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Fig. 1. Effects of acid–base exposure on drinking rates and total body water.
Animals were reared and assayed in media containing NaCl (RS; 59.9 mmol
l–1), or in media in which the only added NaCl was that
present in the food (low-NaCl RS). (A) Effects of pH on drinking rates in the
presence and absence of NaCl. Drinking rates of acclimated larvae were
determined using FITC-dextran ingestion rates (average molecular mass 4.3
kDa). Drinking rates were highest in acidic rearing solutions (column effects;
P<1x10–8, F=50.8, d.f.=47). The
presence or absence of NaCl did not influence the effect of pH on drinking
rates (column effects; F=1.37, P>0.22). Rearing solutions
containing NaCl are indicated by •, while those without added NaCl are
indicated by  . (B) Effects of ambient pH on percentage body water. Body
water was reduced in larvae chronically exposed to acidic media, and was
elevated when larvae were acutely exposed to more acidic media (single factor
ANOVA of arcsine-transformed body water ratio). The presence or absence of
NaCl did not influence the effects of acute pH challenges on body water. RS 7
represents larvae reared and assayed in RS 7, RS 7–3 represents larvae
reared in RS 7 and assayed in RS 3, RS 4 represents larvae reared and assayed
in RS 4, and RS 4–3 represents larvae reared in RS 4 and transferred to
RS 3. For larvae reared and assayed in low NaCl conditions, low-NaCl RS 7
represents larvae reared and assayed in low-NaCl RS 7, while low-NaCl RS
7–3 represents larvae reared in low-NaCl RS 7 and assayed in low-NaCl RS
3. Data are presented as means ± s.e.m.
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