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<br />,:1" <br />. ' <br />; , <br />I~ ! <br /> <br />:/'i <br />~ . I <br />!' I <br /> <br />i <br />I <br />ii <br /> <br />r: <br /> <br />Ii <br />l <br />1" <br />j! <br />, <br />I. <br />i. <br />II <br />If <br />II <br />I. <br />II <br />i' <br />f <br />11 <br />I <br />" <br /> <br />Del.orcsl, Brix, and AdanlS <br /> <br />percent hatch, or larval survival to 14 days. For each of these endpoinls, lhe <br />responses werc similar to the conlrols, suggesting that thc dietary sc\cnium <br />threshold for rcproductive effccts is greater than the highcst dictary conccn- <br />tration measured (29,5 mg/kg dw, Talllc 2). Correspondingly, no reproduc- <br />tive effccts werc obscrvcd ill fish Wilh a mcan ovary concclllralion of <br />10.9 mg/kg dw (Tallie 4) or a whole llody concentralion of 7.5 mg/kg c1w <br />(Tallie 3). SimilarlY,Jarvinen and Ankley (1999) reponed Ihatno reproduc- <br />live effects in lish Wilh a mean ovary concentration of 10.9 mg/kg dw or a <br />whole body concenlration of 7.5 mg/kg dw. <br />Schullr. and Hemlanulz. (1990). Falhead minnows were exposed 10 selenium <br />in experimental slreams conlinuously dosed Wilh 10 ~g/Lselenile. The slreams <br />cOlllaiued well-developed assemblages of li.sh li.IOd organisms, so an cnviron- <br />mentally relevalll dielary exposure palhway was simulaled. Submcrgcd spawn- <br />ing platforms wcre provided and checked daily for embryos, Samplcs of <br />collected embl"}'os were lhen reared in incubation cUJls containing slream <br />water with the same seleniull1 concelllralions as in thc streams li'oll1which they <br />were collected, Each sample was obsclved each post-hatch day for cdema and <br />lordosis (Ialvae were not fed, and obselvalions cOlllinued until alllalvae died), <br />Selenium concentrations in the ovaries of the adull ICmales were also <br />detennined, The incidence of edema and lordosis in lalvae from the doscd <br />slream, 24.6 and 23.4%, respectively, was signilicantly (p < 0.(5) greater Ihan <br />in the control stream (0,9 and 5.6%). The mean selenium concentralion in <br />ovaries of the parentallish was 39,3 mg/kg dw (assuming ovaries conlain 85% <br />lIloisture [Gillespie and Banmann, 1986]) (Table 4). Lemly (1993a), assullled <br />a 75% moisture content and reported that an ovary concentration of <br />15 mg/kg dw was associated wilh repl'Oductive failure (Tablc 4). Thc hasis for <br />this concentration is unclcar, howcvcr, as a moisture content of 75% would <br />result in a dry weight concentration of 23.6 mg/kg dw, .Jalvinen and Anklcy <br />(1999) did not review this study, so their inlerpretation is not availablc fi)r <br />comparison, <br />Dobbs, Cherry, and Cairns (1996). A three trophic level test system consisting <br />of algae, rotifers, and larval falhead minnows was dosed Wilh various concen- <br />lration5 of selenate for 25 days. Fathead minnow larval growth was signi/icanlly <br />(P < 0,05) I'educed relalivc to thc controls in /ish fed rotifcrs with a selclliulII <br />cuncentratiun rangillg li'ulII approximalely 33 to GO mg/kg dw Crablc :1), Whole <br />body selcnium cOllcelltl'illions in thc allccted /ish ranged hom 47.5 to 76,0 IIIg/ <br />kg dw (Table 3).Jalvinen and Ankley (1999) reponed the same concelllriuion <br />range in their rcview, As the study was conductcd aher I !J93, it was not <br />rcvicwed in Lemly (1993a). <br /> <br />Bluegill Sunfish (Lepomis macrochims) <br /> <br />Brysoll el ai. (1984, 1985a, 1985b). Neither Lemly (l993a) norJarvinen and <br />Ankley (I !l99) ciled Ihese sludics in thcir reviews of oval)' seleniulll COIlCClllra- <br />lions. BI)'son el at. (1984) collected blucgills from the selcniulll-contaminated <br />Hyco Reselvoir and from a refercnce lake. All combinations of males and <br /> <br />Debate/Commentary <br /> <br />females were artificially crossed in differenl ash pond concentrations (0, 20, <br />and 50%). Swim-up larvae were fcd zooplaukton from either Hyco Reselvoir <br />or the reference lake. LaJvae were obselved for 28 days after hatching. All <br />larvae from a Hyco Reservoir female exhibited abnormal development and <br />100% monality prior to reaching swim-up. The mean ovary concenlrationin <br />the fcmales from Hyco Reselvoir was 49 mg/kg dw (Tallie 4). <br />BI)'son el at, (1985a), based on a study similar to BI"}'sou el at. (1984). <br />reponed thal egg hatchability from female bluegills averaging 9.1 mg/kg dw <br />iu the ovaries was 88%, and that 93% survived lhrough swim-up Crable 4). <br />Swim-up was only approximately 5.6% in larvae from females averaging <br />30 IIIg/kg dw in the ovaries (Tallie 4). The results reported in Bryson el at, <br />(1985b) arc sOlllewhat dilficult to interpret because none of the control/ish <br />spawned, but hatching and swim-up success were 83.8 to 8fi,6 and 91.1 to <br />95.5%, rcspectively, from parents with a mean oval"}' concentration of 14,8 mg/ <br />kg dw, and 86,0 and 83.3 to 97.4% from parents with a mean ovary concentra- <br />tion of 9.2 mg/kg dw. The above resu\Ls indicate that reproductive failure <br />would not be cxpected to occur al ovary selenium concentrations of 10 mg/ <br />kg dw, iu contl'astto Lemly (1993a). <br />Fillley (1985), llluegills were fed sclenium-contmninated burrowing maylly <br />nymphs (l/exagenia tilllbal(J) in the laboratory for 41 days. The maylly nymphs <br />were collectcd from Uelcws Lake and cOlltained au average whole body sele- <br />nium concclltration of 54.4 mg/kg dw. After 4'1 days, three of four bluegills <br />had died, while no control fish died. The dietary concentration of 54.4 mg/ <br />kg dw assoc.:iated with the obselved mortality is comparable to the dietal)' <br />concentration of 50 mg/kg dw reported by Lelllly (1993a). <br />(;ilks/Jie ant/lJaumanll (1986). Adult bluegills were collected from the sele- <br />niulll-colltaminated Hyco Reservoir and from an uncontaminated reservoir, <br />and all possible combinations of parents wel'e artificially crossed. Zygotes were <br />rcarcd in unc.:ontaminatcd watcr and evaluated for percent fertilizalion and <br />hatching success, In over 18 crosses during a 2-year period, no signilicant <br />dilfcrences in percent fenilization or percent hatch were found between all <br />parcnt combinations. Howevcr, all crosses involving a female from the sele- <br />nium-contaminated water body resulted in larvae with gross abnormal mor- <br />pholob'Y (6!) to 100%), and all larvae died before they rcached the swim-liP <br />stagc. <br />The ovary selenium concentration in the female producing 65% abnormal <br />lalvae was 38,(j mg/kg dw (assuming a moisture content of 85%) (Table 4). <br />Lemly (199ja) reported that an oval)' selenium concentration of 12 mg/kg dw <br />in this study was associated with reproductive failure (Taule 4). The basis of <br />this conccnlralion is unclear given that the lowest ovary selenium concentra- <br />tion reponed by Gillespie and BaulTlannwas 5.79 mg/kg on a wet weight basis; <br />a moisture conlenl or 75%, as assumed by Lemly (I 993a) , would result in an <br />oval}' concelltration of 23.2 mg/kg on a dry weight basis, Jarvinen and Ankley <br />(1999) interpreted this sludy as indicating thal an ovary concentration of <br />6.96 mg/kg ww resulted in larval mortality prior to swim-up; a moisture con- <br /> <br />1111111, Ecol. Risk Assess. Vol. 5, No.6, 1999 <br /> <br />1205 <br />