Plasticity and acclimation to light reflected in temporal and spatial changes of small-scale macroalgal distribution in a stream

Abstract

The small-scale distribution pattern of macroalgae in the river Ilm, in Germany was monitored. These patterns were then related to abiotic factors and tested to discover whether the distribution of the common macroalgae, Cladophora glomerata (L.) Kütz. and Vaucheria sp., was linked to differences in their photosynthetic plasticity. Cladophora glomerata revealed higher maximum photosynthetic electron transport rates after acclimation to high light (HL) compared with low light (LL) acclimated samples. By contrast, Vaucheria sp. did not acclimate to different growth light conditions. The photosynthetic performance of both algae also varied according to diurnal conditions. High light caused a reversible decrease of the dark-adapted quantum yield (F(v)/F(m)) in C. glomerata and a concomitant reversible decrease of the light-adapted quantum yield (DeltaF/F'(m)). In Vaucheria sp., F(v)/F(m) remained mostly unchanged over the day, whereas DeltaF/F'(m) decreased during the morning at low light. Photosynthetic pigments confirmed acclimational differences between the species. HL C. glomerata showed increased chlorophyll a:chlorophyll b ratios, and higher amounts of xanthophyll-cycle pigments compared with LL samples, whereas Vaucheria sp. did not reveal differences between the light treatments. While preferences for substrate size, water velocity, and depth are similar for C. glomerata and Vaucheria sp., the physiological responses to light conditions are different. It is concluded that light conditions significantly affect the small-scale spatial distribution of macroalgae and that fitness is enhanced in species with a higher plasticity in photosynthetic acclimation in unstable environments.

Chlorophyll fluorescence in micropropagated Rhododendron ponticum subsp. baeticum plants in response to different irradiances

“…Although a decrease in α at HL as a result of an imbalance between light absorbed by light-harvesting systems and the energy consumed by Calvin-cycle reactions is generally expected, it is not uncommon that photoacclimation comes for changes in ETR max not accompanied of relevant variation in α. Ensminger et al (2005) attributed these discrepancies to real differences or to methodologies used to assess acclimation. In this study, acclimation changes in α might not be detectable with the chlorophyll fluorescence technique used, since alternative electron sinks are able to maintain an electron flow from PS 2, which may contribute to photoprotection of PS 2.…”

The Genus Cladophora Kützing (Ulvophyceae) as a Globally Distributed Ecological Engineer

“…Over 5°C-20°C, the minimum irradiance needed for positive net photosynthesis of L. Huron C. glomerata was about 30 lmol photons Á m À2 Á s À1 , although biomass did not accumulate unless daytime photosynthetic rates were greater than nighttime respiration rates (Graham et al 1985). Cladophora glomerata in the river Ilm, Germany rapidly acclimated to changes in irradiance (Ensminger et al 2000a(Ensminger et al , 2005. Cladophora exposed to high irradiance displayed decreased quantum yield of PS II (assessed by chl a fluorescence), increased chl a: chl b ratios, and higher amounts of xanthophyll-cycle pigments than in lower irradiances.…”

AN ECOLOGICAL REVIEW OFCLADOPHORA GLOMERATA(CHLOROPHYTA) IN THE LAURENTIAN GREAT LAKES1

“…While low ambient light intensities control the depth distribution of Cladophora , and may be an important factor in controlling seasonal sloughing, high light intensities have been demonstrated to induce photoinhibition and light‐enhanced photorespiration in some studies (e.g., Graham et al. 1982, Ensminger et al. 2005), although not in others (e.g., Lester et al.…”