Effects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins

Despite growing recognition that complex population portfolios are important sources of ecosystem stability and resilience, the structure of such stock complexes is often not considered in monitoring schemes to inform environmental impact assessments. The use of “index” or “indicator” sites, and of...

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Autores principales:	Brooke M. Davis, Daniel E. Schindler
Formato:	article
Lenguaje:	EN
Publicado:	Elsevier 2021
Materias:	Portfolio effect Environmental impact assessment Monitoring Salmon Stock complex Resilience Ecology QH540-549.5
Acceso en línea:	https://doaj.org/article/b9f09d5568b54e3d8b8627a5688d8571
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spelling	oai:doaj.org-article:b9f09d5568b54e3d8b8627a5688d85712021-12-01T04:45:58ZEffects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins1470-160X10.1016/j.ecolind.2021.107427https://doaj.org/article/b9f09d5568b54e3d8b8627a5688d85712021-05-01T00:00:00Zhttp://www.sciencedirect.com/science/article/pii/S1470160X21000923https://doaj.org/toc/1470-160XDespite growing recognition that complex population portfolios are important sources of ecosystem stability and resilience, the structure of such stock complexes is often not considered in monitoring schemes to inform environmental impact assessments. The use of “index” or “indicator” sites, and of short assessment windows, to make broad claims about the relative importance of specific habitats or populations within a portfolio, assume that regional populations are highly synchronous and that abundance is stable through time. Asynchrony among populations and changes in population productivity over time render these assumptions fundamentally flawed. We used 57 years of abundance data for sockeye salmon (Oncorhynchus nerka) spawning in a set of eight streams in the Wood River watershed, southwest Alaska, to demonstrate how natural patterns of variability affect the ability of fixed assessment windows to characterize the contribution of individual populations to the entire portfolio. Additionally, simulations were used to demonstrate how different levels of synchrony and autocorrelation affect the ability of monitoring schemes to estimate the contributions of individual populations to a portfolio over the long-term. We found that fixed assessment windows were distinctly limited in their ability to characterize a population’s contribution to a portfolio over the long-tem. Asynchronous dynamics among populations, and the presence of autocorrelation that creates slow changes in populations, weaken the ability to characterize a stream's potential contribution to a portfolio from short-term assessments. These results suggest that the structure of population portfolios, and the presence of directional changes in productivity within individual populations, need to be taken into account when carrying out environmental risk assessments that aim to measure the contribution of an individual population or habitat to system wide dynamics. Typical risk assessments that depend on short monitoring periods are likely to vastly underestimate the potential long-term value of any specific habitat, and the population it supports, as a component of a multi-population portfolio.Brooke M. DavisDaniel E. SchindlerElsevierarticlePortfolio effectEnvironmental impact assessmentMonitoringSalmonStock complexResilienceEcologyQH540-549.5ENEcological Indicators, Vol 124, Iss , Pp 107427- (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Portfolio effect Environmental impact assessment Monitoring Salmon Stock complex Resilience Ecology QH540-549.5
spellingShingle	Portfolio effect Environmental impact assessment Monitoring Salmon Stock complex Resilience Ecology QH540-549.5 Brooke M. Davis Daniel E. Schindler Effects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins
description	Despite growing recognition that complex population portfolios are important sources of ecosystem stability and resilience, the structure of such stock complexes is often not considered in monitoring schemes to inform environmental impact assessments. The use of “index” or “indicator” sites, and of short assessment windows, to make broad claims about the relative importance of specific habitats or populations within a portfolio, assume that regional populations are highly synchronous and that abundance is stable through time. Asynchrony among populations and changes in population productivity over time render these assumptions fundamentally flawed. We used 57 years of abundance data for sockeye salmon (Oncorhynchus nerka) spawning in a set of eight streams in the Wood River watershed, southwest Alaska, to demonstrate how natural patterns of variability affect the ability of fixed assessment windows to characterize the contribution of individual populations to the entire portfolio. Additionally, simulations were used to demonstrate how different levels of synchrony and autocorrelation affect the ability of monitoring schemes to estimate the contributions of individual populations to a portfolio over the long-term. We found that fixed assessment windows were distinctly limited in their ability to characterize a population’s contribution to a portfolio over the long-tem. Asynchronous dynamics among populations, and the presence of autocorrelation that creates slow changes in populations, weaken the ability to characterize a stream's potential contribution to a portfolio from short-term assessments. These results suggest that the structure of population portfolios, and the presence of directional changes in productivity within individual populations, need to be taken into account when carrying out environmental risk assessments that aim to measure the contribution of an individual population or habitat to system wide dynamics. Typical risk assessments that depend on short monitoring periods are likely to vastly underestimate the potential long-term value of any specific habitat, and the population it supports, as a component of a multi-population portfolio.
format	article
author	Brooke M. Davis Daniel E. Schindler
author_facet	Brooke M. Davis Daniel E. Schindler
author_sort	Brooke M. Davis
title	Effects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins
title_short	Effects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins
title_full	Effects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins
title_fullStr	Effects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins
title_full_unstemmed	Effects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins
title_sort	effects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins
publisher	Elsevier
publishDate	2021
url	https://doaj.org/article/b9f09d5568b54e3d8b8627a5688d8571
work_keys_str_mv	AT brookemdavis effectsofvariabilityandsynchronyinassessingcontributionsofindividualstreamstohabitatportfoliosofriverbasins AT danieleschindler effectsofvariabilityandsynchronyinassessingcontributionsofindividualstreamstohabitatportfoliosofriverbasins
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Effects of variability and synchrony in assessing contributions of individual streams to habitat portfolios of river basins

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