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Responses of benthic algal communities and their traits to experimental changes in fine sediments, nutrients and flow

Published on Sep 1, 2017in Freshwater Biology3.40
· DOI :10.1111/fwb.12965
Érika M. Neif3
Estimated H-index: 3
(UEM: Universidade Estadual de Maringá),
Daniel Graeber14
Estimated H-index: 14
(AU: Aarhus University)
+ 6 AuthorsAnnette Baattrup-Pedersen20
Estimated H-index: 20
(AU: Aarhus University)
Abstract
Summary Lowland stream ecosystems are subjected to multiple anthropogenic stressors, usually nutrient enrichment in combination with sedimentation of fine particles and low flow periods in summer. Here, we investigated the temporal development of the benthic algae community in response to these three stressors and linkages to the trait characteristics of the community to explore the mechanisms responsible for stress-induced community changes. We investigated the response of benthic algae species composition, traits (life forms, cell size categories), biovolume and chlorophyll a (Chl-a) concentration to low flow in combination with nutrient enrichment and fine sedimentation in twelve large outdoor stream flumes (12 m long) resembling small streams in size and habitat characteristics. The experiment consisted of two phases: a normal-flow phase followed by a low-flow phase (90% current velocity reduction), each spanning 4 weeks. We applied a eutrophication scenario (mean increases of 1.14–5.48 mg N/L and 0.01–0.06 mg P/L in the flumes for dissolved inorganic nitrogen and phosphate respectively) throughout the experiment. Under low flow, we supplemented this with a fine sedimentation scenario (>90% stream bed cover). We took samples once in the normal-flow phase and every week during the low-flow phase. We observed strong responses in the benthic algae community to sudden changes in low flow and fine sedimentation, mediating rapid species turnover with a decreased algal biovolume and increased abundance of large, motile species. However, we did not observe any pronounced responses to nutrient enrichment. In contrast to the observations for other variables, we found a continuous increase in Chl-a concentration during low flow. This was likely due to continuous fine sedimentation during this phase, reducing light availability which probably resulted in an increase of cell-level Chl-a concentration in response to light limitation and lower rates of light-induced Chl-a degradation. The rapid response of the benthic algal community to the applied stressors suggests that even short periods of major stressor exposure may significantly affect benthic algae in lowland systems. We suggest that short-term stress events may have cascading effects on several important ecosystem processes given the importance of benthic algae for the productivity of these systems.
  • References (50)
  • Citations (3)
References50
Newest
#1Emma Göthe (AU: Aarhus University)H-Index: 10
#2Annette Baattrup-Pedersen (AU: Aarhus University)H-Index: 20
Last.Nikolai Friberg (AU: Aarhus University)H-Index: 32
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#1Peter S. Levi (UW: University of Wisconsin-Madison)H-Index: 1
#2Tenna Riis (AU: Aarhus University)H-Index: 26
Last.Annette Baattrup-Pedersen (AU: Aarhus University)H-Index: 20
view all 7 authors...
#1Jeremy J. Piggott (University of Otago)H-Index: 13
#2Colin R. Townsend (University of Otago)H-Index: 65
Last.Christoph D. Matthaei (University of Otago)H-Index: 27
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#1Daniel Graeber (AU: Aarhus University)H-Index: 14
#2G. Goyenola (AU: Aarhus University)H-Index: 1
Last.Erik Jeppesen (AU: Aarhus University)H-Index: 85
view all 11 authors...
#1Daniel Hering (University of Duisburg-Essen)H-Index: 43
#2Laurence Carvalho (NERC: Natural Environment Research Council)H-Index: 35
Last.Jenica Hanganu (Delta Air Lines)H-Index: 8
view all 20 authors...
#1Daniel Graeber (AU: Aarhus University)H-Index: 14
#2Martin T. Pusch (Leibniz Association)H-Index: 29
Last.Mario Brauns (Helmholtz Centre for Environmental Research - UFZ)H-Index: 12
view all 4 authors...
Cited By3
Newest
#1Brianna Levenstein (UNB: University of New Brunswick)
#2Joseph M. Culp (WLU: Wilfrid Laurier University)
Last.Jennifer Lento (UNB: University of New Brunswick)H-Index: 5
view all 3 authors...
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