Connectivity and seasonality cause rapid taxonomic and functional trait succession within an invertebrate community after stream restoration

Abstract

General colonization concepts consent that a slow process of microhabitat formation and subsequent niche realization occurs during early stages after new habitat is released. Subsequently, only few species are able to colonize new habitat in the early onset of succession, while species richness increases steadily over time. Although most colonization studies have been performed in terrestrial ecosystems, running water ecosystems are equally or even more prone to colonization after disturbance due to their dynamic nature. We question how invertebrate succession patterns reconcile with general colonization concepts. With this study we provide insight into the colonization process in newly created lowland stream trajectories and answer how within-stream bio- and functional diversity develops over time. Our results show a rapid influx of species, with a wide range of functional traits, during the first season after water flow commenced. During more than two years of regular monitoring, immigration rates were highest in autumn, marking the effects of seasonality on invertebrate dispersal. Biodiversity increased while abundance peaks of species alternated between seasons. Moreover, also days since start of the experiment explains a considerable part of the variability for taxa as well as traits. However, the relative trait composition remained similar throughout the entire monitoring period and only few specific traits had significantly higher proportions during specific seasons. This indicates that first phase colonization in freshwater streams can be a very rapid process that results in a high biodiversity and a large variety of species functional characteristics from the early onset of succession, contradicting general terrestrial colonization theory.

Lowland stream restoration by sand addition: Impact, recovery, and beneficial effects on benthic invertebrates

“…Nonetheless, the adverse effects of the sand addition were followed by a rapid recovery in terms of richness, diversity, and representation of Ephemeroptera, Plecoptera, and Trichoptera taxa and an increase in the number of rheophilic taxa. This fast colonization is in line with observations of Westveer et al (), who studied the colonization of reconnected former channels in the same stream in autumn. In the recovered plots, the increased habitat heterogeneity appeared to have provided suitable habitat and flow conditions for the arriving colonists (Astudillo, Novelo‐Gutiérrez, Vázquez, García‐Franco, & Ramírez, ; Eros & Campbell Grant, ; Matthaei, Weller, Kelly, & Townsend, ; Muehlbauer, Collins, Doyle, & Tockner, ; Rolls et al, ), which might have opened a “window of opportunities” ( sensu Balke, Herman, & Bouma, ) for the rheophilic species present in the catchment.…”

“…Although our study only recorded the short‐term effects of sand addition, eventually, all downstream impacted plots were expected to recover in a similar way as we observed in the plot closest to the initial sand addition. Additionally, we observed that taxa present in the unimpacted parts of the catchment colonized the stabilized stretches, indicating that within this catchment, dispersal limitation does not hamper recovery, as often observed in restoration projects (Sarremejane, Mykrä, Bonada, Aroviita, & Muotka, ; Sundermann & Stoll, ; Westveer et al, ). Such a fast biotic recovery suggests a high resilience of lowland stream ecosystems, an important condition to make restoration projects successful (Palmer et al, ).…”

“…The rheophilic taxa richness was derived using the flow preference classification from the autecological database for freshwater organisms, Version 7.0 (Schmidt‐Kloiber & Hering, ). The size of the autumn species pool for this specific catchment was obtained from Westveer, van der Geest, Emiel van Loon, and Verdonschot (). Based on this information, the proportion of the number of rheophilic taxa present in the plots was calculated.…”

Kennisdocument : het belang van dispersie en connectiviteit voor macroinvertebraten en planten

“…In beken is de kans het grootst dat macroinvertebratensoorten die al in het stroomgebied aanwezig zijn, trajecten die door het nemen van maatregelen geschikt geworden zijn als leefgebied op korte termijn koloniseren. Zijdelingse of laterale dispersie is veel meer beperkt ten opzichte van de verplaatsingen binnen een stroomgebied (Westveer 2018) en gaat vaak over tientallen tot honderden meters. Sundermann et al (2011) concludeerden dat de afstand waarbinnen nog regelmatige dispersie van beek naar beek plaatsvindt circa 5 km is.…”

Factsheet KIWK : Droogte

“…De terrestrische imago's van veel waterinsecten zijn relatief slechte vliegers en hebben een beperkt dispersievermogen (Sundermann et al, 2011). De ligging van het te koloniseren water ten opzichte van wateren met potentiële bronpopulaties en het seizoen zijn belangrijke factoren die de kolonisatiesnelheid bepalen (Westveer et al, 2018): hoe dichterbij, hoe gunstiger. Het omliggende landschap en dan met name de aanwezige begroeiing speelt een belangrijke rol bij het faciliteren van dispersie; voor beken geldt bijvoorbeeld dat natte bossen erg geschikt zijn voor beekinsecten om zich dwars op de beek te verplaatsen en zo andere wateren te bereiken (Collier & Smith, 1998).…”