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

Abstract

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.

Evaluating Sampling Designs for Demersal Fish Communities

“…A systemic sampling design can be easily operated and is more suitable for sampling fish communities with no prior information [3,41]. A stratified random sampling design is also commonly used in many fishery surveys [2,12,15] and the variance between strata can be reduced by suitable stratification. Previous studies have shown that a systemic sampling design and stratified sampling design tend to have higher accuracy than simple random sampling [16,42].…”

“…A heterogeneous distributional area can be divided into different strata with more homogeneous distributions within strata [13]. As fish populations tend to have patchy distributions following their optimal habitats or biological behavior-like migrations even within an optimal habitat, the stratified sampling design can be cost effective in improving sampling precisions at the same or less cost compared to simple random sampling [15]. There are many rules to allocate the sample sites of sampling among strata, such as the Neyman allocation and allocating samples among strata in a way that is proportional to the strata area.…”

Insight into best practices: a review of long-term monitoring of the rocky intertidal zone of the Northeast Pacific Coast

“…It is generally understood that statistical evaluation and regular reevaluation of sampling methods is important to maximize the efficiency of data collection efforts (Hinds, 1984;Gilbane et al, 2022). Studies that compare aspects of sampling design (Foster et al, 1991;Meese and Tomich, 1992;Dethier et al, 1993;Miller and Ambrose, 2000) and provide recommendations for carrying out LTM of the rocky intertidal zone (Hartnoll and Hawkins, 1980;Hawkins and Hartnoll, 1983;Steinbeck et al, 2005;Murray et al, 2006;Irvine and Shelly, 2013;Mieszkowska et al, 2014;Raimondi et al, 2019b;Gilbane et al, 2022) are available and can help ensure statistically sound sampling, increase sampling efficiency, and improve the prospect of long-term program sustainability. Still, power analysis and other statistical evaluation has not been prioritized by practitioners on the NPC (NCCN Interview 2, MARINe Interview 2).…”

“…The SEAN utilizes systematic sampling of a limited number of sites following shoreline geomorphological classification to allow extrapolation to areas with similar features (Irvine, 2010). This approach requires extensive coastal geomorphology data that is often lacking, and inference may still be limited to within regions (Schoch and Dethier, 1996;Schoch et al, 2006;Irvine and Shelly, 2013). The PISCO program uses a spatially nested site distribution scheme, where sampling is replicated hierarchically to allow comparison of communities across a range of scales (Schoch et al, 2006).…”

A pioneer morphological and genetic study of the intertidal fauna of the Gerlache Strait (Antarctic Peninsula)

“…To evaluate and document future changes in faunal composition, a current intertidal biodiversity baseline is urgently needed (Irvine & Shelly 2013, Griffiths & Waller 2016.…”