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274 records · Page 16Linked to original sources
USGS2003

Effects of methyl mercury exposure on the growth of juvenile common loons

We conducted a dose–response laboratory study to quantify the level of mercury exposure associated with negative effects on the development of common loon chicks reared in captivity from hatch to 105 days. A dose regimen was implemented that provided exposure levels that bracketed relevant exposure levels of methyl mercury found in loon chicks across North America. We observed no overt signs of mercury toxicosis and detected no significant effect of dietary mercury exposure on growth or food consumption. However, asymptotic mass was lower in chicks that hatched from eggs collected from nests on low pH lakes relative to eggs from neutral pH lakes. Rapid excretion of methyl mercury during feather growth likely provides loon chicks protection from methyl mercury toxicity and may explain the lack of convincing toxicological findings in this study. Lake-source effects suggest that in ovo exposure to methyl mercury or other factors related to lake pH have consequences on chick development.

Ecotoxicology↗
USGS2004

Physiological changes in largemouth bass exposed to paper mill effluents under laboratory and field conditions

We report here on studies designed to asses the effects of paper mill effluents on non-reproductive functions of free-ranging and captive Florida largemouth bass (Micropterus salmoides floridanus) This was accomplished by conducting an outdoor tank study, in which fish were exposed to well water or to 10%, 20%, 40%, and 80% full strength effluent for 28 or 56 days, and by sampling largemouth bass from sites within the St. Johns River, Florida, upstream and downstream from a paper mill plant. Blood and plasma samples from fish from the tank study and from fish sampled from the ambient sites were analyzed for over 20 variables. We also determined liver and spleen weights and examined them histologically. The most significant finding from the tank study was an increase in the concentration of albumin and hepatosomatic index for bass exposed to ???20% effluents for 56 days. Spleenosomatic index and number of melanomacrophage centers were decreased in bass from effluent-dominated sites (Palatka and Rice Creek), whereas concentrations of calcium, phosphorous, glucose, and creatinine were elevated in fish from these sites, compared to fish from reference streams. Fish from Rice Creek also had fewer red blood cells, and male bass from Palatka had lower concentrations of cholesterol. Plasma concentrations of albumin and hepatic concentrations of glutathione were elevated in males from Palatka, and both females and males from Rice Creek had higher concentrations of globulin. These results indicate a complex pattern of effects of paper mill effluents on several physiological functions. However, despite the myriad of treatment and site-related effects, most physiological parameters fell within normal ranges when compared to reports on largemouth bass and other freshwater species.

Ecotoxicology↗
USGS2011

A survey of spontaneous occurrence of ochratoxin A residues in chicken tissues and concurrence with histopathological changes in liver and kidneys

Toxicological and histopathological investigations of tissues of commercially slaughtered chickens were carried out to provide a preliminary evaluation of the incidence of occurrence of ochratoxin A (OTA) in chicken sold in Serbian retail market. In addition, the etiology of nephropathies of these chickens was elucidated. The majority of these tissue samples were not found to contain measurable amounts of OTA. Moreover, the OTA levels found in analyzed tissues were generally low and there was no positive correlation between the presence of OTA and the frequency of histopathological changes. Histopathological changes such as degenerative changes in the kidneys and liver differed from the classical description of the mycotoxic nephropathy, indicating that the chicken nephropathy observed in Serbia may have a multitoxic etiology with possible synergistic effect between microorganisms and natural toxins, usually present in low concentrations. The low OTA results also suggested that chicken meat available in the retail market in Serbia are unlikely to pose any significant adverse health risk to the consumers with respect to OTA toxicity.

Journal of Environmental Science and Health, Part ↗
USGS2003

Trace elements in lesser scaup (Aythya affinis) from the Mississippi flyway

Previous research reported that concentrations of selenium in the livers of 88a??95% of lesser scaup from locations in Lake Erie, Lake St. Clair, and Lake Michigan, USA were either elevated (10a??33 A?g/g dry weight [dw]) or in the potentially harmful range (>33 A?g/g dw). In order to determine the geographic extent of these high selenium concentrations, we collected lesser scaup in Louisiana, Arkansas, Illinois, Minnesota, Wisconsin, and Manitoba and analyzed the livers for 19 trace elements. We found that all trace element concentrations, except for selenium, generally were low. Arsenic, which usually is not detected in liver samples, was detected in Louisiana and may be related to past agricultural usages. Chromium, which also is not usually detected, was only present in lesser scaup from Arkansas and may be related to fertilizer applications. Cadmium and mercury concentrations did not differ among locations and concentrations were low. Selenium concentrations in Arkansas (geometric mean=4.2 A?g/g dw) were significantly lower than those in Louisiana (10.7 A?g/g dw), Illinois (10.5 A?g/g dw), and Minnesota (8.0 A?g/gdw); concentrations in Wisconsin and Manitoba were intermediate (6.6 and 6.5 A?g/g dw). About 25% of lesser scaup livers contained elevated selenium concentrations; however, none were in the harmful range. We concluded that selenium concentrations in lesser scaup in the Mississippi Flyway are elevated in some individuals, but not to the extent that has been documented in the industrial portions of the Great Lakes.

Ecotoxicology↗