Divernet

Now, you wont be late, will you
The words kept reverberating in my mind as I frantically grabbed my diving gear, hurriedly sealed my camera in its underwater housing and drove to Falmouth station.
I was to pick up Dr Jason Hall-Spencer, a research fellow of Glasgow University who had come to dive on the maerl beds in the Fal estuary. I had been asked to act as his guide.
It was Saturday morning and I had been away from home. Dropping in to pick up gear is not the ideal way to prepare for a dive. As it turned out, being a few minutes late was the least of my worries.
Conditions could hardly have been better. It was March, but it could have been early summer. The skies were clear and the sea flat, with hardly a hint of wind. Under water, the red maerl beds glistened as the suns rays danced over them.
Jason was impressed by what he saw. One of the best beds Ive seen, he declared.
Maerl is a type of calcified seaweed that forms a mattress of branching, reddish-to-purple-coloured twiglets just a few millimetres thick. It looks like a miniature coral reef. The water was crystal clear, which helped reinforce the illusion of being on some tropical reef.
But abandoning myself to paradise didnt last long. Something was wrong: bubbles were streaming past my face mask. With a sickening feeling I looked down, not wanting to believe my eyes - the bubbles were coming from my camera housing. There was already a good mug-full of water swishing around the camera. For the umpteenth time, I vowed never again to rush my preparations, and always to check my camera housing seals before submerging!
Its strange how one reacts. I surfaced, passed the camera to the boatman, and resumed the dive. There was nothing else I could do. I already knew that the camera was a write-off, so I might as well enjoy the dive.
This is one of the few places around the British coast where you can dive in winter or early spring and find the bottom teeming with life, thanks to these maerl beds. Its a brilliant dive, but one often overlooked because its so near the main launch site for this area - Falmouth slipway, by the docks.
I had taken Jason to the Roseland headland in the Fal estuary by the green-painted East Narrows navigation buoy - due east and one mile from the docks. This is the edge of the shipping channel into Falmouth docks. Its the old river bank created thousands of years ago, when the Fal was a river valley.
Eastwards from the buoy towards the shore stretch several acres of maerl beds, among the best and biggest in England.
Westwards from the buoy, the bottom starts to shelve from 10m to just around 20m - the edge of the old river bank - and a rock wall drops vertically to 30m. This wall is heavily fractured, providing an ideal refuge for squat lobsters, edible crabs and all the species of wrasse found in British waters, such as cuckoo, ballan, goldsinny, corkwing and rockcook.
Incoming tides also bring at certain times of the year shoals of mackerel and bass, dolphins, basking sharks and giant jellyfish. In September, the crevices in the wall are crammed with hundreds of mating pairs of velvet swimming crabs, exciting swarms of fish into a feeding frenzy.
For me, the best way to dive this site is to drop off by the East Narrows buoy in about 8m of water, fin to the edge of the old river bank and descend the wall diagonally until you are as deep as you want to go - 25, 30 or 40m. Then slowly ascend the wall vertically, and fin back over the bank and onto the maerl beds in 7-4m of water, spending as much time as you like taking in all the marine life.
Its really two dives in one, with a total dive time of 45 minutes or more but without necessarily coming anywhere near decompression stops.
Among the first things to greet you on the dive are often thornback rays looking for crabs and small molluscs among the maerl. Heading westwards, the bottom shelves and you pass over a bed of vase-shaped seasquirts before hitting outcrops of rock which signal the edge of the bank and the start of the wall.
Finning southwards down the slope, the wall gradually emerges from the maerl/shell bottom, revealing its full face at a depth of about 25m.
Travelling across the face is like peering through the windows of a towerblock of flats. At each level or crevice there is a community of animals and plants. You might see a goby flanked by prawns in one, a goldsinny and edible crab in another.
However sunny a day it is, down here lights are essential. At 30m it can be pitch black. Here you are likely to encounter dogfish, cuckoo wrasse and pollack. For the adventurous, the slope steepens at the end of the wall, descending to 40m or more and the bottom of the old riverbed.
This is a popular area for scallop-collecting, and local divers come here for spectacular night dives, emerging with bulging sacks of shellfish.
This is also a shipping channel, and on the bottom can be found all manner of objects dumped or lost from ships that have passed overhead through the centuries. Old bottles are a favourite collecting item. Plates, cutlery and ammo have also been found - even cannonballs.
We once picked up what looked like a cake of Stilton, about a foot in diameter. It turned out to be phosphorus, and it spontaneously ignited when it came into contact with the air! So beware of strange objects.
Jasons object of desire was anything but strange. In the Fal maerl is everywhere, with the dead variety lining the seabed - but looks can be deceptive.
His mission was to collect both live and dead samples for carbon-dating. For the past 20 years dead maerl has been harvested intensively in the Falmouth estuary and environmental agencies such as English Nature fear that because of slow growth rates, commercial extraction is not sustainable. It wants it stopped.
I didnt really appreciate the age of this maerl until several months later, when Jason started to get results back from the lab. I was astonished. The live maerl is likely to be between 200 and 700 years old, and the dead maerl probably dates back to before the first millennium!
No wonder English Nature is worried. How long will it take to replace What we see has taken thousands of years to create.
Maerl is composed of chalk - calcium carbonate - with an outer living plant layer. Extracting calcium carbonate from the water takes time for the plant, which means that maerl grows only by a small amount each year - probably 2-7mm. The warmer and clearer the waters, the faster it grows.
These maerl beds are very different from what a diver normally encounters, and I have spent hours observing this alien world straight out of Deep Space 9.
Small black eyes watch your every movement, like sentinels amid some performing troupe. On top of a grey vase perches a creature wearing a yellow costume of velvet appearance puffed up to make him look big and powerful. Below it is another character dressed in flowing robes of emerald green - a long-legged spider crab, decked out with sponges and seaweed to camouflage it from marauding cuttlefish and thornback rays.

Dotted around on long stems are rainbow-coloured fans that sparkle as they sweep back and forth, catching the suns rays. These peacock worms disappear down their tubes at lightning speed at the slightest disturbance
Cutting lonely figures on the periphery are heavily disguised dervishes with red scimitars - spider crabs. Rings of transparent arms flashing dozens of blue, iridescent eyes belong to the anemone Cerianthus lloydii, and they are watched by rows of scintillating scallop eyes. Around these bizarre creatures stretches that intertwining structure of purple-red branches.
In March the beds are also covered in red, white and yellow ribbons - the spawn from thousands of sea lemons and sea hares that make an annual excursion to this area.
Its a fantastic site, but a few cautionary notes are necessary. Beginners should not tackle it. They would be perfectly safe on the bank during neap tides but maerl is easily crushed, so it is essential that divers have perfect buoyancy control and can keep off the bottom. The wall is not for beginners anyway, because it can be so dark at depth, and disorientating. Always have a torch and back-up.
There are also strong tides in the Fal and the area is much used for both leisure and commercial activities, so an SMB is essential. Never dive in a spring tide - in mid-tide the water races over the maerl beds at more than two knots and you can be swept several hundred metres in minutes.
Always ascend up the bank, not in mid-channel. Carry a compass and note the banks bearing beforehand.
Fears of pollution from the new outfall sewer pipe by Black Rock at the mouth of the Fal have receded. South West Water is installing further treatment works including sand filtration and ultra-violet disinfection which, we are assured, are intended to make the Fals waters among the cleanest in the country.




Divernet

FACTFILE

GETTING THERE: From Exeter take the A30 to Redruth, then the A393 to Falmouth. Follow the signs to the docks. Falmouth slipway is a few hundred metres further on by the watersports centre, between the car and dinghy park in Bank Place.
DIVING:You must get the all-clear from the Harbourmaster before diving in the East Narrows, as this is a docks area. Call 01326 312285 or fax 01326 211352. Cornish Diving Services, near the slipway, runs trips to the site and others in the region, and has air and nitrox (01326 311265). Falmouth slipway is run from the Harbourmasters office. Launch fee is£5.
ACCOMMODATION: Wide range of hotel, B&B and camping facilities available.
FURTHER INFORMATION: Falmouth Tourist Information 01326 312300.