AbstractEggs of Hexagenia rigida McDunnough transferred directly from 20° to 36°, 32°, 28°, 24°, 20°, 16°, 12°, and 8 °C were monitored for start of hatch, hatching rate, success of hatch, and hatching period. Eggs did not hatch at 36 °C or 8 °C. There was a direct relationship between temperature and start of hatch (from day 7 at 32 °C to day 77 at 12 °C). Over 90% hatch occurred at all temperatures except 12 °C. Hatching periods ranged from about 6 days at the higher temperatures to over 80 days at 16 °C and 12 °C. Hatching occurred at 36 °C when eggs were transferred in increments of 4 °C every 2 days.Storage capabilities of eggs in "early", "middle", and "late" stages of embryonic development were tested at 12 °C and 8 °C using a direct or stepwise transfer method. Hatching parameters monitored were hatch rate, success of hatch, and hatching period up to 90% hatch of total number of eggs. Middle stage eggs transferred in a stepwise manner could be held at 8 °C for up to 52 weeks with least effect on hatching parameters. Middle and late stage eggs could be stored for up to 16 weeks at 8 °C using the direct transfer method, and early stage eggs, which were affected most by cold storage, could be held for 2 days at 12 °C with minimal effect on hatching parameters. The storage of eggs, shown here to be possible, is potentially useful for providing such material for bioassays throughout the year.
The Effects of Temperature on Leaching of Antimony from Plastic Bottles and Subsequent Impact on Brine Shrimp Hatch Rate
