TY  - JOUR
A1  - Bissinger, Vera
A1  - Tittel, Jörg
T1  - Process rates and growth limiting factors of planktonic algae (Chlamydomonas sp.) from extremely acidic (pH 2,5 3) mining lakes in Germany
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Tittel, Jörg
A1  - Weithoff, Guntram
A1  - Bissinger, Vera
A1  - Gaedke, Ursula
T1  - Ressourcennutzung und -weitergabe im planktischen Nahrungsnetz eines extrem sauren (pH 2,7) Tagebausees
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Bissinger, Vera
A1  - Jander, Jörn
A1  - Tittel, Jörg
T1  - A new medium free of organic carbon to cultivate organisms from extremely acidic mining lakes (pH 2.7)
N2  - An algal culture medium was developed which reflects the extreme chemical conditions of acidic mining lakes (pH 2.7, high concentrations of iron and sulfate) and remains stable without addition of organic carbon sources. It enables controlled experiments e.g. on the heterotrophic potential of pigmented flagellates in the laboratory. Various plankton organisms isolated from acidic lakes were successfully cultivated in this medium. The growth rates of an Chlamydomonas- isolate from acidic mining lakes were assessed by measuring cell densities under pure autotrophic and heterotrophic conditions (with glucose as organic C-source) and showed values of 0.74 and 0.40, respectively.
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Wölfl, S.
A1  - Tittel, Jörg
A1  - Zippel, Barbara
A1  - Kringel, R.
T1  - Occurrence of an algal mass development in an acidic (pH 2.5), iron and aluminium-rich coal mining pond
Y1  - 2000
ER  - 
TY  - JOUR
A1  - Stottmeister, Ulrich
A1  - Weißbrodt, Erika
A1  - Tittel, Jörg
T1  - Von der Altlast zum See : natürliche Selbstreinigung
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Klapper, H.
A1  - Boehrer, Bertram
A1  - Packroff, G.
A1  - Schultze, M.
A1  - Tittel, Jörg
A1  - Wendt-Potthoff, Katrin
T1  - Bergbaufolgegewässer
Y1  - 2001
ER  - 
TY  - JOUR
A1  - Koschorreck, Matthias
A1  - Frömmichen, René
A1  - Herzsprung, Peter
A1  - Tittel, Jörg
A1  - Wendt-Potthoff, Katrin
T1  - Function of straw for in situ remediation of acidic mining lakes
Y1  - 2002
SN  - 0049-6979
ER  - 
TY  - JOUR
A1  - Koschorreck, Matthias
A1  - Tittel, Jörg
T1  - Benthic photosynthesis in an acidic mining lake (pH 2.6).
Y1  - 2002
ER  - 
TY  - JOUR
A1  - Tittel, Jörg
A1  - Bissinger, Vera
A1  - Zippel, Barbara
A1  - Gaedke, Ursula
A1  - Bell, Elanor M.
A1  - Lorke, Andreas
A1  - Kamjunke, Norbert
T1  - Mixotrophs combine resource use to outcompete specialists: Implications for aquatic food webs
N2  - The majority of species can be grouped into those relying solely on photosynthesis (phototrophy) or those relying solely on the assimilation of organic substances (heterotrophy) to meet their requirements for energy and carbon. However, a special life history trait exists in which organisms combine both phototrophy and heterotrophy. Such 'mixotrophy' is a widespread phenomenon in aquatic habitats and is observed in many protozoan and metazoan organisms. The strategy requires investment in both photosynthetic and heterotrophic cellular apparatus, but the benefits must outweigh these costs. In accordance with the mechanistic resource competition theory, laboratory experiments revealed that pigmented mixotrophs combined light and prey as substitutable resources. Thereby, they reduced prey abundance below the critical food concentration of competing specialist grazers [Rothhaupt, K. O. (1996) Ecology 77, 716-724]. Here, we demonstrate for the first time the important consequences of this strategy for an aquatic community. In the illuminated surface strata of a lake, mixotrophs reduced prey abundance so steeply that grazers from higher trophic levels, consuming both the mixotrophs and their prey, could not persist. Thus, the mixotrophs escaped from both competition and grazing, and remained dominant. Furthermore, the mixotrophs structured the prey abundance along the vertical light gradient creating low densities near the surface and a pronounced maximum of their algal prey at depth. Such deep algal accumulations are typical features of nutrient poor aquatic habitats, previously explained by resource availability. We hypothesize instead that the mixotrophic grazing strategy is responsible for deep algal accumulations in many aquatic environments.
Y1  - 2003
UR  - www.pnas.org/cgi/doi/10.1073/pnas.2130696100
ER  - 
TY  - JOUR
A1  - Tittel, Jörg
A1  - Kamjunke, Norbert
T1  - Metabolism of dissolved organic carbon by planktonic bacteria and mixotrophic algae in lake neutralisation experiments
N2  - 1. Lakes formed in mining pits often contain high concentrations of dissolved ferric iron and sulphate (e.g. 2 and 16 mmol L)1, respectively) and the pH is buffered between 2.5 and 3.5. Efforts to neutralise their water are based on the stimulation of lake internal, bacterial iron- and sulphate reduction. Electron donors may be supplied by organic carbon compounds or indirectly by enhancement of primary production. Here, we investigated the function of mixotrophic algae, which can potentially supplement or deplete the organic carbon pool, in the carbon metabolism and alkalinity budget of an acidic mining lake. 2. Two weeks after organic substrates had been added in a large in situ mesocosm of 30 m diameter, a bloom of Chlamydomonas occurred, reaching a biovolume of 80 mm3 L)1. Growth experiments using filtered lake water showed that the alga reduced the overall dissolved organic carbon (DOC) concentration despite significant photosynthetic activity. However, when Chlamydomonas were grown together with natural bacterioplankton, net DOC consumption did not increase. 3. Uptake experiments using [14C]-glucose indicated that bacteria dominated glucose uptake and remineralisation. Therefore, the DOC leached in the water column was processed mainly by planktonic bacteria. Leached DOC must be regarded as loss, not transferred by larger organisms to the sediment, where reduction processes take place. 4. From phytoplankton biomass and production 2 years after fertilisation we estimated that pelagic photosynthesis does not supply an electron donor capacity capable of reducing more than 2% of actual stock of acidity per year. We estimated that only the benthic primary production was in a range to compensate for ongoing inputs of iron and sulphate.
Y1  - 2004
ER  -