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Hong Kong: Toxic red tides again!
Marine Pollution Bulletin
consortium Nuova Venezia, made up of 200 pubIic and private designers, engineers, and construction groups. It has taken 25 years to reach agreement and it is hoped that the plan will be implemented by the year 2000. The Venice lagoon will be protected by three mobile dams which will cover the three entrances and yet cause the minimum of disturbance to the shipping wharf in Venice's harbour, which itself will be modernized and enlarged. The dams will be formed from 80 enormous steel canisters which will be able to be inflated at the forecast of any surges of exceptionally high waters. Normally they will lie on rubberized cushions on the sea floor across the entrances of the Lido, Chioggia and Malamocco channels. Once floating they will effectively seal the lagoon off from the open sea. The canisters will be remote-controlled and they will be precisely positioned by the movements of air in and out. The canisters will be 20 m long, 17 m deep and 4 m thick and will rest on a 1300 t rubberized steel frame. At the present time the surges at high water mean that certain parts of the city are underwater at least 50 times a year. Natural geological changes coupled with rise in sea level from the melting of glaciers in the North Pole have both been blamed and are believed to be the underlying cause of the recent subsidence of the lagoon floor and the increase in exceptional high water surges. Prototypes for the barrier have been under test for at least 2 years and involve pioneering technology which it is hoped will allow Venice to win its battle against the elements. PHILIPPA AMBROSE
Hong Kong: Toxic Red Tides Again! The first toxic red tide in Hong Kong occurred in March 1989 when an enclosed bay in the eastern portion of Hong Kong, namely Junk Bay, was affected by the bloom of a toxic dinoflagellate species. During the bloom, the seawater was discoloured by Alexandrium catenella at a maximum concentration of up to 5000 cell ml-l and an extremely high level of PSP toxins (>13 500 MU kg-1) was detected in the tissues of green-lipped mussels. Shellfish sale was suspended for almost two weeks leading to significant losses in the aquaculture industry In the middle of March 1990, Alexandrium catenella toxins were again detected and a PSP level of 20 000 MUS kg-1 occurred in shellfish samples collected at the southern portion of Hong Kong Island. However, this toxicity was not immediately announced to the public by the relevant authorities since the affected waters were not fishery and aquacultural grounds and there was concern that the shellfish toxicity announcement would result in overreaction by the general public. Some scientists speculate that A. catenella was imported into the coastal waters of Hong Kong through oceanic currents, particularly the Kuro Shio Current, which is dominant in the southeastern portion of Hong Kong during winter, and that it bloomed as a result of 4
optimal climatic factors and water quality. However, a recent survey carried out in the Department of Botany, University of Hong Kong, revealed that the cysts of this toxic dinoflagellate persist in the sediments of eastern Hong Kong waters. Although the concentration of cysts is rather low (10-20 cysts kg-l of sediment), their presence indicates that these toxic dinoflagellates will bloom again during similar seasons, in coming years. JOHN HODGKISS K. C. HO
Ozone Layer Hits Record Low Japanese and American scientists working in the Antarctic have recently released new figures that indicate a further deterioration in the ozone layer. Measurements sent back by the NASA satellite, Nimbus 7, show that the ozone layer is thinner than last year. These findings were confirmed by the space shuttle Discovery which carries an ultraviolet detector in its cargo bay. Continued deterioration of the ozone layer has also been reported by the Japanese Antarctic expedition. Record low values were recorded for September 1990. The Japanese meteorological agency, using measurements taken by the expeditions, have also shown that the 'hole' in the ozone layer is getting larger.
Beluga Whale Deaths Alarm has been growing in recent months over the deaths of many beluga whales in the St Lawrence Estuary, Canada. Around one corpse a week is being washed up, exhibiting a range of symptoms of the digestive and immune system as well as tumours. The corpses are so heavily polluted that they must be treated as toxic waste. The St Lawrence flows from the Great Lakes through the industrial heartlands of North America. A cocktail of chemicals including PCBs and Mirex, the production of which is now banned, as well as DDT, BAP, and a range of PAHs derived from many varied sources, including several old dump sites. The prospects for an effective clean-up operation are therefore reduced. Though the main beluga whale populations are found in the open ocean it is feared that the isolated St Lawrence population may soon be wiped out. Local Fisheries widely exploited by Mohawk Indians have been closed as a result of the pollution. PETER JONES
Monk Seals Threatened It is feared that a virus similar to that which killed 20 000 seals in the North Sea two years ago may now threaten one of the world's rarest marine mammals, the monk seal. Scientists from the Veterinary Research Laboratory, Belfast have been analysing tissue samples from the 400 striped dolphins washed up in recent months (Mar. Pollut. Bull. 21, 501). They have isolated
consortium Nuova Venezia, made up of 200 pubIic and private designers, engineers, and construction groups. It has taken 25 years to reach agreement and it is hoped that the plan will be implemented by the year 2000. The Venice lagoon will be protected by three mobile dams which will cover the three entrances and yet cause the minimum of disturbance to the shipping wharf in Venice's harbour, which itself will be modernized and enlarged. The dams will be formed from 80 enormous steel canisters which will be able to be inflated at the forecast of any surges of exceptionally high waters. Normally they will lie on rubberized cushions on the sea floor across the entrances of the Lido, Chioggia and Malamocco channels. Once floating they will effectively seal the lagoon off from the open sea. The canisters will be remote-controlled and they will be precisely positioned by the movements of air in and out. The canisters will be 20 m long, 17 m deep and 4 m thick and will rest on a 1300 t rubberized steel frame. At the present time the surges at high water mean that certain parts of the city are underwater at least 50 times a year. Natural geological changes coupled with rise in sea level from the melting of glaciers in the North Pole have both been blamed and are believed to be the underlying cause of the recent subsidence of the lagoon floor and the increase in exceptional high water surges. Prototypes for the barrier have been under test for at least 2 years and involve pioneering technology which it is hoped will allow Venice to win its battle against the elements. PHILIPPA AMBROSE
Hong Kong: Toxic Red Tides Again! The first toxic red tide in Hong Kong occurred in March 1989 when an enclosed bay in the eastern portion of Hong Kong, namely Junk Bay, was affected by the bloom of a toxic dinoflagellate species. During the bloom, the seawater was discoloured by Alexandrium catenella at a maximum concentration of up to 5000 cell ml-l and an extremely high level of PSP toxins (>13 500 MU kg-1) was detected in the tissues of green-lipped mussels. Shellfish sale was suspended for almost two weeks leading to significant losses in the aquaculture industry In the middle of March 1990, Alexandrium catenella toxins were again detected and a PSP level of 20 000 MUS kg-1 occurred in shellfish samples collected at the southern portion of Hong Kong Island. However, this toxicity was not immediately announced to the public by the relevant authorities since the affected waters were not fishery and aquacultural grounds and there was concern that the shellfish toxicity announcement would result in overreaction by the general public. Some scientists speculate that A. catenella was imported into the coastal waters of Hong Kong through oceanic currents, particularly the Kuro Shio Current, which is dominant in the southeastern portion of Hong Kong during winter, and that it bloomed as a result of 4
optimal climatic factors and water quality. However, a recent survey carried out in the Department of Botany, University of Hong Kong, revealed that the cysts of this toxic dinoflagellate persist in the sediments of eastern Hong Kong waters. Although the concentration of cysts is rather low (10-20 cysts kg-l of sediment), their presence indicates that these toxic dinoflagellates will bloom again during similar seasons, in coming years. JOHN HODGKISS K. C. HO
Ozone Layer Hits Record Low Japanese and American scientists working in the Antarctic have recently released new figures that indicate a further deterioration in the ozone layer. Measurements sent back by the NASA satellite, Nimbus 7, show that the ozone layer is thinner than last year. These findings were confirmed by the space shuttle Discovery which carries an ultraviolet detector in its cargo bay. Continued deterioration of the ozone layer has also been reported by the Japanese Antarctic expedition. Record low values were recorded for September 1990. The Japanese meteorological agency, using measurements taken by the expeditions, have also shown that the 'hole' in the ozone layer is getting larger.
Beluga Whale Deaths Alarm has been growing in recent months over the deaths of many beluga whales in the St Lawrence Estuary, Canada. Around one corpse a week is being washed up, exhibiting a range of symptoms of the digestive and immune system as well as tumours. The corpses are so heavily polluted that they must be treated as toxic waste. The St Lawrence flows from the Great Lakes through the industrial heartlands of North America. A cocktail of chemicals including PCBs and Mirex, the production of which is now banned, as well as DDT, BAP, and a range of PAHs derived from many varied sources, including several old dump sites. The prospects for an effective clean-up operation are therefore reduced. Though the main beluga whale populations are found in the open ocean it is feared that the isolated St Lawrence population may soon be wiped out. Local Fisheries widely exploited by Mohawk Indians have been closed as a result of the pollution. PETER JONES
Monk Seals Threatened It is feared that a virus similar to that which killed 20 000 seals in the North Sea two years ago may now threaten one of the world's rarest marine mammals, the monk seal. Scientists from the Veterinary Research Laboratory, Belfast have been analysing tissue samples from the 400 striped dolphins washed up in recent months (Mar. Pollut. Bull. 21, 501). They have isolated