@article{QuintanaArimBadosaetal.2015,
  author    = {Quintana, Xavier D. and Arim, Matias and Badosa, Anna and Maria Blanco, Jose and Boix, Dani and Brucet, Sandra and Compte, Jordi and Egozcue, Juan J. and de Eyto, Elvira and Gaedke, Ursula and Gascon, Stephanie and Gil de Sola, Luis and Irvine, Kenneth and Jeppesen, Erik and Lauridsen, Torben L. and Lopez-Flores, Rocio and Mehner, Thomas and Romo, Susana and Sondergaard, Martin},
  title     = {Predation and competition effects on the size diversity of aquatic communities},
  series = {Aquatic sciences : research across boundaries},
  volume    = {77},
  journal   = {Aquatic sciences : research across boundaries},
  number    = {1},
  publisher = {Springer},
  address   = {Basel},
  issn      = {1015-1621},
  doi       = {10.1007/s00027-014-0368-1},
  pages     = {45 -- 57},
  year      = {2015},
  abstract  = {Body size has been widely recognised as a key factor determining community structure in ecosystems. We analysed size diversity patterns of phytoplankton, zooplankton and fish assemblages in 13 data sets from freshwater and marine sites with the aim to assess whether there is a general trend in the effect of predation and resource competition on body size distribution across a wide range of aquatic ecosystems. We used size diversity as a measure of the shape of size distribution. Size diversity was computed based on the Shannon-Wiener diversity expression, adapted to a continuous variable, i.e. as body size. Our results show that greater predation pressure was associated with reduced size diversity of prey at all trophic levels. In contrast, competition effects depended on the trophic level considered. At upper trophic levels (zooplankton and fish), size distributions were more diverse when potential resource availability was low, suggesting that competitive interactions for resources promote diversification of aquatic communities by size. This pattern was not found for phytoplankton size distributions where size diversity mostly increased with low zooplankton grazing and increasing nutrient availability. Relationships we found were weak, indicating that predation and competition are not the only determinants of size distribution. Our results suggest that predation pressure leads to accumulation of organisms in the less predated sizes, while resource competition tends to favour a wider size distribution.},
  language  = {en}
}
@article{MehnerLischkeScharnweberetal.2018,
  author    = {Mehner, Thomas and Lischke, Betty and Scharnweber, Inga Kristin and Attermeyer, Katrin and Brothers, Soren and Gaedke, Ursula and Hilt, Sabine and Brucet, Sandra},
  title     = {Empirical correspondence between trophic transfer efficiency in freshwater food webs and the slope of their size spectra},
  series = {Ecology : a publication of the Ecological Society of America},
  volume    = {99},
  journal   = {Ecology : a publication of the Ecological Society of America},
  number    = {6},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0012-9658},
  doi       = {10.1002/ecy.2347},
  pages     = {1463 -- 1472},
  year      = {2018},
  abstract  = {The density of organisms declines with size, because larger organisms need more energy than smaller ones and energetic losses occur when larger organisms feed on smaller ones. A potential expression of density-size distributions are Normalized Biomass Size Spectra (NBSS), which plot the logarithm of biomass independent of taxonomy within bins of logarithmic organismal size, divided by the bin width. Theoretically, the NBSS slope of multi-trophic communities is exactly - 1.0 if the trophic transfer efficiency (TTE, ratio of production rates between adjacent trophic levels) is 10\% and the predator-prey mass ratio (PPMR) is fixed at 10(4). Here we provide evidence from four multi-trophic lake food webs that empirically estimated TTEs correspond to empirically estimated slopes of the respective community NBSS. Each of the NBSS considered pelagic and benthic organisms spanning size ranges from bacteria to fish, all sampled over three seasons in 1 yr. The four NBSS slopes were significantly steeper than -1.0 (range -1.14 to -1.19, with 95\% CIs excluding -1). The corresponding average TTEs were substantially lower than 10\% in each of the four food webs (range 1.0\% to 3.6\%, mean 1.85\%). The overall slope merging all biomass-size data pairs from the four systems (-1.17) was almost identical to the slope predicted from the arithmetic mean TTE of the four food webs (-1.18) assuming a constant PPMR of 10(4). Accordingly, our empirical data confirm the theoretically predicted quantitative relationship between TTE and the slope of the biomass-size distribution. Furthermore, we show that benthic and pelagic organisms can be merged into a community NBSS, but future studies have yet to explore potential differences in habitat-specific TTEs and PPMRs. We suggest that community NBSS may provide valuable information on the structure of food webs and their energetic pathways, and can result in improved accuracy of TTE-estimates.},
  language  = {en}
}