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There's a dark side of the seabed, too.
Last week I told you of the seaweed from Heaven and this week
I'm writing of the other kind… from Hell.
This algae is new to the Mediterranean and
comes with a reputation as dangerous as a voodoo curse.
"Caulerpa Taxifolia" was studied
at the "Monaco's Oceanographic Institute, Jacques Cousteau"
in the early 1980s.
The plant seems to be a sign of the times
we go through. It is a "Winner"; it was created
to conquer, especially when circumstances are ideal (with
the right politics and moving in the darkness) and when it
is not expected.
Its nature is stronger, more adaptable and
poisonous than its rivals. It only takes, never gives.
Originally from the Caribbean Sea, it possesses
certain unique characteristics, such as resistance to the
cold, gigantism, vigour of development, density and ecological
dominance. Nothing like it has ever before been observed in
tropical populations of this kind or in other seaweed introduced
in the Mediterranean.
In 1984, just like proper witchcraft, it
got out of human control and appeared for the first time in
the Mediterranean Sea, right by the Institute cliff (most
probably through the laboratory drains).
And now it is threatening the Balearic seabed.
It even has its own unofficial Website -
"Caulerpa Taxifolia" from the European Government
(Life). I am grateful to them for the following:
How to recognise it
It is beautiful, fluorescent green seaweed
with a characteristic creeping stem, called the stolon. The
name "Caulerpa" refers to this feature. In Latin,
"Caulos" means axis and "erpa" comes from
a verb meaning to creep. This stolon can measure over 1 m
in length and is fixed to the bottom by the roots or rhizoids.
The stolon bears leaves or fronds, covered in needles or pinnules.
These long fronds, often exhibiting extensive ramifications,
are 5 cm to 65 cm in length and resemble those of certain
conifers such as the Yew (Latin, yew = Taxus and leaf = folia,
whence the name taxifolia given to seaweed).
Can I handle it? Should I pull up?
You can touch the seaweed without risk to
yourself, but there are laws and guidelines (adopted by France
and Spain and by the International organisations) banning
or recommending against the harvesting, sale or transportation
of "Caulerpa Taxifolia". The harvesting and uprooting
of the plant are delicate operations that should only be undertaken
with proper authorisation (because any handling increases
the risk of dissemination and makes policing the contaminated
area more difficult).
Take care; do not help "Caulerpa Taxifolia"
to spread! Do not contaminate new areas! A fragment of the
seaweed can survive for more than a week out of water in a
warm, damp place (anchor well off a boat, rolled up fishing
net, scuba diving bag or equipment). Once released in the
sea, it will again start to develop.
Unless we are all extremely vigilant, no
site is safe from contamination! It is all too easy to transport
this seaweed unwittingly from already colonised sites to other
areas. This explains how "Caulerpa" has managed
to spread by leaps and bounds sometimes jumping a distance
of several hundred km., and why it is that it is generally
found at anchorages, in ports or in fishing areas.
Recommendations for yachtsmen: Take care
to inspect your anchors and chains when leaving an anchorage.
Fishermen: Check your nets and trawls.
Divers: Check your bag and equipment each
dive.
If you have accidentally picked up fragments
of this seaweed, do not throw it into the sea. Put it in a
bag and put it in a dustbin when you go to shore.
To date, more of 90% of known "Caulerpa"
locations have been reported by divers, yachtsmen or fishermen.
If we are to monitor the progression of this seaweed and thus
be in a position to devise effective strategies to control
and combat its spread, we need your assistance.
Since its introduction into the Mediterranean
in 1984, the surface area colonised by "Caulerpa"
has increased constantly. The rate of increase at each location
is similar to that recorded at the first site (at Monaco,
the first hectare was covered in 5 years). The most extensive
areas thus correspond to the oldest colonies. At the end of
1996, these stretched for 10 km on either side of the site
where first sighting was made, and 99% of the total colonised
surface area was to be found within 100 of it, between Toulon
(France) and Alassio (Italy).
All the stable substrates (rock, sand, stilt,
and Posidonia meadows) can be colonised. All types of bottom,
especially from 3 m to 40 m, can be invaded. "Caulerpa"
has even been found in summer, alive and well established,
as deep as 99 m. It is to be found both in good quality water
and in polluted harbours, on rocky headlands exposed to waves
and in sheltered bays.
It can survive for a few days at 7°
C and for 3 month at 10° C. It starts growing again when
the water rises above 15° C. No winter, however rigorous,
will make it disappear all together.
A devastating impact
The spread of this permanent vegetal meadow
continues from year to year, until it has covered all the
available bottom area. Little by little, it dominates or eliminates
the other seaweed and affects the Posidonia meadows. The Fauna
too undergoes profound changes, especially the fixed species
(Gorgonia, sponges, etc.) and small mobile fauna, sea urchins,
crustaceans, molluscs, etc. This new dominant plant is little
or not at all consumed by fish or marine invertebrates and
thus is not replacement food, which makes its ecological impact
even more severe.
In areas that have been invaded most densely
and for the longest time, a decline in the abundance of some
fish has been observed. Repercussions on the economy and human
activities have also begun to make themselves felt, with offshore
fishing and diving beginning be affected in some areas.
Overall, there has been a decline in biodiversity.
Gradually, richly coloured and varied Mediterranean populations
are being replaced by the uniform fluorescent green landscape
of the "Caulerpa Taxifolia" meadows.
It is major risk for the Mediterranean shallow
water ecosystems. Research on the progression of this seaweed
and its impact has confirmed the fears of scientists, who,
as long as 1990, alerted the authorities to the major risk
that the invasion of this introduced species might represent
for the biodiversity, ecological balance and commercial resources
of all the shallow water areas in the Mediterranean.
Eradication
Although it was called for back in 1991,
when it would still have been possible, the total eradication
of "Caulerpa" was not undertaken.
Since the end of 1992, the surface area
covered by the seaweed has become too extensive and it is
now known that it will not be possible to eliminate it altogether
by chemical or physical means (manual extraction, aspiration
salt, copper, etc.). Some of these techniques are still being
tested. They could be used to eliminate small isolated patches
that are far enough away from the large colonised areas and
this has already been done successfully in some places. There
have also been some promising results from biological studies
(involving the use of slugs -molluscs- that feed exclusively
on "Caulerpa").
In short, while little can be done to save
areas that have already been invaded by "Caulerpa",
at least measures can be taken to slow its spread.
In the first colonised areas at Monaco,
a vast, monotonous fluorescent green blanket has gradually
replaced richly coloured and variant underwater landscapes.
Since 1990, more then 30 Spanish, French,
Italian and Croatian organisations and more then 200 research
scientists have taken part in monitoring the spread of "Caulerpa
Taxifolia" or have been published in about 300 scientific
Journals or publications for the general public.
As we can see, the problem is well-known
by now, yet at the end of the 1990s, the plant was detected
in the Adriatic Sea and in the West coast of Mallorca, and
still remains today. Other suspicious areas are the anchorage
sites of Ibiza-Formentera, where it has been detected on boats.
The Heavenly, delicate and generous "Posidonia",
has no chance. Those days have gone and its time has passed.
How can anybody be generous nowadays? Live and let live is
not enough for today, not enough to survive, like our ancestral
culture that is vanishing away, pushed out by a Devil-like
"Territorial Caulerpa" also poisonous and green,
Dollar green, that shines even brighter then proper "Caulerpa",
invading our Islands and society, stealing (or buying) our
hearts and feelings, turning us greedy, selfish, rich and
vulgar.
Goodbye century, goodbye Posidonia, goodbye
to a sensible style of life.
Goodbye love, I think I'm going to cry.
Warning!
If you know of or find any news of areas
that "Caulerpa Taxifolia" has already reached, it
is vital to warn us as quickly as possible at these numbers:
Turkey: Prof. Dr Sukran Cirik Telephone
+90 232 278 52 72 / 278 55 65.
Institute of Marine Science and Technology Izmir
France: Prof. A Meinesz. Telephone 04 92
07 68 46 & Fax 04 92 07 68 49.
Laboratoire Environnemant Marin Littoral. Nice
Italy: Prof. Francesco Cinelli Telephone
050 23054/500018 & Fax 050 49694
Universita di Pisa
Liguria (Italy): Prof. Dott Giorgio Matricardi
Telephone 010 3538053
Universita di Genova
Sicily (Italy): Dott. Carla Frada Orestano
Telephone 091 6161493
Universita degli studi di Palermo
Spain: Dr E Ballesteros Telephone 972 33
61 01 & Fax 972 33 78 06
Centro de estudios avanzados de Blanes (CSIC)
Croatia: Dr N Zavodnik or A Jaklin Telephone
052 811 544 - Dr B Antolic Telephone 021 358 688
Institute of Oceanography and Fisheries. Split.
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Caulerpa Taxifolia invading a Posidonia Oceanica meadow
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Caulerpa Taxifolia: The Bad Guy
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José P Ribas
josepribas@ibizahistoryculture.com
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