Assessing ecosystem dynamics amongst zooplankton, phytoplankton and jellyfish ( Mastigias) in meromictic marine lakes
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Authors
Schimon, Ann K.
Issue Date
2010
Type
Thesis
Language
en_US
Keywords
Alternative Title
Abstract
Interactions between trophic levels can create a complex network of population
dynamics, such as higher trophic levels regulating lower trophic levels (top-down
control), lower trophic levels regulating higher trophic levels (bottom-up control) or
organisms within a trophic level competing for resources (intraguild predation). These
interactions have been greatly studied in many ecosystems but not as thoroughly in some
aquatic environments, such as meromictic marine lakes. In this particular lake type, water
does not mix between the top and bottom due to a chemocline. Therefore, I conducted
this study to better understand if dynamics between trophic levels, such as top-down
control or intraguild predation, were influencing organism abundance within meromictic
marine lakes. Jellyfish Mastigias (Scyphozoa), zooplankton and phytoplankton samples
were collected for approximately 10 yr from a meromictic marine lake, Jellyfish Lake. I
calculated the abundance of the different organisms in the lake. Eighteen samples were
selected, and I hand-counted the total amount of copepods: Oithona, Acrocalanus,
nauplii, eggs and carapaces. Top-down control and intraguild competition were not
observed to be influencing the ecosystem dynamics. Possible strongly influential abiotic
factors, like El Nino-Southern Oscillation (ENSO), or other organisms, like human
recreationalists, could have been disturbing trophic level dynamics. Other possible
suggestions for the observed results were that the diel vertical migration (DVM) of
zooplankton and the presences of symbiotic zooxanthellae on Mastigias could have
diminished the ability or need for Mastigias to capture zooplankton.
Description
v, 26 p.
Citation
Publisher
Kalamazoo College
License
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