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L
LH\i1NOLOGY LIBRARY APR 0 3 2003
FISH BLOOD OSMOLALITY, GILL HISTOLOGY AND OOCYTE ATRESIA AS EARLY WARNING ACID STRESS
INDICATORS
J.H. McCormlck(1), K.M. Jensen(2), R.L. Leino(3) and G.N. Stokes(1)
4J) U.S. Environmental Protection Agency, Environmental ~rch Laboratory • Duluth, &201 Congdon Blvd., Duluth, Minnesota 55804, USA
(2) C.nter for Lillie Superior Environmental Studies, University of Wisconsin-Superior, · Superior, WI 54880, USA
/ 'J 1 9U I
(3) Department of Biomedical Anatomy, SChool of MediCine, Unlvenslty of Minnesota-Duluth, Duluth. MN 55812, USA
Abstra·ct
yellow perch (f!.t.t..ti flavescens), -rock bass (Ambloplltes
bl -ack cnppie'(romoxis niuoma.cu!atus), a~d largemouth bass
.~J..l'.a!~~ salmoid~s) exposed to acidified soft water ran,ing from pH 7.0
maintained blood osmotic homeostasis for up to 30 days·.: At pH 4.0.
od osmotic homeostasis was lost and all but the yellow perch ·aied with in
Blood osmolality decreased from a normal value of · 2B0-320 mmol/kg
a few days before ·death. Yellow perch exposed to pH ·4.1 were ;
death within 58 days. Gill hyperplasia and chloride cell
observed in 'these species a't pH 4. 5 and 4.0. In fathead
exposed to ~cidifled water, the chloride cells developed apical pits
evaginations at pH 5.5. The incidence of these ·chloride cell changes was "'£ ..
&ressi_vely greater at lower pH values, particularly at pH 5.~. Abnormally
'i.. :h numbers or atretic oocyte~ obsirved in -cid exposed fathead minnows were
t prevalent in the latter part of the spaw~in, season.
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