Trajectories of aquatic insect functional groups along the
resistance/resilience axis when facing water flow changes
Abstract
1. Understanding how differences in intensity and frequency of
hydrological disturbances affect the resistance and resilience of
aquatic organisms is key to manage aquatic systems in a fast-changing
world. Organisms’ responses to environmental changes can be influenced
by different life strategies. Some aquatic organisms have strategies
that improve the permanence in aquatic systems, while others use
strategies that enhance colonization. 2. Therefore, we carried out a
manipulative experiment to understand the resistance/resilience of
aquatic insects based on their functional characteristics to
hydrological disturbances in streams in the Cerrado hotspot. 3. We
placed 200 artificial substrates in five streams and submitted them to
changing water flow regimes that differed both in frequency and
intensity. Then we observed the response of the aquatic community for 39
days. We used a Hierarchical Bayesian strategy approach to estimate the
probabilities of permanence and colonization of each life strategy group
(nine groups). 4. We observe that the most intense changes in the water
flow tend to affect the permanence of almost all groups. However, this
effect was reduced in intensity over time. On the other hand, less
frequent disturbances, regardless of intensity, tend to reduce the
permanence of most groups of aquatic insects over time. The difference
in the effect of disturbance regarding intensity (higher or lower) may
be related to a greater dispersal capacity of some groups. 5. These
results are worrisome in a scenario of reduced riparian vegetation
around streams and with the expectation of precipitation to become more
concentrated in shorter periods of time due to climate change in the
Cerrado hotspot. Together, these anthropogenic changes tend to increase
the effect of runoff on the lotic systems and, consequently, reduces the
permanence of many groups of aquatic insects in their habitat,
particularly those with traits associated with permanence.