Integrating Scales of Seagrass Monitoring to Meet Conservation Needs

Abstract

We evaluated a hierarchical framework for seagrass monitoring in two estuaries in the northeastern USA: Little Pleasant Bay, Massachusetts, and Great South Bay/Moriches Bay, New York. This approach includes three tiers of monitoring that are integrated across spatial scales and sampling intensities. We identified monitoring attributes for determining attainment of conservation objectives to protect seagrass ecosystems from estuarine nutrient enrichment. Existing mapping programs provided large-scale information on seagrass distribution and bed sizes (tier 1 monitoring). We supplemented this with baywide, quadrat-based assessments of seagrass percent cover and canopy height at permanent sampling stations following a spatially distributed random design (tier 2 monitoring). Resampling simulations showed that four observations per station were sufficient to minimize bias in estimating mean percent cover on a bay-wide scale, and sample sizes of 55 stations in a 624-ha system and 198 stations in a 9,220-ha system were sufficient to detect absolute temporal increases in seagrass abundance from 25% to 49% cover and from 4% to 12% cover, respectively. We made highresolution measurements of seagrass condition (percent cover, canopy height, total and reproductive shoot density, biomass, and seagrass depth limit) at a representative index site in each system (tier 3 monitoring). Tier 3 data helped explain system-wide changes. Our results suggest tiered monitoring as an efficient and feasible way to detect and predict changes in seagrass systems relative to multi-scale conservation objectives.

Cover versus recovery: Contrasting responses of two indicators in seagrass beds

“…patchiness, depth distribution, meadow edge, etc.) of the system studied (Neckles et al, 2012). The choice of indicators, as suggested by the European Water Framework Directive, should include several parameters at the individual, the population and the landscape scale (i.e.…”

“…healthy or in decline). These monitoring programs also use environmental parameters such as water and sediment quality in combination with seagrass measurements to infer the causes of changes in seagrass cover and distribution (Duarte et al, 2004;Short et al, 2006;Neckles et al, 2012).…”

Establishing a Baseline for Regional Scale Monitoring of Eelgrass (Zostera marina) Habitat on the Lower Alaska Peninsula

“…The establishment of baseline data detailing the current distribution, abundance, and characteristics of seagrass meadows to serve as a starting point for future comparisons is fundamental to understanding, monitoring, and mitigating changes to this critically important habitat [9,35]. Remote sensing provides an accurate and cost effective approach for mapping and evaluating eelgrass beds for change in spatial distribution over broad areas [16,21,36,37].…”

“…Remote sensing provides an accurate and cost effective approach for mapping and evaluating eelgrass beds for change in spatial distribution over broad areas [16,21,36,37]. Field surveys supply precision data describing internal characteristics of eelgrass meadows, such as canopy height, percent cover and associated species, which can be used to assess condition and predict or explain changes in spatial extent [9,35]. There are major challenges, however, to conducting field research, especially in Alaska, due to the cost in time and money required to reach and survey large meadows in remote locations.…”

“…There are major challenges, however, to conducting field research, especially in Alaska, due to the cost in time and money required to reach and survey large meadows in remote locations. An effective way to meet these challenges is to apply a hierarchical approach that uses a three-tier framework of monitoring integrated across decreasing geographic scales to answer increasingly specific questions [35,38]. Tier 1 monitoring applies broad scale data derived using remote sensing techniques to determine spatial extent and distribution of eelgrass meadows.…”