Document zo9q1B6BVGRjp48wQj1prG2Ra

per und rinc lead to regressive changes in the gut diverticula and damage to the stomach wall. Predatory animals which do not normally accumulate metals may as a result of their feeding behaviour attain a sufficient quantity of these metals to kill them. For example, an inshore demersal fish feeding on the ragworm may die as a result of the worm's ability to concentrate copper in its tissues. Copper and zinc discharged from estuaries may prevent Atlantic Salmon reaching their spawning grounds, for it has been discovered that they will avoid waters containing these pollutants even at very low concen trations. Mercury and Silver The industrial uses of mercury compounds arc numer ous; (hey are used as fungicidal seed dressings, in paper making, and as cata lysts in the manufacture of PVC. Numerous cases of sterility of seed-eat ing birds and predators, including man, Iwvc been (raced to the habit of seed dressing with mercury compounds. This practice is also a harard to coastal marine life which is exposed to mercury' as a result of fresh-water run off. A recent research report that a very low concentration (1 part per billion) of fun gicidal mercury is sufficient to cause a 50 per cent drop in photosynthetic activity of a pbytoplanktonic test organism is particularly alarming, for such concentrations are frequently found at the mouths of rivers draining agricultural land and near industrial outfulls. It is possible that inshore phytoptunkion land consequently those animals that feed on it) are being seriously affected. The concentration of mercury and silver found around certain industrial outfalls is also sufficient to cause abnor mal or inhibited development of eggs and larvae of certain barnacles and sea urchins. Other marine organisms, how ever may accumulate meiale without any readily apparent harm being done to them. Some shellfish and fish have such a high concentration of mercury within their tissues that people are ad vised not to eat them for fear of being poisoned. From 1953 to 1960 almost one hundred people were killed after eating ftsh and shellfish taken from Minamata Bay in Japan. The cause of their death was a lethal amount of mer cury in the bodies of the marine life derived from the mercury-laden effluent of a plastics factory. The danger of mercury in the marine environment has now been recognised by many governments, but how many other metals may be accumulating un detected in the bodies of sea life? From the few examples cited it can be seen that the directly poisonous action of heavy metals is not the only consideration, for there is evidence that long-term accumulation and concentra tion of metals by marine organisms can lead, if not always to their own death, to death of others that eat them. Clearly discharge of heavy metals into coastal waters should be actively discouraged. Pesticides and PCBs Pesticides are deliberately applied in the terrestrial environment in order to con trol insect pests, weeds, fungi etc. They reach (he sea not only as a result of land drainage, but also from the atmos phere. Indeed, it has been concluded by some American workers that the observed distribution of the chlorinated hydrocarbon pesticide DDT and its re sidues off the coast of California can only be explained by assuming distribu tion through the atmosphere. Corro boratory evidence for atmospheric dis tribution comes from the fact that prganochlorine residues can be detec ted in ice and in the fatty tissues of penguins and seals from the Antarctic where pesticides to the best of our know ledge have never been appiiod. Polychlorinated biphenyls (PCBs). unlike pesticides, reach the environment by accident. They are used in the manu facture of paints and varnishes, as soft eners in plastics, and for improving elec trical insulation in cables. Many high temperature lubrication oils now con tain PCBs. PCBs reach the ocean in liquid waste from industrial and domes tic sources, from decomposing rubbish dumped at sea. and from the atmos phere polluted by smoke from Industry, motor vehicles and rubbish dumps. The danger of both chlorinated hydrocarbon pesticides and PCBs is that they are extremely stable aod persist for long periods of time without biodegrad ing into a harmless form. Some organochlorines have been in use for 30 years or more so that if only minute quanti ties have been reaching the sea during this period they have had lime to buttd up in the water and sedimenta. In addi tion many invertebraies have the ability Heat h strundline in the age of the non-returnable container. MQNS 085053 to concentrate them many thousands of times and store them in their fatty tissues in much the same way as metals ere concentrated and stored. Many planktonic species of animal and plant as well as fish and benthonic invertebrates are extraordinarily sensitlve to organochlorine pesticides, especi ally in the earlier stages of their life history, and can be killed outright by residues reaching the sea by land drain age and in effluents from manufacturing plants. The waste from a parathion manufacturing plant on the Danish North Sea Coast led to many dead and dying lobsters being cast up on local beaches. Other species higher up food chains may be poisoned by eating animals and plants that have accumula ted pesticides in their tissues. Sandwich Terns dying in tremors and convulsions in the Danish Waddenzee were found to have been poisoned by chlorinated hydrocarbons passed on from herrings and sand eels, which in turn had been feeding on planktonic and benthonic coptpod invertebrates with a high level of organochlorine entering their diet due to pesticide discharge from the Rhine. By the time the pesticides had reached the Terns they had been con centrated many thousands of times. Doe to the greeter sensitivity to pesticides of some marine species as compared with others, the balance of certain ecosy stems can be seriously affected, animals at the top of the food chain dying as a result of non-availability of a particular food source. The demise of the CallforniAn Sardine industry has been attri buted to such a situation. As disturbing as the direct kills attributed to pesticides are the numerous sub-lethal effects that have been reported in scientific papers. Thme include alterations in body chemistry, disturbance of growth and gonad forma tion. interference with themiaJ acclima tion mechanisms, lowering of resistance to disease, and changes in the basic behaviour patterns of various species. Of necessity much of this experimental work has been carried out on commer cially important shellfish and fish but this does not mean that other groups of animals are aoy the less affected. Organophosphorous and carbamate pesticides which are oow being used increasingly for pest control are much leu stable than orginochlorines and consequently do not accumulate through food chains to the same degree. There is thus leu chance that animals higher up the food chains will receive sufficiently large doses of pesticides to affect their biology. The chemical similarity between PCBs and organochlorine pesticides suggests similar physiological effects on marine organisms. However, at present little is known of the adverse effects of PCBs. although in laboratory experi ments it has been shown that these chemicals can effect the production of sex hormones in such a way that animals are rendered infertile. It may not be entirely coincidental that the fer tility rate of guillemots at breeding situ on the British West coast is dropping. In September 1969 between 10 and IS,000 dead sen birds, mostly guille mots, were washed up along the west coast of Britain. Although it is by no means certain what caused their deaths, fatty tissues of the birds contained re latively high amooats of PCBs. Marine life will be increasingly placed at risk if the release of chlorinated hydrocarbon pesticides and PCBs into the environment is allowed in anything but very small quantities. No-one will deny the short-term benefits that have been reaped by the use of DDT and its derivatives but we have got to consider the long-term consequences of their use. Already in a confined area like the Baltic marine species contain on aver age 8-10 timet more DDT than the same species in the North Sea. Organo chlorine pesticide* should only be used in an emergency and should not be applied as a prophylactic. Radioactive waste Radiation has long been recognised as a factor constituting a potential hazard to human populations, if not to marine life. Radioactive materials reach the sea (!) from the atmosphere (2) as a result of natural leeching of rocks con taining radioactive compounds (3) from containers of radioactive waste dumped at sea (4) from outfall pipes of coastal nuclear installations. Due to concern over the wide dis semination of radioactive dust following nuclear explosions in the atmosphere very small amounts of radioactive dust take plaoe above ground. Hence only very small amounts of radio active dust in excess of the background quantities oow reach the sen via the atmosphere. In certain coastal areas of the world high background radiation is present due to naturally occurring radionucleides in the soil. Unfortunately, there is as yet ao published information avail able on the effects on marine life in these areas, although statistical surveys on human populations in one of these regions has shown a significantly higher than normal rate of occurrence of chromosome abnormalities. Radioactive wastes of short half-life can be stored at the point of production until inactive, but the problems of stor age of wastes which deray at a slow rate are enormous. Much radioactive waste is stored in heavily shielded containers on land, but other wastes are enriaert and dumped in selected deepwaiar sites in the ocean. Due to the high coat of providing adequate shielding for dum ped containers, some do not completely prevent escape of radiation. It must be accepted, therefore, that damage to marine life may occur in the region of these dumps. The continuous discharge of low level radioactive wastes from coastal nuclear plant may also be raining sub-lethal damage to marine life in the vicinity of the discharge point For it has bean shown experimentally that low leveia of radiation can cause chramoeamal damage, with subsequent growth ab normalities, in both maria* inverte brates and vertebrates. Effects may be even more subtle, as there is 'some evidence to suggest that exposure at fish to radiation can reduce Mr ability to tolerate changes in temperalure and salinity. Marine organisms, such as alga* and shellfish, which concentrate metals can not discriminate between radioactive and non-radloactive elements. Thus the radiation levels in certain orgaatims may be many thousands of times higher than that in the surrounding seawater. For example, oysters gathered some 230 miles from a nuclear source west seen to contain 200,000 times more radio active zinc than the surrounding ocean. In theory the existing regulation mint ing to the discharge at radioactive waste take into account the ability at many organisms to concentrate elements in their tissues. However, the number of species examined in relation to the number occurring in coastal waters is very small. It is certainly unwise to set any acceptable dose levels of radiation as far as marine life is conoereed in view of the subtle nature of radiation damage unless they are baaed on toog-ienn statistical experiment*. 7 HUNS 0ti505A