Poster Presentation Freshwater Sciences 2023

Rapidly decomposing litter of invasive Solidago canadensis may alter resource dynamics and affect invertebrate communities of small water bodies (#649)

Marek Svitok 1 2 , Viktória Čabanová 3 , Vladimíra Dekanová 1 , Daša Jaďuďová 1 , Milan Novikmec 1 , Marcela Sedlačková Přidalová 1 , Ivana Svitková 4 , Emília Židišinová 1
  1. Department of Biology and General Ecology, Faculty of Ecology and Environmental Sciences, Technical University in Zvolen, Zvolen, Slovakia
  2. Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
  3. Institute of Virology, Biomedical Research Center Slovak Academy of Sciences, Bratislava, Slovakia
  4. Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovakia

The decomposition of allochthonous plant litter is a fundamental ecosystem process that affects nutrient cycling and the functioning of many freshwaters. The quality and quantity of organic matter supplied to the aquatic environment depends directly on the composition of plant communities in the riparian zone. Riparian habitats in Central Europe are often heavily invaded by alien plant species which leads to substantial changes in native communities. Japanese knotweed (Fallopia japonica) and Canada goldenrod (Solidago canadensis) belong to the most aggressive invaders rapidly spreading in riparian and floodplain areas. We used a series of litter bag experiments conducted in small lentic and lotic water bodies, mesocosms and microcosms to compare the decomposition and its consequences in knotweed, goldenrod and native black alder (Alnus glutinosa).
Leaf litter of Canada goldenrod decomposed significantly faster than the other species in both, standing and running waters. Immediately after entering an aquatic ecosystem, the goldenrod lost more than 30% of its initial weight and almost completely decomposed within a few weeks releasing a lot of nutrients. Mesocosms supplied by the goldenrod litter had significantly more dissolved organic carbon, nitrogen and phosphorus than the experimental units with other litter species. These nutrient-rich conditions attracted ovipositing females of the mosquito Culex pipiens showing elevated numbers of egg clutches and larval densities. However, an opposite effect was observed in the invasive bush mosquito Aedes japonicus japonicus; the goldenrod suppressed its local density. On the other hand, the decomposition of knotweed litter was comparable to the native species. Terrestrial invasions by plants with contrasting litter quality than that of native species may considerably alter the resource dynamics in small waterbodies leading to bottom-up effects on higher trophic levels.
The study was supported by the Slovak Research and Development Agency under contract No. APVV-16-0236 and APVV-19-0134.