Freshwater Fish Directive

EEC Directive on information on water pollution 78/176/EEC Directive on titanium dioxide waste 78/659/EEC Directive on water standards for freshwater fish 79/115/EEC Directive on pilotage of sea vessels... 

Exposure of two species of freshwater fish to 0.106 ppb of a commercial formulation containing 50% methyl parathion increased serum levels of T3 and reduced T4 (Bhattacharya 1993). This effect was attributed to inhibition of acetylcholinesterase activity in the fish brain, but no direct evidence was presented. Similar treatment of freshwater perch for 35 days resulted in decreased release of progesterone from the ovaries (Bhattacharya and Mondal 1997). Also, treatment of freshwater perch for up to 90 days with methyl parathion induced a decrease in the gonadosomatic index (not defined) after day 15 of... 

Within an ecotoxicological perspective, mammalian methods cannot be extrapolated automatically to other species. Sperm of teleosts, for example, differs in a few very important aspects from that of mammals. Unlike mammalian sperm it is not motile on ejaculation and attains motility only on contact with water. After activation it only moves for a few minutes (for freshwater fish typically around 1 min). Furthermore it enters the egg via the micropyle rather than through an acrosomal reaction. The first minute after the start of motility is therefore crucial to its success in fertilizing an egg, and even when it is deposited on the egg s surface it still has to move fast enough in the right direction to reach the micropyle. Clearly the fertilizing ability of fish sperm is very dependent on its motility, and any pollutant that decreases this movement may be expected to affect fertilization. 

Humans eat fish of more than 1000 fish species approximately 350 of these species are regarded as commercially valuable. The term fish products applies to all marine and freshwater animals, including finfish (i.e., scale fish or bony fish, and sharks and rays) and shellfish (i.e., the crustaceans [e.g., prawns, shrimps, lobsters, Antarctic krill], and mollusks [e.g., squid, oysters, abalone]). The only exceptions are aquatic mammals and frogs (EC Directive 91/493/EEC). Overall, the number of species from aquatic environments consumed by humans is consequently much higher. The marine and freshwater fish consumed by humans are mainly wild-caught. On the other hand, cultured fish contribute about 12% to the world fish catch, but these are mainly freshwater fish. Edible parts of fish include fillets (mainly the muscle tissue called the fish meat, with or without skin), carcasses (e.g., canned), and by-products of some fish species, mainly gonads (roe) and livers (of lean fish). 

Freshwater fish populations can be directly damaged by prolonged exposure to diazinon... 

The set of data that are regularly obtained on radionuclide concentrations in locally produced agricultural foodstuffs can be used directly to assess the annual intake and the associated committed dose. In regions where the inhabitants normally consume substantial amounts of natural food products (e.g. game, freshwater fish, forest mushrooms and berries) with elevated radionuclide concentrations, available data from measurements should also be used for the estimation of intakes of radionuclides. 

Figure 3. Time course of Na+ binding to the exterior surface ( , gill and body combined) of 10 g rainbow trout compared with uptake into the entire plasma volume (O) or whole livers ( ) of the fish. Na+ uptake into the liver is also normalised to 0.325 g of fresh liver weight (A) to enable a direct comparison with the blood volume of the 10 g fish (0.325 ml, see Gingerich and Pityer [87]). Fish were dipped in 500 ml fresh water containing 0.2 mmol l 1Na+ and 10 p,Ci of 22Na+ (see [30] for other water-quality details), and then rinsed in 30 1 of unlabelled freshwater for 15 s to remove excess radio-isotope. Data are means S.E. (n = 6 fish). Note that Na+ measurements in/on tissues are absolute amounts in nmoles, not concentration units...

Previous studies have found that cyanotoxic compounds may accumulate in sym-patric plants as well as in the tissues of herbivorous fish and invertebrates (reviewed in Zurawell et al. 2005). The accumulation of cyanotoxins at these trophic levels provides a direct path to both aquatic and, potentially, terrestrial consumers (Negri and Jones 1995 Kotak et al. 1996 Giovannardi et al. 1999). However, these compounds are rarely encountered in higher trophic levels in freshwater systems (Kotak et al. 1996 Zurawell et al. 2005). Nevertheless, attempts to minimize cyanotoxins in water bodies for recreational use should remain a major focus of environmental and public health managers, especially in light of the evidence that low doses may still have sublethal effects on the larval development of aquatic vertebrates (Oberemm et al. 1999). 

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