Volume 17/Number 9/September 1986
Juan de Fuca Ridge Exploration Focuses on Hot Water Vents A joint Canadian/American expedition with the deepdiving submersible, Pisces IV, and the tender, Pandora II, is under way to explore the underwater steam vents at 1600-2000 m depth in the Juan de Fuca Ridge. The team led, by marine biologist Verena Tunnicliffe, is studying, among other things, the sea animals unique to the hot, sulphur-laden marine environment of hot vents. Ms. Tunnicliffe discovered these hot vents and their associated fauna, 320 km off the west coast of southern Vancouver Island, on an expedition in 1983, when geologists also found rich deposits of zinc and copperbearing sulphides (see Mar. Pollut. Bull. 17,241). The Juan de Fuca Ridge is a craggy underwater mountain ridge, mostly 2000-2500 m below the surface, off the west coast of North America, extending from near the northwestern tip of the Queen Charlotte Islands to a point about 250 km west of northern California. Down the centre of this range runs a great crack, or rift. Along this rift, two of the crustal plates, the Juan de Fuca Plate to the east and the Pacific Plate to the west, are drifting apart at the rate of 2-6 cm per year. Lava from the earth's mantle wells up into the rift, cools and solidifies on the edges of the diverging plates. It is in the rift that the hot vents occur and the unique ecosystem has developed. The temperature of hydrothermal emissions has been measured at 304"C, but they are known to be even hotter. Seawater seeps downward into the fractured ocean crust where it is heated to as much as 400"C. The superheated seawater leaches metals from the rocks beneath the seafloor and transports the minerals in solution upward to the surface of the vents. As this hot, metal-rich seawater mixes with the near-freezing ambient seawater it cools rapidly, precipitating out the minerals as sulphides, and forms chimneys that can be as much as 30 m high. Dense billowing plumes of rapidly precipitated minerals gush out of these chimneys, known as 'black smokers' or ~white smokers', depending on the temperature and contents of the mineral-laden seawater. Deposits of iron, copper, zinc, and lead sulphides, and iron and manganese oxides are being accumulated around the hydrothermal vents. Rather than by photosynthesis, the basic carbon material is produced by chemosynthesis in this deep, dark oceanic zone. The bacteria derive their energy and food by oxidation of the hydrogen sulphide and methane; and the corals, tube worms, anemones, sponges, and clams feed on the abundant bacteria. Squat lobsters, brittle stars, and snails feed on the lower organisms present below the hydrothermal vents. Many of the organisms found near these vents are new to science. Adaptation to high temperature and high metal concentrations in these creatures is one subject of considerable interest to ecologists. M I K E WALDICHUK
Sewage Pollutes Vancouver Beaches Sunset Beach, one of the most popular beaches in Vancouver, was posted as unsafe for bathing because of
high faecal coliform counts during the first week of July 1986. The standard used for posting of beaches as unsafe for bathing by medical health authorities in British Columbia is an MPN (most probable number) of 200 or more faecal coliforms per 100 ml. The chief medical health officer of Vancouver stated that weekly testing over a 30 day period showed an MPN of 243 faecal coliforms per 100 ml at Sunset Beach. He noted that no problems were found in the sewage treatment plant and no breaks had been discovered in the Greater Vancouver Regional District sewerage system. There is increasing evidence that the source of sewage in the beach waters is from the large number of recreational vessels in the area at this time of year. Panorama Beach in Deep Cove of Indian Arm and Eagle Harbour in West Vancouver on outer Burrard Inlet have also been posted by the North Shore Health Unit as unsafe for bathing because of high coliform counts. Heavy traffic of recreational boats in these areas has also been suggested as the source of the high counts. MIKE W A L D I C H U K
Round-the-World News Ecuador The Government of Ecuador has declared the waters surrounding the Galapagos Islands a marine reserve. The previously unprotected marine areas will now safeguard the unique marine fauna living in the waters surrounding the archipelago made famous by Charles Darwin over 150 years ago. The islands were declared a national park in 1959 and were subjected to a disasterous fire in 1985 which devastated nearly 400 square kilometres of wilderness.
Japan Mercury pollution is posing a major threat to ground water in Japan. Apparently mercury, a key component in most batteries, is seeping into the soil around refuse dumps and contaminating the ground water. The problem is so great that local stores are being urged to encourage people to return their exhausted batteries for safe disposal. One Tokyo suburb collected 64 tonnes of batteries in two years.
Canary Islands Telecommuniation engineers have been experiencing problems with a new undersea fibre optic cable between Teneriffe and Gran Canaria. Sudden electrical leaks were detected at depths between 1000 and 1700 metres. Retrieval of the cable revealed shark teeth embedded in the punctured areas which are thought to belong to a small deep water species. Traditional coaxial cable has rarely been damaged by sharks and it is thought that the sharks may be responding to small electro-magnetic fields around the power lines to the fibre optic system repeaters. 393