@article{BizicIonescuKarnataketal.2022,
  author    = {Bizic, Mina and Ionescu, Danny and Karnatak, Rajat and Musseau, Camille L. and Onandia, Gabriela and Berger, Stella A. and Nejstgaard, Jens C. and Lischeid, Gunnar and Gessner, Mark O. and Wollrab, Sabine and Grossart, Hans-Peter},
  title     = {Land-use type temporarily affects active pond community structure but not gene expression patterns},
  series = {Molecular ecology},
  volume    = {31},
  journal   = {Molecular ecology},
  number    = {6},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0962-1083},
  doi       = {10.1111/mec.16348},
  pages     = {1716 -- 1734},
  year      = {2022},
  abstract  = {Changes in land use and agricultural intensification threaten biodiversity and ecosystem functioning of small water bodies. We studied 67 kettle holes (KH) in an agricultural landscape in northeastern Germany using landscape-scale metatranscriptomics to understand the responses of active bacterial, archaeal and eukaryotic communities to land-use type. These KH are proxies of the millions of small standing water bodies of glacial origin spread across the northern hemisphere. Like other landscapes in Europe, the study area has been used for intensive agriculture since the 1950s. In contrast to a parallel environmental DNA study that suggests the homogenization of biodiversity across KH, conceivably resulting from long-lasting intensive agriculture, land-use type affected the structure of the active KH communities during spring crop fertilization, but not a month later. This effect was more pronounced for eukaryotes than for bacteria. In contrast, gene expression patterns did not differ between months or across land-use types, suggesting a high degree of functional redundancy across the KH communities. Variability in gene expression was best explained by active bacterial and eukaryotic community structures, suggesting that these changes in functioning are primarily driven by interactions between organisms. Our results indicate that influences of the surrounding landscape result in temporary changes in the activity of different community members. Thus, even in KH where biodiversity has been homogenized, communities continue to respond to land management. This potential needs to be considered when developing sustainable management options for restoration purposes and for successful mitigation of further biodiversity loss in agricultural landscapes.},
  language  = {en}
}
@article{IonescuBizicKarnataketal.2022,
  author    = {Ionescu, Danny and Bizic, Mina and Karnatak, Rajat and Musseau, Camille L. and Onandia, Gabriela and Kasada, Minoru and Berger, Stella A. and Nejstgaard, Jens Christian and Ryo, Masahiro and Lischeid, Gunnar and Gessner, Mark O. and Wollrab, Sabine and Grossart, Hans-Peter},
  title     = {From microbes to mammals: Pond biodiversity homogenization across different land-use types in an agricultural landscape},
  series = {Ecological monographs},
  volume    = {92},
  journal   = {Ecological monographs},
  number    = {3},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {0012-9615},
  doi       = {10.1002/ecm.1523},
  pages     = {28},
  year      = {2022},
  abstract  = {Local biodiversity patterns are expected to strongly reflect variation in topography, land use, dispersal boundaries, nutrient supplies, contaminant spread, management practices, and other anthropogenic influences. Contrary to this expectation, studies focusing on specific taxa revealed a biodiversity homogenization effect in areas subjected to long-term intensive industrial agriculture. We investigated whether land use affects biodiversity levels and community composition (alpha- and beta-diversity) in 67 kettle holes (KH) representing small aquatic islands embedded in the patchwork matrix of a largely agricultural landscape comprising grassland, forest, and arable fields. These KH, similar to millions of standing water bodies of glacial origin, spread across northern Europe, Asia, and North America, are physico-chemically diverse and differ in the degree of coupling with their surroundings. We assessed aquatic and sediment biodiversity patterns of eukaryotes, Bacteria, and Archaea in relation to environmental features of the KH, using deep-amplicon-sequencing of environmental DNA (eDNA). First, we asked whether deep sequencing of eDNA provides a representative picture of KH aquatic biodiversity across the Bacteria, Archaea, and eukaryotes. Second, we investigated if and to what extent KH biodiversity is influenced by the surrounding land use. We hypothesized that richness and community composition will greatly differ in KH from agricultural land use compared with KH in grasslands and forests. Our data show that deep eDNA amplicon sequencing is useful for in-depth assessments of cross-domain biodiversity comprising both micro- and macro-organisms, but has limitations with respect to single-taxa conservation studies. Using this broad method, we show that sediment eDNA, integrating several years to decades, depicts the history of agricultural land-use intensification. Aquatic biodiversity was best explained by seasonality, whereas land-use type explained little of the variation. We concluded that, counter to our hypothesis, land use intensification coupled with landscape wide nutrient enrichment (including atmospheric deposition), groundwater connectivity between KH and organismal (active and passive) dispersal in the tight network of ponds, resulted in a biodiversity homogenization in the KH water, leveling off today's detectable differences in KH biodiversity between land-use types. These findings have profound implications for measures and management strategies to combat current biodiversity loss in agricultural landscapes worldwide.},
  language  = {en}
}
@article{VillalbaKarnatakGrossartetal.2022,
  author    = {Villalba, Luis Alberto and Karnatak, Rajat and Grossart, Hans-Peter and Wollrab, Sabine},
  title     = {Flexible habitat choice of pelagic bacteria increases system stability and energy flow through the microbial loop},
  series = {Limnology and oceanography : L \& O},
  volume    = {67},
  journal   = {Limnology and oceanography : L \& O},
  number    = {6},
  publisher = {Wiley-Blackwell},
  address   = {Oxford [u.a.]},
  issn      = {0024-3590},
  doi       = {10.1002/lno.12091},
  pages     = {1402 -- 1415},
  year      = {2022},
  abstract  = {Pelagic bacteria can be classified into free-living and particle-attached life modes, which either dwell in the water column or attach to suspended particles. Bacteria with a generalist life style, however, can actively shift between these two habitats. Globally increasing densities of natural and artificial particles enhance habitat heterogeneity, with potential consequences for system stability and trophic transfer through aquatic food webs. To better decipher the dynamics of microbial communities, we investigated the influence of adaptive vs. fixed habitat choice on species coexistence for a simplified bacterial community by analyzing a corresponding food web model, consisting of two specialist bacterial prey species (free and attached), a generalist bacterial prey species with the ability to shift between both habitats, and two protist predators, specialized on either water or particle compartment. For simplicity we assume a shared resource pool, considering particles only for colonization but not as a source for nutrients or carbon, that is, inert particles like microplastics or inorganic sediments. The model predicts coexistence on a cyclic attractor between fixed and flexible bacteria, if the costs for adaptive habitat choice can be balanced by adaptation speed. The presence of adaptive prey dampens predator-prey cycle amplitudes, contributing to system stabilization resulting in higher mean predator biomass compared to specialist prey only. Thus, in pelagic microbial systems, flexible habitat choice at the prey level has important implications for system stability and magnitude of energy flow through the microbial loop.},
  language  = {en}
}