Organotin compounds are ubiquitous contaminants in the environment. The high biological activity of some compounds toward aquatic organisms lead to deleterious impacts in aquatic ecosystems. Here, the aquatic ecotoxicology of organotins is reviewed based on a multidisciplinary approach involving environmental chemical, toxicological, and ecological aspects. Basic results were obtained both with field and laboratory studies, and some of the most important recent results and conclusions are critically reviewed. The contamination of and fate in aquatic systems is reported and linked with effects at different levels of biological organization. Major emphasis is placed on the development of a concept of ecotoxicology that encompasses not only effect assessment alone, but also integrates environmental chemistry with aquatic toxicology. Thereby, the influence of speciation for bioavailability, basic modes of toxic action, and aquatic toxicity are discussed. This case study on organotins allows to a certain extent generalizations to ecotoxicology in general.

Ecotoxicology of organotin compounds.

Trace minerals in fish nutrition

Factors affecting the proximate composition of cultured fishes with emphasis on salmonids

Review of selenium toxicity in the aquatic food chain.

The utilisation of dietary carbohydrates and their effects on fish metabolism are reviewed. Details on how dietary carbohydrates affect growth, feed utilisation and deposition of nutrients are discussed. Variations in plasma glucose concentrations emphasizing results from glucose tolerance tests, and the impact of adaptation diets are interpreted in the context of secondary carbohydrate metabolism. Our focus then shifts to selected aspects of hormonal regulation of carbohydrate metabolism and dietary carbohydrates and their variable effects on glycogen and glucose turnover. We analyse the interaction of carbohydrates with other nutrients, especially protein and protein sparing, and de novo synthesis of lipids, and finish by discussing the correlation of dietary carbohydrates with fish health.

Carbohydrates in fish nutrition: effects on growth, glucose metabolism and hepatic enzymes

Juvenile trout were reared on either a high available carbohydrate (HC) or low available carbohydrate (LC) diet supplemented with from 0 to 10 micrograms selenium per gram of diet for 16 weeks, to determine if excess liver glycogen deposition affected the metabolism and toxicity of dietary selenium. Trout reared on the HC diet with 10 micrograms selenium per gram diet first demonstrated signs of selenosis and had significantly higher (P less than 0.05) liver selenium levels than trout reared on the LC diet with 10 micrograms selenium per gram diet after 16 weeks, indicating that excess dietary carbohydrate enhances dietary selenium toxicity in trout. The mechanism of the interaction is unclear since neither selenium elimination rates nor carcass and kidney selenium levels were affected by the dietary carbohydrate level. Trout reared on high dietary selenium diets (10 micrograms/g) had an increased incidence of renal calcinosis. In addition, liver copper levels were significantly affected by both dietary selenium and liver glycogen content indicating a significant copper-selenium and copper-glycogen interaction in trout. The development of renal calcinosis and the copper interactions suggest a variety of toxic effects of selenium on trout that may all be responsible for the observed changes in growth and feed efficiency.

Effect of increased dietary carbohydrate on selenium metabolism and toxicity in rainbow trout (Salmo gairdneri).

Acute toxicity, uptake, depuration and tissue distribution of tri-n-butyltin in rainbow trout, Salmo gairdneri.

Temperature-induced changes in pentachlorophenol chronic toxicity to early ufe stages of rainbow trout

The acute toxicities of chlorophenols (CP’s) chlorobenzenes (CB’s) and para-substituted phenols (PP’s) to rainbow trout (Salmo gairdneri) as intraperitoneal injection lethality, serum sorbitol dehydrogenase activity, and 96-hr lethal concentration are investigated in terms of quantitative structure-activity correlations (QSARs). The effects of CP’s and CB’s are primarily related to the chemicals’ octanol/water partition coefficients (log P). The slopes of the QSARs of CP’s for rainbow trout are nearly parallel to those of acute and semichronic CP toxicities to bluegill (Lepomis macrochirus), guppy (Poecilia reticulata), waterflea (Daphnia magna), and the marine organismPhotobacterium phosphoreum, indicating similar mechanisms of toxic effects. The toxicites of PP’s are dependent on both log P and other molecular descriptors, such as molar refractivity and field and resonance constants of the para-substituents.

Peter V. Hodson

Papers

Effect of increased dietary carbohydrate on selenium metabolism and toxicity in rainbow trout (Salmo gairdneri).

Acute toxicity, uptake, depuration and tissue distribution of tri-n-butyltin in rainbow trout, Salmo gairdneri.

Temperature-induced changes in pentachlorophenol chronic toxicity to early ufe stages of rainbow trout

Qsar Studies On Chlorophenols, Chlorobenzenes and Para-Substituted Phenols

Mirex in the North American Great Lakes: New Detections and Their Confirmation