Ecological status of shallow Lake Gorbacz (NE Poland) in its final stage before drying up

Abstract

The article assesses the ecological status of shallow Gorbacz Lake (NE Poland) in the last stage before complete drying up. For last few years hydrological regime of the lake catchment has been changed dramatically which was caused by functioning nearby peat mine and longer autumn drought periods for following years. Progressing macrophytes succession leaded complete emergent macrophytes overgrowth of the lake beginning from 2000. The analyses include records of previous samples and data for morphology, water quality, phytoplankton, zooplankton and macrophytes. The trophic status of Gorbacz Lake was verified compare to the previous studies. The results indicate that even with minimum amount of water Gorbacz Lake itself still keeps its dystrophic character with increasing of water color and of DOC, biogenic substances, chlorophyll a concentrations. Humic State Index (HSI) and hydrochemical dystrophy index (HDI) confirm the dystrophic status of the lake with values 71.3 and 76.2 respectively. Both typical phytoplankton representatives of eutrophic and dystrophic waters were recorded. Very high diversity of desmids in the 1 Corresponding author: p.zielinski@uwb.edu.pl telmatoplankton, indicates the observed process of shallowing in the reservoir. Planktonic crustacean fauna was represented by small filtrators. Rotifera community was strongly dominated by Trichocerca simonei. The article concludes with the main causes of the observed changes and some future remarks for the lake state.

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

“…Lakes Sucharek and Wądołek should, in light of their past and present qualities, be classified as atypical humic lakes that are on the cusp between dystrophic and eutrophic (Nürnberg and Show 1998). This also means that these lakes can be classified as alloiotrophic (Wetzel 1983), mixotrophic (Williamson and Morris 1999), or humoeutrophic lakes (Górniak 2006;Chmiel 2009;Zieliński et al 2011). In Estonia, Sweden, and Finland, lakes called dystrophic (humic), semidystrophic, and dyseutrophic are identified (Arst and Reinart 2009).…”

Phototrophic microflora of dystrophic Lake Sęczek, Masuria, Poland

“…Water in the lake was characterized by acidic pH and a high content of dissolved organic carbon compounds similarly to other dystrophic lakes (Table 1) , Górniak 2006, Zieliński et al 2011, Wilk-Woźniak et al 2012. Average concentration of total phosphorus, total nitrogen and a mineral form of nutrients in the Sphagnum littoral was higher than in pelagial.…”

“…Gonyostomum semen is a mixotrophic species characteristic of dystrophic waters, acidic lobelia waters and peat pits in the northern and eastern part of Poland (Grabowska & Górniak 2004, Hutorowicz et al 2006, Zieliński et al 2011, Pęczuła 2013). According to Karosienė et al (2014), G. semen is an invasive species in Lithuanian lakes where it occurred in humic, lobelia and eutrophic lakes.…”

The influence of hydromorphological modifications of the littoral zone in lakes on macrophytes

“…Strong tourism pressure also increases the contamination and degradation of a waterbody (Drzewiecki 1997). Macrophytes as a group of organisms that occur in the littoral zone on the borderline between water and land are particularly sensitive to changes in the water level (Keto et al 2006, Zieliński et al 2011, but this relationship is not clear. For example Rørslett (1991) reported that small changes in the water level (about 1-3 m) contribute to an increase in the biodiversity of lakes.…”