Egg Banks

Abstract

Egg banks represent the accumulation of dormant propagules of algae, protists, and invertebrate animals in the sediments of lakes and ponds. Many of these propagules remain in dormancy or diapause for periods much longer than a single growing season; some can hatch or emerge from dormancy after decades or even more than a century. They have been called ‘time travelers’ because they enter a protective capsule at one time and emerge from dormancy many generations later with the ability to experience and influence the population and ecosystem that they enter. They have been called ‘the living dead’ because their metabolic rates, while in dormancy, are so low that they cannot be detected even with sophisticated methods. The dormant propagules of egg banks provide a means for species possessing them to persist though harsh environmental periods that the active life-history stages cannot survive. In temporally varying environments, egg banks are an important component of the maintenance of genetic variation within species and community diversity among species. The long-term egg bank, formed by the sequential burial of a portion of the dormant propagules in lake sediments over time, provides a historical record of past genetic, population, community, and ecosystem processes.