Abstract:

Biodiversity, whether functional, taxonomic, or genetic, can influence a range of marine ecosystem services such as productivity and resource utilization. Theory predicts that the effects of diversity on ecosystem function may be strongest in the presence of disturbance or changing environmental conditions (e.g., the insurance effect). This positive effect of diversity on resistance and stability is particularly clear in marine salt marsh plants and seagrasses. The Chandeleur Islands provide a natural setting to investigate the inter-relationship between oiling disturbance and biodiversity in coastal ecosystems because areas in close proximity varied in their exposure to oil from the DWH spill.

Suggested Citation:

Hughes, Randall. 2016. Impact of DWH oil spill on Spartina alterniflora in the Chandeleur Islands, Louisiana, June 2015- September 2016. Distributed by: Gulf of Mexico Research Initiative Information and Data Cooperative (GRIIDC), Harte Research Institute, Texas A&M University–Corpus Christi. doi:10.7266/N7QJ7FBZ

Purpose:

We sampled across sites that varied in exposure to oiling to characterize the relationships among (a) taxonomic diversity and (b) oil exposure. We surveyed natural assemblages of marsh plants only (Spartina alterniflora), mangroves only (Avicennia germinans), and marsh plants and mangroves (Spartina and Avicennia). We will repeat the survey at the beginning and end of the growing season for two years to examine temporal variation in ecosystem responses.

Data Parameters and Units:

Location: initial group sites (A-D), Latitude: latitude taken at the site (decimal degrees), Longitude: longitude taken at the site (decimal degrees), Oiled: if location previously thought to be oiled or not from the DWH oil spill;, Habitat: vegetation assemblage where data was collected, Date: MM/DD/YYYY date that data was collected, Replicate: quadrat number (i.e. low in low marsh, high in higher marsh), Quadrat_Location: grid location of individual plots within the site, Spartina_Density_Live: live Spartina stem counts in the 25X25 cm quadrat, centered in the larger quadrat, Spartina_Density_Dead: dead Spartina stem counts in the 25X25 cm quadrat, centered in the larger quadrat, percent_Spartina: percentage of Spartina in the 0.5X0.5meter quadrat, percent_Avi_Pneumat: percentage of Avicenna pneumatophores in the 0.5X0.5meter quadrat, percent_Avi_Veg: percentage of Avicenna vegetation in the 0.5X0.5meter quadrat, percent_Bare: percentage of Bare (i.e. empty of vegetation) in the 0.5X0.5meter quadrat, percent_Batis: percentage of Batis in the 0.5X0.5meter quadrat, percent_Borr: percentage of Borrichia in the 0.5X0.5meter quadrat, percent_Sal: percentage of Salicornia in the 0.5X0.5meter quadrat, Spar_H1: first Spartina height measured in cm in 0.5x0.5 meter quarat, Spar_H2: second Spartina height measured in cm in 0.5x0.5 meter quarat, Spar_H3: third Spartina height measured in cm in 0.5x0.5 meter quarat, Spar_H4: fourth Spartina height measured in cm in 0.5x0.5 meter quarat, Spar_H5: fifth Spartina height measured in cm in 0.5x0.5 meter quarat, Avi_Pneumat_Density_live: live Avicennia pneumatophores counts in a 25X25cm quadrat, Avi_Veg_Density_live: live Avicennia vegetation counts in a 25X25cm quadrat, Avi_seed_H1: first Avicennia seedling height in cm within one meter of the center of the plot, Avi_seed_H2: second Avicennia seedling height in cm within one meter of the center of the plot, Avi_seed_H3: third Avicennia seedling height in cm within one meter of the center of the plot, Avi_seed_H4: fourth Avicennia seedling height in cm within one meter of the center of the plot, Avi_seed_H5: fifth Avicennia seedling height in cm within one meter of the center of the plot, Avi_Tree_H1: height of first Avicennia tree with branches measured in cm within one meter of the center of the plot, Avi_Tree_H2: height of second Avicennia tree with branches measured in cm within one meter of the center of the plot, Avi_Tree_H3: height of third Avicennia tree with branches measured in cm within one meter of the center of the plot, Avi_Tree_H4: height of fourth Avicennia tree with branches measured in cm within one meter of the center of the plot, Avi_Tree_H5: height of fifth Avicennia tree with branches measured in cm within one meter of the center of the plot, Avi_Tree_D1A: first Avicennia tree diameter measured in cm for the first tree, Avi_Tree_D1b: second Avicennia tree diameter measured in cm for the first tree, Avi_Tree_D2A: first Avicennia tree diameter measured in cm for the second tree, Avi_Tree_D2b: second Avicennia tree diameter measured in cm for the second tree, Avi_Tree_D3A: first Avicennia tree diameter measured in cm for the third tree, Avi_Tree_D3b: second Avicennia tree diameter measured in cm for the third tree, Avi_Tree_D4A: first Avicennia tree diameter measured in cm for the fourth tree, Avi_Tree_D4b: second Avicennia tree diameter measured in cm for the fourth tree, Avi_Tree_D5A: first Avicennia tree diameter measured in cm for the fifth tree, Avi_Tree_D5b: second Avicennia tree diameter measured in cm for the fifth tree, Redox: Oxidation Reduction Potential measured in mV, Number_Spar_Flowers: number of Spartina flowers within a meter of the center of the plot Salinity: porewater salinity in the middle of the plot measured in ppt.

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