Scottish Islands Explorer 44: Jul / Aug 2017

It’s a Shore Thing
The browns, largely comprising kelps and wracks, are the
most obvious group and their knobbly elongated fronds
represent everyone’s idea of a seaweed-strewn shore. A patch
of seemingly impenetrable Forest Kelp, anchored to rocks by
their clawlike base, can intimidate swimmers, snag a
fisherman’s hook or catch a kayaker’s paddle. It always makes
the sea look strangely mysterious and the long wavering
fronds seem to exaggerate the depth of the water.
Particularly Tricky
Oar Weed (appropriately also called Tangle) has a similar
effect and can easily grow up to two metres in height. The
olive green wracks are usually tough, leathery and particularly
tricky to walk over when wrapped around wet rocks. They
are usually distinguishable by their flat branched ribbonlike
fronds and some species are easily identified by their wellknown
air bladders.
These are usually paired on Bladder Wrack, with one on
either side of the central mid-rib, but may be absent in young
plants. Spiraled Wrack, another common species in the
islands, also appears to have bladders, but these warty lumps
are the result of gases developing in the fibre of the fronds.
Serrated Wrack has flattened fronds which terminate in
broad serrated fingers, while the long strands of Thong Weed
used to be collected to be boiled up as a side dish with
poultry.
Green seaweeds are classed as plants and their colour comes
from the chlorophyll found in plants. Around 100 species are
found around the Scottish coast and they vary from tiny
varieties which actually live inside other seaweeds to the
velvety half-metre long branches of Green Sponge Fingers.
Types of Sea Lettuce, whose flattish wriggly leaves frequently
appear in aquariums, are found from exposed shores to
brackish drainage ditches but large rafts can sometimes drift
onto beaches.
An Abundant Source
In August 2009, unprecedented amounts were washed up
on the islands and beaches of Brittany and the rotting leaves
produced quantities of unwelcome toxic gas. Despite the fact
that seaweed neither looks nor smells edible, it would have
been an abundant source of food for the first, transient
hunter-gatherers and for early farmers who probably spotted
how deer and cattle grazed on the foreshore.
During the long Hebridean winters, brown seaweeds used
to be collected as an essential source of fodder and this helped
to free valuable stored crops for use by families as well as
vulnerable livestock. Space in the old island black houses was
often taken by the storage of seaweed.
The semi-feral sheep on North Ronaldsay have actually
evolved subsisting almost entirely on seaweed. They are one
of few mammals with such an unusual diet and are now
confined to the shoreline by a six-foot dry-stone wall
encircling the island. This was originally built to enclose the
sheep, but as seaweed farming became uneconomic they were
displaced outside to help protect the fields and crofts. Their
meat is intense and gamey due, in part, to the
high iodine content in seaweed.
Two Crops of Oats
Nutrient-rich seaweed, an abundant source
of fertiliser, improved barren and often
meagre plots of land. Composted heaps were
gathered after winter storms and, dug directly
into the soil, created the piled up ‘lazy beds’
crisscrossing awkward slopes above coasts. A
crofter with a good supply of seaweed could,
apparently, grow two crops of oats in successive
years on the same plot, without any need
for rotation.
In the late 17th Century, new uses for
seaweed were discovered which led to island
boom years. Soda and potash, used in the
soap and glass industries, were extracted by
burning kelp and wrack and this helpfully
removed Britain’s reliance upon imports from
Spain. In 1695, Martin Martin noted the
potential of kelp on his journey through the
Western Isles and by 1722 production was
underway in Orkney.
The kelp industry spread, though not to
Shetland, and even unpopulated islands were
seen as a source of seaweed. Kelp was burned
for up to eight hours at a time in large pits and
the following day the ash would be sent to
Glasgow or further afield. The industry was
profitable until potash deposits were discovered
in Germany. Iodine was later taken from
kelp, although this was soon being mined, at
lower cost, in distant Chile.
Ice Cream Production
The late 19th Century brought another
development when chemicals derived from
seaweed were discovered. These are called
alginates and they continue to be used as gels
and stabilisers in food manufacturing,
including ice cream production. A thriving
alginate factory was established by the west
coast of South Uist, but this closed some years
ago when imports began to dominate.
The Hebridean Seaweed Company, based on
Lewis, is currently Britain’s largest producer of
these organic products for animal feed, soil
enhancement and cosmetics. A new Shetland
distillery is making gin, with a strong hint of
Bladder Wrack, and a commercial seaweed
farm has recently been established off Oban.
Some say Scottish seaweed could once again
play an important role in island life.
Page 28 top: This dazzling pink
seaweed - it could be one of several
red species - was washed up on the
sands of Iona.
Below: Egg Wrack, here showing
fresh annual growth, is found
throughout the islands though it
appears to be absent from the
western coast of Skye.
Page 29: Gut Weed, which can
thrive to a depth of up to 22ft, is
closely related to Sea Lettuce and
forms bright moss-like carpets in
the shallow sub-tidal zones on the
islands.
Left: These old ‘lazy beds’ on the Isle
of Muck are reminders of the times
when islanders used composted
brown seaweeds to improve their
barren plots. The Isle of Eigg can be
seen in the distance.
Below: The rosy-red Beautiful Fan
Weed has broad forked fronds and
can be distinguished from similar
species by its curled and ragged
edges.
Photographs taken by the author,
Roger Butler.
30 SCOTTISH ISLANDS EXPLORER JULY / AUGUST 2017