Miroslav Macek

Biological recovery of the Bohemian Forest lakes from acidification

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.

Beyond the “Code”: A Guide to the Description and Documentation of Biodiversity in Ciliated Protists (Alveolata, Ciliophora)

Recent advances in molecular technology have revolutionized research on all aspects of the biology of organisms, including ciliates, and created unprecedented opportunities for pursuing a more integrative approach to investigations of biodiversity. However, this goal is complicated by large gaps and inconsistencies that still exist in the foundation of basic information about biodiversity of ciliates. The present paper reviews issues relating to the taxonomy of ciliates and presents specific recommendations for best practice in the observation and documentation of their biodiversity. This effort stems from a workshop that explored ways to implement six Grand Challenges proposed by the International Research Coordination Network for Biodiversity of Ciliates (IRCN‐BC). As part of its commitment to strengthening the knowledge base that supports research on biodiversity of ciliates, the IRCN‐BC proposes to populate The Ciliate Guide, an online database, with biodiversity‐related data and metadata to create a resource that will facilitate accurate taxonomic identifications and promote sharing of data.

Seasonal dynamics, composition and feeding patterns of ciliate assemblages in oligotrophic lakes covering a wide pH range

Seasonal changes in the structure of ciliate assemblages in eleven oligotrophic mountain lakes at different altitudes, covering a wide pH range from 4.9 to 6.9, were studied. Seven mountain lakes lay above the timberline (0vre NeÅdalsvatn and Stavsvatn, Norway; Lochnagar, Scotland; Starolesnianske pleso and Nizne Terianske pleso, Slovak Republic; Chuna ozero, Russia; Lago Paione Superiore, Italy) and four acidified lakes (Cerne, Certovo, Plesne and Prasilske jezero, Sumava Mountains, Czech Republic) in the mountain forest. Additionally, thr tropical high latitude Lago de Alchichica (Mexico) was analysed. Ciliate taxons were identified using the quantitative protargol staining approach, and feeding patterns were tentatively detected by using fluorescence microscopy methods. Nano- to microphytoplankton hunters and/ or mixotrophic ciliates prevailed in all acidic lakes. Numbers of ciliates were very low (seasonal lake mean below 200 cells/I) except in two Tatra lakes (to 21000 cells/I). Prostomes of the genera Urotricha, Holophrya and Prorodon dominated in most of the samples, both numerically as well as in biomass (seasonal lake mean from 13.6 to 100% and 4.6 to 99.7%, respectively), particularly in acidified water lakes (Starolesnianske, Certovo and Prasilske jezero). Among mixotrophs, oligotrichs of genera Pelagostrombidium and Limnostrombidium were the most prominent (up to 49.9 and 64.6%, respectively). The picoplankton-feeders (minute oligotrichs, peritrichs and scuticociliates) were found to be an important component even in the oligotrophic environment but this ecological type never dominated within the water column (up to 22.2 and 30.3 %, respectively). Major food sources of gymnostomes, prevailing only in Lochnagar (82.5 and 87.5 %, respectively; Mesodinium sp.), remained unclear; large Askenasia spp. were apparently mixotrophic. Using a cluster analysis, the lakes were grouped according to the total numbers of ciliates and contributions of distinct ecological groups with different feeding patterns. Within low acidic lakes, Lochnagar differed from all others. The rest of the lakes was divided into two subgroups: remote pristine lakes of the Northern transect (the Norwegian lakes and Chuna ozero), and the others, geographically affiliated to the south transect (Pyreneans, Alps, Tatra Mts.). Such a differentiation is in good agreement with the clustering based on chemical parameters reported for the lakes. No marked differences in the ciliate distribution were detected when the above timberline- and forest surrounded mountain lakes were compared.

Temporal and spatial variation of bacterioplankton abundance in a tropical, warm-monomictic, saline lake: Alchichica, Puebla, Mexico

An important part of the carbon and energy flow in aquatic ecosystems is channeled through the microbialloop in planktonic food webs (AzAM et al. 1983, PoRTER et al. 1985), where bacterioplankton play a fundamental role in the transfer of dissolved organic matter, mainly produced by phytoplankton, to higher levels in the food chain. Several studies show that bacteria are important components of both marine and freshwater environments. Additionally, the metabolic activity of heterotrophic bacteria in the water column may have an important influence on such fundamental limnological variables as oxygen concentration, pH and nutrient concentrations as well as the rate at which nutrients are regenerated (ÜCHS et al. 1995). The purpose of this study was to examine patterns and causes of spatial and temporal dynamics of bacterial densities in a deep saline tropicallake.

In situ measured elimination of Vibrio cholerae from brackish water

In situ elimination of fluorescently labelled Vibrio cholerae (FLB) was measured in two saline water bodies in Mexico: in a brackish water lagoon, Mecoacán (Gulf of Mexico; State of Tabasco) and an athalassohaline lake, Alchichica (State of Puebla). Disappearance rates of fluorescently labelled V. cholera O1 showed that they were eliminated from the environment at an average rate of 32% and 63 %/day, respectively (based on the bacterial standing stocks). The indirect immunofluorescence method confirmed the presence of V. cholerae O1 in the lagoon. However, the elimination of FLB was not directly related either to the presence or absence of the bacterium in the water body or to the phytoplankton concentration.

Insights on Short-term Blooms of Planktonic Ciliates, Provided by an Easily Recognised Genus: Cyrtostrombidium

Planktonic ciliates occasionally form brief rapid increases in numbers (blooms) that can be trophically important. Although model simulations and mesocosm studies indicate that blooms occur over 10 to 20 days, field data are rarely sufficiently detailed to reveal their occurrence and demise. Our data (collected over 57 weeks across a coastal lagoon) offer insights into the population dynamics of a single species, place these in the context of the entire ciliate assemblage, and provide guidance on what should continue to be examined. Specifi- cally, to evaluate population dynamics we examine two species of Cyrtostrombidium, characterise temporal and spatial variation of their abundance, and relate these to abiotic phenomena and biological factors. This is also the first report of Cyrtostrombidium in a tropical coastal lagoon. Collectively our analysis reveals key aspects of the dynamics of this genus: 1) small-scale peaks in abundance are ~30 m in size and can persist for ~10-30 days, reaching a maximum of 100 cells ml -1 ; 2) these increases are driven by biotic factors (revealed through autocorrelation analysis); 3) long-term trends are driven by the shift between dry and rainy seasons and by the periods of isolation of lagoon from the sea (revealed through multiple regression analysis); 4) blooms may at times control primary production; 5) conjugation, an ecologi- cally important event, may be associated with blooms (at times 9% of population was conjugating); and 6) dinoflagellate parasitism, poorly described in oligotrichs, is potentially important in population demise. These results both reflect on how ciliates may behave in short-term events and should encourage the continued need for detailed observations of field samples at a high taxonomic resolution.

Pelagic food webs and microbial loop in low-alkalinity mountain lakes

Remote mountain lake ecosystems are exposed to harsh climatic conditions, including low temperatures, short ice-free periods, high variations in precipitation and snow and ice-melt, which results in high seasonal variations of water chemistry (MosELLO et al. 1998) and changes in biotic assemblages. Lakes located on crystalline bedrock are sensitive to acidification. Pelagic food webs are simple compared to more trophic lowland lakes; fish might be extinct or absent, and the biomass and species diversity of metazoic zooplankton are very low (FoTI et al. 1992). However, the microbial parr of the pelagic biomass including bacteria, heterotrophic protists and autotrophic phytoplankton might be rather active and well developed (STRASKRABOVA & SIMEK 1988}. We present data on pelagic biomass and its structure in some European mountain lakes differing in morphometry, elevation, geographic location and water chemistry.

Elimination of Special Bacteria from Treatment Effluent by Ciliates

Publisher Summary This chapter describes the elimination of special bacteria from treatment effluent by ciliates. Activated-sludge treatment is the best technology for the elimination of organic pollution from waste waters. However, the efficiency of the treatment may be low if they contain specific substrates, which are degradable only by dispersed growing bacteria with very low growth rate. These bacteria could be eliminated by effective predators (e.g., rotifers) and nondegraded pollution leaves the system or, these substances as the dominant substrate promote growth of dispersion and therefore the effluent is polluted by bacteria. Ciliates could suppress these problems caused by the means of two mechanisms, which affect the bacterial community as: (1) alternative prey, and (2) induced flocculation. The selective effect of the substrate on the bacterial community structure was verified using nitrilotriacetic acid as the sole organic carbon and nitrogen source.