Derivation of Population-Level Ecological Remedial Action Objectives: Tualatin River Case Study

In 1997, Oregon enacted rules that define an unacceptable population-level risk as a >10% chance of >20% of the total local population receiving an exposure greater than the toxicity reference value. This rule applies to populations of plants and animals not listed as threatened or endangered. An operational procedure was developed to perform such population-level ecological risk assessments. This case study describes how this procedure was used to develop site-specific groundwater remedial action objectives for resident aquatic populations at a site in Northwest Oregon, where an upland petroleum pipeline released gasoline-range hydrocarbons (TPH-G) into soils and groundwater immediately upgradient of the Tualatin River. With an interim response in place, the goal was to proactively establish a remedial action objective that would equate to an acceptable risk level for populations of aquatic receptors potentially threatened by future groundwater discharges to the river. Approximately 10 and 32% dilutions of the water-soluble fraction of pure product produced an acceptable risk level for zooplankton and forage fish populations, respectively. The proposed population-level remedial action objective, based on zooplankton as the most sensitive receptor, was a TPH-G groundwater concentration of 17.4?mg/L.     

Spatial genetic structure and landscape connectivity in black bears: Investigating the significance of using different land cover datasets and classifications in landscape genetics analyses

Landscape genetic analyses allow detection of fine‐scale spatial genetic structure (SGS) and quantification of effects of landscape features on gene flow and connectivity. Typically, analyses require generation of resistance surfaces. These surfaces characteristically take the form of a grid with cells that are coded to represent the degree to which landscape or environmental features promote or inhibit animal movement. How accurately resistance surfaces predict association between the landscape and movement is determined in large part by (a) the landscape features used, (b) the resistance values assigned to features, and (c) how accurately resistance surfaces represent landscape permeability. Our objective was to evaluate the performance of resistance surfaces generated using two publicly available land cover datasets that varied in how accurately they represent the actual landscape. We genotyped 365 individuals from a large black bear population (Ursus americanus) in the Northern Lower Peninsula (NLP) of Michigan, USA at 12 microsatellite loci, and evaluated the relationship between gene flow and landscape features using two different land cover datasets. We investigated the relative importance of land cover classification and accuracy on landscape resistance model performance. We detected local spatial genetic structure in Michigan''s NLP black bears and found roads and land cover were significantly correlated with genetic distance. We observed similarities in model performance when different land cover datasets were used despite 21% dissimilarity in classification between the two land cover datasets. However, we did find the performance of land cover models to predict genetic distance was dependent on the way the land cover was defined. Models in which land cover was finely defined (i.e., eight land cover classes) outperformed models where land cover was defined more coarsely (i.e., habitat/non‐habitat or forest/non‐forest). Our results show that landscape genetic researchers should carefully consider how land cover classification changes inference in landscape genetic studies.     

CETACEAN LENS ZONES OF DISCONTINUITY—INDICES OF HEALTH AND DEVELOPMENT

Details of the lenses of eyes in two living Tursiops truncatus and one Grampus griseus were photographed. In the laboratory the lens cortex could be retro-illuminated by a fundus camera and spatially periodic stria could be visualized, in large part because of the highly developed tapetum of the cetacean eye. Varying spaces were present between the stria. On a three-dimensional basis, the best analogy is the layering of an onion. One photograph was digitized giving good quantification of the sizes of the layers and their number. Similar, but less easily resolved, lens cortex organization has been described frequently in humans as "zones of optical discontinuity." These have been explained as a periodic temporal consequence of normal aging with layer thickness depending on general health. We found that young cetaceans have few "zones" and older cetaceans have many. Lens zones measurement may be developed to Provide objective data on history of cetacean health and age.     

Genetic variation in red-cell adenosine deaminase and glucosephosphate isomerase in a laboratory colony of the marsupial Sminthopsis crassicaudata (Gould)

Biochemical Genetics -     

Expression of PGK-A in the Australian brush-tailed possum,Trichosurus vulpecula (Kerr), consistent with paternal X inactivation

An extensive survey of erythrocytes of marsupials other than kangaroos for electrophoretic variation in X-linked enzymes revealed two rare PGK-A phenotypes in the phalangerid Trichosurus vulpecula and one in Trichosurus caninus. Four putatively heterozygous females expressed only the variant allelic isozyme in some tissues but expressed a trace of the normal isozyme in others. A putatively hemizygous male expressed only the variant isozyme in all tissues. The phenotypic patterns were consistent with those observed in kangaroos known to exhibit partial or complete paternal X inactivation in cells of females. Two of the T. vulpecula were a mother and her female pouch young, further suggesting that paternal X inactivation occurs in T. vulpecula. This peculiar mechanism of dosage compensation may not be restricted to kangaroos.This work was supported by grants to D. W. C. from the Australian Research Grants Committee and Macquarie University, J. L. V. was the recipient of a Fulbright-Hays Award from the Australian-American Educational Foundation and a postgraduate fellowship from General Motors-Holden.     

Retrospective study of morbidity and mortality of captive jaguars (Panthera onca) in North America: 1982–2002

One hundred seventy‐two medical records of captive jaguars (Panthera onca) were examined from 30 American Zoo and Aquarium Association (AZA) institutions housing jaguars between 1982–2002. The study determined common causes of morbidity and mortality, and the influence of age, gender, and melengestrol‐acetate (MGA) exposure on these rates. The most common causes of morbidity in captive jaguars were found to be dental, gastrointestinal, integumentary, and musculoskeletal diseases. Prevalence of types of disease varied with age, with older animals experiencing a higher prevalence of multiple types of disease. Females developed reproductive disease more frequently than males, and the data suggest that MGA exposure increased the risk of developing female reproductive disease. The most common causes of mortality were reproductive diseases in females and musculoskeletal diseases in males. There was a high rate of neonate and pediatric mortality, primarily due to stillbirths or unexplained neonatal death, trauma, and pneumonia. Other diseases or clinical signs that seemed remarkable were a high prevalence of episodes of epistaxis among young, as well as old, jaguars. Based on these findings, management suggestions for the captive jaguar population are presented. Zoo Biol 0:1–12, 2006. © 2006 Wiley‐Liss, Inc.