A Preliminary Study Into the Possibility of δ13C Being Used as a Sensitive Indicator of the Trophic and Hydrobiological Status of Aquatic Ecosystems

There is a need to search for additional indicators allowing for more accurate identification of both the trophic status of waters as well as its chemical and biological consequences. The work detailed in this paper involved a preliminary analysis pertaining to the possibility of using an isotopic index in association with the values for trophic and saprobic indicators in describing a dam reservoir experiencing a far-reaching eutrophication. The water samples for the physicochemical analysis were collected from three sites along the axis of the dam reservoir in Rzeszów three times during the spring and summer of 2013. The results sustained the classification of the Reservoir's waters as hypertrophic, irrespective of the particular zone sampled. While phytoplankton blooms characterised by reference to the numbers of organisms per unit volume of water were also similar throughout the Reservoir, diversification in terms of taxonomic composition was to be noted, given the occurrence of cyanobacteria among the dominant diatoms in the area close to the dam. This presence was accompanied by enrichment of the Reservoir's suspended organic matter with carbon of the heavier ¹³C isotope. On this basis, the δ¹³C isotopic index can be regarded as a potentially useful indicator allowing for more accurate identification of both the level and the nature of the ongoing trophic degradation in bodies of water.