Dystrophy or eutrophy: phytoplankton and physicochemical parameters in the functioning of humic lakes

Abstract

The studies were carried out in six humic lakes (Polesie Region, Eastern Poland) in order to present a role of phytoplankton in relation to physical and chemical parameters characteristic of particular processes. On the basis of physical and chemical properties of waters (SD, colour, pH, EC, Ca 2+ , DIC, DOC), these lakes are divided into three groups: dystrophic (Lakes Orchowe and Płotycze), humoeutrophic (Lakes Brudzieniec and Pereszpa) and mesoeutrophic (Lakes Moszne and Długie). The occurrence of dystrophication, humoeutrophication or eutrophication processes is clearly reflected in the phytoplankton composition and its abundance, as well as its biomass. In both dystrophic and humoeutrophic lakes, flagellates dominated in the phytoplankton. Among them, the invasive species Gonyostomum semen was very abundant. Mesoeutrophic lakes were characterized by other phytoplankton composition, mainly by non-flagellate species (green algae).

Zooplankton Feeding on the Nuisance Flagellate Gonyostomum semen

“…Blooms mainly occur in small lakes with high dissolved organic carbon (DOC) content and low pH [5], [6], but have also been reported from other lake types and reservoirs [3], [7], [8]. Several studies have shown an increase in the geographical distribution and bloom incidence of G. semen in Northern Europe during recent decades [5], [9], [10]. Increasing levels of DOC in freshwaters and rising temperatures [11], [12] are potential drivers of the expansion, as the growth of G. semen is enhanced by humic substances and both growth and recruitment from benthic resting stages are temperature-dependent [5], [13].…”

Grazing resistance allows bloom formation and may explain invasion success of Gonyostomum semen

“…This raphidophyte is now considered to be an invasive species, with a special concern in Scandinavia and Finland. Recently, G. semen was found to form dense invasive populations in Poland (Poniewozik et al 2011), suggesting that the species is now spreading to southern countries of Europe. G. semen is a bloom-forming species that can dominate the phytoplankton community to up to 97% during extended periods of time despite a low growth rate (Cronberg et al 1988;Findlay et al 2005;K.…”

Developmental Changes in the Historical and Present-Day Trophic Status of Brown Water Lakes. Are Humic Water Bodies a Uniform Aquatic Ecosystem?

“…For example, even the very term dystrophy is controversial, because it suggests only the lack of nutrients in lakes (Hansen 1962), while the lack of nutrients is also linked with a higher amount of humic substances (HS), giving brown water color and low pH (4.0-6.0). The other characteristic features of humic lakes include peat-covered catchment area, sometimes overgrown with coniferous forests, peat mosses in the vicinity of water bodies, spreading floating mats on water surfaces, low water and sediment calcium content, dy sediments, small algal biomass, poor taxonomic biodiversity, and higher respiration than primary production (Miles and Brezonik 1981;Salonen et al 1983;Wetzel 1983;Hessen and Tranvik 1998;Górniak et al 1999;Brönmark and Hansson 2005;Gąbka and Owsianny 2006;Poniewozik et al 2011;Rodriguéz et al 2011). Large amounts of humus flow into lakes from catchment basins (De Haan 1992;Hessen 1992), causing water acidification (Kullberg et al 1993).…”