Fig. 3. Unidirectional, whole-body Na⁺ (A) and Cl^– (B) efflux rates of Culex quinquefasciatus, a freshwater-obligate (open columns), and C. tarsalis, a euryhaline osmoconformer (filled columns), held in Irvine tapwater, low-NaCl medium for 2 days, 30 % sea water (SW) for 2 days, and transferred to 50 % sea water at 2 and 4 h post-transfer. Values are means + S.E.M.; N=5–14 for Na⁺ efflux, N=5–8 for Cl^– efflux. * denotes a significant difference from the tapwater value (P0.05). denotes a significant difference from 30 % seawater value (P0.05). denotes a significant difference between species for a given treatment (P0.05). ^¶ denotes a significant difference from the hour 2 post-transfer, 50 % seawater value (P0.05).