Empirical evidence of an approaching alternate state produced by intrinsic community dynamics, climatic variability and management actions

Hewitt, Judi E.; Thrush, Simon F.

doi:10.3354/meps08626

Cited by 39 publications

(24 citation statements)

References 60 publications

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“…Early warning signals for regime shifts would be useful for managing transitions, however, response patterns still remain ambiguous limiting application in management. While most of the proposed indicators are theoretically well developed, there have been few empirical tests [26]–[28], but see [23], [29], with effective long-term time-series monitoring required [21], [29], [30]. In this context, there is a need to understand connectivity and heterogeneity patterns before systems transition to a degraded state.…”

Section: Introductionmentioning

confidence: 99%

Counting on β-Diversity to Safeguard the Resilience of Estuaries

2013

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Coastal ecosystems are often stressed by non-point source and cumulative effects that can lead to local-scale community homogenisation and a concomitant loss of large-scale ecological connectivity. Here we investigate the use of β-diversity as a measure of both community heterogeneity and ecological connectivity. To understand the consequences of different environmental scenarios on heterogeneity and connectivity, it is necessary to understand the scale at which different environmental factors affect β-diversity. We sampled macrofauna from intertidal sites in nine estuaries from New Zealand’s North Island that represented different degrees of stress derived from land-use. We used multiple regression models to identify relationships between β-diversity and local sediment variables, factors related to the estuarine and catchment hydrodynamics and morphology and land-based stressors. At local scales, we found higher β-diversity at sites with a relatively high total richness. At larger scales, β-diversity was positively related to γ-diversity, suggesting that a large regional species pool was linked with large-scale heterogeneity in these systems. Local environmental heterogeneity influenced β-diversity at both local and regional scales, although variables at the estuarine and catchment scales were both needed to explain large scale connectivity. The estuaries expected a priori to be the most stressed exhibited higher variance in community dissimilarity between sites and connectivity to the estuary species pool. This suggests that connectivity and heterogeneity metrics could be used to generate early warning signals of cumulative stress.

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Section: Introductionmentioning

confidence: 99%

Counting on β-Diversity to Safeguard the Resilience of Estuaries

2013

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“…For some marine species, the spatial arrangement of their habitat is determined by other species, referred to as foundation species. In such biogenic habitats, species like coral reefs, kelp, marine algae, and seagrasses host a vast biodiversity of associated invertebrates, fish, and seaweeds (Thompson et al 2002, O'Hara et al 2008, Hewitt and Thrush 2010, Perry et al 2011. Structural connectivity in the ocean will inevitably respond to changes in the spatial rearrangement of biogenic habitats resulting from climate change.…”

Section: Structural Connectivity: Relating Environmental Conditions Tmentioning

confidence: 99%

Climate change impacts on connectivity in the ocean: Implications for conservation

et al. 2014

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Abstract. Effective spatial management in the ocean requires a network of conservation areas that are connected by larval and adult dispersal. We propose a conceptual framework for including the likely impacts of a changing climate on marine connectivity, and synthesize information on the relationships between changing ocean temperature and acidification, connectivity and conservation tools. Our framework relies on concepts of functional connectivity, which depends on an organism's biological and behavioral responses to the physical environment, and structural connectivity, which describes changes in the physical and spatial structure of the environment that affect connectivity and movement. Our review confirms that ocean climate change likely reduces potential dispersal distance and therefore functional connectivity. Structural connectivity in the ocean will inevitably change with the spatial arrangement of biogenic habitats resulting from disturbance as well as enhanced growth and mortality due to climate change. Climate change will also likely reduce the spatial scale of connectivity, suggesting that we will need more closely spaced protected areas.

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“…). Empirical studies often assume fold bifurcation dynamics (Boettiger and Hastings ) or make heuristic arguments for the presence of “regime shifts” with similar dynamics (Hewitt and Thrush , Litzow et al. , Wouters et al.…”

Section: Introductionmentioning

confidence: 99%

Early warning signals, nonlinearity, and signs of hysteresis in real ecosystems

Litzow

Hunsicker

2016

Ecosphere

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Abstract. Early warning signals (EWS) might dramatically improve our ability to manage nonlinear ecological change. However, the degree to which theoretical EWS predictions are supported in empirical systems remains unclear. The goal of this study is to make recommendations for identifying the types of ecological transitions that are expected to show EWS. We conducted a review and meta-analysis of published studies and comparative analysis of eight northeast Pacific Ocean time series to illustrate the importance of testing for nonlinearity in empirical EWS studies. We found that published studies demonstrating nonlinearity in ecosystem dynamics are more likely to support EWS predictions than studies with linear or undetermined dynamics. The northeast Pacific time series in our analysis were often too short for formal tests of nonlinearity, a common problem in empirical studies. To assess the evidence for nonlinear dynamics in these data, we tested for state-dependent driver-response relationships consistent with hysteresis, a central feature of nonlinear ecological models. This analysis supported the results of the literature metaanalysis. Four time series with driver-response relationships consistent with hysteresis generally supported theoretical EWS predictions, while four without evidence of hysteresis failed to support EWS predictions. Theoretical support for EWS is largely generated from nonlinear models, and we conclude that tests for either nonlinear dynamics or hysteresis are needed before employing EWS.

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Empirical evidence of an approaching alternate state produced by intrinsic community dynamics, climatic variability and management actions

Cited by 39 publications

References 60 publications

Counting on β-Diversity to Safeguard the Resilience of Estuaries

Counting on β-Diversity to Safeguard the Resilience of Estuaries

Climate change impacts on connectivity in the ocean: Implications for conservation

Early warning signals, nonlinearity, and signs of hysteresis in real ecosystems

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