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Kew magazine
Underwater world
Among tanks of colourful tropical fish and a seaweed-strewn shoreline washed by artificial tides, Carolyn Fry meets the team who look after Kew’s fascinating aquatic displays
Beneath the Palm House lies a very different botanical world from the steamy rainforest that enthrals visitors at ground level. Venture down the spiral staircase at the northern end of the glasshouse and you enter the Marine Display, a unique collection of water-loving plants and some of the many aquatic animals they support.
The stars of this underwater
world are not elegant palms or glossy-leaved citrus trees, but slippery
brown ribbons of kelp and microscopic phytoplankton, which are the smallest
plants in the world. But these algae are no less important than their
terrestrial counterparts. “Marine plants provide
50 per cent of the Earth’s oxygen and take up a vast amount of
carbon dioxide,” says Pete Morris, manager of the Marine and Tropical
Aquatic Freshwater Unit. “They were the forerunners of all the
plants on Earth.”
Together with assistant manager Mark Wilkinson, Pete is responsible for the 19 aquaria in the Marine Display, along with six tanks and half of the pond in the Princess of Wales Conservatory. The Palm House aquaria include warm-water exhibits representing coral reef and mangrove swamp ecosystems, plus cold water habitats found on Britain’s rocky shores and salt marshes.
As young schoolchildren snap pictures of clownfish on their mobile phones, and mums lift up toddlers to peer at tiny orange jellyfish, Pete tells stories about the plants. The young coconut palm in the mangrove swamp tank germinated at Kew, and is possibly the first to have done so under electric light. One slow-growing red alga lives 100m down in the ocean, at the limits of where sunlight penetrates. And the green, feathery fronds of Caulerpa are fantastic at absorbing pollutants and have helped to clean up Monaco Bay in the Mediterranean Sea.
Most of Pete and Mark’s work, though,
takes place out of the visitors’ gaze.
Behind the display, an impressive collection of pipes, pumps, switches,
chillers and nitrogen-removing filters keeps the water at the correct
temperature, turns day into night when required, and ensures the tide
goes in and out twice a day in the exhibit representing Britain’s
rocky shore. In all, the marine tanks hold 10,000 gallons of synthetic
sea water, made on site from pharmaceutical-grade salt and very pure
water. It takes about three hours each morning to ensure everything is
working correctly and to gently hose down habitats such as the mangrove
swamp.
In case something does go wrong and plants or animals have to be replaced, Pete keeps some back-up stocks. One heavy-duty plastic tub is home to a spare beady-eyed water dragon, which cocks its head and eyes him suspiciously as he passes. Another reserve tank holds floating carpets of Salvinia, a water fern that is useful for keeping down unwanted weed species of algae that grow in the aquaria. Piled up against a wall are pieces of white and red coral. Donated by Customs from confiscated shipments, these are used to help create realistic-looking tropical habitats.
Keeping
all the livestock fed is another daily ritual. In addition to the fish,
fiddler crabs, mudskippers and lobsters that live in the Palm House displays,
Pete and Mark look after a range of aquatic livestock in the Princess
of Wales Conservatory. One tank there is home to a mean-looking lone
piranha – having devoured the fish introduced to keep it company,
it now lives with a shoal of guppies that are too fast for it to catch.
The neighbouring aquaria contain green water dragons, rainbow crabs,
frogs, toads and discus fish, all from tropical rainforest regions. They’re
fed on live or frozen fish and shrimps or crickets, depending on their
natural diets.
Opposite these tanks, which line one side of the subterranean corridor in the Princess of Wales Conservatory, are three large circular portholes that give visitors an insight into life beneath the surface of the pond. As Mark drops a mixture of frozen fish and shrimps into the water at feeding time, shoals of giant tetras speed over and begin ripping at the morsels, followed by a surly 60cm-long black shark. When most of the pieces have sunk to the sand, one of the pond’s six freshwater stingrays ripples over, eager to hoover up the leftovers.
One
of the less pleasant jobs is cleaning the aquaria. Every six months or
so, Pete and Mark empty the tanks, scrub the rocks, glass and plants
to remove the algae, then refill them. However, when the portholes need
cleaning, Pete has to don his scuba-diving gear and get into the water
with the stingrays. In light of the death of natural history TV presenter
Steve Irwin, who was stabbed in the heart by a stingray, this sounds
rather dangerous. “They’re fine if you’re careful,” says
Pete reassuringly. “However, one of the stingrays is very friendly and is always around when
I’m in the water – it can be a bit worrying if the water’s
cloudy and I can’t see where he is.”
Looking after the Marine Unit does have its perks, however. Pete and Mark regularly head down to Studland in Dorset to gather new algae and seagrasses for the tanks. In the past, Pete has also travelled to Australia and the Caribbean on missions to collect plants and visit other aquaria.
Every so often, they
make time to design a new display, sourcing various plants and animals
to imitate a specific habitat. The most recent additions are the British
fish exhibit in the Palm House and the green water dragons in the Princess of Wales Conservatory. Next they hope to restock a nearby tank that
currently stands empty. One idea is to track down some black stingrays. “I
love creating a new display and seeing the public’s reaction to
it,” says Mark. “I’ve got kids of my own and watching
children enjoying the displays is the best part of the job for me.”
Carolyn Fry is author of the BBC book The World of Kew.