Abstract:

This dataset contains images and productivity data from a yearlong mesocosm experiment. We included three plant composition treatments: Spartina alterniflora only, Avicennia germinans only, and S. alterniflora and A. germinans mix (SA+AG). In addition, within the treatments containing S. alterniflora, we examined the effects of plant genotypic identity and diversity using 1 genotype (monoculture) or 3 genotypes (3 genotypes randomly selected from a pool of 6 genotypes; polyculture). In the two oil-exposed mesocosms, we used a 5-day repetitive dosage procedure, with each experimental tub receiving an initial 1 L m-2 of a 1:1 oil-water mixture. In the two non-oiled mesocosms, seawater was added using the same procedure. During each of our four post-oil sampling events (Dec. 2015 - Sept. 2016), we quantified plant survival, growth, morphology, and production of both Spartina and Avicennia as a function of plant diversity and oiling. Related data can be found in GRIIDC datasets R4.x262.000:0025, R4.x262.000:0026, and R4.x262.000:0035.

Suggested Citation:

A. Randall Hughes, J. Cebrian, K. Heck, J. Goff, T. C. Hanley, W. Scheffel, R.A. Zerebecki. 2018. Effects of oil exposure, plant species composition, and plant genotypic diversity on salt marsh and mangrove assemblages: A mesocosm study from September 2015 to 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/N7K93629

Publications:

Hughes, A. R., Cebrian, J., Heck, K., Goff, J., Hanley, T. C., Scheffel, W., & Zerebecki, R. A. (2018). Effects of oil exposure, plant species composition, and plant genotypic diversity on salt marsh and mangrove assemblages. Ecosphere, 9(4), e02207. doi:10.1002/ecs2.2207

Purpose:

To test the effects of plant species identity and composition (A. germinans, S. alterniflora), as well as plant genotypic diversity (S. alterniflora only) on the response of coastal wetlands to oiling disturbance.

Data Parameters and Units:

AG_SA_repeatedmeasures_includingRawdata(1).csv: Mesocosm: Large cattle container (1-4) Oil: Refers to if the mesocosm received oil or not Tub: Individual tub (1-25) within each mesocosm that plants were planted in AG present: Yes, if Avicennia germinans was planted in Tub SA present: Yes, if Spartina alterniflora was planted in Tub Species trt: Species treatment in Tub; One of three combinations: AG only (Avicennia only), SA only (Spartina only) or SA and AG (both Spartina and Avicennia planted) Genetic trt: In tubs that contained Spartina (i.e. SA only and SA + AG), Spartina genotypic diversity was manipulated as either Poly (refers to polyculture of 3 different genotypes planted) or Mono (refers to monoculture of a single Spartina genotype planted) Plant treatment: Combination of Species trt and Genetic trt Spartina ID: If Spartina was present in tub, this indicates which genotypes were planted (1 if monoculture and 3 genotypes separated by commas if polyculture) Date: Refers to sampling date SA live: number of live Spartina stems in tub SA live per transplant: number of live Spartina stems divided by the number of Spartina transplants planted initial (i.e. 3, or 6) SA H1-H6: height of individual Spartina stems (H1) in cm SA avg ht: average height of 5-6 randomly chosen Spartina stems (H1-6) # AG transplant: number of Avicennia transplant originally planted (i.e. 0, 3, or 6) AG H1-6: height of individual Avicennia transplants (cm) AG Leaf 1-6: number of leaves on individual Avicennia transplants AG Branch 1-6: number of branches on individual Avicennia transplants AG D1 1-6: tree diameter one for each individual Avicennia transplants AG D2 1-6: tree diameter two for each individual Avicennia transplants AG avg ht: average Avicennia height (of all live individual in tub) AG leaves: average number of Avicennia leaves per individual AG crown: average Avicennia crown area. Crown area was calculated using the equation for an ellipse and measurement of crown diameter in two perpendicular directions at the top of the tree for each individual AG volume: average Avicennia crown volume. Crown volume was calculated as crown area * height for each individual AG leaf area: average Avicennia leaf area. Estimated using a leaf tagging technique developed by Onuf et al. (1977). 5 leaves from each of 2 seedlings per tub were tagged and photographed in September 2015 and then re-photographed in Dec. 2015, July 2016, and Sept. 2016. All images were processed with ImageJ to estimate leaf area. AG survival: proportion of live Avicennia seedlings per tub AG_SA_indiv_timepoints_mesocosm_2015_2016.csv: Mesocosm: Large cattle container (1-4) Oil: Refers to if the mesocosm received oil or not Tub: Individual tub (1-25) within each mesocosm that plants were planted in AG present: Yes, if Avicennia germinans was planted in Tub SA present: Yes, if Spartina alterniflora was planted in Tub Species trt: Species treatment in Tub; One of three combinations: AG only (Avicennia only), SA only (Spartina only) or SA and AG (both Spartina and Avicennia planted) Genetic trt: In tubs that contained Spartina (i.e. SA only and SA + AG), Spartina genotypic diversity was manipulated as either Poly (refers to polyculture of 3 different genotypes planted) or Mono (refers to monoculture of a single Spartina genotype planted) Plant treatment: Combination of Species trt and Genetic trt Spartina ID: If Spartina was present in tub, this indicates which genotypes were planted (1 if monoculture and 3 genotypes separated by commas if polyculture) Dec 2015 SA flowers: Number of Spartina flowering stems in each tub in December 2015 Dec 2015 SA seeds: Total number of seeds from all Spartina flowering stem in December 2015 Sept 2016 SA Above biomass: Average aboveground Spartina biomass (g) in September 2016. Biomass was estimated by collecting two sediment cores (5 cm diameter and 10 cm deep), rinsing away sediment and splitting biomass into above (shoots and leaves) and below (roots and rhizomes), then dried for 72hrs at 60C. Sept 2016 SA Root biomass: Average belowground Spartina root biomass (g), see above for methods Sept 2016 SA Rhiz biomass: Average belowground Spartina rhizome biomass (g), see above for methods Sept 2016 SA flower: Number of Spartina flowering stems in each tub in September 2016 Sept 2016 SA seeds: Total number of seeds from all Spartina flowering stem in September 2016 Sept 2016 Redox: Sediment oxidation reduction potential measured in mV using a Thermo Scientific Orion Star Series A321 Portable pH meter at depth of 5 cm. Sept 2016 Temp: Sediment temperature (C), measured at same time and methods as Redox Sept 2016 SA Below biomass: Average total belowground Spartina biomass (g), combination of both roots and rhizome, see above for methods Sept 2016 AG Below biomass: Average total belowground Avicennia biomass (g), see above for methods Dec 2015 SA leaf growth: Average Spartina leaf growth in December 2015. Similar methods to AG leaf area above Sept 2016 SA leaf growth: Average Spartina leaf growth in September 2016. Similar methods to AG leaf area above Mangrove_productivity_image.csv: Date: Date that samples were collected (2015 and 2016 only) Mesocosm: Number assigned to each mesocosm at the beginning of the experiment. Mesocosms 2 and 4 received oil, 1 and 3 were controls Replicate: Replicates within each mesocosm. Numbers systematically assigned M Plant Treatment: Mangrove treatment assigned to the replicate. "AM and SA" denotes Black Mangrove and Spartina alterniflora mixed together in the same replicate. "AM ONLY" denotes that only Black Mangrove is present in the treatment M Type: Notes replicate mangrove tree measured within the treatment replicate Comments: Comments cultivated during leaf tagging and image analysis Image File Name: The file name assigned to each image taken Leaf No.: The number assigned to a leaf on each replicate tree. Leaf 1 is a randomly chosen leaf near the base of the tree, and subsequent leaves are assigned in order as you move vertically (i.e. the "highest leaf" is leaf 5). Leaf Area: Area of the leaf determined by image analysis

Methods:

Mesocosms 2 and 4 received oil, 1 and 3 were controls. A 30 L sample of Louisiana sweet crude oil was procured and weathered outdoor using bubble aeration for 5 days resulting in approximately 20% volume lost. Oiling began Oct. 6, 2015. A 5 day repetitive dosage procedure was used for the oiling treatment. Each mesocosm received an initial 1:1 oil to seawater mixture (350:350 mL). This was allowed to percolate through the sediment and drain into a collection tray. The collected mixture was then reapplied the following day. Control treatments received 700 mL of seawater only. No additional applications of oil were conducted after the initial oiling. All images were processed with ImageJ software.

Provenance and Historical References:

Onuf CP, Teal JM, Valiela I (1977) Interactions of nutrients, plant growth and herbivory in a mangrove ecosystem. Ecology 58:414-526

Individual Files: