Delayed egg hatching accounts for replacement of burrowing mayflies Hexagenia rigida by Hexagenia limbata after recolonization in western Lake Erie

作者：Bustos Claudia; Corkum Lynda D^*

来源：Journal of Great Lakes Research, 2013, 39(1): 168-172.

DOI：10.1016/j.jglr.2012.12.009

• Egg banks
• Species replacement
• Burrowing mayflies
• Lake Erie

Egg banking may have played a role in the recolonization of two burrowing mayfly species (Hexagenia limbata and Hexagenia rigida), which recolonized western Lake Erie after over 30 years of near extirpation. H. rigida was the first of the two to colonize successfully, but was overtaken by H. limbata (the historically dominant species). To understand mechanisms of species replacement, we compared egg hatching between the two species at 20 degrees C in the lab under typical hatching temperatures (no incubation) and after cold storage (8 degrees C) for 2, 6 and 12 months. Prolonged storage at cold temperatures simulates temperature conditions to which embryos are exposed when deposited by late-emerging female imagos. Without incubation, H. rigida (95.4 +/- 2.02) exhibited significantly higher egg hatching survivorship than H. limbata (85 +/- 3.2) (P = 0.01). First hatch date for H. rigida was one day earlier than H. limbata, but time for 50% to hatch (5 d) and hatching duration (5 d) was the same for both species. After 2 and 6 months of incubation, H. limbata exhibited an earlier hatch date, but there was no significant difference in mean percentage of egg survival (ca 63%) between species. After 12 months of cold storage, hatching success for H. limbata was 44.6 +/- 4.17%, but H. rigida eggs did not hatch. Banking of eggs at low temperature increases the chance of successful recolonization, once stressful conditions pass. The viability H. limbata eggs after long quiescence may help to explain the shift in dominance from H. rigida to H. limbata.

• 出版日期2013-3