Latitudinal variation in long-term stability of North American rocky intertidal communities.

C Melissa Miner,Benjamin H Becker,Jennifer L Burnaford,Karah Ammann,Steven C Fradkin,Stacey Ostermann‐Kelm,Peter T Raimondi,Jayson R Smith,Stephen G Whitaker

doi:10.1111/1365-2656.13504

Abstract

Although long‐term ecological stability is often discussed as a community attribute, it is typically investigated at the species level (e.g. density, biomass), or as a univariate metric (e.g. species diversity). To provide a more comprehensive assessment of long‐term community stability, we used a multivariate similarity approach that included all species and their relative abundances.We used data from 74 sites sampled annually from 2006 to 2017 to examine broad temporal and spatial patterns of change within rocky intertidal communities along the west coast of North America. We explored relationships between community change (inverse of stability) and the following potential drivers of change/stability: (a) marine heatwave events; (b) three attributes of biodiversity: richness, diversity and evenness and (c) presence of the mussel, Mytilus californianus, a dominant space holder and foundation species in this system.At a broad scale, we found an inverse relationship between community stability and elevated water temperatures. In addition, we found substantial differences in stability among regions, with lower stability in the south, which may provide a glimpse into the patterns expected with a changing climate. At the site level, community stability was linked to high species richness and, perhaps counterintuitively, to low evenness, which could be a consequence of the dominance of mussels in this system. Synthesis. Assessments of long‐term stability at the whole‐community level are rarely done but are key to a comprehensive understanding of the impacts of climate change. In communities structured around a spatially dominant species, long‐term stability can be linked to the stability of this ‘foundation species’, as well as to traditional predictors, such as species richness.

Highlights

Coastal marine ecosystems are experiencing major alterations in oceanic conditions associated with climate change, including warming, acidification, sea-level rise, increased stratification and subsequent decline in dissolved oxygen, increased wave power, and changes in local and regional ocean circulation patterns (Alheit & Bakun, 2010; Bindoff et al, 2019; Brierley & Kingsford, 2009; Doney et al, 2012; Keeling et al, 2010; Narayan et al, 2010; Reguero et al, 2019)
Extreme events resulting in rapid changes in environmental conditions, such as El Niño Southern Oscillation (ENSO) events and marine heatwaves, are becoming more frequent and intense (Freund et al, 2019; Frölicher & Laufkötter, 2018; Oliver et al, 2018)
Our results suggested a similar pattern, and motivated a final question: Is there a relationship between community stability and persistence in cover of the mussel, Mytilus californianus, a spatially dominant foundation species within the community (Dayton, 1972; Seed & Suchanek, 1992; Suchanek, 1992)?

Summary

Introduction

Coastal marine ecosystems are experiencing major alterations in oceanic conditions associated with climate change, including warming, acidification, sea-level rise, increased stratification and subsequent decline in dissolved oxygen, increased wave power, and changes in local and regional ocean circulation patterns (Alheit & Bakun, 2010; Bindoff et al, 2019; Brierley & Kingsford, 2009; Doney et al, 2012; Keeling et al, 2010; Narayan et al, 2010; Reguero et al, 2019). Extreme events resulting in rapid changes in environmental conditions, such as El Niño Southern Oscillation (ENSO) events and marine heatwaves, are becoming more frequent and intense (Freund et al, 2019; Frölicher & Laufkötter, 2018; Oliver et al, 2018) These large-scale agents of disturbance can result in short-and long-term modifications of community structure and can be disruptive when multiple ecological factors are affected. Elevated ocean temperature can result in local extirpations, species range shifts, altered ecosystem functioning and changes in biotic interactions (Harley et al, 2006; Sanford et al, 2019) These impacts can be compounded by other factors associated with marine heatwaves, such as harmful algal blooms or disruption of upwelling intensity and duration (Bograd et al, 2009; Harley et al, 2006). Broad, long-term ecological community monitoring surveys can provide important ‘natural experiment’ data that can be used to link variation in environmental conditions or natural or anthropogenic disturbance to community change (e.g. Croll et al, 2005; Rogers et al, 2012)

Objectives

Findings

Discussion

Conclusion