TITLE:
Trophic State Evaluation of a Large Mediterranean Lake Utilizing Abiotic and Biotic Elements
AUTHORS:
George Kehayias, Evangelia Doulka
KEYWORDS:
Lake Zooplankton; Eutrophication; Abundance; Trichonis Lake; Indicator Species; Mediterranean
JOURNAL NAME:
Journal of Environmental Protection,
Vol.5 No.1,
January
23,
2014
ABSTRACT: The trophic state of a freshwater ecosystem reflects its
environmental quality. This is why several trophic indicators have been
developed for such water bodies based on chemical, physical and biological
parameters. Apart from that, there are several biotic elements which can be
used in accessing the environmental condition of a freshwater ecosystem.
Zooplankton organisms are important elements of the structure and function of
lakes and are considered useful indicators of alterations in their trophic
dynamics and ecological state related to changes in nutrient loading and
climate. In accordance to the above, the present study is an attempt to assess
the trophic condition of the largest lake in Greece (Lake Trichonis) through
the investigation of the physicochemical elements, along with the biotic
indications provided by a three-year study of the lake’s zooplankton. The
present results, compared with previous studies conducted between 15 and 25
years before, showed that there was an increase in the maximum values of the
concentrations of chlorophyll-α and nutrients, while there was a decrease in
water transparency. The implementation of Carslon’s trophic state index (TSI)
revealed that Lake Trichonis still remains an oligo-to mesotrophic ecosystem as
it was in the past. However, although the zooplankton investigation showed
several features that are common in oligotrophic lakes, there are certain
eutrophic characteristics of the zooplankton community (e.g. abundance
variation pattern, indicator species, seasonal succession of cladocerans)
pointing out a different state of the ecosystem in comparison to the past. In
conclusion, the use of a biotic element like zooplankton revealed that Lake
Trichonis is experiencing a transitional condition towards the eutrophic state
and points out the necessity for constant inspection and monitoring of this
ecosystem.