OWNA participation: Article-Sargasso Weed Explosion research during world solo sail
Article:
Atlantic Ocean - The Sargassum Phenomenon is a Serious Issue for Atlantic
sailors
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
sources”.
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
encountered.
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
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.
--
Joan E. Conover
SV Growltiger, Hampton, VA