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{"Abstract":["To characterize spatial variation in barnacle recruitment at the creekbank, and across a gradient in salinity and distance to ocean, we deployed PVC poles to passive sample barnacle settlement. Eight poles were deployed between 4-5m apart adjacent to the creekbank vegetation monitoring plots at each GCE LTER permanent monitoring site each Fall beginning in 2012. These poles were then collected the following Fall and all barnacle that settled on the poles were identified and counted on 50cm-long sections of the 8, 3/4" diameter PVC poles. Four species settled on poles and were counted and recorded: Chthamalus fragilis, Balanus spp., Geukensia demissa, and Oysters (Crassostrea virginica)."]} 

Abstract: A quadrat survey was conducted in October 2024 to measure the species and size distribution of plants at 3 sampling sites on the creekbank of the Altamaha River. The sites were chosen to capture the transition from Spartina alterniflora to Spartina cynosuroides (site SCSA) and the transition from Spartina cynosuroides to Zizaniopsis miliacea (sites ZSC1 and ZSC2). The quadrats were established as permanent plots in October 2012 by placing PVC stakes along the creekbank at each site. Plots were evenly spaced, but were not randomly located because the goal was to start with mixtures of vegetation in most of the plots, and vegetation was distributed in patches along the creekbanks. Therefore, these plots provide useful measures of vegetation change, but are not a random sample of the vegetation at the site. Plots will be replaced each year as necessary to replace any lost to disturbance. The plots were visually surveyed and the species, shoot height, and flowering status was recorded individually for each shoot over 10 cm in height present in each plot. Observations from plots exhibiting signs of disturbance were noted in a separate data set. This survey will be repeated annually to assess changes in plant distribution and biomass in relation to environmental changes documented by other GCE LTER monitoring efforts. 

Abstract: This data set is the Fall 2024 estimate of crab densities at the GCE-LTER marsh sites used for population monitoring. Crab abundance was determined by counting the number of crab holes within a 625 cm^2 quadrat and converting the counts to number per square meter. Counts were made in the mid-marsh and creek bank zones (n = 4 per zone) at GCE sites 1 through 10. Note that this census method does not differentiate which species made a particular hole and therefore only estimates total burrowing crab abundance, potentially including species Uca pugnax, Uca minax, Uca pugilator, Armases cinereum, Eurytium limosum and Sesarma reticulatum, and others. Crab holes that are not actively maintained are quickly covered by tidal activity and other sediment disturbances, therefore plugged holes were assumed to be unoccupied and excluded from the counts. 

Abstract: To characterize spatial variation in the adult and juvenile density of periwinkle snails, Littoraria irrorata, within two zones in the salt marsh, the mid-marsh and creekbank, and across a gradient in salinity and distance to ocean, we surveyed snail density in October 2024. In each marsh zone at each GCE LTER permanent monitoring site, we counted the number of adult and juvenile snails in 8 creekbank and 12 mid-marsh replicate quadrats. 

Abstract: Soil samples were collected in conjunction with Fall 2024 plant monitoring at half of the permanent vegetation monitoring plots in the creekbank and midmarsh zones at 10 GCE study sites. Pore-water salinity was determined by analysis of supernatant salinity in dried soil samples hydrated with a measured volume of deionized water. 

Abstract: The biomass of plants surveyed in permanent plots at 10 GCE LTER sampling sites in October 2024 was estimated based on allometric relationships between biomass and shoot height and flowering status derived for each site, zone, and species in October 2002 and October 2008. Biomass was calculated for dominant species, including Spartina alterniflora, S. cynosuroides, Juncus roemerianus, and Zizaniopsis miliacea, as well as rarer species including Scirpus spp, Panicum spp. And Typha angustifolia. This data set is based on GCE plant monitoring survey data set PLT-GCEM-2111a, and allometric relationships were based on GCE data sets PLT-GCEM-0211b, PLT-GCEM-0711, and PLT-GCEM-2011. 

Abstract: This data set is the Fall 2023 report of infaunal and epifaunal mollusc species size distributions at the GCE-LTER marsh sites used for population monitoring. Infaunal and epifaunal molluscs were hand-collected from within quadrats of known area from mid-marsh and creekbank zones (n = 4 quadrats per zone) at all sites. The molluscs were returned to the lab, preserved in ethanol, measured and counted (count data is reported separately). Length of each measurable individual was determined using calipers or an ocular micrometer mounted in a stereomicroscope. Species abundance and density data for these collections may be found in the GCE-LTER data set INV-GCEM-2407. Numbers of individuals of each species in the abundance data file may not correspond exactly to the numbers of individuals in the size data file because some individuals may not have been measureable. 

Abstract: This data set is the Fall 2023 estimate of infaunal and epifaunal mollusc abundance at the GCE-LTER marsh sites used for population monitoring. Species abundance was determined by hand-collecting all the infaunal and epifaunal molluscs from within quadrats of known area in mid-marsh and creekbank zones (n = 4 quadrats per zone) at all sites. The molluscs were returned to the lab, fixed in ethanol, transferred to and preserved in ethanol, counted and measured (size data is reported separately). The counts were converted to number per square meter. Gastropod species are listed first, followed by bivalve species. Size distribution data for these collections may be found in the GCE-LTER data set INV-GCEM-2407a. 

Abstract: A quadrat survey was conducted in October 2024 to measure the species and size distribution of plants at 10 GCE LTER sampling sites. The quadrats were established as permanent plots at GCE sampling sites in October 2000 by placing wooden (since replaced with pvc) stakes at random locations across two nominal zones at each site, designated based on marsh structure (creekbank and high marsh). New plots were added each year as necessary to replace those lost due to catastrophic wrack disturbance or creek bank erosion. The plots were visually surveyed and the species, shoot height, and flowering status was recorded individually for each shoot over 10 cm in height present in each plot. Observations from plots exhibiting signs of disturbance were noted in a separate data set (PLT-GCEM-1801). This survey will be repeated annually to assess changes in plant distribution and biomass in relation to environmental changes documented by other GCE LTER monitoring efforts.