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  - 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  - 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  - 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  - 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  - Stottmeister, Ulrich
A1  - Weißbrodt, Erika
A1  - Tittel, Jörg
T1  - Von der Altlast zum See : natürliche Selbstreinigung
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  - Kamjunke, Norbert
A1  - Gaedke, Ursula
A1  - Tittel, Jörg
A1  - Weithoff, Guntram
A1  - Bell, Elanor M.
T1  - Strong vertical differences in the plankton composition of an extremely acidic lake
N2  - Vertical differences in food web structure were examined in an extremely acidic, iron-rich mining lake in Germany (Lake 111; pH 2.6, total Fe 150mg L-1) during the period of stratification. We tested whether or not the seasonal variation of the plankton composition is less pronounced than the differences observed over depth. The lake was strongly stratified in summer, and concentrations of dissolved organic carbon and inorganic carbon were consistently low in the epilimnion but high in the hypolimnion. Oxygen concentrations declined in the hypolimnion but were always above 2mg L-1. Light attenuation did not change over depth and time and was governed by dissolved ferric iron. The plankton consisted mainly of single-celled and filamentous bacteria, the two mixotrophic flagellates Chlamydomonas sp. and Ochromonas sp., the two rotifer species Elosa worallii and Cephalodella hoodi, and Heliozoa as top predators. We observed very few ciliates and rhizopods, and no heterotrophic flagellates, crustaceans or fish. Ochromonas sp., bacterial filaments, Elosa and Heliozoa dominated in the epilimnion whereas Chlamydomonas sp., single-celled bacteria and Cephalodella dominated in the hypolimnion. Single-celled bacteria were controlled by Ochromonas sp. whereas the lack of large consumers favoured a high proportion of bacterial filaments. The primarily phototrophic Chlamydomas sp. was limited by light and CO2 and may have been reduced due to grazing by Ochromonas sp. in the epilimnion. The distribution of the primarily phagotrophic Ochromonas sp. and of the animals seemed to be controlled by prey availability. Differences in the plankton composition were much higher between the epilimnion and hypolimnion than within a particular stratum over time. The food web in Lake 111 was extremely species-poor enabling no functional redundancy. This was attributed to the direct exclusion of species by the harsh environmental conditions and presumably enforced by competitive exclusion. The latter was promoted by the low diversity at the first trophic level which, in turn, was attributed to relatively stable growth conditions and the independence of resource availability (inorganic carbon and light) from algal density. Ecological theory suggests that low functional redundancy promotes low stability in ecosystem processes which was not supported by our data.
Y1  - 2004
ER  -