Data Parameters and Units:
[Big Lagoon, FL: Gongora, State Park, Spanish Cove, Langley Point] -- Nekton collected by Fyke, Trawl, Seine; PAH analysis. [Grand Bay, AL: Long Island, Marsh Island, West Point-aux-Pins] -- Nekton collected by Fyke,Trawl; Spartina alterniflora quadrats. 1. Nekton Collection (ID), Date (DD/MM/YYYY), Location (island name), Trap (ID), Trap type [Fyke, Trawl, Seine], ABUNDANCE Species Abundance (number of individuals) [Palaemonetes pugio, Litopenaeus setiferus, Farfantepenaeus aztecus, Callinectes sapidus, Alpheus heterochaelis, Fundulus grandis, Hippolyte sp., Tozeuma carolinense, etc], Total Organisms at each site (count), Total Organisms not counting P.pugio (count), H = Species Diversity Shannon-Weaver Index (index on scale of low to high community diversity), Species not counting P.pugio Diversity Shannon-Weaver Index (index on scale of low to high community diversity), s (number of species encountered in the community), Hmax = ln(s) (maximum diversity possible). h(J) = H/Hmax Shannon's equitability i.e., the evenness of species present in the community and h(J) ranges from 0 to 1 where index value of 1 means that all groups are encountered with the same frequency. Exp(h(J)) exponential of Shannon-Wiener diversity index i.e., Nekton diversity or effective number of species in the community (number of species), also Nekton diversity not counting P.pugio (number of species) BIOMASS Initial Foil Mass (g), Dry Mass + Pan Fauna (g), Dry Mass (g), Mean Dry Mass/Individual (g), Proportional Total i.e., Dry Mass/sum of Dry Masses (g), Proportional Total not counting P.pugio (g), Statistics BIOMASS (number of individuals per tidal cycle), Evironmental BIOMASS (dry mass per tidal cycle), [penaeid trap and trawl, crab trap and trawl, nekton trap and trawl]. LENGTHS [C. sapidus, F. aztecus, L. setiferus] Carapace Width (mm), Body Length (mm), Head Length (mm), SL Standard Length (mm), TL Total Length (mm). 2. Spartina (live plants only) - Collection (ID), Date (DD/MM/YYYY), Location (place name) [Long Island quadrats1-3 West to East, Marsh Island quadrats1-3 West to East, West Point-aux-Pins quadrats1-3 North to South], Quadrat (ID), Plant number (ID), Culm Height (cm), Pan/Foil Mass (g), Dry Tissue Mass + Pan/Foil Mass (g), Dry Tissue Mass (g), Density (number of stems/meters^2). 3. PAH compound concentration wet weight (ppb) for [Reporting Limit, System Blank, Spike], Net Recovery (%), PAH compound (name) [napthalene, acenapthalene, fluorine, phenanthrene, anthracene, fluoranthene, pyrene, benzoa[b]fluoranthene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene, dibenzo[a,h]anthracene, benzo[g,h,i]perylene, indeno[1,2,3-cd]pyrene], sample type [vegetation, sediment], vegetation type (Juncus-Low, Juncus-High, Seagrass), Location (place name).
Methods:
Nekton Collections: Salt Marsh Habitats Modified fyke nets are used to collect nekton that utilize the marsh vegetation during high water (Fig. 2). Three 6-m wide nets are randomly positioned at the edge of the vegetation at each site during low water and left in place for 24 hr (approximately one tidal cycle). The nets are designed to permit lateral movement of organisms within the marsh vegetation as the marsh surface is flooded and to capture all organisms as they exit the marsh vegetation on the subsequent falling tide. All organisms collected from the traps are immediately placed on ice for transport back to the laboratory for analysis. Nekton Collections: SAV Habitats Three 2-min trawl swaths are used to sample seagrass-associated nekton at the Grand Bay sites, as well as at Langley Point Outer and Spanish Cover Outer. The shallow depth of the other sites prohibits trawling. These sites are sampled by pulling a 7.3-m wide seine for 20 m parallel to the marsh edge (in triplicate): Gongora, Big Lagoon State Park, Kee's Bayou, Joe’s Site, Langley Point Inner and Spanish Cove Inner. Measurements All organisms are identified to the species level and enumerated: standard and total lengths are obtained for fish, carapace widths (measured across the lateral spines) for crabs, and body lengths (rostrum to telson) for shrimp. All sizes are measured to the nearest 0.01 mm. Biomass estimates are obtained by pooling species within samples (per fyke net or per seine pull), and drying the specimens at 70 °C for 24 hr. The mass of each species is measured to the nearest 0.001 gram. Environmental Parameters Salinity, water temperature, and dissolved oxygen are measured at the start and end of each fyke-net deployment and following each seine/trawl pull. The following samples have been collected for PAH analysis at Langley Point Outer, Spanish Cove Inner, Gongora, Kee’s Bayou and State Park: (1) five fringing Juncus plants; (2) five upland Juncus plants; (3) five 5-cm deep sediment cores; and (4) five Halodule plants. Samples are homogenized with dry ice by site and sent to Virginia Tech for analysis.
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