TY  - JOUR
A1  - Weithoff, Guntram
A1  - Taube, Anne
A1  - Bolius, Sarah
T1  - The invasion success of the cyanobacterium Cylindrospermopsis raciborskii in experimental mesocosms
BT  - genetic identity, grazing loss, competition and biotic resistance
JF  - Aquatic Invasions
N2  - The potentially toxic, invasive cyanobacterium Cylindrospermopsis raciborskii, originating from sub-tropical regions, has spread into temperate climate zones in almost all continents. Potential factors in its success are temperature, light and nutrient levels. Grazing losses through zooplankton have been measured in the laboratory but are typically not regarded as a factor in (failed) invasion success. In some potentially suitable lakes, C. raciborskii has never been found, although it is present in water bodies close by. Therefore, we tested the invasive potential of three different isolates introduced into natural plankton communities using laboratory mesocosm experiments under three grazing levels: ambient zooplankton densities, removal of large species using 100 mu m mesh and a ca. doubling of large species. Three C. raciborskii isolates originating from the same geographic region (North-East Germany) were added separately to the four replicates of each treatment and kept in semi-continuous cultures for 21 days. Two isolates disappeared from the mesocosms and were also not viable in filtered lake water indicating that the lake water itself or the switch from culture medium to lake water led to the decay of the inoculated C. raciborskii. Only one out of the three isolates persisted in the plankton communities at a rather low level and only in the treatment without larger zooplankton. This result demonstrates that under potentially suitable environmental conditions, top-down control from zooplankton might hamper the establishment of C. raciborskii. Non-metric multidimensional scaling showed distinct variation in resident phytoplankton communities between the different grazing levels, thus differential grazing impact shaped the resident community in different ways allowing C. raciborskii only to invade under competitive (= low grazing pressure) conditions. Furthermore, even after invasion failure, the temporary presence of C. raciborskii influenced the phytoplankton community.
KW  - alien species
KW  - Cyanobacteria
KW  - competitive resistance
KW  - consumptive resistance
KW  - herbivory
KW  - harmful algae
KW  - microbial invasion
Y1  - 2017
U6  - https://doi.org/10.3391/ai.2017.12.3.07
SN  - 1798-6540
SN  - 1818-5487
VL  - 12
SP  - 333
EP  - 341
PB  - Regional Euro-Asian Biological Invasions centre-reabic
CY  - Helsinki
ER  -