OWNA participation: Article-Sargasso Weed Explosion research during world solo sail


Atlantic Ocean - The Sargassum Phenomenon is a Serious Issue for Atlantic


How can the cruising community help?

In an effort to better understand critical aspects of this phenomenon, the

USM research team is accepting reports from cruisers in the Atlantic who

come across large quantities of Pelagic Sargassum. Data received will help

researchers identify the source and examine the movements and causes of

this extraordinary event.

By Sue Richards — last modified Sep 21, 2015 02:53 PM

Contributors: Joan Conover, Jim Franks, Donna Lange, Andrew Bishop

Single-hander Donna Lange who started a non-stop sail around the world in

July from Bristol, RI, USA, kicked off a serendipitous scientific event by

showing how scientists can benefit from the support of a group of people

with a keen interest in the oceans - world-cruising sailors.

Published: 2015-09-21 00:00:00

Topics: Atlantic Crossing , Environment

Countries: Sierra Leone , Cape Verdes

Taken by Donna Lange

Currently in the South Atlantic, Donna is actively assisting researchers

with her reports on Sargassum weed mats encountered.

Donna became caught in a huge Sargassum mat off Sierra Leone, Africa,

recently and sought help from the Seven Seas Cruising Association. Whilst

assisting Donna, Joan Conover of the SSCA was struck by the seriousness of

this issue for cruisers. “From Donna’s reports, this problem seems to be

pretty widespread, yet no one is talking about it outside of the

Caribbean. It surprised me that there is currently NO way for satellites

to ID weed in the oceans and there is a need to determine the extents of

the weeds, or the scope of the problem which will eventually end up in the

Caribbean we all love. If Atlantic cruisers can assist with Sargasso weed

locations, then with enough information the extent of the issue can be

mapped out.”

During 2011, massive quantities of Pelagic Sargassum occurred throughout

the Caribbean, impacting aquatic resources, fisheries, shorelines,

waterways, and tourism. A similar event is occurring in 2014 and continues

in 2015.

However, as indicated by research and by Donna’s reports, the phenomena is

not only isolated to Caribbean waters.

The Sargasso Sea, a 1.5-million-square-mile circle of ocean filled with

vast rafts of free-floating algae, occupies the North Atlantic Subtropical

Gyre, a large system of rotating currents within the Atlantic. The

Sargasso Sea is bounded by the Gulf Stream, the North Atlantic current,

the Canary Current and the North Atlantic Equatorial Current.

Jim Franks, a senior research scientist at the University of Southern

Mississippi’s Gulf Coast Research Laboratory, and his colleagues, have

reason to believe - based on their preliminary research - that the event

most likely has no direct connection to the Sargasso Sea. See the website

for information about Sargassum (http://www.usm.edu/gcrl/sargassum/).

Why so much Sargassum?

Franks says, "We believe this is an on-going equatorial regional event and

our research has yet to find a direct connection with the Sargasso Sea. We

believe that there is a massive Sargassum bloom occurring all along the

equatorial Atlantic impacting Sierra Leone and perhaps reaching to the Bay

of Guinea. The Sargassum growth and mass accumulations are being 'fuelled'

by very warm sea temperatures and nutrient input from a variety of


This phenomenon is a serious issue for West African and Caribbean coastal

communities. In large doses, the algae harms coastal environments, even

causing the deaths of endangered sea turtle hatchlings after they wriggle

out of the sand where their eggs were buried. Clean-up efforts by work

crews may also worsen beach erosion.

Location of Sargassum

Jim Franks, recently created a website to collect eyewitness reports of

large quantities of Sargassum. Those reports confirm the seaweed is

showing up in areas where before it had been seen only rarely or not all.

Circulation patterns in the equatorial Atlantic have reportedly carried

mats to Africa for the first time and most likely elsewhere.

Donna Lange photographed large mats of Sargassum on the 13th September in

the East Atlantic off the coast of Africa at approximately 10N. It is

quite possible these mats are spread all the way across the ITCZ region.

Donna reports NO weed at 5S 17W, however north of that position the

situation she says, is very bad. It is hoped she will continue South and

West of that position, to hopefully give an idea of where a boat could go

if the weed is that much of a problem.

Is it a danger to yachts?

The mats of weed are rarely thick enough to impede a boat, however Donna

Lange did get stuck in a dense mat off Sierra Leone in dead calm

conditions that she reported to be at least a foot thick (see

http://www.sailblogs.com/member/sailtwicearound/?xjMsgID=372173). Donna

has no engine, so came to a complete standstill and it is likely

catamarans would be severely slowed by larger weed areas such as Donna


Depending on how large the mats are, it’s probably advisable to skirt

around them if possible to avoid weed getting caught in the rudders/keel

and prop keg (although this is unavoidable in the dark). Occasional

bursts of reverse when using the engine will help clear any weed from the

prop and if motoring through be sure to check the raw water engine cooling

pump strainer for blockages to avoid any major problems.

How can the cruising community help?

In an effort to better understand critical aspects of this phenomenon, the