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Resting eggs of lake‐ Daphnia I. Distribution, abundance and hatching of eggs collected from various depths in lake sediments

Resting eggs of lake‐ Daphnia I. Distribution, abundance and hatching of eggs collected from... SUMMARY. 1. Resting eggs (ephippia) of Daphnia galeata, D. hyalina, D. cucullata and D. galeata X D. hyalina hybrids were collected from the upper 8 cm of sediments at various water depths from two glacial lakes in the Northern Federal Republic of Germany. 2. The horizontal distribution of ‘intact’ ephippia (i.e. those containing two apparently healthy eggs) was extremely patchy, with mean densities in the upper 8 cm ranging from 1325 to 113,907 m−2 (coefficient of variation, C=65.5%; Schöhsee, Holstein) and 25,343–159,143 m−2 (C=58.5%; Kel‐lersee. Holstein). Ephippial densities were greatest in sediments from deep waters. The highest densities of intact ephippia were in the upper 4 cm of sediment, with progressively fewer with increasing depth. 3. A proportion of eggs obtained from sediments during autumn (September‐November 1985) and spring (March‐May 1986) were exposed to continuous light (approximately 18 W m−2) at three temperatures (6, 12, 20°C), and the incidence of hatches recorded. 4. Hatching success was consistently low (maximum 14.4%), with most hatching occurring at 12°C. There was no significant difference between the hatching success of ephippia collected during autumn and spring. Decapsulation of ephippial eggs inhibited hatching. Hatching was highly synchronous within each treatment, and the pattern did not differ significantly with sediment depth, though hatching success was lower in deep sediments. A huge reservoir of ephippia is present in lake sediments, of which a proportion may remain viable for many years. Periodic recruitment of hatchlings to the pelagic population may provide an important mechanism for the maintenance of genetic diversity in Daphnia populations, as well as affecting rates of evolutionary change. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Freshwater Biology Wiley

Resting eggs of lake‐ Daphnia I. Distribution, abundance and hatching of eggs collected from various depths in lake sediments

CARVALHO, GARY R.; WOLF, HANS GEORG
Freshwater Biology , Volume 22 (3) – Dec 1, 1989
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References (41)

Publisher
Wiley
Copyright
Copyright © 1989 Wiley Subscription Services, Inc., A Wiley Company
ISSN
0046-5070
eISSN
1365-2427
DOI
10.1111/j.1365-2427.1989.tb01118.x
Publisher site
See Article on Publisher Site

Abstract

SUMMARY. 1. Resting eggs (ephippia) of Daphnia galeata, D. hyalina, D. cucullata and D. galeata X D. hyalina hybrids were collected from the upper 8 cm of sediments at various water depths from two glacial lakes in the Northern Federal Republic of Germany. 2. The horizontal distribution of ‘intact’ ephippia (i.e. those containing two apparently healthy eggs) was extremely patchy, with mean densities in the upper 8 cm ranging from 1325 to 113,907 m−2 (coefficient of variation, C=65.5%; Schöhsee, Holstein) and 25,343–159,143 m−2 (C=58.5%; Kel‐lersee. Holstein). Ephippial densities were greatest in sediments from deep waters. The highest densities of intact ephippia were in the upper 4 cm of sediment, with progressively fewer with increasing depth. 3. A proportion of eggs obtained from sediments during autumn (September‐November 1985) and spring (March‐May 1986) were exposed to continuous light (approximately 18 W m−2) at three temperatures (6, 12, 20°C), and the incidence of hatches recorded. 4. Hatching success was consistently low (maximum 14.4%), with most hatching occurring at 12°C. There was no significant difference between the hatching success of ephippia collected during autumn and spring. Decapsulation of ephippial eggs inhibited hatching. Hatching was highly synchronous within each treatment, and the pattern did not differ significantly with sediment depth, though hatching success was lower in deep sediments. A huge reservoir of ephippia is present in lake sediments, of which a proportion may remain viable for many years. Periodic recruitment of hatchlings to the pelagic population may provide an important mechanism for the maintenance of genetic diversity in Daphnia populations, as well as affecting rates of evolutionary change.

Journal

Freshwater Biology – Wiley

Published: Dec 1, 1989

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