Photoinhibition and the assembly of light‐limited phytoplankton communities

Abstract

Photoinhibition is characterised by a decreasing rate of photosynthesis with increasing light. It occurs in many photosynthetic organisms and is especially apparent in phytoplankton species sensitive to high light. Yet, the population and community level consequences of photoinhibition are not well understood. Here, we present a resource competition model that includes photoinhibition. The model shows that, in strong light, photoinhibition leads to an increase of the specific growth rate with increasing population density due to self‐shading. This so‐called Allee effect can be either weak or strong. In monoculture, a strong Allee effect results in two alternative stable states. A low population density does not provide sufficient shade to protect itself against photoinhibition, such that the population goes extinct. Conversely, above a threshold population density the population may create sufficiently turbid conditions to suppress photoinhibition, so that the population can establish itself. When several species compete for light, a species which cannot establish itself due to photoinhibition can be facilitated by other species less sensitive to photoinhibition. If such facilitators are absent, photoinhibition may cause alternative stable states in community composition. Since each alternative stable state is dominated by a single species, photoinhibition does not favour species coexistence. The model predictions are consistent with published competition experiments, and illustrate the complex effects of photoinhibition on community assembly.

The relationships of meteorological factors and nutrient levels with phytoplankton biomass in a shallow eutrophic lake dominated by cyanobacteria, Lake Dianchi from 1991 to 2013

“…Our previous in situ study conducted from March to April (dry season) revealed the presence of photoinhibition in Lake Dianchi (Zhou et al 2015b). In the present study, low phytoplankton biomass was detected during the SHs of the dry season (with a relative increase in SHs and a lower bloom biomass compared to the rainy season), which might have resulted from less self-shading and more photoinhibition (Gerla et al 2011).…”

“…These results indicated that the SHs were sufficient for phytoplankton growth in the low-latitude plateau region of Lake Dianchi, which features a relatively high level of solar radiation and a predominance of cyanobacteria with gas vesicles ). An exceedingly high light intensity induces algal photoinhibition, and a low population density does not allow for sufficient self-shading for protection (Gerla et al 2011). Our previous in situ study conducted from March to April (dry season) revealed the presence of photoinhibition in Lake Dianchi (Zhou et al 2015b).…”

Effect of volcanic eruption on nutrients, light, and phytoplankton in oligotrophic lakes

“…Thus, eruptions present unique opportunities for scientific discovery though such studies are often hindered by a lack of pre-eruption and post-eruption data that allow comprehensive assessment of their effects and the mechanisms of those outcomes (Lindenmayer et al 2010;Larson 2011). Past studies of the effect of eruptions on aquatic ecosystems have emphasized fertilization by ash-borne elements such as phosphorus and iron (Hamme et al 2010;Lin et al 2011). Studies in marine environments have shown that, after volcanic eruptions, the concentrations of chlorophyll, as a proxy of phytoplankton biomass, increase (Hamme et al 2010;Lin et al 2011).…”

“…Past studies of the effect of eruptions on aquatic ecosystems have emphasized fertilization by ash-borne elements such as phosphorus and iron (Hamme et al 2010;Lin et al 2011). Studies in marine environments have shown that, after volcanic eruptions, the concentrations of chlorophyll, as a proxy of phytoplankton biomass, increase (Hamme et al 2010;Lin et al 2011). Paleolimnological evidence from a lake in Iceland also shows that, after a volcanic eruption that deposited considerable amounts of tephra, there was an increase in chlorophyll-derived pigments in sediments, indicating an increase in phytoplankton biomass following volcanic ash deposition (Einarsson et al 1993).…”

Competition for Light and Nutrients in Layered Communities of Aquatic Plants

“…In a two-species community such as ours, the species stably coexist when each species can invade (1) an equilibrium density of the other (11), and the species are alternative stable states when neither can invade (2) an equilibrium density of the other (2 2), while (1 2) or (2 1) leads to competitive exclusion of the species that cannot invade (e.g., Gerla et al 2011). In the case of alternative stable states, the species that establishes first outcompetes the other.…”