Death of fish

Spraying of PCP to control populations of water snails in rice fields of Surinam resulted in the death of fish and birds, including snail kites (Rostrhamus sociabilis), certain egrets and herons, and wattled jacanas (Jacana jacana). Levels of PCP in these birds and their food items suggested that PCP-contaminated food probably caused the deaths (Vermeer et al. 1974) (Table 23.5). 

As noted above, Gyrodinium aureolum, has been implicated in the death of fish and benthic invertebrates in the North Sea (principally southern Norway, 61) and the Irish Sea, but only since 1966. It was first described from Massachusetts but has not caused kills in that region. 

The toxicity of aluminum has been recognized most clearly by the development of bone disease caused by deposition of A1 in bones of patients on hemodialysis and in infants on intravenous therapy/ 6 Excessive A1 in the water used for dialysis may also cause brain damage. Dietary aluminum may be one cause of Alzheimer s disease/ h but this is controversial as is a possible role of aluminum in vaccines in causing inflammation in muscle.1) Solubilization of soil aluminum by acid rain has been blamed for the decline of forests in Europe and North America,) for the death of fish in acid waters,k and for very large reductions in yield for many crops/ An aluminum-resistant strain of buckwheat makes and secretes from its roots large amounts of oxalate which binds and detoxifies the Al3+ ions. ... 

But reduced energy use is only part of the story. Synthetic N, P, K are very soluble in water. This makes it easy for plants to use them, but synthetic fertilizer that is not taken up by the plants readily runs off or leaches out of the field into streams or into groundwater. The consequences have been serious. Excess nutrients in lakes and rivers cause algae to multiply and use up all the oxygen, resulting in death of fish and shellfish. Each summer, a 6,000-square-mile dead zone forms at the mouth of Mississippi River due to high levels of nitrogen and phosphorus drained from thousands of acres... 

C20H26NO3P, Mr 359.41. Toxin from the dinoflagellate Ptychodiscus brevis, a constituent of the so-called red tide, a massive reproduction of dinoflagellates that sometimes leads to the extensive death of fish and shellfish. The toxicity of PB t. for the common guppy, Lebestes reticulatus, amounts to 1 ppm (LDioo). PB t. acts as an inhibitor of acetylcholinesterase and belongs to the same structural type as many, commercial insecticides or neurotoxins. 

Explain why fertilisers in rivers can cause the death of fish. 

These data show that deaths of fish in natural waters under the conditions prevailing today, have not been observed in countries such as the Federal Republic of Germany [90]. 

The death of fish is the most highly publicized effect of acid rain, yet even the loss of fish is due not just to the direct action of acidity itself but also to more subtle changes in the chemistry of lakes brought about by acid rain. It is now known, for example, that acid rain dissolves aluminum — one of the most abundant elements in the soil — and carries it into lakes and streams at levels toxic to fish. Aluminum interferes with salt balance, and produces a clogging of the gUls that causes fish to literally suffocate to death. 

During the past several decades, acid rain in eastern North America has caused sensitive lakes and streams to acidify, leading to the decline and death of fish and other aquatic life. The ex-... 

As discussed in Chapter 1, fish have been lost from several hundred acidified lakes and streams in the Adirondacks, Ontario and Nova Scotia, as well as in Scandinavia. The death of fish illustrates a particularly insidious aspect of acid rain the effects of acidity can be synergistic. For example, acidity can kill fish by interfering with the fish s salt balance by causing reproductive abnormalities by leaching aluminum into the lake at levels toxic to fish gills, so that the fish literally suffocate and by kUling the organisms on which fish feed. The combined effect of these stresses can wipe out a fish population. 

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