TOHU-VA-VOHU OF THE QUASI-STOCHASTIC PHYTOPLANKTON IN THE SEA OF THE GALILEE
Keywords:
phytoplankton, community structure, taxonomic size spectra, composite size spectra, environmental stress, Lake KinneretAbstract
The stability analysis of natural communities and ecosystems requires quantitative means capable of evaluating the structural variability of the aquatic community or assemblage taken as a whole. Size spectrum (SS) provides such assessment and is most often applied to the size distribution of particles or organisms of the given community. Another old, but rarely used, special case of SS describes the size-frequency distribution of taxonomic units encompassed by an assemblage, and is called here ‘taxonomic size spectrum’ (TSS). The phytoplankton assemblage of the Sea of the Galilee (Lake Kinneret), Israel, was used to compare several years (out of the 30-year monitoring period) characterized with the most pronounced abnormalities in many biotic and abiotic parameters. Two types of TSS (TTSS and FTSS) revealed some stable patterns of phytoplankton structure. Simple statistical methods (linear regression) produced quantitative similarity estimates of such patterns. Unpredictability in the annual frequency scores was much higher for particular taxonomic units than for the assemblage size classes. We interpret this distinction as the self-regulation success of the natural aquatic community. A possible explanation can be found in our Ideal Minimal Ecosystem model and in the ideas of G. Cuvier and V.I. Vernadskiy, which provided its theoretical foundation.
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