Browsing by Author "Masche, Simon"
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- Population dynamics of benthic foraminifera in the intertidal mudflat of Northern GermanyPublication . Masche, Simon; Mendes, Isabel; Bijma, Jelle; Raitzsch, MarkusThe population dynamics of benthic foraminifera from the intertidal mudflat near Dorum-Neufeld in Northern Germany was examined. The study covered the period from September 2011 – July 2012. Biweekly, sediment samples were taken from four spatially distributed sites covering an area of approximately 100,000 m2 in the mudflat. Three benthic species are known to dominate the foraminifer population in the study area: Ammonia aomoriensis (Asano, 1951), Haynesina germanica (Ehrenberg, 1840) and Elphidium williamsoni (Haynes, 1973). The aim of this study is to obtain a longterm overview of the population dynamics of the three species and to gain information on the reproduction period for each species, thus providing constrains for optimizing sampling strategies for laboratory cultures. Coexistence and competition for resources among the three dominant foraminifer species in the benthic realm is analyzed. The very high abundance of living foraminifers in the mudflat in May and June with a maximum in May for both A. aomoriensis and H. germanica is observed. The fact that the higher abundance, starting in March and declining in June, is observed at all four sampling locations substantiates this finding. The population dynamics in the intertidal mud flats of Dorum-Neufeld has not been systematically analyzed before and now confirms assumptions previously derived from observations in laboratory stock cultures. In contrast, E. williamsoni has a completely different lifecycle than A. aomoriensis and H. germanica with higher reproduction in colder months between September and March. It is present throughout the year and distributed patchier in all stations. The most appropriate time for sampling foraminifers for culture experiments is between May and June for A. aomoriensis and H. germanica and from September until March for E. williamsoni. The abundance of E. williamsoni does not show a peak during May and June like A. aomoriensis and H. germanica, but exhibits the highest abundance during winter months. This means that either E. williamsoni competes with A. aomoriensis and H. germanica or that a colder climate favors the reproduction of E. williamsoni. In contrast, the similar abundance peak of A. aomoriensis and H. germanica suggests that these species coexist without competing with each other, maybe due to the use of different food sources. Haynesina germanica and E. williamsoni are both cleptoplasts, they are able to use diatom chloroplasts for photosynthesis. This adaptation might grant these two species an ecological niche alongside A. aomoriensis in the intertidal mudflat ecosystem. The sediments from Dorum that exclusively consist out of muddy, non-cohesive silt to fine sand plays a role in the relatively high Foraminifer densities, but very low species richness. In this study, regarding to temperature reconstruction with the help of fossil Foraminifera, the calculated average temperature is ̴ 10° C higher, than the measured average temperature which shows that population dynamics have a significant influence on possible temperature reconstructions with proxy signals (e. g. Mg/Ca).