8145

• UCREFRP Catalog Number: 8145
• Author: Bozek, M. A., L. J. Paulson and G. R. Wilde.
• Title: Effects of Ambient Lake Mohave Temperatures on Development, Oxygen Consumption, and Hatching Success of the Razorback Sucker.
• USFW Year: 1989.
• USFW - Doc Type: \
• Copyright Material: YES

diffusion ratcs through the cgg envclopes and
therefore affect hatching success and development
ratcs. Temperatures used in 1982 were 10. IS. and
2O"C while those in 1983 were 8.12.1:5. and WOC
in the first experiment. and 8. 10. 15. and WOC in
the second.
Eggs were examined. state of development de-
termined. and dead eggs removed three times dai-
ly. The time in hours for S. SO. and 95% of the
indhiduals to attain a particular state of devel-
<lpment was recorded at each temperature. Only
viahle offspring were enumerated to determine
percent of successful hatching.
Oxygen consumption was measured using a Gil-
5On. differential. single-valve-style respirometer.
~. embrym and larvae used in the I'lespirometry
experiments were separate from those used in the
h<\tching success. Test chambers contained 8 mt of
water and 0.2 ml of 10% KOH in the center well
and were temperature controlled by submersion in
a self-contained. thennostatically-controlled water
bath. ~.mplitude of rocking during the experiment
was 4 em with periodicity of 60 cycles min-'. Cham-
bers were ultowed to equilihrate at test tempcr-

Tn"'~ I. Lake Mohave ramrback RICker larvae ,collections.

257

atures for 15 minutes prior to starting and were
adjusted for barometric pressure.
Respiration rates could not be determined for
individual eggs. embryos and. larvae at lower tem-
peratures and earlier life stages. so 30 eggs or 15
larvae were used per chamber and measurements
were recorded hourly. Oxygen consumption was
expressed as ,u O2 15 individuals-' h-'. Three to
eight replicates were made at each temperature
and life interval. Intervals of development were
based upon Mincldey & Gustafson (1982): morula!
blastula (stages 10-11). pre-tailbud (stages 11',-19).
pre-hatch (stages 24-26), immediate post-hatch
(stages 27-29). swim-up (stage 31). and yolkdeple-
tion (stage 33-34).

Results

field collections

Razorback sucker larvae were collected in Lake
Mohavc at 9.S-IS.O"C. indicating sUCCCS5ful incu-
hation of e~ at IhCllC IcmperatuTC5 (Table I). Dicl
variation in temperature at collection sites was as

u..t~. Local ion' Did II~O temp Water deplh em) # u,rvac
M:txIMin rer minute
~1.:!.I911:! YC 11.01111.0 1.0 0.~2
1f1.:!. AB 12.011(11.0 2.5 0.6ll
2~.2. SM 12.0110.0 0.3 0.33
:!f1.:!. YC 12.01)(11.0 0.3 0.40
:!.l.I.IIIK,l YC 11.11/ CJI.5 1.11 0.211
;!.'i.1. SM lUll CJI,5 1.2 0.47
III.:!. SM 12.OIW.~ 1.1 9.R5
19.:!. SM 12.(11)(11.5 2.11 4.69
III.:!. SM 12,(11)(11.5 4.11 0.77
2".:!. NS 12.(1/)(11.5 1.1 3.53
25.J. SM 15.11115.0 1.1 0.0
:!:U. SM 15.0m..O 2.R 0.0
:!5.J. SM 15.0115.11 4.9 0.0
;!(,..1. H.' t';.1lI1 ~'.I1 1.1 II.M
:!h.J. TC 15.tIIIS.1I 6.1 11.11

OcveIopmcn1al~ lItll(!C (ox.)
EP I.P EM
. . .
. . .
. . .
. . .
75.0 25.0 11.0
57.1 42.9 0.0
13.9 71.1 14.9
6.2 <<t.R 27.R
0.0 82.6 17.4
~.2 63.2 7.6

23.1

10.5

(,5.1(

Tlltal numhcr of lilr\";IC collectcd.. 120~
I YC.. Yuma Cove; ^R == Arizona Bay; SM =, Six Mile Area; NS.. Norlh Six Mile Arca; TC.. Tequila Cove
~ EI'.. Early rrotolarvac; LP == Late protolarvac; EM == Early mesolarvae; · - indicalcs developmental stage not determined