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Gary K Ostrander - One of the best experts on this subject based on the ideXlab platform.

  • pigmented skin tumors in gizzard shad Dorosoma Cepedianum from the south central united states range extension and further etiological studies
    Environmental Toxicology and Chemistry, 1998
    Co-Authors: David R Geter, W E Hawkins, Jay C Means, Gary K Ostrander
    Abstract:

    Previous studies reported skin tumors diagnosed as pigmented subcutaneous spindle-cell neoplasms in 22% of gizzard shad (Dorosoma Cepedianum) from Lake of the Arbuckles, Oklahoma, USA. Those studies could not confirm chemical carcinogens or retroviruses as etiological agents. The present study reports the neoplasms in 20% of shad from two additional lakes, Lake Murray and Lake Texoma in south-central Oklahoma, extending the range of the lesion. No neoplasms were found in shad from a reference site, Lake Carl Blackwell, Oklahoma. Further investigations into the etiology of the lesions were conducted. Significant levels of potentially carcinogenic trace elements in the water, sediment, or tissues were not identified by inductively coupled plasma mass spectrometry. Radioactivity, analyzed by liquid scintillation counting of radon and gross alpha/beta radiation, was not above background levels. Genetic marker and band-sharing analysis by random amplified polymorphic DNA and double-stringency polymerase chain reaction could not separate tumor-bearing shad from nontumor-bearing ones. Of 2,128 shad examined, 387 exhibited lesions, with a significantly higher number occurring dorsally (79.5%) than ventrally (20.5%). Overall, this study showed the epizootic is not limited to a single lake and tended to rule out some known carcinogens and radioactivity as proximate causes of the epizootic.

  • pigmented skin tumors in gizzard shad Dorosoma Cepedianum from the south central united states range extension and further etiological studies
    Oklahoma Water Resources Research Institute, 1996
    Co-Authors: Gary K Ostrander, W E Hawkins, David R Geter, Jay C Means
    Abstract:

    Previous studies reported skin tumors diagnosed as pigmented subcutaneous spindle cell neoplasms in 22% of gizzard shad (Dorosoma Cepedianum) from Lake of the Arbuckles, Oklahoma. Those studies could not confirm chemical carcinogens or retroviruses as etiological agents. The present study reports the neoplasms in 20% ofshad from two additional lakes, Murray and Texoma in south-central Oklahoma, extending the range of the lesion. No neoplasms were found in shad from a reference site, Lake Carl Blackwell, OK. Further investigations into the etiology of the lesions were conducted. Significant levels ofpotentially carcinogenic trace elements in the water, sediment, or tissues were not identified by inductively coupled plasma mass spectrometry. Radioactivity analyzed by liquid scintillation counting of radon and gross alphalbeta radiation was not above background. Genetic marker and band sharing analysis by random amplified polymorphic DNA and double-stringency polymerase chain reaction could not separate tumor-bearing shad from nontumor-bearing ones. Of 2128 shad examined, 387 exhibited lesions with a significantly higher number occurring dorsally (79.5%) than ventrally (20.5%). Overall, this study showed the epizootic is not limited to a single lake and tended to rule out some known carcinogens and radioactivity as proximate causes for the epizootic.

  • further investigations of the etiology of subcutaneous neoplasms in native gizzard shad Dorosoma Cepedianum
    Environmental Toxicology and Chemistry, 1995
    Co-Authors: Ann Durham Jacobs, Gary K Ostrander
    Abstract:

    Aspects of the etiology of subcutaneous spindle-cell neoplasms in feral gizzard shad (Dorosoma Cepedianum) collected from Lake of the Arbuckles, Oklahoma, were investigated. Field collections of adult and juvenile gizzard shad were conducted to determine the prevalence and seasonality of neoplasms and site specificity of neoplasms-bearing fish. Overall neoplasm prevalence for adult gizzard shad was 22.1%; no juveniles exhibited neoplasms. Neoplasm occurrence did not appear seasonal. Neoplasm-bearing gizzard shad were found at all three sampling sites within Lake of the Arbuckles with similar neoplasm prevalence rates (Guy Sandy Creek 22.1%, Rock creek, 17.9%, and Buckhorn Creek 22.4%). No gizzard shad (juvenile or adult) collected from Lake Carl Blackwell, Oklahoma, the reference site, exhibited neoplasms. Water, sediment, and shad liver tissue from Lake of the Arbuckles and the reference site were analyzed for total recoverable metals (cadmium, chromium, copper, nickel, and lead, by graphite furnace atomic absorption). Chromium, copper, and nickel were found in the water samples at concentrations of >1 to 8.6 {micro}g/L. Low concentrations (>1 to 13.6 {micro}g/g wet weight) of all the metals were found in the sediment and liver tissue for both sites. Heavy metal contamination does not appear linked to neoplasm occurrence. To determine if amore » nonbacterial infectious agent was responsible for tumor formation, cell-free neoplasm homogenates were injected into healthy rainbow trout. Neoplasms were not transmitted into rainbow trout. Neoplasms were not transmitted into rainbow trout. The etiology of these neoplasms remains unknown.« less

  • pigmented subcutaneous spindle cell tumors in native gizzard shad Dorosoma Cepedianum
    Carcinogenesis, 1995
    Co-Authors: Gary K Ostrander, W E Hawkins, R L Kuehn, Ann Durham Jacobs, Kenneth Berlin, J Pigg
    Abstract:

    An epizootic of pigmented subcutaneous spindle cell tumors affected nearly 25% of the adult gizzard shad (Dorosoma Cepedianum) sampled from Lake of the Arbuckles in central Oklahoma over a 2 year period. Grossly, the tumors were primarily distributed over the head, trunk and fins as superficial raised masses that were almost always darkly pigmented. Histologically, they were located in the dermis, had a variable amount of connective tissue, and consisted of cells in a variety of forms and arrangements. Most tumors were composed of fusiform or spindle cells arranged in wavy bundles, whirling patterns or interwoven fascicles. Pigmentation was attributed to large dense deposits of melanin or to scattered individual melanin-containing cells. Immunohistochemical detection of proliferating cell nuclear antigen revealed a high proliferative activity in the spindle cells. Electron microscopy showed that the tumors were composed of several cell types, including host reactive cells, melanocytes in stages of maturity, and fibroblast-like cells. Tumor cells had neither cell-to-cell junctions nor an external lamina. Although the cell of origin of the tumors was not identified, evidence points toward melanocytes or, possibly, nerve sheath cells. However, an origin from fibroblasts or some other poorly differentiated cell cannot be ruled out. The etiology of the tumors was not determined. Fractionation of lake water and sediment samples followed by GC - MS analysis revealed no carcinogenic compounds. A retroviral etiology is unlikely because assays for reverse transcriptase in tumor homogenates were negative, and no evidence of viral particles was found in specimens examined by electron microscopy.

John M Dettmers - One of the best experts on this subject based on the ideXlab platform.

  • effect of detritus quality on growth and survival of gizzard shad Dorosoma Cepedianum potential importance to benthic pelagic coupling
    Canadian Journal of Fisheries and Aquatic Sciences, 2007
    Co-Authors: Gene W Kim, John M Dettmers, Roy A Stein, Alpa P Wintzer, Trisha K Menker, Russell A Wright, Dennis R. Devries
    Abstract:

    Gizzard shad (Dorosoma Cepedianum) population characteristics vary with lake productivity, competing with and providing prey for sport fishes. Because age-0 gizzard shad (>30 mm total length) are facultative detritivores, they can link benthic energy, carbon, and nutrients to pelagic food webs. To determine how age-0 gizzard shad success varies along a detritus-quality gradient, we completed a 15-day laboratory experiment in which age-0 gizzard shad fed lake sediment and starved gizzard shad both suffered high mortality, whereas fish fed zooplankton grew and survived well. This suggested that detritus alone is insufficient to ensure gizzard shad growth and survival. When sediment quality was high in outdoor mesocosms, density-dependent factors led to rapid growth only at low fish density and high-quality sediments; however, survival generally increased with sediment quality, regardless of gizzard shad density. In four small reservoirs, annual growth of gizzard shad increased with sediment quality. Collect...

  • feeding preferences of omnivorous gizzard shad as influenced by fish size and zooplankton density
    Transactions of The American Fisheries Society, 1996
    Co-Authors: Lisa A Yako, John M Dettmers
    Abstract:

    Abstract In Ohio reservoirs, larval gizzard shad Dorosoma Cepedianum less than 30 mm total length consume only zooplankton but frequently switch to detritus as they grow longer than 30 mm. However, in laboratory studies without detritus, gizzard shad longer than 30 mm consume crustacean zooplankton. To explore the composition of diets of omnivorous 30–100-mm gizzard shad, we completed 1-h laboratory feeding trials with different amounts of zooplankton and detritus and quantified the diets of gizzard shad in reservoirs. In both laboratory and field, gizzard shad ate primarily detritus but also ate zooplankton, consuming more as more became available, which demonstrates that this species is a facultative detritivore. In the field, zooplankton consumption declined as gizzard shad body size increased. We believe gizzard shad maximize growth by supplementing their low-protein detritus diet with more zooplankton as more becomes available. With this strategy, omnivorous gizzard shad may compromise the potential ...

  • quantifying responses to hybrid striped bass predation across multiple trophic levels implications for reservoir biomanipulation
    Transactions of The American Fisheries Society, 1996
    Co-Authors: John M Dettmers, Dennis R. Devries
    Abstract:

    Abstract Top-down effects from piscivores to phytoplankton have been documented in north temperate lakes, thus permitting managers to regulate these food webs. From our review of the literature, reservoir trophic interactions appear less amenable to biomanipulation owing to the presence of a fast-growing, omnivorous planktivore, gizzard shad Dorosoma Cepedianum. If reservoir zooplankton can be enhanced by reducing gizzard shad through biomanipulation, this could increase survival of food-limited early life stages of sport fishes dependent on zooplankton and could improve water clarity by reducing phytoplankton. To quantify this potential, we evaluated responses of age-0 gizzard shad, crustacean zooplankton, and phytoplankton to the addition of hybrid striped bass Morone saxatilis × M. chrysops (22 kg/ha) to four of eight 0.4-ha ponds. Hybrid striped bass nearly eliminated age-0 gizzard shad from ponds within 10 d after being stocked, which permitted zooplankton density and size to increase but had no effe...

  • food web regulation by a planktivore exploring the generality of the trophic cascade hypothesis
    Canadian Journal of Fisheries and Aquatic Sciences, 1995
    Co-Authors: Dennis R. Devries, John M Dettmers
    Abstract:

    The trophic cascade hypothesis currently being tested in north temperate systems may not apply to open-water communities in lower latitude U.S. reservoirs. These reservoir communities differ dramatically from northern lakes in that an open-water omnivore, gizzard shad (Dorosoma Cepedianum), often occurs in abundance. Neither controlled by fish predators (owing to high fecundity and low vulnerability) nor by their zooplankton prey (following the midsummer zooplankton decline, gizzard shad consume detritus and phytoplankton), gizzard shad regulate community composition rather than being regulated by top-down or bottom-up forces. In experiments across a range of spatial scales (enclosures, 1–9 m2; ponds, 4–5 ha; and reservoirs, 50–100 ha), we evaluated the generality of the trophic cascade hypothesis by assessing its conceptual strength in reservoir food webs. We reviewed the role of gizzard shad in controlling zooplankton populations and hence recruitment of bluegill, Lepomis macrochirus (via exploitative c...

  • food consumption by larval gizzard shad zooplankton effects and implications for reservoir communities
    Transactions of The American Fisheries Society, 1992
    Co-Authors: John M Dettmers
    Abstract:

    Abstract Because peak abundance of larval gizzard shad Dorosoma Cepedianum occurs simultaneously with the midsummer decline of macrozooplankton in Ohio reservoirs, we hypothesized that zooplanktivory by larval gizzard shad caused this decline. To test this hypothesis, we compared larval food consumption with zooplankton productivity in two reservoirs. Larval gizzard shad began to influence zooplankton production in a reservoir with high zooplankton productivity (exceeding 125 mg·m−3·d−1) only after peak zooplankton biomass occurred, even at high larval densities (38 shad·m−3). However, consumption by early juvenile (25−30-mm) gizzard shad severely reduced zooplankton in this reservoir. Conversely, relatively low densities of larval gizzard shad (3–7 shad·m−3) had variable effects on zooplankton in a reservoir with low zooplankton productivity (at most 4 mg·m−3·d−1). Depending on larval gizzard shad density and zooplankton production, larval gizzard shad alone or in conjunction with early juveniles may con...

Dennis R. Devries - One of the best experts on this subject based on the ideXlab platform.

  • effect of detritus quality on growth and survival of gizzard shad Dorosoma Cepedianum potential importance to benthic pelagic coupling
    Canadian Journal of Fisheries and Aquatic Sciences, 2007
    Co-Authors: Gene W Kim, John M Dettmers, Roy A Stein, Alpa P Wintzer, Trisha K Menker, Russell A Wright, Dennis R. Devries
    Abstract:

    Gizzard shad (Dorosoma Cepedianum) population characteristics vary with lake productivity, competing with and providing prey for sport fishes. Because age-0 gizzard shad (>30 mm total length) are facultative detritivores, they can link benthic energy, carbon, and nutrients to pelagic food webs. To determine how age-0 gizzard shad success varies along a detritus-quality gradient, we completed a 15-day laboratory experiment in which age-0 gizzard shad fed lake sediment and starved gizzard shad both suffered high mortality, whereas fish fed zooplankton grew and survived well. This suggested that detritus alone is insufficient to ensure gizzard shad growth and survival. When sediment quality was high in outdoor mesocosms, density-dependent factors led to rapid growth only at low fish density and high-quality sediments; however, survival generally increased with sediment quality, regardless of gizzard shad density. In four small reservoirs, annual growth of gizzard shad increased with sediment quality. Collect...

  • quantifying responses to hybrid striped bass predation across multiple trophic levels implications for reservoir biomanipulation
    Transactions of The American Fisheries Society, 1996
    Co-Authors: John M Dettmers, Dennis R. Devries
    Abstract:

    Abstract Top-down effects from piscivores to phytoplankton have been documented in north temperate lakes, thus permitting managers to regulate these food webs. From our review of the literature, reservoir trophic interactions appear less amenable to biomanipulation owing to the presence of a fast-growing, omnivorous planktivore, gizzard shad Dorosoma Cepedianum. If reservoir zooplankton can be enhanced by reducing gizzard shad through biomanipulation, this could increase survival of food-limited early life stages of sport fishes dependent on zooplankton and could improve water clarity by reducing phytoplankton. To quantify this potential, we evaluated responses of age-0 gizzard shad, crustacean zooplankton, and phytoplankton to the addition of hybrid striped bass Morone saxatilis × M. chrysops (22 kg/ha) to four of eight 0.4-ha ponds. Hybrid striped bass nearly eliminated age-0 gizzard shad from ponds within 10 d after being stocked, which permitted zooplankton density and size to increase but had no effe...

  • food web regulation by a planktivore exploring the generality of the trophic cascade hypothesis
    Canadian Journal of Fisheries and Aquatic Sciences, 1995
    Co-Authors: Dennis R. Devries, John M Dettmers
    Abstract:

    The trophic cascade hypothesis currently being tested in north temperate systems may not apply to open-water communities in lower latitude U.S. reservoirs. These reservoir communities differ dramatically from northern lakes in that an open-water omnivore, gizzard shad (Dorosoma Cepedianum), often occurs in abundance. Neither controlled by fish predators (owing to high fecundity and low vulnerability) nor by their zooplankton prey (following the midsummer zooplankton decline, gizzard shad consume detritus and phytoplankton), gizzard shad regulate community composition rather than being regulated by top-down or bottom-up forces. In experiments across a range of spatial scales (enclosures, 1–9 m2; ponds, 4–5 ha; and reservoirs, 50–100 ha), we evaluated the generality of the trophic cascade hypothesis by assessing its conceptual strength in reservoir food webs. We reviewed the role of gizzard shad in controlling zooplankton populations and hence recruitment of bluegill, Lepomis macrochirus (via exploitative c...

  • complex interactions between fish and zooplankton quantifying the role of an open water planktivore
    Canadian Journal of Fisheries and Aquatic Sciences, 1992
    Co-Authors: Dennis R. Devries
    Abstract:

    An open-water planktivore, the gizzard shad (Dorosoma Cepedianum), can drive complex interactions among fish and zooplankton in Ohio reservoirs. In Kokosing Lake, crustacean zooplankton density declined to near zero immediately after larval gizzard shad abundance peaked during 1987 and 1988. This decline can be attributed to increased death rates, due to predation, and to reduced number of eggs per cladoceran. In an enclosure/exclosure experiment, young-of-year gizzard shad at lake densities significantly reduced density of crustacean zooplankton and rotifers within 2 wk. In addition, phytoplankton that were edible to zooplankton were reduced in enclosures, likely due to a combination of direct herbivory by gizzard shad and reduced nutrient availability due to uptake by the growing gizzard shad. Gizzard shad not only directly influenced zooplankton via predation, they also indirectly affected zooplankton by reducing phytoplankton abundance. Because larval bluegill (Lepomis macrochira) migrated to the limn...

Casey W Schoenebeck - One of the best experts on this subject based on the ideXlab platform.

  • long term changes in biotic and abiotic factors influence larval gizzard shad Dorosoma Cepedianum annual peak density
    Journal of Freshwater Ecology, 2018
    Co-Authors: Brett T Miller, Brian C Peterson, Keith D Koupal, Casey W Schoenebeck
    Abstract:

    ABSTRACTGizzard shad (Dorosoma Cepedianum) are an influential forage fish and driver of zooplankton resources in many reservoirs. The ability to identify the biotic and abiotic factors that influence the timing of elevated gizzard shad densities can be important to better utilize this forage fish and manage sport fish. The objective of this study was to investigate which biotic and abiotic factors influence larval gizzard shad annual peak density. We used combinations of six variables (CPUE of adult gizzard shad from the prior fall, mean zooplankton density, turbidity, chlorophyll a, relative reservoir elevation, and water temperature) from a long-term (2003–2014) monitoring program to create 28 a-priori candidate models to assess the relative support of explanatory variables using Akaike's information criterion (AIC). During the course of our study, larval gizzard shad annual peak densities were best explained by zooplankton density and relative reservoir elevation. Zooplankton density provides greater f...

  • Long-term changes in biotic and abiotic factors influence larval gizzard shad (Dorosoma Cepedianum) annual peak density
    'Informa UK Limited', 2018
    Co-Authors: Brett T Miller, Brian C Peterson, Keith D Koupal, Casey W Schoenebeck
    Abstract:

    Gizzard shad (Dorosoma Cepedianum) are an influential forage fish and driver of zooplankton resources in many reservoirs. The ability to identify the biotic and abiotic factors that influence the timing of elevated gizzard shad densities can be important to better utilize this forage fish and manage sport fish. The objective of this study was to investigate which biotic and abiotic factors influence larval gizzard shad annual peak density. We used combinations of six variables (CPUE of adult gizzard shad from the prior fall, mean zooplankton density, turbidity, chlorophyll a, relative reservoir elevation, and water temperature) from a long-term (2003–2014) monitoring program to create 28 a-priori candidate models to assess the relative support of explanatory variables using Akaike's information criterion (AIC). During the course of our study, larval gizzard shad annual peak densities were best explained by zooplankton density and relative reservoir elevation. Zooplankton density provides greater food availability which has been shown to increase larval gizzard shad growth. Relative reservoir elevation was negatively associated with higher densities of larval gizzard shad. This study describes two important factors that may result in greater larval gizzard shad densities, which can assist managers in anticipating available forage for sport fish and identify strategies to improve system management

James T Oris - One of the best experts on this subject based on the ideXlab platform.

  • induction of cyp1a mrna and catalytic activity in gizzard shad Dorosoma Cepedianum after waterborne exposure to benzo a pyrene
    Comparative Biochemistry and Physiology Part C: Pharmacology Toxicology and Endocrinology, 1997
    Co-Authors: Steven L Levine, James T Oris
    Abstract:

    The purpose of this study was to examine the concentration and time-dependent response of hepatic CYP1A mRNA levels and ethoxyresorufin O-deethylase (EROD) activity in gizzard shad (Dorosoma Cepedianum) after waterborne exposure to the polycyclic aromatic hydrocarbon benzo[a]pyrene (BaP). Gizzard shad hepatic CYP1A mRNA levels and EROD activity were increased within 6 hr by waterborne concentrations of 1.01 microgram BaP/l and were highest after 72 hr of exposure. The median effective time to reach 50% of maximum induction (ET50) values for CYP1A mRNA and EROD activity was 12 +/- 9 and 34 +/- 3 hr, respectively. The rise of CYP1A mRNA levels ahead of the rise of EROD activity showed that the CYP1A gene has the general pattern of a gene that is under transcriptional control. Although CYP1A mRNA levels were maximally induced after 72 hr of exposure, they returned to basal levels between 72 and 120 hr of exposure. Despite a decrease in CYP1A mRNA levels between 72 and 120 hr of exposure, EROD activity did not significantly change between 72 and 120 hr of exposure. These results indicate that hepatic CYP1A mRNA levels in gizzard shad can only feasibly identify short-term exposures to BaP concentrations of approximately 1 microgram/l and that are not longer than 72 hr. Consequently, hepatic CYP1A catalytic activity (e.g., EROD) and CYP1A protein levels should be measured in addition to hepatic CYP1A mRNA levels when biomonitoring aquatic systems for certain types of chemical contamination.

  • Effect of the fungicide clotrimazole on the bioconcentration of benzo[a]pyrene in gizzard shad (Dorosoma Cepedianum): In vivo and in vitro inhibition of cytochrome P4501A activity
    Environmental Toxicology and Chemistry, 1997
    Co-Authors: Steven L Levine, Hillary Czosnyka, James T Oris
    Abstract:

    Clotrimazole was found to inhibit in vivo and in vitro hepatic microsomal ethoxyresorufin O-deethylase (EROD) activity in gizzard shad (Dorosoma Cepedianum). Gizzard shad pretreated with 50 mg clotrimazole/kg and then exposed for 1 or 3 d to benzo[a]pyrene (BaP) (0.86 μg/L) had significantly lower EROD activity compared to fish that were exposed to BaP alone. Following 1 and 3 d of BaP exposure, groups pretreated with clotrimazole had a 14- and 4-fold decrease in EROD activity and had biocon-centrated 8 and 11 times more parent BaP, respectively, compared to groups exposed to BaP alone. Addition of clotrimazole to BaP-induced microsomes produced a type II binding spectrum and was an effective in vitro inhibitor of EROD activity. The median inhibitory concentration for EROD activity was 0.51 μM clotrimazole. Kinetic and spectral experiments suggest that the mechanism of inhibition by clotrimazole is noncompetitive. Reduction in the rate of oxidative BaP metabolism is hypothesized to result from noncompetitive inhibition of cytochrome P4501A and other P450 enzymes that metabolize BaP.

  • the role of water ventilation and sediment ingestion on the uptake of hexachlorobenzene by gizzard shad Dorosoma Cepedianum
    Environmental Toxicology and Chemistry, 1996
    Co-Authors: Alan S Kolok, Kory J Groetsch, James T Oris
    Abstract:

    The objective of this study was to determine whether sediment ingestion or water ventilation was the primary route for uptake of hexachlorobenzene (HCB) in the detritivorous fish, gizzard shad (Dorosoma Cepedianum). Twenty nonligated and 30 esophagus-ligated fish were exposed to sediments spiked with 1 μg/g HCB for 29 d. The nonligated fish roiled the water as they fed, forcing the ligated fish to ventilate turbid water. Fish were collected 7, 14, 22, and 29 d after initiation of the experiment. Detectable levels of HCB were found in all ligated and nonligated fish, although the concentration of HCB in the ligated fish only ranged from 14 to 33% of that found in the nonligated fish. Thus, ingestion of contaminated sediments is a significant source of HCB for gizzard shad.

  • the role of water ventilation and sediment ingestion in the uptake of benzo a pyrene in gizzard shad Dorosoma Cepedianum
    Environmental Toxicology and Chemistry, 1996
    Co-Authors: Alan S Kolok, James N Huckins, Jimmie D Petty, James T Oris
    Abstract:

    The objective of this study was to determine whether sediment ingestion or water ventilation was the primary route of uptake for benzo[a]pyrene (BaP) in the gizzard shad (Dorosoma Cepedianum), a detritivorous fish. Two experiments were conducted in which fish were exposed to sediments spiked with 1 {micro}g/g BaP. In the first experiment, fish were prevented from feeding by esophagus ligation. In the second experiment, 20 nonligated fish and 30 ligated fish were added to the aquarium. The nonligated fish roiled the water as they fed. Fish were collected 4, 8, 15, and 22 d after the experiments began. Gizzard shad metabolize BaP; therefore, the concentrations of BaP equivalents (parent BaP plus metabolite) were determined. Concentrations of BaP equivalents were significantly greater in the ligated fish in experiment 2 relative to those in experiment 1. In contrast, the concentration of BaP equivalents in the ligated fish in experiment 2 was not significantly different than that in the nonligated fish. The results suggest that ventilation of turbid water may be a significant source of BaP for gizzard shad. Sediment ingestion, however, does not appear to significantly influence the total body concentration of BaP equivalents in gizzard shad.

  • influence of environmental factors on the physiological condition and hepatic ethoxyresorufin o deethylase erod activity of gizzard shad Dorosoma Cepedianum
    Environmental Toxicology and Chemistry, 1995
    Co-Authors: Steven L Levine, James T Oris, Thomas E Wissing
    Abstract:

    Field and laboratory experiments were conducted to monitor seasonal cytochrome P4501A monooxygenase (MO) activity (measured as ethoxyresorufin O deethylase (EROD) activity) in gizzard shad (Dorosoma Cepedianum) Basal EROD activity declined in midsummer but returned to postspawning spring levels by late summer Seasonal variation in basal EROD activity corresponded with changes in liver somatic index, condition factor, and percent body lipid, indicating that seasonal variation in basal field EROD activity may result from changing physiological condition Benzo[a]pyrene induction experiments demonstrated that, although the level of EROD activity changed seasonally, the magnitude of induction relative to corn oil injected controls remained the same Kinetic studies indicated monthly changes in apparent Vmax but no change in apparent Km Taken together, these results suggest that seasonal changes in EROD activity reflect changes in hepatic P4501A protein concentration This study has demonstrated that it can be inappropriate to interpret EROD activity from a suspect site without first understanding how seasonal field conditions influence P4501A activity