Disturbance history can increase functional stability in the face of both repeated disturbances of the same type and novel disturbances

Abstract

Climate change is expected to increase the incidences of extremes in environmental conditions. To investigate how repeated disturbances affect microbial ecosystem resistance, natural lake bacterioplankton communities were subjected to repeated temperature disturbances of two intensities (25 °C and 35 °C), and subsequently to an acidification event. We measured functional parameters (bacterial production, abundance, extracellular enzyme activities) and community composition parameters (richness, evenness, niche width) and found that, compared to undisturbed control communities, the 35 °C treatment was strongly affected in all parameters, while the 25 °C treatment did not significantly differ from the control. Interestingly, exposure to multiple temperature disturbances caused gradually increasing stability in the 35 °C treatment in some parameters, while others parameters showed the opposite, indicating that the choice of parameters can strongly affect the outcome of a study. The acidification event did not lead to stronger changes in community structure, but functional resistance of bacterial production towards acidification in the 35 °C treatments increased. This indicates that functional resistance in response to a novel disturbance can be increased by previous exposure to another disturbance, suggesting similarity in stress tolerance mechanisms for both disturbances. These results highlight the need for understanding function-and disturbance-specific responses, since general responses are likely to be unpredictable. Microbial communities perform essential functions in different ecosystems, including decomposition, primary production and nitrogen fixation 1-3. Since natural communities undergo regular disturbances, and the incidences of extremes in environmental conditions are expected to increase as climate change becomes more severe 4 , it is essential to investigate how more frequent pulse disturbances affect the ability of microbial communities to cope with a changing environment in order to maintain essential ecosystem services. The effect of disturbances on the composition and function of communities can be addressed in terms of resistance, recovery and resilience, where resistance is defined as the insensitivity to a disturbance and recovery and resilience (more specifically engineering resilience) as the degree and rate of recovery after a disturbance 5. Previous reviews of the literature have shown that microbial communities are mostly not resistant, instead they often change in composition and function in response to disturbances 5-8. In contrast, recovery and resilience are still rarely studied, so it remains unclear under which circumstances and at which rates compositional recovery occurs in microbial communities 5,8. Changes in community composition following a disturbance may also underlie changes in ecological function, although this relationship is not well understood 9. Often, communities undergo changes in composition without concomitant functional changes being found, which might be related

Rapid changes in coastal ocean microbiomes uncoupled with shifts in environmental variables

“…Furthermore, communities whose composition changes can be functionally redundant, where an altered community composition retains the original functional capacity. In environmental systems, disturbances have been shown to alter microbial diversity, biogeochemical rates and functional capacities (Atlas et al ., 1991; Allison and Martiny, 2008; Renes et al ., 2020). In contrast to host‐associated ecosystems where disturbance often results from a disease state or drug treatment, disturbances in non‐host associated ecosystems, such as soil or aquatic environments, are often complex, frequently altering multiple factors simultaneously (e.g.…”

“…storms, wildfires, co‐occurring contaminants). While disturbances vary in origin and specific impacts, non‐resistant microbiomes generally exhibit reduced diversity (Atlas et al ., 1991; Renes et al ., 2020), increased stochasticity in community assembly (Ferrenberg et al ., 2013; Zhou et al ., 2014), increased physiological tolerance and metabolic versatility (Atlas et al ., 1991), and shifts towards disturbance‐resistant taxa (Westergaard et al ., 2001; Renes et al ., 2020).…”

Frequent pulse disturbances influence resistance and resilience in tropical marine microbial communities

“…A history of repeated disturbances may promote community resilience through these methods, according to earlier studies and evaluations. 1, 2, 43, 44…”

“…A history of repeated disturbances may promote community resilience through these methods, according to earlier studies and evaluations. 1,2,43,44 Figure 4 shows how the most common taxa in the Johor Strait alternately became the most abundant species, but none of them ever dominates the community for an extended period of time. The changing environmental conditions constantly open up new niches which can be filled better by other taxa.…”

Microbial ecology in selenate‐reducing biofilm communities: Rare biosphere and their interactions with abundant phylotypes

“…The pervasiveness of RB suggests different ecotypes having overlapping ecological features (Minz et al, 1999) which coincide with the "Insurance Hypothesis" (Yachi & Loreau, 1999), in which more diverse communities contain taxa with complementary response traits that promote community resilience (Renes et al, 2020; Figure S6).…”