Development of a Monitoring Protocol to Detect Ecological Change in the Intertidal Zone of Sitka National Historical Park, Alaska

Irvine, Gail V.; Madison, Erica N.

doi:10.3133/sir20085139

Cited by 2 publications

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“…Sessile species are being sampled by vertical transects set systematically with a random start; large mobile invertebrates currently are sampled by band surveys along the vertical transects; and small mobile invertebrates are sampled in quadrats placed systematically along the transects. Power analyses were conducted to test whether the design can detect desired levels of change in target species (Irvine and Madison, 2008).…”

Section: Comparison With Other Intertidal Monitoring Designsmentioning

confidence: 99%

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Development of monitoring protocols to detect change in rocky intertidal communities of Glacier Bay National Park and Preserve

Irvine¹

2010

Open-File Report

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Glacier Bay National Park and Preserve in southeastern Alaska includes extensive coastlines representing a major proportion of all coastlines held by the National Park Service. The marine plants and invertebrates that occupy intertidal shores form highly productive communities that are ecologically important to a number of vertebrate and invertebrate consumers and that are vulnerable to human disturbances. To better understand these communities and their sensitivity, it is important to obtain information on species abundances over space and time. During field studies from 1997 to 2001, I investigated probability-based rocky intertidal monitoring designs that allow inference of results to similar habitat within the bay and that reduce bias. Aerial surveys of a subset of intertidal habitat indicated that the original target habitat of bedrock-dominated sites with slope less than or equal to 30 degrees was rare. This finding illustrated the value of probability-based surveys and led to a shift in the target habitat type to more mixed rocky habitat with steeper slopes. Subsequently, I investigated different sampling methods and strategies for their relative power to detect changes in the abundances of the predominant sessile intertidal taxa: barnacles-Balanomorpha, the mussel Mytilus trossulus and the rockweed Fucus distichus subsp. evanescens. I found that lowerintensity sampling of 25 randomly selected sites (= coarse-grained sampling) provided a greater ability to detect changes in the abundances of these taxa than did more intensive sampling of 6 sites (= fine-grained sampling). Because of its greater power, the coarse-grained sampling scheme was adopted in subsequent years. This report provides detailed analyses of the 4 years of data and evaluates the relative effect of different sampling attributes and management-set parameters on the ability of the sampling to detect changes in the abundances of these taxa. The intent was to provide managers with information to guide design choices for intertidal monitoring. I found that the coarse-grained surveys, as conducted from 1998 to 2001, had power ranging from 0.68 to 1.0 to detect 10 percent annual changes in the abundances of these predominant sessile species. The information gained through intertidal monitoring would be useful in assessing changes due to climate (including ocean acidification), invasive species, trampling effects, and oil spills.

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Section: Comparison With Other Intertidal Monitoring Designsmentioning

confidence: 99%

“…Large mobile invertebrates were sampled via band surveys along the vertical transects in both CG and FG sampling, but were uncommon. Sampling should be modified to concentrate sampling for this latter group (notably starfish) on the lower areas of the intertidal (Irvine and Madison, 2008).…”

Section: Design Issues For Glacier Bay Intertidal Monitoringmentioning

confidence: 99%

Development of monitoring protocols to detect change in rocky intertidal communities of Glacier Bay National Park and Preserve

Irvine¹

2010

Open-File Report

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Sampling design for long-term regional trends in marine rocky intertidal communities

Irvine

Shelly

2013

Environ Monit Assess

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Probability-based designs reduce bias and allow inference of results to the pool of sites from which they were chosen. We developed and tested probability-based designs for monitoring marine rocky intertidal assemblages at Glacier Bay National Park and Preserve (GLBA), Alaska. A multilevel design was used that varied in scale and inference. The levels included aerial surveys, extensive sampling of 25 sites, and more intensive sampling of 6 sites. Aerial surveys of a subset of intertidal habitat indicated that the original target habitat of bedrock-dominated sites with slope ≤30° was rare. This unexpected finding illustrated one value of probability-based surveys and led to a shift in the target habitat type to include steeper, more mixed rocky habitat. Subsequently, we evaluated the statistical power of different sampling methods and sampling strategies to detect changes in the abundances of the predominant sessile intertidal taxa: barnacles Balanomorpha, the mussel Mytilus trossulus, and the rockweed Fucus distichus subsp. evanescens. There was greatest power to detect trends in Mytilus and lesser power for barnacles and Fucus. Because of its greater power, the extensive, coarse-grained sampling scheme was adopted in subsequent years over the intensive, fine-grained scheme. The sampling attributes that had the largest effects on power included sampling of "vertical" line transects (vs. horizontal line transects or quadrats) and increasing the number of sites. We also evaluated the power of several management-set parameters. Given equal sampling effort, sampling more sites fewer times had greater power. The information gained through intertidal monitoring is likely to be useful in assessing changes due to climate, including ocean acidification; invasive species; trampling effects; and oil spills.

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Development of a Monitoring Protocol to Detect Ecological Change in the Intertidal Zone of Sitka National Historical Park, Alaska

Cited by 2 publications

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Development of monitoring protocols to detect change in rocky intertidal communities of Glacier Bay National Park and Preserve

Development of monitoring protocols to detect change in rocky intertidal communities of Glacier Bay National Park and Preserve

Sampling design for long-term regional trends in marine rocky intertidal communities

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