Seasonality of algal communities in small streams and ditches in temperate regions using delayed fluorescence

Abstract

Because of their high ecological relevance, algae are often used in environmental monitoring of freshwater ecosystems. They are used to assess the state of the environment, and can be used to estimate the diversity and productivity of the ecosystem. Chlorophyll a is the most commonly used indicator where no taxonomic information is obtained. In this two-year study, algae were monitored in small lotic waterbodies using a high precision method of evaluating algal pigments: delayed fluorescence (DF). The method allows quantifying algae and differentiating algal groups using pigments unique to each algal group. DF correlated strongly with biovolume (derived from cell count) data (r 2 D 0.94) and could therefore be recommended as a biomonitoring tool. In addition, seasonal dynamics in both the attached and suspended algal communities were studied. Both algal fractions displayed seasonal variations with either a single peak in biomass in summer (type 1), or with two peaks in biomass in spring and fall (type 2). Green algae dominated type 1 patterned communities whereas diatoms dominated type 2 patterned communities. Spatial synchronicity between sampling sites and waterbodies was observed within the studied watershed. Sampling time rather than spatial site selection was found to be a key factor in the study of algal communities in lotic bodies of water.

Environmental and structural factors influencing algal communities in small streams and ditches in central Germany

“…The sampling sites were in three streams, Klein (K1, K2, K3), Haverbach (H) and Rulfbach (R1, R2), and two ditches, Ditch A (A1, A2) and Ditch B (B1, B2; Figure 1). A detailed description of the waterbodies is provided by Breuer et al (2016). No lentic waterbodies were connected to the investigated streams and ditches.…”

Unexpected shift from phytoplankton to periphyton in eutrophic streams due to wastewater influx

“…Although irradiance regimes affect both suspended and attached phototrophs in flowing waters (Munn et al 1989; Hutchins et al 2010), effects of photon flux vary seasonally with discharge and turbidity (Biggs 1995; Leland 2003), canopy cover (Rosemond et al 2000), nutrient content (Glibert et al 2016), and temperature (Baker and Baker 1979; Munn et al 2002; Wu et al 2011). Such seasonal changes also drive patterns of benthic and suspended community development (Andrus et al 2015), with enhanced production of diatoms in spring and fall and elevated densities of chlorophytes and cyanobacteria in summer (Breuer et al 2016; Moorhouse et al 2018). Overall, the degree to which natural phototrophic phenology interacts with effluent influx is poorly understood (del Giorgio et al 1991; Stevenson and White 1995; Solomon et al 2019), particularly for streams in nonboreal systems such as agricultural grasslands (Dodds et al 2004; Breuer et al 2017).…”

“…Phototrophic communities were quantified using taxonomically diagnostic pigment biomarkers (chlorophylls [Chl], carotenoids) to measure: (1) how regional variation in physico‐chemical conditions affected development of phototrophic biomass and community composition; (2) how modern effluent affected phytoplankton and periphyton; and (3) whether urban effluent had a differential effect on suspended or attached communities. We hypothesized that: (1) landscape patterns of abundance, composition and interaction of phytoplankton and periphyton would reflect spatial and temporal variation in regulation by physico‐chemical parameters (discharge, irradiance, temperature) in these eutrophic streams (Breuer et al 2016, 2017; Moorhouse et al 2018); (2) effluent influx would overwhelm natural landscape controls (discharge, irradiance, temperature) of periphyton (Murdock et al 2004; Hamdhani et al 2020) and phytoplankton development (del Giorgio et al 1991; Stevenson and White 1995; Solomon et al 2019); (3) modern urban effluent would favor phytoplankton over periphyton due to both changes in nutrient (Chambers et al 2012; Dodds and Smith 2017) and irradiance regimes (Munn et al 1989; Rosemond et al 2000); and (4) NO 3 − from effluent would favor siliceous algae and chlorophytes over cyanobacteria downstream of wastewater treatment plant outfall (Glibert et al 2016; Swarbrick et al 2019).…”

Substratum‐Associated Microbiota

“…Delayed fluorescence excitation spectroscopy, a high precision method of measuring photosynthetically active pigments (the composition of which differ in different algal groups) via excitation of algal cells by monochromatic light, correlated strongly with algal biovolume and composition from cell count data and may be used in monitoring of algal biomass (Breuer et al, 2016). A test of the fluormetric probe, BenthoTorch, to rapidly assess toxinproducing algal assemblages like Phormidium, found that chlorophyll a measurements correlated well with thin mats (< 2 mm) and mats < 50% cyanobacteria by biomass, but not more, which may be due to underestimation of phycoerythrin and limitations of the probe to measure the upper layers of biofilms (Echenique-Subiabre et al, 2016).…”