Coupled predator-prey oscillations in a chaotic food web
Benincà, E. ; Johnk, K.D. ; Heerkloss, R. ; Huisman, J. - \ 2009
Ecology Letters 12 (2009)12. - ISSN 1461-023X - p. 1367 - 1378.
wavelet analysis - time-series - ecological dynamics - populations - abundance - models - cycles - synchronization - biodiversity - competition
Coupling of several predator-prey oscillations can generate intriguing patterns of synchronization and chaos. Theory predicts that prey species will fluctuate in phase if predator-prey cycles are coupled through generalist predators, whereas they will fluctuate in anti-phase if predator-prey cycles are coupled through competition between prey species. Here, we investigate predator-prey oscillations in a long-term experiment with a marine plankton community. Wavelet analysis of the species fluctuations reveals two predator-prey cycles that fluctuate largely in anti-phase. The phase angles point at strong competition between the phytoplankton species, but relatively little prey overlap among the zooplankton species. This food web architecture is consistent with the size structure of the plankton community, and generates highly dynamic food webs. Continued alternations in species dominance enable coexistence of the prey species through a non-equilibrium 'killing-the-winner' mechanism, as the system shifts back and forth between the two predator-prey cycles in a chaotic fashion.
10 Year trend of levels of organochlorine pollutants in Antarctic seabirds
Brink, N.W. van den - \ 2003
earth science - human dimensions - environmental impacts - contaminant level/spills - biological classification - animals - vertebrates - birds - biosphere - ecological dynamics - ecotoxicology - toxicity levels
Contaminants like PCBs and DDE have hardly been used Antarctica. Hence, this is an excellent place to monitor global background levels of these organochlorines. In this project concentrations in penguins and petrels will be compared to 10 years ago, which will show time trends of global background contamination levels. Data set description From several birds from Hop Island, Rauer Islands near Davis, samples were collected from preenoil (oil that birds excrete to preen their feathers. This preenoil was then analysed for organochlorine pollutants like polychlorinated biphenyls, (PCBs), hexachlorobenzene (HCB), DDE and dieldrin. The species under investigation were the Adelie penguin (Pygoscelis adeliae) and the Southern Fulmar (Fulmarus glacialoides). The samples were collected from adult breeding birds, and stored in -20 degrees C as soon as possible. The analysis was done with relatively standard but very optimised methods, using a gas-chromatograph and mass-selective detection.