Carla M. Stehr

Dissolved copper triggers cell death in the peripheral mechanosensory system of larval fish

Dissolved copper is an increasingly common non-point source contaminant in urban and urbanizing watersheds. In the present study, we investigated the sublethal effects of dissolved copper on the peripheral mechanosensory system, or lateral line, of larval zebrafish (Danio rerio). Zebrafish larvae were exposed to copper (0-65 microg/L), and the cytotoxic responses of individual lateral line receptor neurons were examined using a combination of in vivo fluorescence imaging, confocal microscopy, scanning electron microscopy, and conventional histology. Dissolved copper triggered a dose-dependent loss of neurons in identified lateral line neuromasts at concentrations > or = 20 microg/L. The onset of cell death in the larval mechanosensory system was rapid (< 1 h). When copper-exposed zebrafish were transferred to clean water, the lateral line regenerated over the course of 2 d. In contrast, the lateral line of larvae exposed continuously to dissolved copper (50 microg/L) for 3 d did not recover. Collectively, these results show that peripheral mechanosensory neurons are vulnerable to the neurotoxic effects of copper. Consequently, dissolved copper in non-point source storm-water runoff has the potential to interfere with rheotaxis, schooling, predator avoidance, and other mechanosensory-mediated behaviors that are important for the migration and survival of fish.

Toxicopathic hepatic lesions as biomarkers of chemical contaminant exposure and effects in marine bottomfish species from the northeast and Pacific coasts, USA

Abstract Relationships between toxicopathic hepatic lesions and chemical contaminants in sediments, stomach contents, liver and bile were evaluated in English sole, starry flounder and white croaker from 27 sites on the Pacific Coast, and winter flounder from 22 sites on the Northeast Coast of the USA, as part of the NOAAs National Benthic Surveillance Program (NBSP). Prevalences of and relative risks for most toxicopathic lesions were significantly higher in fish from contaminated sites in Puget Sound, the Los Angeles area, and San Francisco and San Diego Bays on the Pacific Coast, and in Boston Harbor, Raritan Bay and certain urban sites in Long Island Sound on the Northeast Coast. Exposure to polycyclic aromatic hydrocarbons (PAHs), PCBs, DDTs, chlordanes and dieldrin were significant risk factors for all lesion types in Pacific Coast species. In winter flounder from the Northeast Coast, exposure to PAHs, DDTs or chlordanes were significant risk factors only for hydropic vacuolation, nonneoplastic proliferative and nonspecific necrotic lesions, and less commonly for neoplasms and foci of cellular alteration. Risk of hepatic disease generally increased with fish age, but sex was rarely a risk factor. Temporal trends analyses of hepatic lesion prevalences in starry flounder, white croaker and English sole from NBSP sites on the Pacific Coast failed to detect any significant monotonic increases or decreases in lesion prevalence. Recent studies utilized a two-segment ‘hockey-stick’ regression technique applied to NBSP data to determine threshold levels of sediment PAHs, which are clearly associated with toxicopathic hepatic lesions in English sole. Significant chemical threshold levels for these lesions are in the vicinity of 500–1000 ppb ΣPAHs in sediment, values considerably lower than those reported for other techniques. Application of this dose-response model to these subacute and chronic lesions involved in hepatocarcinogenesis, provides nonlethal sediment quality assessment endpoints for contaminant concentrations that may have long term health implications for chronically exposed native fish populations. Overall, these relationships provide strong evidence for environmental contaminants as etiologic agents for hepatic lesions in several marine bottomfish species, and clearly indicate their utility as biomarkers of contaminant-induced effects in wild fish, whether in national and regional biomonitoring programs or within the injury assessment phase of the legal process of assessing damage to fishery resources.

Toxicopathic liver lesions in English sole and chemical contaminant exposure in Vancouver Harbour, Canada

The prevalence of toxicopathic liver lesions in English sole (Pleuronectes vetulus) was determined along a presumed gradient of chemical contamination in Vancouver Harbour, Canada. Fish were captured from five sites in or near Vancouver Harbour, British Columbia, Canada. No toxicopathic lesions were observed in fish examined at the reference site (Howe Sound outside Vancouver Harbour), or at the outer harbour site. In contrast, 20-23% of the fish from three sites located in the central harbour, Indian Arm and Port Moody Arm had one or more types of toxicopathic lesions. Likewise, aromatic hydrocarbon (AH) metabolites measured in bile exhibited a gradient in levels from lower concentrations at the reference site to significantly higher levels in fish from Indian Arm and Port Moody Arm harbour sites. The occurrence of toxicopathic liver lesions was statistically associated with concentrations of AHs measured in sediment and AH metabolite levels measured in bile.

Organic and trace metal contaminants in sediments and English sole tissues from Vancouver Harbour, Canada

As part of a multinational workshop on marine environmental quality, sediments were collected from seven sites in Vancouver Harbour and analyzed for polynuclear aromatic hydrocarbons (PAHs) and organochlorines (OCs), and for trace metals. English sole were collected from five sites, and muscle was analyzed for trace metals and liver for OCs. As expected, sediment PAH and OC concentrations and tissue OC concentrations were higher at sites east of the First Narrows, compared to the outer harbor and reference sites. Sediment PAH concentrations east of the First Narrows were similar to concentrations at moderately contaminated sites in Puget Sound, south of Vancouver Harbour. In contrast, concentrations of OCs in sediments and tissue were low to moderate, even at relatively contaminated sites within Vancouver Harbour. Although several trace metals in sediments were higher than in contaminated sediments from Puget Sound, trace metals measured in fish muscle were lower.

Chemical contamination and associated liver diseases in two species of fish from San Francisco Bay and Bodega Bay

Starry flounder (Platichthys stellatus), white croaker (Genyonemus lineatus) and sediments were collected annually from selected sites within San Francisco Bay, and a reference site in Bodega Bay between 1984--1991. Fish livers were examined for toxicopathic lesions and analysed for selected chlorinated hydrocarbons (CHs) such as PCBs, DDTs, chlordanes and dieldrin; sediment and fish stomach contents were analysed for polycyclic aromatic hydrocarbons (PAHs) and CHs; and bile was analysed for PAH metabolites. Sediment concentrations of PAHs, PCBs and DDTs; bile concentrations of PAH metabolites; and liver concentrations of PCBs, dieldrin and chlordanes were generally significantly higher at all San Francisco Bay sites compared to the Bodega Bay reference site. For both species, hydropic vacuolation of biliary epithelial cells was the most prevalent liver lesion detected and was statistically associated with sediment and tissue concentrations of PAHs or their metabolites, PCBs, DDTs, chlordanes and dieldrin. Temporal trends analyses showed that at Hunters Point, sediment PAHs and CHs increased between 1984--1991, while liver concentrations of CHs decreased. Liver concentrations of dieldrin in starry flounder decreased at all three San Francisco Bay sites

Exposure of juvenile chinook and chum salmon to chemical contaminants in the Hylebos Waterway of Commencement Bay, Tacoma, Washington

The Hylebos Waterway is an industrialized waterway ofCommencement Bay, Tacoma, Washington, that is severelycontaminated with aromatic and chlorinatedhydrocarbons in the sediment. Juvenile chinook (Oncorhynchus keta) and chum salmon (O.tshawytscha) inhabit this waterway for a few days orweeks during their outmigration from freshwaterstreams to saltwater. The purpose of thisinvestigation was to determine to what degree juvenilechum and chinook salmon captured from the HylebosWaterway might bioaccumulate organic contaminants. These levels of exposure will be compared to previousstudies where such exposures have been linked tobiological dysfunction in juvenile salmon. Theresults showed that juvenile chum and chinook salmonfrom the Hylebos Waterway take up a wide range ofchemical contaminants, compared to fish fromhatcheries or reference estuaries. These contaminantsinclude high and low molecular weight polycyclicaromatic hydrocarbons (PAHs), polychlorinatedbiphenyls (PCBs, including the toxic congeners 105 and118), hexachlorobutadiene (HCBD), hexachlorobenzene(HCB), DDTs, heptachlor, and several pesticides. Immunohistochemical examination of the gill and gut injuvenile chum salmon from the Hylebos Waterway showedthe induction of the P450 metabolizing enzyme. Moreover, concentrations of contaminants in juvenilechinook and chum salmon from the Hylebos Waterway arecomparable to levels previously shown to be associatedwith biological injury in juvenile chinook salmon,such as impaired growth, suppression of immunefunction as demonstrated by reduced B cell function,and increased mortality following pathogen exposure.

Cytopathology of the brain and retina of embryonic surf smelt (Hypomesus pretiosus) exposed to crude oil

Abstract In laboratory experiments, surf smelt (Hypomesus pretiosus) embryos were exposed to 54 or 113 ppb of the seawater-accommodated fraction (SWAF) of Cook Inlet crude oil (CICO) for 3 hr per day, beginning 6 days after fertilization. Embryos 21 and 27 days old (just prior to hatching) exposed to CICO were examined for morphological abnormalities. The only tissues that showed morphological changes in both the 21- and 27-day-old CICO-exposed smelt were the forebrain and the neuronal layer of the retina: both contained numerous necrotic neurons. The retinal receptor cells appeared normal in 21-day-old exposed smelt; in contrast, in 27-day-old treated embryos the ellipsoid and myoid regions of the receptor cell inner segments were severely damaged. Further impact from the SWAF of CICO on developing smelt was indicated by a lower hatching success: approximately 10% in the exposed groups as compared to 50% in the controls.

The Ultrastructure and Histology of Cholangiocellular Carcinomas in English Sole (Parophrys vetulus) from Puget Sound, Washington

The ultrastructure and histology of cholangiocellular carcinomas from feral English sole (Parophrys vetulus) living in polluted waterways of Puget Sound, WA. are described. Electron microscopy confirmed that biliary epithelial cells were the main proliferative cell type composing this variety of neoplasm. The arrangement of these cells varied from well-organized multiple bile duct-like structures to disorganized multilayered sheets of poorly differentiated biliary epithelial cells. A fibrous stroma consisting of multiple layers of collagen fibers and fibroblasts, with macrophages and various blood cell types scattered among these layers occurred between bile duct-like structures or aggregates of biliary epithelial cells. Hepatocytes were not apparent in these neoplasms except within small necrotic regions surrounded by neoplastic biliary epithelial cells. No viruslike particles were observed among the cases examined in this study.

The development of the hexagonally structured egg envelope of the C-O sole (Pleuronichthys coenosus)

The surface of a mature, pelagic C‐O sole egg is composed of polygonal chambers having four to eight sides, most of which are hexagonally shaped. This honeycomb pattern initially appears on primary oocytes as a thin layer of compact, electron‐dense material. Discrete thickenings begin to develop on the envelope of perinuclear stage oocytes. The thickenings lengthen and thin to form the hexagonal walls of the envelope in oocytes undergoing yolk vesicle formation. The walls of each hexagonal chamber occur in an area corresponding to the lateral margins of the adjacent follicle cell, suggesting that the hexagonal walls are produced by the follicle cells. The hexagonal layer is nearly complete at the beginning of vitellogenesis, and as vitellogenesis continues, a striated envelope layer composed of fibrillar lamellae develops between the oocyte and the hexagonal layer. The striated layer appears to be secreted by the oocyte. After vitellogenesis is completed, oocytes are ovulated and double in size during a period of maturation. Concurrently, the striated primary envelope stretches and thins into eight to nine horizontal lamellae. On the mature egg surface, the polygonal chambers are about 24–31 μm in diameter. Within each chamber there is a subpattern of polygonal areas; each polygon is 1.5–2.0 μm in diameter, and circumscribes a pore canal opening. This exceptional envelope may furnish the egg with some degree of protection, resiliency, and buoyancy, but its specific functions are not known.

Barging Effects on Sensory Systems of Chinook Salmon Smolts

Abstract To avoid mortality caused by passage through dam turbines and spillways, juvenile Chinook salmon Oncorhynchus tshawytscha are annually transported downstream by barge through the federal hydropower system on the Snake and Columbia rivers. Survival of transported fish is higher than that of in-river migrants; however, transported fish experience higher rates of postrelease mortality. Increased mortality could result from a decrease in the ability to detect or avoid predators due to stressors associated with the barge environment. This study examined the effects of barging on juvenile Chinook salmon olfaction and auditory function, two sensory systems involved in predator detection. We focused on dissolved metals known to be toxic to the salmon olfactory system and on the level of noise from the barge, which could impair the auditory system. Experimental groups included animals collected (1) before barge loading (control group), (2) at the Bonneville Dam bypass system (migrant fish), (3) immediatel...