Biological recovery of the Bohemian Forest lakes from acidification

Abstract

A limnological survey of eight small, atmospherically acidified, forested glacial lakes in the Bohemian Forest (Šumava, Böhmerwald) was performed in September 2003. Water chemistry of the tributaries and surface layer of each lake was determined, as well as species composition and biomass of the plankton along the water column, and littoral macrozoobenthos to assess the present status of the lakes. The progress in chemical reversal and biological recovery from acid stress was evaluated by comparing the current status of the lakes with results of a survey four years ago (1999) and former acidification data since the early 1990s. Both the current chemical lake status and the pelagic food web structure reflected the acidity of the tributaries and their aluminium (Al) and phosphorus (P) concentrations. One mesotrophic (Plešné jezero) and three oligotrophic lakes (Černé jezero, Čertovo jezero, and Rachelsee) are still chronically acidified, while four other oligotrophic lakes (Kleiner Arbersee, Prášilské jezero, Grosser Arbersee, and Laka) have recovered their carbonate buffering system. Total plankton biomass was very low and largely dominated by filamentous bacteria in the acidified oligotrophic lakes, while the mesotrophic lake had a higher biomass and was dominated by phytoplankton, which apparently profited from the higher P input. In contrast, both phytoplankton and crustacean zooplankton accounted for the majority of plankton biomass in the recovering lakes. This study has shown further progress in the reversal of lake water chemistry as well as further evidence of biological recovery compared to the 1999 survey. While no changes occurred in species composition of phytoplankton, a new ciliate species was found in one lake. In several lakes, this survey documented a return of zooplankton (e.g., Cladocera: Ceriodaphnia quadrangula and Rotifera: three Keratella species) and macrozoobenthos species (e.g., Ephemeroptera and Plecoptera). The beginning of biological recovery has been delayed for ∼20 years after chemical reversal of the lakes.

Element fluxes in watershed-lake ecosystems recovering from acidification: Plešné Lake, the Bohemian Forest, 2001–2005

“…Details on the historical development of cladocerans and chironomids in the lake are given by PRAŽÁKOVÁ et al (2006) andTÁTOSOVÁ et al (2006), respectively. The recent biological status of the lake is evaluated by NEDBALOVÁ et al (2006).…”

Element fluxes in watershed-lake ecosystems recovering from acidification: Čertovo Lake, the Bohemian Forest, 2001–2005

“…The reduction of dissolved Si in lakes is commonly associated with diatom production (Wetzel, 2001). Pelagic diatoms are, however, absent in Čertovo Lake, but Chrysophyceae form an important portion of the phytoplankton biomass (Vrba et al, 2003;Nedbalová et al, 2006). The sedimentation of chrysophycean cysts and scales seems to be a probable biological mechanism contributing to the Si depletion in the lake.…”

“…Partial photochemical degradation of allochthonous DOC produces biologically available compounds for bacterial growth (Wetzel et al, 1995) and can explain the high proportion of bacteria in the total plankton biomass observed in Čertovo Lake (Vrba et al, 2003;Nedbalová et al, 2006). The photochemical and microbial DOC decomposition lowered its concentrations in the outlet, compared to tributaries (Fig.…”

Notes to the use of Aulacoseira taxa in the palaeoecological reconstruction of the Bohemian Forest lakes

“…Origin of the Bohemian Forest lakes was connected with glacial erosion in the last cold period, the end of glaciation there is estimated as early as before Younger Dryas (Mentlík et al 2010). Lacustrine environments were strongly affected by acidification in the 20th century and now are in different stages of recovery (Nedbalová et al 2006), their development is still monitored (Vrba et al 2015). Prášilské Lake is an oligotrophic and slightly acidic basin such as the rest of the lakes in the area except the only mesotrophic Plešné Lake (Nedbalová et al 2006).…”

“…Lacustrine environments were strongly affected by acidification in the 20th century and now are in different stages of recovery (Nedbalová et al 2006), their development is still monitored (Vrba et al 2015). Prášilské Lake is an oligotrophic and slightly acidic basin such as the rest of the lakes in the area except the only mesotrophic Plešné Lake (Nedbalová et al 2006). …”