seafarers are collective authors. The paper reveals importantly, that seafarers are not only good citizen scientists, but that their measurements of the phytoplankton in the sea may be vital to helping us better understand the oceans' changing biology.

The oceans' phytoplankton the sailors are studying underpins the marine food chain to determine the abundance of other life in the sea from the fish we eat to the number of polar bears on the ice. The phytoplankton also provides the World with oxygen and it plays a central role in the global carbon cycle.

A recent study of a 100-year trend in global phytoplankton primary production revealed a 40% decline since 1950 (www.nature.com/nature/journal/v466/n7306/full/nature09268.html). The explanation proposed for the decline was that water column mixing, and so the supply of growth-promoting nutrients to the sea surface, had reduced due to rising sea surface temperatures due to global warming. Because the phytoplankton is so important we need to know much more about how they are changing. Although satellites can now measure phytoplankton at the sea surface remotely from space, direct measurements are essential because of the naturally, uneven distribution of phytoplankton in the water column and this is where any seafarer equipped with a Secchi Disk can help.

A Secchi Disk is arguably, the simplest piece of marine scientific equipment ever invented. When the Secchi Disk is lowered vertically into the water, attached to a tape measure, the depth below the surface when it just disappears from sight is recorded as the Secchi Depth and this reflects the transparency of the water column. Away from estuaries and coasts the phytoplankton are the major influence upon the transparency of the sea and so the Secchi Depth measures the phytoplankton. Scientists have been using Secchi Disks to measure ocean transparency since 1865 and now sailors are joining in around the world. The sailors make their own white Secchi Disk from any material and use the free Smartphone application called Secchi to upload their Secchi depth data to a central database.

Whilst there are more professional marine biologists than ever before, few go to sea and still fewer go far offshore, and open-ocean research cruises rarely return to the same location. In contrast, many of the public go to sea regularly for recreation or work and often to a similar place, and ocean passages sailed by cruisers follow similar routes dictated by the time of year and favourable prevailing winds.

In the paper published in PLOS ONE the Secchi Depths collected by seafarers are compared to satellite ocean colour data to reveal how their data can be used to better interpret satellite colour measurements. So now, sailors around the world are helping us to understand the oceans biology as they cruise along.

Plankton scientist Dr Richard Kirby who founded and runs the Secchi Disk study said: "Secchi Disk data collected by seafarers can help us understand in situ versus satellite observations of phytoplankton. As participation by seafarers using Secchi Disks increases their data will contribute more and more towards understanding how the phytoplankton are changing over long-term timescales to help us understand the essential base of the marine food chain."

Related Articles

A Crown for the Principality
Yacht Club de Monaco wins the 2025 Admiral's Cup The Royal Ocean Racing Club (RORC) is delighted to announce the Yacht Club de Monaco (YCM) as the winner of the 2025 Admiral's Cup. Posted today at 12:41 pm
WASZP Games & Topper Worlds – That's a Wrap
Rooster were proud title sponsors and official clothing partners As proud title sponsors and official clothing partners, we've just wrapped up two unforgettable events: the adrenaline-fuelled WASZP Games in Weymouth and the dynamic, youth-driven Topper Worlds in Medemblik. Posted today at 11:23 am
49er & 49erFX Junior Worlds kicks off in Rungsted
Officially opened last night with a vibrant Opening Ceremony Today, we proudly welcome 105 teams and 210 athletes from across the globe to Rungsted for the start of the 49er and 49erFX Junior World Championship 2025. Posted today at 10:56 am
RS Feva Worlds Qualifying Series complete
Sailors split into three flights of yellow, blue, and red Two days of qualifying series with 168 boats on lake Bourget, Club Nautique Voile d'es Bains, sailors split into three flights of yellow, blue, and red. Posted today at 10:24 am
Royal Harwich Phantom Open
Preceeded by a walk along the river Orwell to the Butt and Oyster pub As usual the Phantom fleet was made very welcome by the Royal Harwich Yacht Club with most competitors arriving on the Friday afternoon for the traditional walk through the wooded path along the river Orwell to the Butt and Oyster pub at Pinn Mill. Posted today at 10:19 am
National 12s at Royal Harwich
Variable conditions for Craftinsure National Series Round 4 After a long heatwave, variable conditions greeted the dozen National 12s for the fourth event in the 2025 Craftinsure National Series. The wind delivered on the forecast ranging from 5 to 20 knots. Posted today at 9:51 am
A defining finale to the Admiral's Cup 2025
Provisional results are in and the overall winner will be officially announced today At the end of the 5th day of the Rolex Fastnet Race just 7 boats in the Admiral's Cup fleet were still racing. The majority had moored up in Cherbourg and the dock was filled with sailors and supporters sharing a beer, a slice of pizza and their stories. Posted today at 9:50 am
ISO Eurocup 2025 at Biscarosse, France Day 2
The racing conditions presented a new challenge The Centre Nautique Biscarosse Olympique hosted a well-organized and enjoyable evening after Day 1 of racing. Sailors and guests gathered for a delightful meal, accompanied by aperitifs and canapés, all served lakeside with a scenic view. Posted today at 8:24 am
Tom Dolan takes second place in IMOCA 60 Class
Wrapped up his season with Team Charal on a high note in the Rolex Fastnet Race Irish sailor Tom Dolan, skipper of Figaro 3 Kingspan, wrapped up his season with Team Charal on a high note, securing second place in the IMOCA 60 class at the centenary edition of the prestigious Rolex Fastnet Race. Posted today at 7:48 am
Elizabeth Mowbray Trophy at Overy Staithe
A luxuriously late start time for the 13 dinghies taking part A luxuriously late start time of 09.30 on a good height tide allowed a fleet of mainly single handed classes, OK's, Lasers, Lightnings, one Topper, one Twinkle Twelve (being sailed single handed), an Enterprise and a Sharpie to race. Posted today at 5:29 am