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A 1990/1991 shoreline ecology program to assess the fate and effects of the Exxon Valdez oil spill in Prince William Sound was updated in 1998 and 1999. This update included a sediment sampling program for organisms at “worst case” sites and at randomly chosen reference sites. Correspondence analysis (CA), a statistical method that examines animal communities in terms of their similarity, was used to define community structure Statistical analysis of the degree of similarity between communities was used to assess effects of site-specific variables (sediment grain size, total organic carbon (TOC) and wave energy), interannual variation, and degree of oiling. Interannual variability had a significant effect on community structure, whereas site specific variables and degree of oiling did not. Differences in communities between 1998 and other years were particularly dramatic. The importance of interannual change demonstrates the importance of multi-year sampling and of appropriate study designs for separating impact effects from the natural occurring environmental factors which affect biological communities.

Background HFE knockout mice (C57BL/6 x 129/Ola strain) mimic the functional aberrations of human hereditary haemochromatosis (HH) in short-term experiments. The present study investigates functional and morphological long-term changes. Methods HFE(o/o), HFE(+/o) and HFE(+/+) mice were maintained on iron-rich and control diets for 2 weeks, 3, 12 and 18 months. Light microscopic tissue iron distribution, pathomorphological alterations, tissue iron content and oxidative stress were analysed in liver, pancreas, spleen, gastrointestinal tract, kidneys and myocardium. Additionally, duodenal 59Fe absorption and 59Fe whole body loss were measured. Results Iron distribution between organs and microscopic iron deposition in the tissues resembled the patterns described in HH. After 3 months of iron-rich feeding duodenal 59Fe absorption decreased to approximately 15% of iron-adequate controls but remained about twice as high in HFE(o/o) as in HFE(+/+) mice. Hepatic iron concentrations reached only half the values known to induce hepatic fibrosis in rats and humans, while whole body 59Fe loss was about twice as high. Consequently no hepatic fibrosis developed, although massive hepatocellular iron deposition and indication for oxidative stress were observed. Conclusion C57BL/6 x 129/O1a HFE(o/o) mice mimic HH iron distribution and the regulation of intestinal iron absorption after long-term feeding. However, characteristic morphological late changes in untreated HH are not modelled.

Beginning in 1989, scientists supported by ExxonMobil conducted a number of scientific studies to assess the fate and effects of the Exxon Valdez oil spill on shorelines in Prince William Sound (PWS), Alaska. The 1990, 1991, and 1993 field programs included concurrent sediment sampling for hydrocarbon chemistry and sediment toxicity. This sediment quality assessment found that spill residues on the oiled shorelines rapidly lost toxicity through weathering. The relative amounts of naphthalenes and chrysenes in the polycyclic aromatic hydrocarbons (PAH) in the sediments were found to be good indicators of weathering and toxicity. Using a standard sediment amphipod bioassay on the field samples increased mortality above background was found at exposure levels above approximately 2,600 ng/g total PAH (TPAH) for oil that had weathered a year or more. For samples with TPAH > 2,600 ng/g, fractions of naphthalenes (R = +0.76) and chrysenes (R = −0.63) significantly correlated with amphipod mortality where samples with high mortalities (> 80%) were dominated by relatively high fractions of naphthalenes (median = 0.26), and the low mortality category (< 30%) was dominated by relatively high fractions of chrysenes (median = 0.24). The amphipod mortality data fit significantly to a logistic model. Estimated LC10 and LC50 values were approximately 4,100 and 10,750 ng/g TPAH, respectively. Sediment grain size and total organic carbon were also found to contribute to increased amphipod mortality and were covariates in the data analysis. As petroleum weathers through exposure to the environment and lighter hydrocarbon fractions are lost, the results of this study show that the Exxon Valdez spill oil rapidly lost toxicity as the fractions of chrysenes increased and fractions of naphthalenes decreased.

A shoreline ecology program was performed in Prince William Sound (PWS), Alaska in 1990 and 1991 (1 and 2 years after the Exxon Valdez oil spill, EVOS) to assess the fate and effects of the oil in the intertidal zone. Major components of the study were repeated in 1998 and 1999. This update included a sediment-sampling program at formerly oiled “worst-case” boulder/cobble (B/C) sites and randomly chosen unoiled B/C reference sites. The samples were analyzed for petroleum hydrocarbons and benthic infaunal community characteristics. This paper focuses on the results of the benthic infaunal community analysis. Analysis of Covariance (ANCOVA) was used to analyze the 1990–1999 infaunal species composition data. Very little effect of oiling was detected in either the analysis of community structure parameters or in individual species abundances. Oiling effects were detected at some sites in 1990 and 1991, but not in 1998 and 1999. Nearly all the change in intertidal community parameters between 1990 and 1999 was attributed to natural interannual variation. The composition of the intertidal community of B/C shores changed over time because of natural factors not related to the spill. A core group of species was found in each of the 4 years. This group of species represented between 9 to 30% of all species identified. Two other groups of species did not co-occur. One group was present in 1990 and 1991, but not in 1998 and 1999; the other group was present in 1998 and 1999, but not in 1990 and 1991. The progressive change in the animal community observed between 1990 and 1999 is very likely related to long-term climatic changes occurring in the study area and not the oil spill. This long-term study demonstrates the importance of study designs that allow separation of oiling effects from natural factors that can affect biological communities.

On 12 January, 1998, a 24 inch pipeline from the IDOHO platform to the Mobil Qua Iboe terminal ruptured. This resulted in the release of approximately 40 000 bbl of Qua Iboe light crude oil into the marine environment. In response to the spill, cleanup and containment equipment were immediately deployed. Dispersant application played an important role in the cleanup response because the bulk of the oil remained offshore and was transported westward by prevailing currents, thus providing an extended opportunity for treatment at sea. As a result of dispersant application, natural dispersal and evaporation, over 90% of the oil was dispersed and evaporated offshore. Heavy shoreline oiling was limited and localized, with oiling of sensitive estuarine mangrove habitats limited to a few locations. Remnants of the spill that tracked 5–10 km offshore from the spill source were observed at Lagos harbor, about 900 km west of the spill site. Most of the exposed sand beaches in the spill zone self-cleaned within 2–3 w...

Shoreline assessment studies may be used after an oil spill to determine whether an injury has occurred and estimate the extent of injuries. Design of these studies generally cannot meet the randomization and replication requirements of classical experimental designs. For example, oil spills cannot be replicated, nor can oiling be applied randomly to experimental units (sites). Furthermore, species counts and other measures of abundance generally do not meet the assumptions of normal theory models. This leaves the statistician and principal investigators the task of finding design and analysis strategies that take into account these departures from standard statistical practices. This paper examines the study design, analysis methods and statistical power (i.e. the ability to detect oil spill effects) of three shoreline assessment programs conducted after the Exxon Valdez oil spill (Exxon's Shoreline Ecology Program, the Exxon Valdez Oil Spill Council's Coastal Habitat Injury Assessment study, and NOAA's Biological Monitoring Survey) and shows that the types of techniques used are influenced by study objectives.

After the March 24, 1989 grounding of the Exxon Valdez and the release of 258,000 barrels of Alaska North Slope (ANS) crude oil into the marine environment of Prince William Sound (PWS), Alaska, a number of scientific studies were conducted from 1989 to 1998 to assess the fate and effects of the spill. These included the 1990–1991 shoreline ecology program (SEP), which detected little measurable impact of the spill, except at certain heavily oiled sites. In 1998, these 1990 and 1991 studies were updated. The 1998 study found spill small remnants from originally heavily oiled sites represent a minute fraction of the total PWS shoreline area. Any isolated deposits of remaining oil residues from the spill generally were found at the top of the tidal zone and highly weathered and therefore in a form and location unavailable and non-toxic to biota. Between 1991 and 1998, the concentrations of petroleum hydrocarbons at the “worst case” sites studied decreased dramatically. The polycyclic aromatic hydrocarbon (PAH) concentrations measured at these sites in 1998 were at least three times lower than the effects range-low (ER-L) sediment toxicity threshold values of 4,022 ng/g for total PAH. Mussels sampled at heavily oiled “worst case” sites in 1998 also had dramatically lower tissue PAH concentrations compared with samples taken in 1993, indicating low bioavailability of any hydrocarbons present and thus low risk to biota. Natural interannual variability in the structure of the biological infaunal communities is the largest, most consistent signal observed in this study, not any residual oil spill effects. The results of statistical analyses of the data (ANCOVA) indicated no continuing oiling effects in 1998. Consistent differences were observed between oiled and unoiled reference sites, but they were significant in only one analysis. These differences were unrelated to differences in the total PAH present among sites. Any observed differences are more likely related to the fact these “worst case” oiled sites were not selected in an unbiased, random manner.

Interactions of the T cell coreceptors, CD4 and CD8, with MHC molecules participate in regulating thymocyte development and T lymphocyte activation and differentiation to memory T cells. However, the exact roles of these interactions in normal T cell development and function remain unclear. CD4 interacts with class II MHC7 molecules via several noncontiguous regions in both the class II MHC α- and β-chains. We have introduced a double mutation that disrupts interaction with CD4 into the I-Aβk gene and used this construct to generate transgenic mice expressing only mutant class II MHC. Although CD4+ thymocytes matured to the single-positive stage in these mice, their frequency was reduced by threefold compared with that of wild-type transgenics. Positive selection of CD4+ T cells in the mutant transgenic mice may have been mediated by TCRs with a higher than usual affinity for class II MHC/Ag complexes. In Aβk mutant transgenics, peripheral CD4+ lymphocytes promoted B cell differentiation to plasma cells. These CD4+ T cells also secreted IFN-γ in response to various stimuli (e.g., protein Ag, bacterial superantigen, and alloantigen), but were deficient in IL-2 secretion. Interactions between CD4 and class II MHC molecules appeared to regulate lymphokine production, with a strong bias toward IFN-γ and against IL-2 in the absence of these interactions. Our results have implications for the manipulation of T cell-dependent immune responses.

Current illicit drug and alcohol users were identified by laboratory evaluation of urine samples from nonpsychotic patients without a primary clinical diagnosis of a substance use disorder seen in a psychiatric emergency room. Urine screens revealed that 32 of 93 nonpsychotic patients (34 percent) had used a substance just before visiting the emergency room. Compared with nonusers, users were more often Caucasian females with adjustment disorders who admitted their previous substance use. The prevalence of concurrent use among nonpsychotic patients was higher than among psychotic patients. Nonpsychotic and psychotic users differed in gender, marital status, level of suicidality, self-report of use, the clinician's suspicion of use, use of seclusion during the visit, admitting status, level of care, and disposition.

This study was conducted to assess the subtidal effects of the Exxon Valdez oil spill in a large embayment in Prince William Sound, AK. A stratified random-sampling design was used to compare stations in an oiled bay, the Bay of Isles, with stations in Drier Bay, a bay that received little impact from the spill. The study included sediment chemistry, benthic ecology, and bioaccumulation elements. Only the results on chemistry of the oil in the bottom sediments are reported here. Analyses of sediment samples revealed four types of polycyclic aromatic hydrocarbons (PAH) in the two bays: (1) Alaska North Slope (ANS) crude oil attributable to the spill, (2) natural oil seep-derived background, (3) pyrogenic, and (4) diagenetic. The Bay of Isles subtidal sediments contained significantly higher levels of weathered ANS-PAH attributable to the spill than did Drier Bay. However, the levels of ANS-PAH in the Bay of Isles were generally lower than those of the petrogenic background PAH naturally present in the sub...

The grounding of the Exxon Valdez on March 24, 1989, released about 41 million L of crude oil into the waters of Prince William Sound, Alaska, USA, and oiled about 16% of the Prince William Sound shoreline to various degrees. Although winter storms, cleanups, and natural biodegradation have removed the majority of the oil on the shorelines, some residual oil still remains trapped in sediments immediately below mussel beds. This oil was protected from wave action by the dense covering of mussels. Field surveys found that mussels in such beds constituted less than 3% of the mussels available for foraging in two areas that had been extensively oiled in 1989. Levels of polycyclic aromatic hydrocarbons (PAHs) in these mussels were also measured. Mean PAH concentrations in mussel tissues ranged between 20 and 4,000 ng/g dry weight and in sediments between 20 and 26,000 ng/g dry weight. Assuming that the species considered most at risk (i.e., harlequin ducks, black oystercatchers, and sea otters) consumed the mussel proportion of their diets exclusively from such beds (at either the median or 95th percentile of mussel tissue PAH concentration), the estimated PAH dosage they would receive was one to three orders of magnitude below doses known to cause sublethal effects in surrogate species. Considering the low frequency of mussel beds with residual oil, the patchy distribution of remaining weathered oil residues, and the relatively low PAH concentrations in the mussels, the risk of quantifiable injury at the level of an individual bird or otter, or at the population level, is minimal. Furthermore, based on a review of the mussel PAH data in Prince William Sound, the risk to wildlife has been minimal since 1990, 1 year after the spill.

Image analysis of historical aerial photographs was used to examine the effects of the Amoco Cadiz oil spill and resulting clean-up on marsh ecology. Two heavily oiled marsh systems were compared. The marsh which received no clean-up recovered to its prior condition. The marshes in the system cleaned by sediment removal were extensively altered as a result of changes in intertidal height of the sediment surface.

The disposition of tributyltin (TBT) within Mytilus edulis tissues and the depuration of TBT from various organs was determined for field populations of animals chronically exposed to environmental sources of TBT. Analysis of dissected organs demonstrated that TBT accumulated to the greatest extent in gill tissue, with TBT concentrations approximately twice that of whole-animal homogenates. A transplant study showed that the depuration of TBT from gill tissue and digestive gland tissue is a biphasic two-compartment process involving a rapid TBT loss process and a concurrent slower TBT depuration process. Whole-body and gonadal tissue depuration followed a slower monophasic depuration process. Depuration half life values ranged from 2.2–5.3 d for the fast depuration component and 28–69 d for the slow component.

This study describes the biological results of a comprehensive shoreline ecology program designed to assess ecological recovery in Prince William Sound following the Exxon Valdez oil spill on march 24, 1989. The program is an application of the ``Sediment Quality Triad`` approach, combining chemical, toxicological, and biological measurements. The study was designed so that results could be extrapolated to the entire spill zone in Prince William Sound. The spill affected four major shoreline habitat types in Prince William Sound: pebble/gravel, boulder/cobble, sheltered bedrock, and exposed bedrock. The study design had two components: (1) one-time stratified random sampling at 64 sites representing four habitats and four oiling levels (including unoiled reference sites) and (2) periodic sampling at 12 nonrandomly chosen sites that included some of the most heavily oiled locations in the sound. Biological communities on rock surfaces and in intertidal and shallow subtidal sediments were analyzed for differences resulting from to oiling in each of 16 habitat/tide zone combinations. Statistical methods included univariate analyses of individual species abundances and community parameter variables (total abundance, species richness, and Shannon diversity), and multivariate correspondence analysis of community structure. 58 refs., 13 figs., 9 tabs.

The effects of quantitative differences in class II cell surface expression have been difficult to address in intact animals. This study uses several lines of H-2s/s mice carrying an A beta k transgene that differ significantly in terms of class II cell surface expression. Due to inefficient chain pairing, mice carrying 60 to 65 copies of this transgene express only low levels of A alpha s/A beta k on the cell surface, and cell surface expression of the endogenous A alpha s/A beta s complex (and total Ia) is severely reduced (to 7-15% control levels). The significant decrease in class II cell surface expression in the thymic cortex of these mice did not affect the frequency of peripheral T cells expressing at least 10 distinct TCR V beta chains. However, T cell proliferative responses to the A alpha s/A beta s-restricted peptide MBP 89-101 were abrogated in high copy number A beta k mice. Experiments using bone marrow chimeras demonstrated that both inefficient Ag presentation and failure to positively select appropriate T cells contributed to this lack of response. Inefficient Ag presentation was clearly the dominant defect, and the density of class II cell surface expression required for positive selection appeared to be quite low.

In 1981, two test oil spills were made in Maine. One spill was 975 L (250 gal) of Murban crude oil; the other was 975 L of Murban crude oil premixed with 97 L (25 gal) of Corexit 9527. The uptake of the oil and its effects on enzymatic activity in two species of common intertidal bivalve mollusks, Mya arenaria and Mytilus edulis, were studied. Data were obtained on uptake and depuration of the oil for each species; data were also obtained on the activity of glucose-6-phosphate dehydrogenase and aspartate aminotransferase for each species. Data were collected both before and after each of the spills. Much less oil was taken up by the populations of animals exposed to chemically dispersed oil than by those exposed to nondispersed oil. Rates of depuration were the same for each species; they were also the same regardless of oil exposure. Significant long-term effects on enzyme activity were detected only in those animals exposed to nondispersed oil.

In 1981, an oil spill field experiment was done in Maine to assess the effects to the benthos of dispersant used in nearshore oil spills. Three test plots, each 60 by 100 m, were set up, each with an upper and a lower intertidal sampling area. There were also five subtidal sampling stations in water depths from 5 to 20 m. One plot was exposed to 945 L (250 gal) of Murban crude oil released on an ebbing tide withincontainment booms and cleaned up by conventional mechanical methods 24 h later. A second plot was exposed to 945 L of Murban crude oil premixed with 94 L (25 gal)of a widely available self-mix nonionic dispersant. The dispersant-treated oil was discharged over a 2-h period around high water slack tide. Dispersed oil in water reaching the bottom had lost most of the hydrocarbons more volatile than n-C/sub 17/ compared with dispersed oil in water sampled at the same time near the surface. Petroleum retention by intertidal sediments and bivalves measured one week postspill was less in areas exposed to dispersed oil than in areas exposed to untreated oil.

HFE knockout mice (C57BL/6 x 129/Ola strain) mimic the functional aberrations of human hereditary haemochromatosis (HH) in short-term experiments. The present study investigates functional and morphological long-term changes.HFE(o/o), HFE(+/o) and HFE(+/+) mice were maintained on iron-rich and control diets for 2 weeks, 3, 12 and 18 months. Light microscopic tissue iron distribution, pathomorphological alterations, tissue iron content and oxidative stress were analysed in liver, pancreas, spleen, gastrointestinal tract, kidneys and myocardium. Additionally, duodenal 59Fe absorption and 59Fe whole body loss were measured.Iron distribution between organs and microscopic iron deposition in the tissues resembled the patterns described in HH. After 3 months of iron-rich feeding duodenal 59Fe absorption decreased to approximately 15% of iron-adequate controls but remained about twice as high in HFE(o/o) as in HFE(+/+) mice. Hepatic iron concentrations reached only half the values known to induce hepatic fibrosis in rats and humans, while whole body 59Fe loss was about twice as high. Consequently no hepatic fibrosis developed, although massive hepatocellular iron deposition and indication for oxidative stress were observed.C57BL/6 x 129/O1a HFE(o/o) mice mimic HH iron distribution and the regulation of intestinal iron absorption after long-term feeding. However, characteristic morphological late changes in untreated HH are not modelled.

An 1-year study of the 1989 Exxon Valdez oil spill found that spill residues on the oiled shorelines rapidly lost toxicity through weathering. After 1990, toxicity of sediments remained at only a few heavily oiled, isolated locations in Prince William Sound (AK, USA), as measured by a standard amphipod bioassay using Rhepoxynius abronius. Data from 648 sediment samples taken during the 1990 to 1993 period were statistically analyzed to determine the relationship between the total concentration of 39 parent and methyl-substituted polycyclic aromatic hydrocarbons (defined as total polycyclic aromatic hydrocarbons [TPAH]) and amphipod mortality and the effect of oil weathering on toxicity. A logistic regression model yielded estimates of the lower threshold, LC10 (lethal concentration to 10% of the population), and LC50 (median lethal concentration) values of 2,600, 4,100, and 10,750 ng/g TPAH (dry wt), respectively. Estimates of the threshold and LC50 values in this field study relate well to corresponding sediment quality guideline (SQG) values reported in the literature. For sediment TPAH concentrations2,600 ng/g, samples with high mortality values (90%) had relatively high fractions of naphthalenes and those with low mortality (20%) had relatively high fractions of chrysenes. By 1999, the median sediment TPAH concentration of 117 ng/g for the post-1989 worst-case sites studied were well below the 2,600 ng/g toxicity threshold value, confirming the lack of potential for long-term toxic effects. Analysis of biological community structure parameters for sediment samples taken concurrently found that species richness and Shannon diversity decreased with increasing TPAH above the 2,600 ng/g threshold, demonstrating a correspondence between sediment bioassay results and biological community effects in the field. The low probability of exposure to toxic concentrations of weathered spill residues at the worst-case sites sampled in this study is consistent with the rapid overall recovery of shoreline biota observed in 1990 to 1991.

In mice, the absence of terminal deoxynucleotidyl transferase (Tdt) expression during fetal and neonatal life provides a window in development where clones of lymphocytes are generated that provide protective immunity. Introducing premature Tdt activity interferes with the development of these clones and results in an impaired ability to make protective antibodies. Conversely, gene-targeted disruption of Tdt prevents N additions at all stages of T and B-lymphocyte development and promotes the development of fetal-like T and B-cell clones into adulthood, with accompanying alterations in repertoire. The alternative splice forms of Tdt may be necessary to provide regulatory mechanisms to restrict N addition to appropriate stages of the developmental pathways, the details of which are being revealed. The evidence continues to build that Tdt is a key player in influencing the outcome of V(D)J recombination during lymphocyte and repertoire development.

Temporal control of rearrangement at the TCR alpha/delta locus is crucial for development of the gamma delta and alpha beta T cell lineages. Because the TCR delta locus is embedded within the alpha locus, rearrangement of any V alpha-J alpha excises the delta locus, precluding expression of a functional gamma delta TCR. Approximately 100 kb spanning the C delta-C alpha region has been sequenced from both human and mouse, and comparison has revealed an unexpectedly high degree of conservation between the two. Of interest in terms of regulation, several highly conserved sequence blocks (90% over50 bp) were identified that did not correspond to known regulatory elements such as the TCR alpha and delta enhancers or to coding regions. One of these blocks lying between J alpha 4 and J alpha 3, which appears to be conserved in other vertebrates, has been shown to augment TCR alpha enhancer function in vitro and differentially bind factors from nuclear extracts. To further assess a plausible regulatory role for this element, we have created mice in which this conserved sequence block is either deleted or replaced with a neomycin resistance gene driven by the phosphoglycerate kinase promoter (pgk-neor). Deletion of this conserved sequence block in vivo did have a local effect on J alpha usage, echoing the in vitro data. However, its replacement with pgk-neor had a much more dramatic, long range effect, perhaps underscoring the importance of maintaining overall structure at this locus.

OBJECTIVE This study used laboratory tests to identify current drug and alcohol users among psychotic patients seeking treatment in an urban psychiatric emergency room. Rates of clinician-suspected use and self-reported use were compared, as were treatment and disposition of users and nonusers. METHODS Logistic regression modeling was used to identify factors that differentiated current substance users from nonusers in a sample of 112 psychotic patients. RESULTS Laboratory analyses revealed that 24 of the 112 psychotic patients (21 percent) had used alcohol or an illegal substance before visiting the emergency room. Younger age, male gender, African-American ethnicity, clinician-suspected substance use, and presentation in the emergency room between 7 p.m. and 7 a.m. were associated with a higher likelihood of positive results on the urine test. Only five of the patients who had positive results (21 percent) self-reported substance use. Clinicians suspected that 59 patients (53 percent) were under the influence; however, only 17 of those suspected (29 percent) had positive laboratory results. Patients with positive laboratory results required more intense care in the psychiatric emergency room and were more often hospitalized. CONCLUSIONS Some demographic and clinical factors were associated with concurrent substance use among psychotic patients in the emergency room. Clinicians' suspicions of use in this sample of psychotic patients lacked specificity due to the fact that potential use was suspected in a large number of cases for which laboratory results were negative. In contrast, self-reported use was uncommon among patients with positive results. Because neither clinician judgment nor patient self-report meaningfully predicts current substance use, routine urine drug screens may be appropriate.

The effects of quantitative differences in class II cell surface expression have been difficult to address in intact animals. This study uses several lines of H-2s/s mice carrying an A beta k transgene that differ significantly in terms of class II cell surface expression. Due to inefficient chain pairing, mice carrying 60 to 65 copies of this transgene express only low levels of A alpha s/A beta k on the cell surface, and cell surface expression of the endogenous A alpha s/A beta s complex (and total Ia) is severely reduced (to 7-15% control levels). The significant decrease in class II cell surface expression in the thymic cortex of these mice did not affect the frequency of peripheral T cells expressing at least 10 distinct TCR V beta chains. However, T cell proliferative responses to the A alpha s/A beta s-restricted peptide MBP 89-101 were abrogated in high copy number A beta k mice. Experiments using bone marrow chimeras demonstrated that both inefficient Ag presentation and failure to positively select appropriate T cells contributed to this lack of response. Inefficient Ag presentation was clearly the dominant defect, and the density of class II cell surface expression required for positive selection appeared to be quite low.

Epidemiologic studies to assess the prevalence of infectious disease in small ruminants in the Sahel have been limited. Previous work by Abu Elzein (1985) on bluetongue and Zain Eldin, Elkhawad and Kheir (1985) on toxoplasmosis has established that these two diseases have contributed significantly to the morbidity and mortality of ruminants in the Sudan. To date, however, few studies have been done to assess the prevalence of either disease among small ruminants as far west as Niger. The present study was conducted to assess antibody prevalence for bluetongue and toxoplasmosis in a flock of 70 sheep in south-western Niger. Sera were tested for the presence of antibodies to bluetongue by the agar gel immunodiffusion method and a commercially prepared test for toxoplasma antibody usingant igen covalently bound to latex particles by an indirect agglutination microtitre method was supplied by TechAmerica Inc. (Kansas City, MO 64141). Seropositivity for bluetongue in the study region reached 22% while that for toxoplasmosis was 14%. While both diseases can deplete flock numbers and seriously affect production, neither were determined to be significant enough a threat to animal health to warrant a full scale control programme in that country.

The dependency and behavioural characteristics of 1,461 elderly people in long stay geriatric and psychogeriatric wards and Part IV accommodation were surveyed. Misplacement, defined as having dependency and behaviour characteristics normally associated with admission to another form of care, was widespread, ranging from 5-51% in the different facilities visited. It was greatest in psychogeriatric wards and least in geriatric wards. In Part IV accommodation there was a significant inverse relationship between length of stay and appropriateness of placement.

During 1978 and 1979, sediment samples were collected in the mangrove areas on the west side of Bahia Sucia, Puerto Rico, to examine the effects of oil discharged from the tanker Zoe Colocotroni (March 18, 1973) on the infaunal community. Samples for benthic community analysis and hydrocarbon analysis were taken in representative types of mangrove habitats and compared with habitats in a reference area some distance from the spill site. Infaunal organisms larger than 0.5 mm were included in this study. Correlation of biological and chemical data indicates that for the high salinity habitats there were more infaunal organisms larger than 0.5 millimeters in the oiled area than in the unoiled area. Analyses of the red mangrove fringe areas showed that the distribution of infaunal organisms was not related to the distribution of oil in an obvious way. Large numbers of organisms were found in some heavily oiled areas. Even the most diverse communities seen in the impact area were not as diverse as the community seen in the unoiled reference area. We conclude that only in the red mangrove environment is there remaining damage to infaunal communities from the Zoe Colocotroni oil spill.

A number of experiments were carried out in the Canadian Arctic on Baffin Island with the purpose of defining the short- and long-term effects of exposure to dispersed crude oil on marine benthic invertebrates. The study reported here assessed metabolic responses by physiological and biochemical indices, and evaluated these in relation to exposure concentration. The overall objective of the study was to evaluate the potential for long-term survival of benthic communities in the Arctic following an oil spill. This objective was consistent with the goals of the larger Baffin Island Oil Spill (BIOS) program, which was implemented to evaluate the relative mitigating effectiveness of chemical dispersants, as compared to conventional oil spill counter-measures.

Samples of sediment were taken at intervals between 1979 and 1986 from soft sediment locations in the Aber Benoit, an estuary heavily impacted by the Amoco Cadiz oil spill of 1978, and from a comparable reference site outside the spill zone. Each sample was analyzed for aliphatic hydrocarbons by capillary gas chromatography. The data demonstrate the progressive weathering of the Amoco Cadiz oil resulting in an assemblage of biogenic hydrocarbons similar to the reference site by 1986 at all but the most heavily impacted locations. The data indicate that any residues of weathered Amoco Cadiz oil present in 1985-86 were in the final stages of degradation.

The relationship between sediment hydrocarbon concentration and leaf Na K ratios has been examined in two marine halophytes, Rhizophora mangle and Spartina alterniflora. The plants examined were exposed to petroleum hydrocarbons in the field. Elevated Na K ratios were observed in the leaves of both species of halophytes. The degree of elevation of the Na K ratios was related to the concentration and state of weathering of petroleum in the sediments in which the plants were growing. The mechanism of damage appears to be similar in both species. Elevated Na K ratios appear to result from damage to root membranes.

The fate and effects of two nearshore discharges of Murban crude oil at Long Cove, Searsport, Maine in August 1981 were studied following a one-year, pre-spill baseline study of the test areas. An upper and a lower intertidal sampling area within a 60 × 100 meter test plot were exposed to dispersed oil in water resulting from the discharge of 250 gallons of oil pre-mixed with 25 gallons of Corexit 9527 dispersant. Release of treated oil was around high-water slack tide on the surface of the water, with added mixing energy provided by mixing gates deployed by small boats. The maximum water depth over the test areas was 3.5 meters. Untreated crude oil (250 gallons) was released on an ebbing tide within a separate, boomed-off 60 × 100 meter test plot. A third test plot served as an oil-free reference plot. Water samples taken near the surface and near the bottom during and after discharge showed that chemically dispersed oil loses lower boiling hydrocarbons in both the aliphatic and aromatic fractions below n-C17as the droplets diffuse downward. Data are given for sediment samples taken from the test plots 11 months pre-spill and 10 months post-spill. Hydrocarbon analyses of the sediment samples show little incorporation of dispersed oil into the sediments of the treated oil plot relative to the sediments exposed to undispersed oil.

Cultures of Gonyaulax tamarensis were grown on Hastings medium based on 100%, 10%, 1%, 0.1% and 0% (control) of seawater elutrients of bottom sediments. Both “clean” and heavily polluted sediments were used. Very low concentrations of polluted elutrients (0.01% v/v) slightly enhanced the growth of Gonyaulax tamarensis; greater concentrations of polluted elutrient depressed growth. Elutrient from “clean” sediments did not enhance growth; the depression of growth at any given elutrient concentrate was not as great as that seen with the polluted elutrients.

As part of the American Petroleum Institute sponsored tidal area dispersant project involving two test spills of Murban crude oil in Long Cove, Searsport, Maine in August, 1981, water samples were collected. This paper deals with the analytical results for the analyses of water samples collected for analysis of non-volatile hydrocarbons by: infrared spectrophotometric quantitation of total CCl4 extractables, and gravimetric analysis of aliphatic and aromatic hydrocarbon fractions followed by capillary gas chromatography. In the dispersant-treated oil discharge area, there were two primary water sampling locations during the discharge phase of the experiment: an upper intertidal area (maximum depth = 2 meters) and a lower intertidal area (maximum depth = 3.5 meters). The gas chromatographic data for the water samples were treated numerically to obtain parameters whose values reflect the extent of dispersed oil weathering. For the aliphatics, the peak area ratio for n C14/n C18 was calculated for each sample. For the aromatics, the ratio for the peak area sum of the mono, di, and trimethyl naphthalenes to that for the mono, di, tri, and tetramethyl dibenzothiophenes was determined for each sample. At both sampling locations, dispersed oil in water sampled 10 cm off the bottom consistently had a smaller fraction of lower boiling aliphatic and aromatic hydrocarbons than water sampled at the same place and the same time ½ meter below the surface. In addition, the data show that there is a 12–50 fold decrease in hydrocarbon concentration on going from near surface to near bottom at any given time, even in water as shallow as 2 meters. The data indicate that the primary mechanism for hydrocarbon loss involves volatilization of hydrocarbon fractions. Analyses of water samples taken from submerged plumes of dispersed oil outside the sampling areas demonstrated slower loss of low boiling components consistent with the importance of atmospheric exchange in the weathering process. In the chemical dispersal of an oil spill, it may be most advantageous to use mixing methods that minimize vertical mixing in order to maintain a high concentration of emulsified oil in the upper ½ meter water layer. This will maximize the extent of loss of lower boiling hydrocarbon components into the atmosphere and thus minimize the toxicity of any dispersed oil fractions that diffuse downward and interact with benthic communities.

Samples of oiled sediment and tar were taken at locations in the area of Brittany, France known as the ‘Pink Granite Coast’. Each sample was analysed for hydrocarbons by gas chromatography and gas chromatography/mass spectrometry to determine the probable source of any petroleum residues present. The results show numerous recent inputs of various petroleum products including crude oils and light fuel oils at various locations. By 1985, the data indicate that the contribution from remaining weathered residues of Amoco Cadiz oil to the hydrocarbon baseline is small compared to more recent inputs of petroleum.

Effects of crude oil and salinity stress on the metabolism of two common filter-feeding animals (Mytilus edulis and Modiolus demissus) have been investigated. Carbon budgets have been calculated for each species under a variety of combinations of oil content and salinity. Both reduced salinity and the presence of crude oil tend to decrease the net carbon flux for each species; stresses from each source interacted in their effects on experimental animals. Although similar responses to oil were shown by each species, Mytilus edulis appeared to be slightly more resistant to oil than Modiolus demissus.

Six vascular surgeons independently examined 44 legs in patients with suspected peripheral arterial disease. Each surgeon recorded whether the femoral and popliteal pulses were present or absent, and if thought to be present, whether they were normal or reduced in amplitude. Interobserver agreement was determined by calculating both observed agreement (Po) and agreement after correction for chance (kappa-k). The results were calculated both for each possible pair of surgeons and as an overall value for all possible pairs combined. Agreement as to whether pulses were present or absent was significantly better than expected by chance but was only moderately good (overall kappa for femoral pulse = 0.53, and overall kappa for popliteal pulse = 0.52). More often than not, agreement as to whether the pulses were normal or reduced was no better than expected by chance (overall kappa for femoral pulse = 0.15, and overall kappa for popliteal pulse = 0.01). For each assessment, agreement was no better for the more experienced than the less experienced pairs of surgeons. The results indicate that more objective methods than pulse palpation are required to determine whether there is significant disease in the aorto-iliac and femoro-popliteal arterial segments.

The effect of two nearshore discharges of Murban crude oil on community structure in intertidal benthic communities was studied. One discharge consisted of 250 gallons of Murban crude only. Following the discharge, no measurable amount of Murban crude could be found in sediments exposed to the cloud of dispersed oil. Significant amounts were found in the test plot exposed to untreated oil. In the area exposed to untreated oil, more oil was found in the upper intertidal zone than lower down. Effects on infaunal communities mirrored the analytical results. There was no evidence of adverse effects on infaunal community structure from exposure to dispersed oil. There is clear evidence that exposure to untreated oil did adversely affect community structure. Some indigenous species were reduced in number or eliminated; there were blooms of opportunistic polychaetes. The changes in community structure brought about by the untreated oil are consistent with results observed at real-world oil spill sites.

Further examination of the 1971 spill site in Long Cove, Searsport, Maine, has been carried out during 1976, and has led to the following observations: 1. Petroleum residues isolated from this spill give the appearance of weathering particularly slowly in the cold anoxic sediments of Long Cove. 2. Leaching from contaminated terrestial sediments onto portions of the intertidal zone on the west shore of the Cove while continuing in trace concentrations does not appear to be making a major contribution to the maintenance of a nearly steady state pollution problem found in several areas of the Cove. 3. On the average, the spill area currently appears to contain roughly 20% less material than in 1971. At a number of sites, however, there appears to have been either little or no decline in gross hydrocarbon concentrations, and essentially no weathering of the aliphatic portions of the petroleum residues. 4. One of the principal factors to influence the character of petroleum residues isolated 5 yr postspill appears to have been the weathering of the hydrocarbons during transport to the site of sediment penetration from upland locations. Thus, the current compound distribution was determined early in the spill period. 5. Repopulation of the Cove by M. arenaria, which is proceeding very slowly, correlates directly with the gross concentration variations of petroleum hydrocarbons. Key words: petroleum, gas chromatography, weathering, clay sediments, Maine

On August 19, 1981, two test spills of Murban crude oil were carried out in Long Cove, Searsport, Maine. One spill was chemically dispersed; the other was not. Measurements were made to make quantitative comparisons of the chemical fates and biological effects of the two spills. Hydrocarbon analyses were carried out on water samples, animal tissue samples, intertidal sediment samples, and subtidal sediment samples. Biological measurements were carried out at the community level, whole animal level, and biochemical level of organization. No significant biological effects attributable to the dispersed oil spill were observed. This lack of effects is, in part, a result of changes in the physical and chemical properties of dispersed oil which help limit its availability and toxicity. The chemical fate and biological effects of the undispersed oil spill were typical of those reported from actual oil spill sites. Oil was incorporated into sediments and animal tissue. On the community level of organization mortality, reduced diversity and evenness, increased population density, and increased dominance by opportunists were all observed immediately after the spill, and up to 1 year later. On the whole animal level of organization, no effects on scope-for-growth were observed in two filter feeding bivalves. On the biochemical level of organization, activities of two sensitive enzyme systems were elevated.

Two populations of soft-shell clam, Mya arenaria, one from a chronically oiled lagoon (since the Arrow oil spill in 1970) and the other from a nonoiled lagoon, were compared as to population structure, growth, and metabolism. The oiled lagoon sediments contained up to 3800 μg/g oil (UV determination), and clams up to 200 μg/g hydrocarbon in their tissues (fluorescence). The oiled population of clams differed from the nonoiled population in lower total numbers with fewer mature adults, a 1–2-yr lag in tissue growth, a lower shell growth rate, and a reduced carbon flux with a lower assimilation rate. Results are interpreted to indicate that the recovery potential of M. arenaria in these oiled sediments is low and that these oiled populations remain under continued stress 6 yr after the Arrow spill. Key words: physiology, petroleum, growth, carbon flow, clams, recruitment

On March 16, 1978, the tanker Amoco Cadiz ran aground off the coast of North Brittany. Her cargo of 221,000 tons of light crude oil was released into the sea. More than 126 miles of coastline were oiled, including a number of oyster (Crassostrea gigas) growing establishments. The North Brittany coastline already was stressed by earlier additions of oil and metals. In December 1979, 21 months after the oil spill, measurements of glucose-6-phosphate dehydrogenase activity, aspartate aminotransferase activity, and condition index were made in 14 populations of C. gigas. Five of the populations were outside the oil spill impact zone; nine populations were within it. At the same time the body burden of Cr, Ag, Pd, Zn, Cu, Cd, and Hg, as well as the body burden of aliphatic and aromatic hydrocarbons, was determined. Also at the same time, the numbers of total and fecal coliform bacteria in the ambient water were determined. Results of stepwise multiple regression have shown that 21 months after the Amoco Cadiz oil spill, aromatic hydrocarbons were only one of three factors adversely affecting C. gigas populations in North Brittany. Multiple regression techniques can be extremely useful in identifying those stressors associated with physiological effects in populations of animals.

A study was performed on the state of an oil spill site on the southwest coast of Puerto Rico. The location of the study was Bahia Sucia, the site of the Zoe Colocotroni spill of 17 March, 1973. Particular attention was given to the weathering characteristics of the stranded oil remaining at the sites and to the presence of biogenic hydrocarbons in the sediments. High resolution gas chromatography of the aliphatic and aromatic fractions of the sediment hydrocarbons was used to distinguish the types of hydrocarbons present and their distribution. It was observed that oil weathers much more rapidly in a tropical environment as compared with spills in temperate areas. Even in the most heavily impacted areas, the Zoe Colocotroni oil had weathered practically to the point of being tar. It was also observed that a tropical site has a significant chronic input of hydrocarbons from both natural and anthropogenic sources. Gas chromatograms of extracts of leaf waxes from live mangroves compared with biogenic hydrocarbons observed in the sediments. Tar-balls also account for a significant fraction of the hydrocarbon burden in the sites studied. The conclusion is that a tropical area has the potential for making a much more rapid recovery from an oil spill than a temperate one. Moreover, in assessing the effects of a tropical oil spill, care must be taken to distinguish the relative contribution to the total hydrocarbon burden in a spill area by oil, pelagic tar, and biogenic sources.