Transient demographic approaches can drastically expand the toolbox of coral reef science

Abstract

Coral communities are threatened by an increasing plethora of abiotic and biotic disturbances. Preventing the ensuing loss of coral coverage and diversity calls for a mechanistic understanding of resilience across coral species and populations that is currently lacking in coral reef science. Assessments into the dynamics of coral populations typically focus on their long-term (i.e. asymptotic) characteristics, tacitly assuming stable environments in which populations can attain their long-term characteristics. Instead, we argue that greater focus is needed on investigating the transient (i.e. short-term) dynamics of coral populations to describe and predict their characteristics and trajectories within unstable environments. Applying transient demographic approaches to evaluating and forecasting the responses of coral populations to disturbance holds promise for expediting our capacity to predict and manage the resilience of coral populations, species, and communities.

Recent exposure to environmental stochasticity does not determine the demographic resilience of natural populations

“…short-term) phase, where their dynamics vary considerably from their asymptotic trajectories (Hastings, 2001; Figure 1). Long-term measures of population performance are, therefore, unlikely to reveal how environmental stochasticity influences the resilience of populations (Cant, Salguero-Gómez, et al, 2022). Alternatively, transient population metrics, describing how the dynamics of populations can change following disturbance relative to their long-term characteristics (Koons et al, 2005;Stott et al, 2011), offer greater insight into the inherent resilience (i.e.…”

Reproducing within-reef variability in coral dynamics with a metacommunity modelling framework

“…With a mechanistic modelling framework, complex processes that occur within-reefs, spanning from individual corals, populations and metapopulations, that are interconnected across seascapes, can be investigated [20, 21]. Several processes are key to such a framework.…”

“…On a reef, corals are recruiting, growing, reproducing, and dying, through a life cycle that has evolved over millennia. These demographic processes determine population growth rate and can vary spatially and temporally in response to the local environmental conditions [1, 21–24]. Additionally, stress experienced during acute disturbances varies spatially across a reef due to the localised physical and environmental conditions [25–29].…”

“…A demographic foundation to a mechanistic modelling framework for coral offers many opportunities for advancing coral reef research [21, 22, 34–36]. Integral Projection Models (IPMs) use empirical information on an individual’s vital rates – survival, growth and reproduction – to estimate population statistics such as growth rate [37, 38].…”

Coral assemblages at higher latitudes favor short‐term potential over long‐term performance

“…Within stochastic environments, recurrent disturbances impose short‐term changes upon the structure of populations that can elevate (i.e., demographic amplification) or diminish (i.e., demographic attenuation) their growth rates, resulting in population performance characteristics deviating from long‐term expectations (Ezard et al, 2010 ; Stott et al, 2011 ). Quantifying how transient population performance (henceforth short‐term potential) deviates from long‐term expectations therefore is crucial for predicting the success or failure of natural populations (Koons et al, 2005 ), an approach that remains neglected within coral research (Cant, Salguero‐Gómez, & Beger, 2022 ).…”