Publications (27)26.8 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: Juvenile yellowfin sole (Pleuronectes asper), rock sole (Pleuronectes bilineatus), and Pacific halibut (Hippoglossus stenolepis) had reduced growth following 30-90 days of exposure to sediments laden with Alaska North Slope crude oil. Changes in fish health bioindicators after 90 days, i.e., increases in fin erosion, liver lipidosis, gill hyperplasia, and gill parasites, coupled with decreases in macrophage aggregates, occurred at hydrocarbon concentrations (1600 µg/g) that reduced growth 34-56% among the flatfishes. Chronic hydrocarbon pollution of nearshore nursery sediments could alter growth and health of juvenile flatfishes. Recruitment of juveniles to the fishery may decline because of increased susceptibility to predation and slower growth.
- [Show abstract] [Hide abstract] ABSTRACT: We compared the impact of exposure to seawater on three sockeye salmon (Oncorhynchus nerka) stocks: one that normally migrates to sea as underyearlings (sea-type) and two with the more common life history strategies of 1 (river-type) or 2 (lake-type) yr of freshwater residence prior to seaward migration. Innate differences in survival, ability to regulate tissue chlorides, and oxygen consumption when first introduced into salt water were more evident in April and May when fish were less than 50 mm in length. In fish longer than 50 mm, the only significant differences among the stocks were in saltwater growth. Between June and August, sea-type fish showed faster growth than river-type fish which in turn grew faster than lake-type fish. When introduced into salt water in October, virtually no growth occurred in any stock, regardless of fish size. River-type and lake-type sockeye, which normally overwinter 1 and 2 yr, respectively, in freshwater, can be reared in seawater if underyearlings are raised to a length of 50 mm before release into salt water, similar to the normal life history of sea-type underyearlings. Early life history appears to be influenced more by habitat than by genetics.
- [Show abstract] [Hide abstract] ABSTRACT: To determine if hydrocarbon levels in salmon-rearing lakes are affected by seasonal increases in the number of two-stroke powered watercraft, passive hydrocarbon sampling devices were deployed in Auke Lake in southeast Alaska for five successive summers (1999–2003). Estimates of the number of two-stroke powered water craft were made by daily census in 2003. Passive samplers mimic the bioconcentration of trace waterborne lipophilic contaminants by living organisms and are used worldwide for in situ monitoring of organic contaminants such as polycyclic aromatic hydrocarbons (PAHs). Monthly increases in PAHs coincided with monthly increases in the number of two-stroke powered watercraft (jet skis and powerboats) on the lake during the summer. This increase in PAHs varied in magnitude from year to year. PAHs were detected in the surface waters (1 m), particularly in high use areas, and were not detected at 9 m depth. These localized seasonal inputs appeared to come primarily from recreational watercraft rather than from runoff. Alaska's recreational boating season is very compressed and coincides with migrations of anadromous fish. Increased use of two-stroke engines may transfer enough hydrocarbons to the lake to affect fish populations.
- [Show abstract] [Hide abstract] ABSTRACT: Coho salmon (Oncorhynchus kisutch) smolts infected with the nematode Philonema agubernaculum had 36% lower mean lipid content (1.4%) than nonparasitized coho salmon (2.2%) harvested simultaneously from the same outmigration. Lengths, weights, and condition factors, as well as protein and moisture content, did not differ significantly between the two groups. Lipid class compositions differed significantly between the parasitized and nonparasitized fish. None of the nematode-infected fish contained detectable triacylglycerols (TAG) or monoacylglycerols (MAG). In contrast, mean TAG and MAG contents of the nonparasitized fish totaled 5.5% of the extracted lipid. Infected smolts had lower cholesterol contents than did uninfected coho (17% for infected, 33% for uninfected). Parasitized fish had significantly higher levels of free fatty acids (mean of 57% for parasitized vs. 35% for nonparasitized) as well as the phospholipids phosphatidylethanolamine (PE) and phosphatidylcholine (PC). However, the PC/PE ratios for infected and noninfected coho did not differ significantly (2.2 for infected vs. 2.0 for uninfected). These differences suggest that the parasitic nematodes are either harvesting storage energy directly from the coho or are placing additional energetic demands on the fish to cope with the infection.
- [Show abstract] [Hide abstract] ABSTRACT: This chapter discusses the largest marine oil spill in the United States and the largest spill in a sub Arctic ecosystem; however, the damage from the Exxon Valdez oil spill (EVOS) was due as much to when and where it happened as it was to the size of the spill. The oil inundated seabird, sea otter, and harbor seal habitat just prior to their breeding seasons and that of many other vulnerable species. Oil persisted beyond a decade in surprising amounts and in toxic forms. The residual oil was sufficiently bioavailable to induce chronic biological exposures to near shore species and oil had both short-term and long-term effects on a wide variety of species, with prolonged effects on species associated with oiled sediments. The Exxon Valdez spill is the most thoroughly studied oil spill in the history. The conceptual models based on laboratory tests and previous oil spills proved inadequate for describing or predicting the outcome of the Exxon Valdez oil spill. The nature confounded the tracking and observed changes over time, this spill was not burdened with the layering of other spills, industrial effluents, or urban development and sewage.
- [Show abstract] [Hide abstract] ABSTRACT: Fish serve as intermediate hosts for a number of larval parasites that have the potential of maturing in marine mammals such as Steller sea lions (Eumetopias jubatus). We examined the prevalence of parasites from 229 fish collected between March and July 2002 near two islands used by Steller sea lions in Southeast Alaska and island habitats in the Aleutian Islands. Sea lion populations have remained steady in Southeast Alaska but have been declining over the last 30 yr in the Aleutian Islands. Even though the fish samples near the Southeast Alaska haul-outs were composed of numerous small species of fish and the Aleutian Islands catch was dominated by juveniles of commercially harvested species, the parasite fauna was similar at all locations. Eleven of the 20 parasite taxa identified were in their larval stage in the fish hosts, several of which have been described from mammalian final hosts. Four species of parasite were more prevalent in Southeast Alaska fish samples, and seven parasite species, including several larval forms capable of infecting marine mammals, were more prevalent in fish from the Aleutian Islands. Nevertheless, parasites available to Steller sea lions from common fish prey are not likely to be a major factor in the decline of this marine mammal species.
- [Show abstract] [Hide abstract] ABSTRACT: Conventional passive sampling devices for monitoring pollution input often prove to be cost-prohibitive when assessing large spatial and temporal scales. The Kenai River, a major salmon-producing river in Alaska (USA), served as the perfect laboratory to test the utility of polyethylene membrane devices for assessing chronic nonpoint-source inputs to a large riverine watershed. Comparison of the relative levels of polycyclic aromatic hydrocarbons (PAHs) at a large number of locations over time allowed us to assess the significance and potential source of these compounds in the river. Concentrations of PAH were greatest near urban areas and peaked during the late winter, when streams flows and dilution were low. Vessel activity and PAH levels peaked in July and were heaviest in the lower 16 km of the river, where fishing activity was concentrated. Nearly one-third of the vessels observed on the river were powered by two-stroke engines, which release a higher proportion of unburned fuel into the water than the cleaner burning four-stroke engines. The low concentrations of hydrocarbons upriver of the boat traffic suggest very little remote delivery of these contaminants to the watershed. Polyethylene strips proved to be an excellent, low-cost tool for determining the PAH patterns in a large watershed.
- [Show abstract] [Hide abstract] ABSTRACT: Mussels, Mytilus trossulus (average shell length 43+/-0.8 mm), were sampled from a beach in Alaska that received untreated sewage for several years, a second beach adjacent to a secondary wastewater outfall, and two nearby reference beaches. Survival time in air, byssal thread production rate, and prevalence of trematode parasites were determined for each group. Tolerances to aerial exposure was significantly lower (P<0.05) at both sewage outfall sites than at the reference sites. Mussels exposed to untreated sewage produced fewer byssal threads and had a significantly higher prevalence of encysted trematodes than mussels from the other beaches, including the secondary wastewater site. Survival in air, byssal thread production, and trematode prevalence in mussels may be useful indicators in evaluating the longterm health of beaches exposed to sewage.
- [Show abstract] [Hide abstract] ABSTRACT: Habitat damage resulting from oil contamination is underestimated by acute toxicity assays. Nearshore substrates oiled by spills may become persistent pollution sources of toxic polycyclic aromatic hydrocarbons (PAH). Recent findings resulting from research following the Exxon Valdez oil spill include: (1) PAHs are released from oil films and droplets at progressively slower rates with an increasing molecular weight, leading to greater persistence of larger PAHs; (2) eggs from demersally-spawning fish species accumulate dissolved PAHs released from oiled substrates, even when the oil is heavily weathered; and (3) PAHs accumulated by embryos from aqueous concentrations of < 1 μg/L can lead to adverse sequelae appearing at random over the lifespan of an exposed cohort, probably as a result of damage during early embryogenesis. Polycyclic Aromatic Hydrocarbons (PAH) can be a slow-acting poison, and toxic effects may not manifest until long after exposure. These considerations have important policy implications regarding protection of fish natal and rearing habitats.
- [Show abstract] [Hide abstract] ABSTRACT: The effect of various states of weathering (no weathering, 20% evaporatively weathered, and emulsification) on the effectiveness of oil dispersants Corexit 9527 and 9500 in dispersing Alaska North Slope crude oil into the water column was tested under laboratory conditions at a combination of realistic subarctic salinities and temperatures. A modified version of the swirling flask effectiveness test was conducted at temperatures of 3, 10 and 22 °C with salinities of 22‰ and 32‰. Petroleum dispersed into the water column following application of dispersant was measured by gas chromatography with flame ionization detection. Based on comparison of unresolved complex mixtures, dispersants dispersed less than 40% of the fresh oil and less than 10% of the weathered oil and were most effective (25–75%) when used to disperse a stable oil/water emulsion at 10 °C. At the combinations of temperature and salinity most common in the estuaries and marine waters of Alaska, dispersants effectiveness was less than 10%, the detection limits of the tests. The results indicate that oil weathering state, seawater salinity and temperature are important factors affecting dispersant performance, however because our laboratory tests were conducted at low mixing energy, considerable caution should be used in extrapolating these laboratory studies to field conditions.
- [Show abstract] [Hide abstract] ABSTRACT: Injury to a species resulting from long-term exposure to low concentrations of pollutants is seldom noted or even tested. One of the products of the Exxon Valdez oil spill was the first report of damage to eggs and larvae of pink salmon (Oncorhynchus gorbuscha) following long-term exposure to low concentrations of weathered crude oil. These life stages were previously thought to be highly resistant to injury from oil. Growth rate among migrating fry was depressed, and the population was reduced via size-dependent mortality. Elevated egg mortality in oiled streams continued for at least 4 years after the spill. Laboratory tests verified that embryos are sensitive to long-term exposure to weathered oil in the low parts per billion range. These results are compared with those of studies conducted by investigators funded by Exxon Corporation and, where controversy exists, we attempt to reconcile the studies. These findings are important to the pink salmon fisheries of Prince William Sound (PWS) and are also broadly applicable to toxicity and impact from nonpoint source pollution of urban estuaries.
- [Show abstract] [Hide abstract] ABSTRACT: Immediate damage from an oil spill is usually obvious (oiled birds, oiled shoreline), but long-term damage to either fauna or habitat is more subtle, difficult to measure, difficult to evaluate, and hence often controversial. The question is, are too many of response decisions such as dispersant use or shoreline cleanup based on short-term acute toxicity models? Have long-term damage scenarios been discounted because of the inherent difficulty in deriving definitive answers? Experience with the Exxon Valdez oil spill is shedding new light on the potential for long-term damage. Government-funded studies demonstrated that oil persists in certain habitats for extended periods of time, such as the interridal reaches of salmon streams, in soft sediments underlying mussel beds, and on cobble beaches armored with large boulders. Observation of long-term persistence of oil in some habitats is not new, but an increasing number of studies indicate that fauna may be chronically and significantly exposed to oil in these habitats. The toxic components in oil responsible for much of the long-term effects are believed to be the larger 3- and 4-ring polyaromatic hydrocarbons (PAHs) that can induce cellular and genetic effects rather than the narcotic monoaromatic hydrocarbons (MAHs) responsible for acute mortalities. Observation of long-term persistence of Exxon Valdez oil, coupled with adverse effects on sensitive life stages, leads to the conclusion that strategies based on minimizing acute mortalities immediately following a spill probably do not provide adequate protection against long-tenn damage. When making environmental decisions in response to a spill (prevention measures or restoration measures), more weight should probably be given to long-term issues rather than discounting their significance. Total environmental cost is the sum of short-term damage and long-term damage, and long term-damage to habitats and sensitive life stages probably needs more consideration even though it is very difficult to evaluate and compare to the relatively obvious acute issues.
- [Show abstract] [Hide abstract] ABSTRACT: Recent advances in oil toxicity research may well alter the way oil spill response decisions are made. Those responding to spills should be aware of the limitations surrounding the use of acute toxicity data to predict even short-term oil effects. Many animals previously classified as tolerant of short-term oil exposure, such as fish eggs and benthic organisms, are just as or much more sensitive than pelagic fishes to chronic exposures. Toxicity bioassays proved to be of limited value in predicting the long-term damage from the Exxon Valdez oil spill because such toxicity information only measured mortality to water-accommo-dated fractions of fresh oil over a 96-hour period. During the spill, many of the aquatic organisms were exposed to weathered oil resolubilized from nearshore sediments rather than to fresh oil in the water column. Oil allowed to sequester in the sediments of streams, mussel beds, and estuaries provided a persistent source of contamination in natal and nursery fish habitats over several years. Eggs, larvae, and juveniles that inhabit these habitats are especially sensitive to long-term exposure to sediment accommodated weathered oil. Spill response should be geared toward preventing oil from reaching streams, fine sediment beaches, and estuaries that serve as critical fish habitats rather than solely toward reducing initial mortalities.
- [Show abstract] [Hide abstract] ABSTRACT: Behavioural preference tests were used to determine if sediment selection played a role in habitat choice. Four species of juvenile pleuronectids were given a choice of eight sediments in a carousel and final choices were recorded after 20 h. Juvenile flatfishes demonstrated strong selection for sediments less than 500 μm. Juvenile starry flounder (Platichthys stellatus) selected larger particles with increasing fish size. Starry flounder under 25 mm in length chose mud, 50–80 mm fish chose mud and mixed mud sediments and larger juveniles (>150 mm) confined themselves to find sand. Juvenile halibut (Hippoglossus stenolepis) at 50–80 mm preferred a combination of mud and fine sand and were spatially segregated. Yellowfin sole (Pleuronectes asper) at 50–80 mm showed a slight preference for mud and mixed mud sediments over sand, a selection that became stronger in larger (>150 mm) fish. Juvenile rock sole (Pleuronectes bilineatus) at 50–80 mm preferred substrata of sand and mixed sand nearly 90% of the time. All species seldom selected sediments which were too coarse to allow the flatfishes to bury themselves, such as granular or pebble substrata. The results of these laboratory studies can be used to predict the distribution of juvenile flatfishes in a nursery area.
- [Show abstract] [Hide abstract] ABSTRACT: Behavioural tests were used to determine whether juvenile flatfishes were capable of detecting and avoiding sediment containing various concentrations of petroleum hydrocarbons. Three species of juvenile Alaskan flatfishes: rock sole (Pleuronectes bilineatus), yellowfin sole (P. asper), and Pacific halibut (Hippoglossus stenolepis) were tested in laboratory chambers containing contaminated mud or sand offered in combination with clean mud, sand or granule. The flatfishes were able to detect and avoid heavily oiled (2%) sediment, but they did not avoid lower concentrations of oiled sediment (0.05%). Oiled sediment was favoured over unoiled sediment if the unoiled sediment was of the grain size not preferred by that species. Oiled sand or mud was always preferred unoiled granule. The observed lack of avoidance at concentrations likely to occur in the environment may lead to long-term exposure to contaminated sediment following a spill. Recruitment of juveniles may be affected if the exposure to oil is long enough to affect growth and survival.
- [Show abstract] [Hide abstract] ABSTRACT: 1.1. Coho salmon smolts accumulated up to 30 times more hydrocarbon in selected tissues than did coho salmon jacks when exposed to water-soluble fraction of Cook Inlet crude oil.2.2. Aryl hydrocarbon hydroxylase (AHH) activity continued to increase during 12 days of exposure in coho smolts, in contrast to jacks in which AHH activity peaked at 2 days and remained elevated during 20 days of exposure.3.3. Cytochrome P-450 concentrations peaked in 48 hr and returned to control levels in exposed smolts. In exposed and control jacks, cytochrome P-450 decreased during the 20 day experimental period. Concentrations of P-450 were significantly greater, however, in exposed jacks than in control jacks.4.4. Aryl hydrocarbon hydroxylase (AHH) activity and cytochrome P-450 concentrations were greater in non-exposed coho smolts and jacks than in non-exposed pre-spawning adults.5.5. Coho jacks were not as responsive as coho smolts in terms of P-450 induction, however, they were more responsive than anticipated for a fish in a terminal life stage.
- [Show abstract] [Hide abstract] ABSTRACT: Pink salmon, Oncorhynchus gorbuscha, alevins (5 and 60 days after hatching) were continuously or intermittently exposed for 30 days to the water-soluble fraction (WSF) of Cook Inlet crude oil in fresh water or in a simulated freshwater-seawater cycle. Alevins exposed to 0·7−2·4 mg/liter WSF in the simulated tidal cycle were more sensitive to oil, had reduced yolk reserves, and accumulated more hydrocarbons than did alevins exposed to the same concentrations in fresh water. Alevins in fresh water were more sensitive to continuous than to intermittent exposures. In all exposures, 60-day alevins were more severely affected than were 5-day alevins.
National Marine Fisheries ServiceSilver Spring, Maryland, United States
National Oceanic and Atmospheric Administration
Juneau, Alaska, United States
- Auke Bay Laboratories
University of Alaska Fairbanks
Fairbanks, Alaska, United States
- Institute of Marine Science
NOAA FisheriesSilver Spring, Maryland, United States