Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Lehmann, G. Articles by Hohenegger, J. Search for Related Content GeoRef GeoRef Citation

LIFE CYCLE VARIATION INCLUDING TRIMORPHISM IN THE FORAMINIFER TROCHAMMINA INFLATA FROM NORTH EUROPEAN SALT MARSHES

¹ Institut für Allgemeine Mikrobiologie der Universität Kiel, Biologiezentrum, Am Botanischen Garten 9, D - 24118 Kiel, Germany
² Institut für Paläontologie, Geozentrum Universität Wien, Althanstr. 14, A – Wien, Austria

^* E-mail: rroettger{at}ifam.uni-kiel.de

The proloculus diameters were analyzed in 15 samples of 200 individuals each of the agglutinated foraminifer Trochammina inflata from five salt marsh localities in Germany, Denmark and Sweden. Accumulations of dead specimens from the uppermost centimeter of sediment between the roots of salt marsh halophytes include microspheric and, as revealed by statistical analyses, two classes of megalospheric individuals. These size classes are consistent with the occurrence of three generations in a trimorphic life cycle as has been described in several other foraminiferal taxa, and they support the interpretation of a biologically trimorphic life cycle in Trochammina inflata. The three size classes of proloculi correlate with: agamonts (microspheric tests), schizonts (smaller megalospheric tests) and gamonts (larger megalospheric tests). This interpretation, however, has not been confirmed by studies on cultivated specimens. Other factors that may cause the bimodal size distribution of the megalospheric proloculi are discussed. The sample means of the agamonts range from 16.1–22 µm, those of the supposed schizonts from 28.6–34.2 µm and those of the supposed gamonts from 36.5–41.7 µm. The proportions of the three generations are used to infer long-term life cycles in time-averaged assemblages. Samples from Bottsand (Kiel Bight, Germany) contain particularly high proportions of schizonts, indicating that schizogony may be the dominant or sole mode of reproduction at the latter sites. Proportions of gamonts are relatively high in the Heden saltmarsh (Swedish west coast) and in the remaining localities, indicating a higher incidence of the dimorphic cycle, relative to the trimorphic cycle. A varying importance of the respective mode of reproduction results in differing proportions of reproductive products, agamonts, gamonts and schizonts in the sediment. Previous investigations have focussed on trimorphism in tropical environments; herein, we present an example from temperate supralittoral-semiterrestrial habitats subject to strong fluctuations in water content, temperature and salinity.

This article has been cited by other articles:

				M. R. Langer, W. A. Makled, S. J. Pietsch, and A. Weinmann ASYNCHRONOUS CALCIFICATION IN JUVENILE MEGALOSPHERES: AN ONTOGENETIC WINDOW INTO THE LIFE CYCLE AND POLYMORPHISM OF PENEROPLIS Journal of Foraminiferal Research, January 1, 2009; 39(1): 8 - 14. [Abstract] [Full Text] [PDF]

				I. Polovodova and J. Schonfeld FORAMINIFERAL TEST ABNORMALITIES IN THE WESTERN BALTIC SEA Journal of Foraminiferal Research, October 1, 2008; 38(4): 318 - 336. [Abstract] [Full Text] [PDF]