Mercury exposure associated with altered plasma thyroid hormones in the declining western pond turtle (Emys marmorata) from California mountain streams.

Mercury (Hg) is a global threat to wildlife health that can impair many physiological processes. Mercury has well-documented endocrine activity; however, little work on the effects of Hg on the thyroid hormones triiodothyronine (T3) and thyroxine (T4) in aquatic wildlife exists despite the fact that it is a sensitive endpoint of contaminant exposure. An emerging body of evidence points to the toxicological susceptibility of aquatic reptiles to Hg exposure.

Regional inhibition of cholinesterase in free-ranging western pond turtles (Emys marmorata) occupying California mountain streams.

The present study investigated the potential effects of cholinesterase (ChE)-inhibiting pesticides on western pond turtles (Emys marmorata) occupying streams in two regions of California, USA. The southern region was suspected of having increased exposure to atmospheric deposition of contaminants originating from Central Valley agriculture. The northern region represented reference ChE activities because this area was located outside of the prominent wind patterns that deposit pesticides into the southern region.

Children's school performance: impact of general and oral health.

Objectives: The purpose of this study was to examine: a) the sociodemographic and health factors associated with poor school performance among North Carolina children; and b) the impact of poor oral health status on school performance while controlling for other health and sociodemographic factors.

Methods: We used data from the 2005 Child Health Assessment and Monitoring Program, a follow-back telephone survey to the Behavioral Risk Factor Surveillance System involving parents/guardians of children 0 to 17. This project includes sections on oral health and school performance.

Body size and food web structure: testing the equiprobability assumption of the cascade model.

The cascade model successfuly predicts many patterns in reported food webs. A key assumption of this model is the existence of a predetermined trophic hierarchy; prey are always lower in the hierarchy than their predators. At least three studies have suggested that, in animal food webs, this hierarchy can be explained to a large extent by body size relationships.