Not all disturbances are created equal: disturbance magnitude affects predator–prey populations more than disturbance frequency

Abstract

Disturbance plays a key role in ecological structure and function. Two important and often studied components of disturbance are frequency and magnitude. Despite the potential for non‐linear interactions between frequency and magnitude, their effects are often assumed to combine in a linear manner. Additionally, studies of disturbance have mainly examined effects on species diversity and competitive interactions within a single trophic level, with less focus on exploitative interactions across trophic levels. Furthermore, while the effects of disturbance are often viewed in terms of reducing population abundance, disturbances can also alter demographic processes, ‘indirectly’ changing abundances. We analyzed several classic dynamic models of species interactions to examine the effects of varying disturbance frequency and magnitude on population persistence in predator–prey and competition systems. Our analysis revealed the potential for non‐linear interactions between frequency and magnitude and their effect on population persistence. Effects differed depending on the form of population dynamics and whether disturbance affected abundance or demographic rates. It is critical to management efforts aiming to improve chances of population persistence to further understand the effects of varying disturbances on interacting populations.

Pulse disturbances in age‐structured populations: Life history predicts initial impact and recovery time

“…For example, in systems with tightly coupled consumer-resource or competitive species interactions, the nature of those interactions will also affect recovery trajectories (e.g. Commander & White, 2020). Alternatively, a system with multiple attractors (e.g.…”

Effects of Multiple Karenia brevis Red Tide Blooms on a Common Bottlenose Dolphin (Tursiops truncatus) Prey Fish Assemblage: Patterns of Resistance and Resilience in Sarasota Bay, Florida

“…In addition, Powell and Wells (2011) and Christiansen et al (2016) reported a rapid increase in conditioning to human interactions through food provisioning beginning in 2005-2006 resulting, at least in part, from the effects of red tide on fish populations and community structure in Sarasota Bay (see Gannon et al, 2009). Understanding how different red tide events affect the dynamics and persistence of populations linked by predator-prey interactions, including possible temporary alterations in the strength or rate of interspecific interactions within a community without directly changing abundances, is critical for effective management efforts (Commander and White, 2020).…”

“…However, chronic ecological disturbances can negatively impact environmental conditions, resulting in ecosystems with lower resilience to perturbation events, and greater risk of surpassing a tipping point between stable states (Scheffer et al, 2001;Lewis et al, 2021). Much work has focused on the dynamics of single species or guilds of species at the same trophic level, therefore the direct and indirect disturbance effects on the dynamics of populations linked by predator-prey interactions, across different trophic levels, are not as well understood (Commander and White, 2020).…”

The ecological consequences of the timing of extreme climate events

“…Using dynamic models, Commander & White, 2020 showed the effects of various disturbances based on different predator–prey population dynamics, we hypothesized predator–prey dynamics over time after an ECE. An ECE near or at the peak of growth in populations of predator and prey (purple arrow) could result in a decrease in the predator's population growth and an increase in prey's population growth.…”

“…The timing of an ECE will be important when considering the consequences of extreme weather on populations that cycle with another species, such as in predator–prey dynamics. In a predator–prey scenario, we may observe that the ECE will first alter the dynamics of the prey or the predator, with the magnitude of the effects depending on the timing of the populations, later cascading to consequences on predator–prey dynamics (Commander & White, 2020) (Figure 4). Finally, in a population that has non‐stationary dynamics we could observe various scenarios where the timing of ECE can have unpredictable effects or no effects.…”