Land use temporarily affects active pond-community structure but not
gene expression patterns
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 communities across the three domains of life,
Bacteria, Archaea, and eukaryotes, to land use. 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 eDNA study which revealed 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 in eukaryotes than in bacteria. In
contrast, gene expression patterns did not differ between months or
across land-use type, suggesting a high degree of functional redundancy
across the KH communities. Variability in gene expression was best
explained by active community structure, suggesting that these changes
in functioning are primarily driven by interactions between organisms.
Our results show 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 needs to be considered when
developing sustainable management options for restoration purposes and
for successful mitigation of further biodiversity loss in agricultural
landscapes.