This experiment was conducted in 1993 and 1994. The design was
balanced over years in terms of size range and species tested to avoid
any confounding effects of time and weather. Water temperature
(± 0.1°C) was recorded with a hand-held thermometer about six times
per 24-h period in 1993 and with a HOBOTM temperature logger every
8 min in 1994. In 1993, the average water temperature during the
experiment was 12.69 ± 0.15°C (SE, n = 39) and in 1994 was 13.31
± 0.05°C (n = 750).