Fine‐layer depth relationships of lakewater chemistry, planktonic algae and photosynthetic bacteria in meromictic Lake Fidler, Tasmania

Abstract

1. Use of a multi-column thin-layer pneumatic sampler and modified analytic procedures has enabled resolutions of chemical and biological strata at 2.5 or 5,0 cm depth intervals. Examination of meromictic Lake Fidler. Tasmania, indicates the presence of a thin, intense stratum of bacteriochlorohyll d in the upper monimolimnion. associated with a discrete stratum of Chlorobium cf, limicola at the microaerobic interface between the oxygenated and sulphide-rich zones.2. Algae included small populations of Chlorophyceae, Chrysophyceae, Bacillariophyceac and Cryptophyceac. Bacteria included microacrophils and obligate anaerobes, pigmented and colourless, in well-defined strata in the upper monimolimnion. A population of the microcrustacean Calamoecia tasmanica tasmatiica was present in the mixolimnion. Chaohortts larvae were concentrated within the Chlorohiutn layer.3. The chemical profile of Lake Fidler was stable, with a chemocline constant in position relative to the lake bottom. The surface water levels rose and fell through a distance of 1 m in conjunction with heavy rainfall in the rainforest, and with river level variation, but had no measurable effect on the absolute position of the chemocline. Marked heterogeneity of dissolved substances at depths in the vicinity of bacteria suggested endogenous influence on pH and gelbstoff ('gilvin" in Australia).4. Downwelling light attenuation was influenced primarily by gclbstolf ('gilvin") in the mixolimnion. with only red light (peak at 7(HI nni) measurable below 2 m. Light was absorbed mainly by Chlorobium in the monimolimnion. and was unmcasurable deeper than 3 m. 5. The absorption spectrum of the bactcriochlorophyll d in vivo, with a maximum absorbance at 721 nm. eorresponds with the available downwelling light penetrating the mixolimnion to the Chlorobium layer.

The ecological niche of the consortium " Pelochromatium roseum "

“…C Flagella stained with crystal violet. Highly refractile appearance of whole consortia is caused by the stain (bar 10 µm) Anagnostidis and Overbeck (1966), Baker et al (1985), Blakar (1979), Caldwell and Tiedje (1974a, b), Croome and Tyler (1984), Dubinina and Kuznetsov (1976), Eichler and Pfennig (1990), Gasol et al (1995), Gorlenko (1988), Gorlenko and Chebotarev (1981), Gorlenko and Kusnetsov (1971), Gorlenko and Kusnezow (1972), Gorlenko and Lokk (1979), King and Tyler (1982), Mechsner (1957), Overbeck (1974), Overmann (Grünen-plan, unpublished), Overmann and Tilzer (1989), Parkin and Brock (1980), Skuja (1957), Utermöhl (1923) colored counterparts (0.2-10 m; data from the references cited in Table 2). Due to the absorption characteristics of lake water, the underwater light spectrum progressively narrows with depth.…”

Green sulphur bacteria as a component of the photosynthetic plankton community in small dimictic humic lakes with an anoxic hypolimnion

“…The few microscopic (e.g. Baker et al 1985, Arvola et al 1992 and molecular (Taipale et al 2009, 2011, Peura et al 2012) studies suggest that the microbial communities in anoxic layers of these lakes are dominated by bacteria, which are distinct from bacteria typical for epilimnetic communities, such as green sulphur bacteria (GSB) and candidate phylum OD1. GSB are strictly anaerobic and obligatory phototrophic; thus, they require the presence of reduced sulphur compounds and the availability of light for growth (Van Gemerden & Mas 1995).…”

Diel changes in the microstratification of the metalimnetic community in Lake Cisó

“…This creates a vertical succession of microenvironments with drastically different conditions across the thermo-or chemocline (Caldwell & Tiedje, 1975). Different microorganisms develop at each microhabitat and a very fine stratification of microbial populations results (Baker et al, 1985b;Borsheim et al, 1985;Pedrbs-Alib et al, 1986).…”

“…Thus, a line sampling method is necessary. In aquatic environments two line sampling systems have been used: pumping through a weighted piece of tubing (Cohen et al, 1977;Lindholm et al, 1985;Borsheimet al, 1985;Guerreroet al, 1985;Blinn & Green, 1986;Arvola et al, 1987;Pedros-Al% et al, 1987) or simultaneous tilling of syringes held together in a frame (Broenkow, 1969;Baker, 1970;Clasby et al, 1972;Blakar, 1979;King & Tyler, 1982;Croome & Tyler, 1984;Baker et al, 1985aBaker et al, , 1985bMitchell, 1987). The first system has the advantage of being easy to handle and providing theoretically unlimited volumes of sample from any one depth.…”