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| Titel |
Biding their time – Insights from propagule experiments into the assemblage composition of shallow-water foraminifera under environmental change |
| VerfasserIn |
Anna E. Weinmann, Susan T. Goldstein |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250121628
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| Publikation (Nr.) |
 EGU/EGU2016-417.pdf |
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| Zusammenfassung |
| The assemblage composition of shallow-water foraminifera in coastal environments is often
strongly influenced by water temperature and salinity. Community structures of
foraminifera have long been used as indicators for environmental change. This is – at least
partly – due to their ability to respond quickly to changing local conditions, which
becomes increasingly important in the wake of ongoing climate change. In this
study, we examined the range of assemblage compositions that grow and develop
under different combinations of temperature and salinity. We did this by applying
the Propagule Method using several coastal sites in Georgia and Florida (United
States).
The Propagule Method is an experimental tool for examining the growth of foraminiferal
assemblages from suites of tiny juveniles that occur in the “propagule banks” found within
the fine fraction of the sediment. We exposed the propagule banks from our study sites to
different temperatures (18, 24, and 30∘C) and salinities (15 and 35) over a period of 5 weeks,
to simulate different shallow-water conditions.
Results show that foraminifera grew abundantly in all experimental treatments, with
increased growth and reproduction occurring at higher temperatures (24 and 30∘C). Salinity
had a strong influence on the species composition of the experimental assemblages. The
most successful species were opportunists and known “pioneer” species such as
Ammonia tepida (Cushman) or Quinqueloculina seminula (Linné). However, we also
found significant numbers of allochthonous or “exotic” species that occurred only in
rare numbers or were even absent from the living in situ assemblages of the study
sites.
The presence of allochthonous taxa resulted from propagule recruitment from areas
beyond our immediate study sites. These propagules – which might be transported even
beyond their ecological range – may remain viable within the propagule bank until
environmental conditions become favorable. As such, they are “biding their time” in the
sediment – ready to become a part of the local assemblage, should environmental
conditions change. This provides insights into dispersal and an important tool for
examining the effects of warming oceans and changing salinity regimes in coastal
environments. |
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