Retrospective study of mercury in raccoons (Procyon lotor) in south Florida.

Museum and recent collections of raccoon hair were used to assess whether temporal or spatial trends existed in MMHg distributions in south Florida. The hypothesis that MMHg in raccoon hair had remained the same since 1947 could not be rejected. Some sampling regions showed increases while others did not. However, large differences existed between sites, amounting to a factor of 20 for raccoons collected during 2000 and during the period prior to 1960 (museum samples). Raccoon feeding behavior and the production of MMHg most probably accounted for the spatial differences. Large differences in MMHg concentrations existed in different tissues ranging in order of hair, liver, kidney, muscle, heart, brain, and blood in their respective ratios to blood: 96:10:6:5:4:2.5:1. Liver Hg is 7% MMHg, while hair Hg is 99% MMHg. These associations appear largely regulated by metabolic processes. Speciation of Hg is very important for gaining an understanding of ecosystem and organism Hg dynamics. Further work is needed to establish whether Se plays a role in Hg sequestration and whether hair Hg is a good surrogate for estimating Hg concentrations in other tissues in south Florida raccoon populations.

Determining arsenic distribution in urban soils: a comparison with nonurban soils.

There are many challenges in the determination of arsenic background concentrations in soils. However, these challenges are magnified when those determinations are carried out on urban soils. Irrespective of this, it is important to correctly identify and understand the extent of pollution in order to provide efficient preventative, remedial actions and cost-effective management of contaminated areas. This review paper discusses the factors that make the determination of arsenic background concentrations in urban areas different from similar determinations in nonurban areas. It also proposes solutions, where applicable, that are based on experience in determining arsenic background concentrations in both urban and nonurban areas in Florida, and from other studies in the literature. Urban soils are considerably different from nonurban areas because they have significant human disturbance, making them more difficult to study. They are characterized by high spatial and temporal variability, compaction, and modified chemical and physical characteristics. These differences have to be addressed during site selection, sample collection, and statistical analyses when determining arsenic distribution.

The sheepshead minnow as an in vivo model for endocrine disruption in marine teleosts: a partial life-cycle test with 17alpha-ethynylestradiol.

The sheepshead minnow (Cyprinodon variegatus Lacépède), an estuarine fish species, was exposed to 17alpha-ethynylestradiol (EE2) at nominal test concentrations of 0.2, 2, 20, 200, 400, 800, 1,600, and 3,200 ng/L. Fish were exposed for up to 59 d, from subadult stages to sexual maturity, under flow-through conditions. The exposure period was followed by an evaluation of reproductive success and survival of progeny. The reproductive success of exposed sheepshead minnows, as determined from data on egg production from two subsequent spawning trials, was reduced in fish exposed to 200 ng/L EE2 and, in one spawning trial, in the 20-ng/L treatment. Hatching success was reduced in the progeny of fish exposed to 200 ng/L EE2, but survival was good among fry that successfully hatched. Histological examination indicated generalized edema, damage to gill epithelia, hepatic toxicity, fibrosis of the testis, and evidence of sex reversal, including testes-ova and spermatagonia-like cells in ovaries. The maximum acceptable toxicant concentration (MATC) for gonadal development in males was within the normal range of EE2 concentrations in sewage treatment plant effluents. The exposure regimen and choice of test organism, combined with histological examination, allowed independent evaluation of ecologically significant acute, reproductive and estrogenic endpoints. Estrogen receptor-mediated effects occurred at concentrations where reproductive effects were measurable under standard reproduction assays. The sheepshead minnow appears to be a sensitive in vivo model for partial life-cycle testing of compounds that have the potential to disrupt the endocrine system as well as reproduction in estuarine and coastal marine fish species.

TEMPERATURE ADAPTATIONS OF COPEPOD EGGS FROM THE ARCTIC TO THE TROPICS.

The development times to hatching (D) of eggs of eleven species of copepods are closely described as functions of temperature (T) by Belehrádek's temperature function, D = a (T - α)b using the assumption that the same value of b applies to all species. The value of a is related to egg diameter among three species of Calanus, and is unaffected by the greater opacity (presumably yolkiness) of eggs of C. hyperboreas. The value of a remains as the "real" indicator of temperature adaptation, and is closely and linearly related to estimates of environmental temperature based on mean annual temperatures within the range of each species between the pole and South America, along the east coast of the Americas.

Culture of a Planktonic Calanoid Copepod through Multiple Generations.

Acartia tonsa has been propagated through 12 filial generations during 1 year in small laboratory cultures. The mean generation time was 25 days at 17 degrees C on a slightly suboptimum, mixed algal diet. Body size, reproductive capacity, and generation time were unchanged during the culture period.