Effect of eutrophication and humification on nutrient cycles and transfer efficiency of matter in freshwater food webs

Abstract

We evaluated how eutrophication and humification impacted nutrient cycles and the efficiency of carbon transfer in the planktonic food webs of 12 lakes in north-eastern Poland that differed in trophic state. Our results indicated that the effectiveness of carbon transfer between phytoplankton and zooplankton varied from 0.0005% to 0.14%, which is much lower than the theoretical 10%. The highest efficiency of carbon transfer occurred in the mesotrophic lakes due to the higher hypolimnetic zooplankton production, while the lowest efficiency was observed in the dystrophic lakes and in one eutrophic lake that was dominated by cyanobacteria. Inedible algae (e.g. Gonyostomum semen) and cyanobacteria appeared to be the main factors reducing the efficiency of the transfer of matter in pelagic food webs. The results of our study showed that plankton communities are a key component of the nutrient cycle in freshwater food webs. Phytoplankton were a very effective nitrogen sink, and in the mesotrophic lakes, up to 99% of the total nitrogen was sequestrated in phytoplankton. As a result, there was a depletion of inorganic nitrogen in the upper water layer. Furthermore, zooplankton were an important phosphorus sink, thus significantly influencing the nutrient cycles.

Cladocera paleocommunity to disentangle the impact of anthropogenic and climatic stressors on a deep subalpine lake ecosystem (Lake Iseo, Italy)

“…Zooplankton plays a pivotal role in the biogeochemical cycles, and it is a key component transferring energy and matter from primary producers to higher trophic levels (Karpowicz et al 2020). Small-bodied species, such as small cladocerans, are mainly regulated by the ''bottom-up'' process, while larger species are mostly regulated by ''top-down'' control by fish (Gliwicz 2003).…”

Limnological Characteristics and Diatom Dominants in Lakes of Northeastern Poland

“…As Witkowski et al [9] stated, when pH values fall, species richness is curtailed, and the structure of diatom assemblages can be changed profoundly. Such environments of lowered resilience are susceptible to stressors other than an excess of hydrogen ions e.g., the expansion of Gonyostomum semen (Ehrenberg) Diesing 1866 reported [50,51]. On the other hand, low diversity in the distrophic group can be related to low conductivity (as reported in [52]).…”

“…Despite reports regarding HDI (the Hydrochemical Dystrophy Index) [11,12], some physical, chemical, and biological variables of Lake SW show differences from other dystrophic lakes, encouraging some scientists to describe it as moderately dystrophic [53]. The unique features of lake SW are also described by Karpowicz et al [51]. Their data show a lower abundance of Gonyostomum semen and a higher biomass of zooplankton in Lake SW in comparison to the lower biomass in the other dystrophic lakes, as well as a deep and oxygenated epilimnion in contrast to lower oxygen concentration in other disharmonic lakes.…”

Potential of valuable materials recovery from aquaculture wastewater: An introduction to resource reclamation

“…Eutrophication promotes the growth of floating macrophytes, which limits the amount of sunlight penetrating into the underwater (Lusiana et al, 2020). The decrease in underwater sunlight penetration disrupts the photosynthesis activity of phytoplankton, thereby decreasing the concentration of dissolved oxygen in the aquatic environment (Karpowicz et al, 2020).…”