Non-native species affect the long-term dynamics of native stream fish
assemblages
- Istvan Czegledi,
- Péter Takács,
- Kai Feng,
- Tibor Eros
Péter Takács
HUN-REN Balaton Limnological Research Institute
Author ProfileTibor Eros
HUN-REN Balaton Limnological Research Institute
Author ProfileAbstract
Characterizing the temporal changes of biotic communities and
disentangling the importance of their driving mechanisms are central
themes in ecology and environmental management. Non-native species have
multiple adverse impact on native communities and species. However,
there is a dearth of information on how non-natives influence the
long-term dynamics of native communities. In this study, we compared the
role of non-native species alongside various local and regional factors
in the long-term dynamics of stream fish assemblages in the catchment
area of Lake Balaton, Hungary, the largest lake in Central-Europe.
Although, we found no consistent trend in species re-ordering between
native and non-native species, native fish assemblages indicated
significantly lower temporal stability with increasing relative
abundance of co-occurring non-natives. Structural equation modelling
revealed that assemblage dynamic patterns were also determined by a
habitat degradation gradient. Moreover, habitat degradation and the
presence of fishponds increased the relative abundance of non-native
species, further affecting native assemblages through indirect
interactions. Fish assemblage dynamics showed also some degree of
finer-scale spatial structure. Non-metric multidimensional scaling
further reinforced the destabilizing effect of non-native species but
highlighted that native fish assemblages could generally be described by
non-directional gradual or saltatory changes over time, regardless of
the relative abundance of non-natives. Our results thus revealed that
the studied native fish assemblages may possess some degree of
resilience against biological invasions. However, increasing temporal
variability induced by non-natives makes native assemblages more
vulnerable to environmental stochasticity threatening their long-term
persistence. This is especially worrying, since the frequency and
intensity of environmental disturbances are expected to rise in the
future due to climate change and increasing anthropogenic pressure on
aquatic ecosystems.