@article{MehnerAttermeyerBraunsetal.2022,
  author    = {Mehner, Thomas and Attermeyer, Katrin and Brauns, Mario and Brothers, Soren and Hilt, Sabine and Scharnweber, Kristin and Dorst, Renee Minavan and Vanni, Michael J. and Gaedke, Ursula},
  title     = {Trophic transfer efficiency in lakes},
  series = {Ecosystems},
  volume    = {25},
  journal   = {Ecosystems},
  number    = {8},
  publisher = {Springer},
  address   = {New York},
  issn      = {1432-9840},
  doi       = {10.1007/s10021-022-00776-3},
  pages     = {1628 -- 1652},
  year      = {2022},
  abstract  = {Trophic transfer efficiency (TTE) is usually calculated as the ratio of production rates between two consecutive trophic levels. Although seemingly simple, TTE estimates from lakes are rare. In our review, we explore the processes and structures that must be understood for a proper lake TTE estimate. We briefly discuss measurements of production rates and trophic positions and mention how ecological efficiencies, nutrients (N, P) and other compounds (fatty acids) affect energy transfer between trophic levels and hence TTE. Furthermore, we elucidate how TTE estimates are linked with size-based approaches according to the Metabolic Theory of Ecology, and how food-web models can be applied to study TTE in lakes. Subsequently, we explore temporal and spatial heterogeneity of production and TTE in lakes, with a particular focus on the links between benthic and pelagic habitats and between the lake and the terrestrial environment. We provide an overview of TTE estimates from lakes found in the published literature. Finally, we present two alternative approaches to estimating TTE. First, TTE can be seen as a mechanistic quantity informing about the energy and matter flow between producer and consumer groups. This approach is informative with respect to food-web structure, but requires enormous amounts of data. The greatest uncertainty comes from the proper consideration of basal production to estimate TTE of omnivorous organisms. An alternative approach is estimating food-chain and food-web efficiencies, by comparing the heterotrophic production of single consumer levels or the total sum of all heterotrophic production including that of heterotrophic bacteria to the total sum of primary production. We close the review by pointing to a few research questions that would benefit from more frequent and standardized estimates of TTE in lakes.},
  language  = {en}
}
@article{BoliusWiednerWeithoff2017,
  author    = {Bolius, Sarah and Wiedner, Claudia and Weithoff, Guntram},
  title     = {High local trait variability in a globally invasive cyanobacterium},
  series = {Freshwater biology},
  volume    = {62},
  journal   = {Freshwater biology},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0046-5070},
  doi       = {10.1111/fwb.13028},
  pages     = {1879 -- 1890},
  year      = {2017},
  abstract  = {1. During the last couple of decades, invasive species have become a worldwide problem in many freshwater systems. Besides higher plants and animals, microbes, in particular the potentially toxic cyanobacterium Cylindrospermopsis raciborskii, has attracted increasing attention, due to its spread towards temperate zones of the northern and southern hemisphere. A number of advantageous functional traits and a high intraspecific plasticity have been suggested to explain its invasion success. 2. The aim of this study was to examine intraspecific functional trait variability in 12 different isolates of C.raciborskii originating from different lakes in an invaded region in Northeast Germany. We measured growth rate, C:N:P ratios, chlorophyll-a content and the abundance of heterocysts under nutrient-replete and phosphorus-limited conditions. Moreover, the isolate-specific morphology and grazing losses by an herbivorous rotifer, as a top-down force, were studied. 3. DNA fingerprinting revealed that all isolates were genetically different. C.raciborskii exhibited a large variability in all measured traits among isolates. The C:P, N:P and Chl-a:C ratios differed by a factor of two or more. The trait variability among isolates was higher under nutrient-replete conditions, except for the C:P ratio, which varied most during phosphorus limitation. The susceptibility to grazing, calculated as maximum ingestion rates of the rotifer Brachionus calyciflorus on C.raciborskii, varied most among isolates, but was not related to any of the measured physiological or morphological traits, i.e. no trade-off was found. 4. Ecological and genetic clustering did not match, indicating that the genetic relationship based on DNA fingerprinting did not cover ecological differences. 5. Our results show a high trait variability within locally occurring and partly co-occurring C.raciborskii isolates. No overall trade-offs between the measured functional traits were found. This demonstrates the ecological relevance of linking multiple traits, e.g. competitive and consumptive. Furthermore, this study emphasises the importance of analysing more than one strain of a species, as different strains show different trait values potentially relevant for their invasibility and the field of general trait-based ecology.},
  language  = {en}
}
@article{SpijkermanStojkovicHollandetal.2016,
  author    = {Spijkerman, Elly and Stojkovic, Slobodanka and Holland, Daryl and Lachmann, Sabrina C. and Beardall, John},
  title     = {Nutrient induced fluorescence transients (NIFTs) provide a rapid measure of P and C (co-)limitation in a green alga},
  series = {European journal of phycology},
  volume    = {51},
  journal   = {European journal of phycology},
  publisher = {Hindawi},
  address   = {Abingdon},
  issn      = {0967-0262},
  doi       = {10.1080/09670262.2015.1095355},
  pages     = {47 -- 58},
  year      = {2016},
  abstract  = {Nutrient Induced Fluorescence Transients (NIFTs) have been shown to be a possible way of testing for the limiting nutrient in algal populations. In this study we tested the hypothesis that NIFTs can be used to detect a (co-)limitation for inorganic phosphorus (Pi) and CO2 in the green alga Chlamydomonas acidophila and that the magnitude of the NIFTs can be related to cellular P:C ratios. We show a co-limitation response for Pi and CO2 via traditional nutrient enrichment experiments in natural phytoplankton populations dominated by C. acidophila. We measured NIFT responses after a Pi- or a CO2-spike in C. acidophila batch cultures at various stages of Pi and inorganic C limitation. Significant NIFTs were observed in response to spikes in both nutrients. The NIFT response to a Pi-spike showed a strong negative correlation with cellular P:C ratio that was pronounced below 3 mmol P: mol C (equivalent to 0.2 pg P cell(-1)). Both cellular P and C content influenced the extent of the Pi-NIFT response. The NIFT response to a CO2-spike correlated to low CO2 culturing conditions and also had a negative correlation with cellular P content. A secondary response within the Pi-NIFT response was related to the CO2 concentration and potentially reflected co-limitation. In conclusion, NIFTs provided a quick and reliable method to detect the growth-limiting nutrient in an extremophile green alga, under Pi-, CO2- and Pi/CO2 (co-)limited growth conditions.},
  language  = {en}
}