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14 HEALTH AND LABORATORY MAGAZINE

WORLD’S LARGEST

PLANT 180 KM LONG

A single plant expanded to

stretch 180 km. This makes it the
world’s largest known plant.

Somehow this single to show that 200 km² (77 There is also a lot of light not appear to reproduce cope?
seedling grew to cover an miles²) of ribbon weed in the waters of Shark Bay, sexually – which would
area of 200 km (77 miles ), meadows expanded from as well as low levels of nu- normally be the best way Researchers hypothe-
2
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stretching through waters a single, colonizing seed- trients and large temper- to adapt to changing con- size that this plant has a
that are quite different in ling. ature fluctuations. Despite ditions. small number of somatic
temperature and salini- this hostile environment, mutations (minor genet-
ty. Based on its size and HOW DID IT EVOLVE? the plant has been able to Scientists have observed ic changes that are not
growth rate, the research- thrive and adapt. seagrass flowers in the passed on to offspring)
ers estimate that it is 4,500 What makes this seagrass Shark Bay meadows, which across its 180 km (112
years old. plant unique from others, It is challenging to deter- indicates the seagrass are mile) range that help it per-
other than its enormous mine the exact age of a sexually active, but their sist under local conditions.
These underwater sea- size, is that it has twice as seagrass meadow, but sci- fruits (the outcome of suc-
grass meadows grow many chromosomes as entists estimate the Shark cessful seagrass sex) are However, this is just a
in two ways: by sexual its relatives. This makes Bay plant is around 4,500 rarely seen. hunch and researchers are
reproduction, which helps it what scientists call a years old, based on its size tackling this hypothesis ex-
them generate new gene “polyploid.” and growth rate. Researchers’ single plant perimentally. They have set
combinations and genetic may in fact be sterile. This up a series of experiments
diversity, and also by ex- Most of the time, a sea- Other huge plants have makes its success in the in Shark Bay to really
tending their rhizomes, the grass seedling will inherit been reported in both variable waters of Shark understand how the plant
underground stems from half the genome of each marine and land systems, Bay quite a conundrum: survives and thrives under
which roots and shoots of its parents. Polyploids, such as a 6,000-tonne plants that don’t have sex such variable conditions.
emerge. however, carry the entire quaking aspen in Utah, but tend to also have low levels
genome of each of their this seagrass appears to of genetic diversity, which THE FUTURE OF
To find out how many parents. be the largest to date. should reduce their ability SEAGRASS
different individual plants to deal with changing envi-
are growing in a seagrass There are many poly- Other huge seagrass ronments. Seagrasses protect the
meadow, you have to test ploid plant species, such plants have also been coasts from storm dam-
their DNA. Researchers did as potatoes, canola, and found, including a closely However, scientists suspect age, store large amounts
this for meadows of ribbon bananas. In nature, they related Mediterranean that their seagrass in Shark of carbon, and provide a
weed seagrass called often reside in places with seagrass called Posidonia Bay has genes that are habitat for a great diversity
Posidonia australis in the extreme environmental oceanica, which cov- extremely well-suited to its of wildlife. Conserving and
shallow sun-drenched conditions. ers more than 15 km (9 local, but variable environ- also restoring seagrass
waters of the Shark Bay miles) and may be around ment, and perhaps that meadows has a vital role in
World Heritage Area, in Polyploids are often sterile, 100.000 years old. is why it does not need to climate change mitigation
Western Australia. but can continue to grow have sex to be successful. and adaptation.
indefinitely if left undis- WHY DOES THIS
The result shocked the turbed. This seagrass has MATTER? Even without success- Seagrasses are not im-
researchers: it was all one done just that. ful flowering and seed mune from climate change
plant. One single plant has In the summer of 2010–11, production, the giant plant impacts: warming temper-
expanded over a stretch of HOW OLD IS THIS a severe heatwave hit land appears to be very resil- atures, ocean acidification,
180 km (112 miles) making PLANT? and sea ecosystems along ient. It experiences a wide and extreme weather
it the largest known plant the Western Australian range of water tempera- events are significant chal-
on Earth. The sandy dunes of Shark coastline. tures (from 17ºC/63ºF to lenges for them.
Bay flooded some 8,500 30ºC/86ºF in some years)
Scientists collected shoot years ago, when the sea Shark Bay’s seagrass and salt levels. However, the detailed
samples from ten seagrass level rose after the last ice meadows suffered wide- picture we now have of
meadows from across age. Over the following spread damage in the Despite these variable the great resilience of the
Shark Bay, in waters where millennia, the expanding heatwave. Yet the ribbon conditions and the high giant seagrass of Shark
the salt levels range from seagrass meadows made weed meadows have light levels (which are typi- Bay provides us with the
normal ocean salinity to shallow coastal banks and started to recover. cally stressful for seagrass), hope they will be around
almost twice as salty. In sills through creating and the plant can maintain its for many years to come,
all samples, they studied capturing sediment, which This is somewhat surpris- physiological processes especially if serious action
18.000 genetic markers made the water saltier. ing, as this seagrass does and thrive. So how does it is taken on climate change.