Compounded Perturbations Yield Ecological Surprises

Abstract

All species have evolved in the presence of disturbance, and thus are in a sense matched to the recurrence pattern of the perturbations. Consequently, disturbances within the typical range, even at the extreme of that range as defined by large, infrequent disturbances (LIDs), usually result in little long-term change to the system's fundamental character. We argue that more serious ecological consequences result from compounded perturbations within the normative recovery time of the community in question. We consider both physically based disturbance (for example, storm, volcanic eruption, and forest fire) and biologically based disturbance of populations, such as overharvesting, invasion, and disease, and their interactions. Dispersal capability and measures of generation time or age to first reproduction of the species of interest seem to be the important metrics for scaling the size and frequency of disturbances among different types of ecosystems. We develop six scenarios that describe communities that have been subjected to multiple perturbations, either simultaneously or at a rate faster than the rate of recovery, and appear to have entered new domains or ''ecological surprises.'' In some cases, three or more disturbances seem to have been required to initiate the changed state. We argue that in a world of ever-more-pervasive anthropogenic impacts on natural communities coupled with the increasing certainty of global change, compounded perturbations and ecological surprises will become more common. Understanding these ecological synergisms will be basic to environmental management decisions of the 21st century.

Incomplete recovery and individualized responses of the human distal gut microbiota to repeated antibiotic perturbation

“…However, the existence of sudden regimen shifts in ecosystems, sometimes triggered by perturbations, is a familiar ecological phenomenon, and the return of external conditions to their former state may not reverse such changes in community composition (21). Repeated perturbations may be particularly likely to cause such shifts, even when the community seems to have recovered from the initial perturbation (22).…”

“…Other traits attributed to members of the gut microbiota, however, such as inhibiting the growth (24), attachment (25), or virulence (26) of particular pathogens, helping to regulate host immunity (21)(22)(23) or energy balance (24), or participating with host enzymes in cometabolism of specific substances (27,28), may be restricted to a small subset of the community. Unlike carbon use, these traits are not essential to the microbes; variation in the trait between close relatives is predicted by evolutionary theory (29,30) and observed in practice (24,31,32).…”

Recovery of the brown alga Fucus gardneri following a range of removal intensities

“…Disturbance plays a key role in structuring the dynamics of natural communities (Dayton, 1971;Connell, 1978;Lubchenco, 1978;Sousa, 1979Sousa, , 1985Paine and Levin, 1981;Paine et al, 1998). The roles of disturbance frequency and intensity can be complex and non-linear (e.g.…”

Untangling interactions: do temperature and habitat fragmentation gradients simultaneously impact biotic relationships?

“…If this study provides insights into widespread trends, the impacts on biota are likely to be predominantly detrimental. As Paine et al [14] describe, and as we have empirically demonstrated, ecological surprises are likely to be commonplace. This research highlights the requirement to consider multiple drivers of global environmental change and multiple biotic measures when predicting the effects of, and solutions to, anthropogenic impacts on biodiversity.…”

“…The latter, antagonistic interactions, was exemplified by Zvereva & Kozlov [13], who found that the adverse impact of carbon dioxide elevation on herbivore performance was offset by the favourable impact of increased temperature. Systems subjected to multiple, usually sequential stressors such as imposed by global change, may therefore enter alternative abnormal stable states, and hence 'ecological surprises' can be expected when attempting to predict effects [14].…”