Relationships between tissue contaminants and defense-related characteristics of oysters (Crassostrea virginica) from five Florida bays.

Evidence linking bivalve defense responses with pollutant exposure is increasing. Contaminant effects on immune or defense responses could influence the ability of an organism to resist infectious disease. This study explored relationships between xenobiotic chemicals accumulated in oyster (Crassostrea virginica) tissue and various measures of putative oyster internal defense activities and physiological condition. Defense-related and physiological measurements were made on individual oysters collected from 22 sites at five Florida bays and pooled oyster tissue from each site was analyzed for polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals and certain pesticides. Chemical concentrations, physiological condition, and hemocyte and hemolymph characteristics varied across bays and among sites within a bay. Within-bay comparisons showed that sites with high oyster defense-related activities often had accompanying high tissue concentrations of one or more classes of xenobiotic chemicals. Correlation analysis performed across bays demonstrated significant positive relationships between most defense-related characteristics and at least one contaminant, including various PAH, PCB and trace metal analytes. In combination with other recent studies, these results strengthen the hypothesis that certain xenobiotic chemicals may be associated with elevated oyster hemocyte activities, even though the ultimate influence on disease resistance remains unknown.

A survey of oysters Crassostrea virginica from Tampa Bay, Florida: associations of internal defense measurements with contaminant burdens.

Oysters from 16 sites in Tampa Bay, Florida, were collected during a 6-week period in winter 1993 and analyzed for both biological characteristics and tissue chemical concentrations. Using previous sediment contamination and toxicity data, oyster tissues from the selected sites were expected to exhibit a wide range in both quantity and type of chemicals. Chemical analysis showed tissue concentrations at some of these sites to be greater than national averages, as reported by the National Status and Trends Mussel Watch Program, for total PAH, total PCB, total chlordanes, DDT, Cu, Pb and Zn. Measures of oyster internal defense, including hemocyte density, rate of locomotion and superoxide generation, varied significantly among sites and were generally higher at sites with higher tissue concentrations of xenobiotic chemicals. Potential associations between oyster defense characteristics and accumulated chemical contaminants, either singly or in chemical classes, were explored using correlation analysis and a composited ranking procedure. Positive relationships were found for hemocyte characteristics with certain trace metal (Cu, Sn and Zn) and PAH analytes, whereas negative relationships were found with certain PCB and pesticide analytes. Heightened defenses in contaminated conditions may reflect a hemocyte process for sequestration and detoxification of environmental contaminants. Oysters from four of the 16 sites were additionally collected in June and September 1993 and site-related differences did not closely parallel those obtained in winter. Seasonal environmental factors may have altered contaminant-related differences among sites.

Relationships between acute sediment toxicity in laboratory tests and abundance and diversity of benthic infauna in marine sediments: a review.

Acute sediment toxicity tests have become important in regulatory, monitoring, and scientific programs, partly because it has been assumed that they are indicative of ecological damage to benthic infaunal resources. Data from tests of sediment toxicity and measures of benthic community structure were examined from > 1,400 saltwater samples to determine the relationships between acute toxicity and changes in the abundance and diversity of infauna resources. Data were compiled from studies conducted along portions of the Atlantic, Gulf of Mexico, and Pacific coasts of the United States. There was considerable variability among the data sets in the relationships between laboratory results and benthic measures. However, in 92% of the samples classified as toxic, at least one measure of benthic diversity or abundance was < 50% of the average reference value. In 67% of these samples, at least one measure of benthic infauna abundance or diversity was < 10% of average reference conditions. No amphipods were found in 39% of samples that were classified as toxic, whereas amphipods were absent from 28% of the nontoxic samples. In many survey areas, the abundance of crustaceans (notably the amphipods) decreased in the infauna as amphipod survival decreased in the laboratory tests. There appeared to be a break point in the data indicating that, generally, amphipod abundance in the field was lowest when survival in the laboratory tests dropped below 50% of controls. Based on the weight of evidence from all the data analyses, we conclude that ecologically relevant losses in the abundance and diversity of the benthic infauna frequently corresponded with reduced amphipod survival in the laboratory tests.

An evaluation of methods for calculating mean sediment quality guideline quotients as indicators of contamination and acute toxicity to amphipods by chemical mixtures.

Mean sediment quality guideline quotients (mean SQGQs) were developed to represent the presence of chemical mixtures in sediments and are derived by normalizing a suite of chemicals to their respective numerical sediment quality guidelines (SQGs). Mean SQGQs incorporate the number of SQGs exceeded and the degree to which they are exceeded and are used for comparison with observed biological effects in the laboratory or field. The current research makes it clear, however, that the number and type of SQGs used in the derivation of these mean quotients can influence the ability of mean SQGQ values to correctly predict acute toxicity to marine amphipods in laboratory toxicity tests. To determine the optimal predictive ability of mean SQGQs, a total of 18 different chemical combinations were developed and compared. The ability of each set of mean SQGQs to correctly predict the presence and absence of acute toxicity to amphipods was determined using three independent databases (n = 605, 2753, 226). Calculated mean SQGQ values for all chemical combinations ranged from 0.002 to 100. The mean SQGQ that was most predictive of acute toxicity to amphipods is calculated as SQGQ1 = ((sigma ([cadmium]/4.21 )([copper]/270)([lead]/ 12.18)([silver]/1.77)([zinc]/ 410)([total chlordane]/6)([dieldrin]/8)([total PAHoc]/1,800)([total PCB]/400))/9). Both the incidence and magnitude of acute toxicity to amphipods increased with increasing SQGQI values. To provide better comparability between regions and national surveys, SQGQ1 is recommended to serve as the standard method for combination of chemicals and respective SQGs when calculating mean SQGQs.

Sediment quality in Los Angeles Harbor, USA: a triad assessment.

Sediment quality in the Los Angeles and Long Beach Harbor area of southern California, USA, was assessed from 1992 to 1997 as part of the California State Water Resources Control Board's Bay Protection and Toxic Cleanup Program and the National Oceanic and Atmospheric Administration's National Status and Trends Program. The assessment strategy relied on application of various components of the sediment quality triad, combined with bioaccumulation measures, in a weight-of-evidence approach to sediment quality investigations. Results of bulk-phase chemical measurements, solid-phase amphipod toxicity tests, pore-water toxicity tests with invertebrate embryos, benthic community analyses (presented as a relative benthic index), and bioaccumulation measures indicated that inner harbor areas of this system are polluted by high concentrations of a mixture of sediment-associated contaminants and that this pollution is highly correlated with toxicity in laboratory experiments and degradation of benthic community structure. While 29% of sediment samples from this system were toxic to amphipods (Rhepoxynius abronius or Eohaustorius estuarius), 79% were toxic to abalone embryos (Haliotis rufescens) exposed to 100% pore-water concentrations. Statistical analyses indicated that amphipod survival in laboratory toxicity tests was significantly correlated with the number of crustacean species and the total number of species measured in the benthos at these stations. Triad measures were incorporated into a decision matrix designed to classify stations based on degree of sediment pollution, toxicity, benthic community degradation, and, where applicable, tissue concentrations in laboratory-exposed bivalves and feral fish.

An evaluation of Australian sediment quality guidelines.

Interim sediment quality guidelines (ISQGs) adapted recently to Australia from North American effects-based guidelines were evaluated with matching chemical and toxicological data collected for sediments (n = 103) from Sydney Harbour and south coast estuaries of New South Wales. The incidence of toxicity for the test battery was low (7%) among samples with all chemical concentrations below ISQG-Low values, indicating these guidelines are accurate and protective of non-toxic conditions. The incidence of toxicity increased greatly (to 73%) when one or more ISQG-Low values were exceeded, suggesting that ISQG-Low guidelines are appropriate for compliance. Frequent toxic effects (in >75% of samples) were associated with chemical concentrations exceeding ISQG-High guidelines. As expected, the high guideline values were more predictive of adverse effects than the low guidelines. Predictive abilities of ISQGs were not markedly affected by normalization of organic compounds to organic carbon or the use of dilute acid extractions for metals, suggesting that the guidelines are applicable to a wide range of conditions.

Relationships between toxicity and concentrations of chemical contaminants in sediments from Sydney Harbour, Australia, and vicinity.

Correlation analyses between measures of toxicity and concentrations of chemical contaminants were conducted for 103 surficial sediments from Sydney Harbour, Australia, and vicinity. Toxicity tests consisted of amphipod survival and reburial tests of whole sediments (Corophium colo), sea urchin fertilisation and larval development tests of pore waters (Heliocidaris tuberculata) and microbial bioluminescence (Microtox) tests of solvent extracts and pore waters. Toxicity in most tests correlated with concentrations of metallic contaminants, in particular, zinc, lead and copper. Organic contaminants did not correlate as significantly with toxicity. However, Heliocidaris tuberculata showed relationships with organochlorine compounds in samples with low to moderate metals contamination. Toxicity in the Microtox solvent extract test appeared to be primarily influenced by the presence of sulfur. This study has no precedent in Australia and the results support the validity of using local indigenous species in toxicity tests of field-collected sediments. This toxicity/chemistry dataset may be used in evaluations of sediment quality guidelines recently introduced to Australia.

MR imaging of posterior fossa infarctions: vascular territories and clinical correlates.

Ischemic infarctions in certain vascular territories of the cerebellum and brain stem can produce some characteristic radiologic and clinical patterns. The cerebellum serves as a coordination center for the maintenance of equilibrium and muscle tone and refines the movements of the somatic muscles. The anatomy of the brain stem is extremely complex, and small infarcts can potentially be disastrous. MR imaging depicts the anatomy of the posterior fossa and infarcts in this region with greater accuracy than was previously possible. Familiarity with the vascular territories and patterns of infarction of the posterior fossa depicted with MR imaging and familiarity with the associated clinical symptoms of stroke in this region can help the radiologist recognize these infarcts and correlate clinical and radiologic findings. When patients are referred for MR imaging of the brain because of clinical findings suggestive of infarction, it may be useful to obtain coronal or sagittal views in addition to axial images to better depict the vascular distribution of a suspected ischemic lesion.

Toxicity of surficial sediments from Sydney Harbour and vicinity, Australia.

The toxicological responses of three species to 103 surficial saltwater sediment samples from Sydney Harbour, and coastal lakes and estuaries on the south-east coast of New South Wales, Australia, were tested in a battery of four to six laboratory toxicity tests. This is the first large-scale toxicological study of sediments in Australia, the objective of which is to assess the protective and predictive abilities of North American biological effects-based sediment quality guidelines, recently adopted in Australia. Amphipods were exposed to whole sediments in survival and reburial tests, sea urchin fertilisation and larval development tests were conducted on porewaters, and bacterial bio-luminescence (Microtox) tests were conducted on organic solvent extracts and porewaters. Local indigenous species were used for the amphipod and sea urchin tests (Corophium sp. and Heliocidaris tuberculata, respectively). A wide range of responses, from <25 to 100% of negative controls were observed in all tests. Mean control-adjusted responses ranged from 46 to 96% for all tests. The percentages of highly toxic samples ranged from 11 to 83% in the various tests. The order of test sensitivity was: amphipod survival < Microtox test of porewaters < amphipod reburial < sea urchin larval development < sea urchin fertilisation < Microtox test of solvent extracts. Concordance between toxicity tests in classifying samples as highly toxic or not, ranged from 47 to 79%, indicating some similarities between test results, but not complete equivalence. Combined toxicity test results showed that the incidence of highly toxic responses occurring in the majority of tests (75-100% of tests) was low (5% of samples), but a large percentage of samples had highly toxic results in at least one test (76% of samples). Toxicity was more pervasive in the Sydney region than in coastal lakes and estuaries south of Sydney. The current study demonstrated the utility of indigenous invertebrate species and the Microtox bacterium in a sediment toxicity test battery for Australian saltwater sediments.

Development and evaluation of sediment quality guidelines for Florida coastal waters.

: The weight-of-evidence approach to the development of sediment quality guidelines (SQGs) was modified to support the derivation of biological effects-based SQGs for Florida coastal waters. Numerical SQGs were derived for 34 substances, including nine trace metals, 13 individual polycyclic aromatic hydrocarbons (PAHs), three groups of PAHs, total polychlorinated biphenyls (PCBs), seven pesticides and one phthalate ester. For each substance, a threshold effects level (TEL) and a probable effects level (PEL) was calculated. These two values defined three ranges of chemical concentrations, including those that were (1) rarely, (2) occasionally or (3) frequently associated with adverse effects. The SQGs were then evaluated to determine their degree of agreement with other guidelines (an indicator of comparability) and the percent incidence of adverse effects within each concentration range (an indicator of reliability). The guidelines also were used to classify (using a dichotomous system: toxic, with one or more exceedances of the PELs or non-toxic, with no exceedances of the TELs) sediment samples collected from various locations in Florida and the Gulf of Mexico. The accuracy of these predictions was then evaluated using the results of the biological tests that were performed on the same sediment samples. The resultant SQGs were demonstrated to provide practical, reliable and predictive tools for assessing sediment quality in Florida and elsewhere in the southeastern portion of the United States.

An approach to brief field testing for neurotoxicity.

A description is offered for a microcomputer-based testing system which utilizes an Apple II microcomputer with the Pascal language and additional hardware resources. Tasks implemented for the system have been selected to broadly sample cognitive functioning with some sensory and motor evaluation as well. Efforts to evaluate sensitivity, task interrelations, and reliability of measurement are described.

Development, evaluation, and application of sediment quality targets for assessing and managing contaminated sediments in Tampa Bay, Florida.

Tampa Bay is a large, urban estuary that is located in west central Florida. Although water quality conditions represent an important concern in this estuary, information from numerous sources indicates that sediment contamination also has the potential to adversely affect aquatic organisms, aquatic-dependent wildlife, and human health. As such, protecting relatively uncontaminated areas of the bay from contamination and reducing the amount of toxic chemicals in contaminated sediments have been identified as high-priority sediment management objectives for Tampa Bay. To address concerns related to sediment contamination in the bay, an ecosystem-based framework for assessing and managing sediment quality conditions was developed that included identification of sediment quality issues and concerns, development of ecosystem goals and objectives, selection of ecosystem health indicators, establishment of metrics and targets for key indicators, and incorporation of key indicators, metrics, and targets into watershed management plans and decision-making processes. This paper describes the process that was used to select and evaluate numerical sediment quality targets (SQTs) for assessing and managing contaminated sediments. These SQTs included measures of sediment chemistry, whole-sediment and pore-water toxicity, and benthic invertebrate community structure. In addition, the paper describes how the SQTs were used to develop site-specific concentration-response models that describe how the frequency of adverse biological effects changes with increasing concentrations of chemicals of potential concern. Finally, a key application of the SQTs for defining sediment management areas is discussed.