Effects of temperature on survival, growth, reproductive and life span characteristics of Branchinecta orientalis G. O. Sars, 1901 (Branchipoda, Anostraca) from Iran

Abstract

Branchinecta orientalis G. O. Sars, 1901 is a common inhabitant of seasonal water catchments in the northwest of Iran. Hatching, growth, survival, and reproductive characteristics of this species were studied at different temperatures in the laboratory. The Cumulative Hatching Success was significantly higher for specimens cultured at 21 degrees C (85.27 +/- 12.21%) compared to those hatched at 12, 15 and 27 degrees C (P < 0.05). Hatching started on the same day (48.00 h after inundation) at temperatures of 21, 24 and 27 degrees C), whereas this took more time at lower temperatures, slowest at 12 degrees C (126.00 +/- 0.58 h after inundation). The initial hatching fraction was the highest at 21 degrees C (44.60 +/- 18.69%) and lowest at 12 degrees C (9.10 +/- 8.28%). Total length was significantly longer at high temperatures, 12.38 +/- 0.71 mm at 27 degrees C, compared to 4.07 +/- 0.42 mm at 12 degrees C on day 15. Nevertheless, contrasting results were obtained for survival, being the lowest at 27 degrees C (22 +/- 4.00%) and highest at 12 degrees C (93.07 +/- 2.08%) on day 15 of growth. The animals reached sexual maturity significantly faster at 27 degrees C (9.38 +/- 1.09 days) compared to all other treatments. A significantly longer life span was detected at 12 and 15 degrees C (63 days), and the higher cyst production at 18 degrees C, compared to other experimental conditions (P < 0.05).