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
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
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.
Check your nets and trawls.
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 7º C
and for 3 month at 10º C. It starts growing again when the water rises above
15º 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.
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
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
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.
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.
Caulerpa Taxifolia: The Bad Guy
Caulerpa Taxifolia invading
a Posidonia Oceanica meadow