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.
) yielded a mean bed recovery time of 9 to 11 yr following dragging, depending on initial degree of plant removal. Model simulations suggested that with favorable environmental conditions, eelgrass beds might recover from dragging disturbance in 6 yr; conversely, recovery under conditions less conducive to eelgrass growth could require 20 yr or longer. This study shows that mussel dragging poses a severe threat to eelgrass in this region and that regulations to protect eelgrass from dragging impacts would maintain the integrity of a substantial amount of habitat.
Seagrasses are valuable coastal marine habitats that support fisheries, contribute to ocean food webs, and filter estuarine waters. As seagrasses are lost due to human impacts to coastal environments, techniques are being developed to effectively mitigate these losses by transplanting. In transplanting seagrasses, both site selection and transplanting method are critical for success at the lowest possible cost. In the northeastern U.S., we have developed a model to choose sites most likely to sustain eelgrass, Zostera marina L., transplants. The high cost of restoring eelgrass beds in subtidal environments, and the difficulty in protecting transplants from various bioturbating organisms, led us to develop a new method not requiring SCUBA.'Transplanting Eelgrass Remotely with Frame Systems" (TERFS') is a modification of bare -root transplanting methods. Eelgrass shoots are attached with biodegradable ties to weighted wire frames that provide mechanical protection from uprooting and bioturbation. The TERFSTM are then deployed from any small boat. After three to five weeks, the frames are retrieved for reuse, leaving behind dense patches of eelgrass. We tested TERFSTM first in the Great Bay Estuary, NH (USA) and again in New Bedford Harbor, Massachusetts (USA); in both cases the TERFSTM method was successful. The ease and success of this technique provides an approach tFo restoration that can involve citizen volunteers. More importantly, it significantly reduces the cost of eelgrass restoration.
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