Fig. 1. Ammonia excretion (J_Amm) (A) and urea excretion (J_Urea) (B) in laboratory-reared Rivulus marmoratus before emersion and at 2 h intervals following 12 h of emersion. Statistical comparisons were performed between pre- and post-emersion excretion rates. For J_Urea (B), comparisons were made at the appropriate time periods to take into consideration the diurnal pattern of J_Urea (i.e. filled columns pre-emersion were compared with filled columns post-emersion). No significant differences were found between pre- and post-emersion J_Amm or J_Urea. Values are expressed as means + S.E.M. (N=18).