Periphyton biomass and life-form responses to a gradient of discharge in contrasting light and nutrients scenarios in experimental lowland streams

Flow pulses shape periphyton differently according to local light and nutrient conditions in experimental lowland streams

“…However, the comparison between the shaded treatments with and without the addition of nutrients revealed no significant differences, indicating that factors other than nutrients limited the biomass values at low baseflow. Grazers usually have a strong impact on periphyton biomass (Hillebrand, 2009;Moulton et al, 2015;Rosemond et al, 2000), but in our study no clear macroinvertebrate effect on periphyton biomass was observed during the colonisation phase (Pacheco et al, 2022), probably because macroinvertebrates were not fully established in the flumes and thus presented extremely low abundances. We further found that at low basal flow and under unlimited access to light and nutrients conditions, the short-term flow pulse enhanced periphyton growth.…”

“…with a potentially strong qualitative effect on the community composition (diatom-dominated vs. green algae-dominated)(Bondar-Kunze et al, 2016). As demonstrated here, previous studies manipulating nutrients and light simultaneously also found stronger community composition effects of nutrient availability than of light(McCall et al, 2017).The gradient of baseflows, typical of lowland streams(Graeber et al, 2017;Neif et al, 2017), and the different conditions of nutrient and light availability, led to the development of different periphyton communities during the colonisation phase (as described inPacheco et al, 2022). Periphyton groups have different life forms that entail different attachment abilities(Baattrup-Pedersen et al, 2020; …”

“…After a month with the pre-set baseflows, we started the prepulse colonisation phase. On 1 July, we randomly assigned the NDS Pacheco et al, 2022). Then, the flumes containing the remaining substrata were exposed to an abrupt increase in the discharge, as a potential disturbance, for one day (two-fold peak during 24 hr, range 1.01-4.50 L/s), and then a reduction in discharge on the subsequent two days (1.5-fold during 48 hr) and on Day 4 a further reduction until the initial baseflow values were resumed (Figure 2).…”

“…Periphyton is a key food resource in stream food webs and a contributor to primary production and nutrient cycling, and it thus generally plays an important role in ecosystem functioning (Allan & Castillo, 2007; Larned, 2010). Besides, as a result of its rapid response to environmental changes, stream periphyton can serve as a bioindicator of water quality (Beck et al., 2019; Pacheco et al., 2022; Stevenson, 2014). The intensity and frequency of extreme short‐term streamflow disturbances play an important role in shaping periphyton biomass and composition (Guo et al., 2020; Peterson & Stevenson, 1992), with quite different effects in different types of streams (Biggs et al., 1999).…”

Synthetic periphyton as a model system to understand species dynamics in complex microbial freshwater communities

“…This guild includes relatively fast moving species, which allows them to physically avoid stress and to move towards resource-rich microhabitats within the benthic mat [24,[26][27][28]. Green algae and cyanobacteria were added to the periphyton in the last group C, since they are most sensitive to nutrient depletion and light attenuation and might produce unfavorable and harmful toxins to the other added species, respectively [29,30]. An exception was made for C. meneghiniana, which was also included in Group C in addition to group A, as this species is not only low profile but also planktonic and can therefore colonize periphyton at any stage of development.…”