Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • BCO-DMO Processing Description
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

Sampling details

Small seagrass plots (0.25m2, all comprised of one species, Thalassia testudinum) were established at 9 shallow sites in the western Atlantic. Each plot was assigned to one of two treatments (n=5/treatment): (1) control plot or (2) plots with the canopy fully clipped. Plots were maintained for 12 months, and at the end, seagrass biomass cores (15cm in diameter) were used to harvest belowground plant material in each plot. Belowground biomass (rhizomes only) were separated from all other material, dried to a constant weight in a 60C oven and ground to a fine powder. This belowground material was then sent to the UC Davis plant lab for the analysis of total soluble carbohydrates (glucose, fructose, sucrose) following the protocols of Smith (1969).

Total Glucose for Total Nonstructural Carbohydrate (TNC) and Startch Methods Summary

The dataset shows soluble carbohydrates expressed as a percentage of belowground dry mass. Nonstructural carbohydrates are those that can be accumulated and then readily mobilized in order to be metabolized or translocated to other plant parts. This method quantitatively determines the amount of the total glucose following enzymatic hydrolysis. Total non-structural carbohydrates (TNC) is the sum of total glucose, free fructose and free sucrose. Starch is the total glucose minus the free glucose multiplied by 0.9. The free carbohydrates are determined by a separate analysis. The samples for total glucose are enzymatically hydrolyzed at 55°C with amyloglucosidase for 12 hours and analyzed by HPLC with mass selective detection. The analysis uses a Phenomenex Luna NH2 (250 mm x 4.6 mm) HPLC column at a flow rate of 2.75 mL min-1 acetonitrile:water (78:22).

The method has a detection limit of 0.5% and is reproducible to within 10% (relative).

Smith, Dale. Removing and Analyzing Total Nonstructural Carbohydrates from Plant Tissue. Wisconsin Agric. Exp. Sta. Res. Report 41. 1969.

Site location details

ANDR: Andros, Bahamas (24°53'54.3" N, 77°54'25.2" W)

BERM: Bailey's Bay, Bermuda (32°15'49.9" N, 64°49'50.5" W)

BOCA: Bocas Del Toro, Panama (9°21'05.8" N, 82°15'27.8" W)

BONA: Lac Bay, Bonaire (12°06'44.3" N, 68°13'42.0" W)

CARR: Carrie Bow Cay, Belize (16°49'24.8" N, 88°06'16.2" W)

CAYM: Little Cayman, Cayman Islands (19°40'14.6" N, 80°03'21.3" W)

CORP: Corpus Christi, TX (27°55'47.9" N, 97°02'05.2" W)

CRYS: Crystal River, FL (28°42'50.4" N, 82°49'08.4" W)

ELEU: Eleuthera, Bahamas (25°27'53.5" N, 76°37'35.8" W)

GALV: Galveston, TX (29°02'41.8" N, 95°10'15.7" W)

JOES: St. Joe's Bay, FL (29°42'05.0" N, 85°19'34.6" W)

NAPL: Naples, FL (26°29'48.6" N, 82°09'40.0" W)

PUER: Puerto Morelos, Mexico (20°52'04.5" N, 86°51'35.4" W)

- removed units from column headers
- converted latitude and longitude columns from degrees, minutes, seconds to decimal degrees
- latitude and longitude values rounded to 6 degrees of precision
- spaces removed from column names and replaced with underscores ("_")
- special characters removed from column names
- split the season field ("Spring 2019") into two separate fields for season ("Spring") and year ("2019")

NSF Award Abstract:
The warming of temperate marine communities is becoming a global phenomenon, producing new biotic interactions that can result in a series of cascading effects on ecosystem structure. For example, the poleward expansion of herbivore populations can lead to the consumption of habitat-forming vegetation, which alters the ecological services provided by coastal environments (a phenomenon known as tropicalization). Many of the habitats at risk, such as kelp forest and seagrass beds, provide foundational habitat that supports complex food webs. Seagrass meadows along the Gulf of Mexico are currently experiencing an influx of tropical grazers, however a integrated understanding of how these communities might ultimately respond is lacking. This project describes the first experiment to quantify the disruptive effect of tropicalization on the ecology of a widely-distributed seagrass. A major contribution of this project will be the development of a seagrass research collaborative network to serve as a platform for broader scientific inquiry and future collaboration. The collaboration spans a total of 11 institutions, and this network will foster extensive collaborations among junior and senior scientists, as well as many undergraduate and graduate students. Given the geographic scope of this work, the research team will further pursue outreach opportunities across the network by hosting a series of public lectures and science café events promoting topics in marine ecology and conservation.

This study will develop a large-scale manipulative experiment across the Caribbean, premised upon a comparative network of 15 marine sites, which will quantify how temperature and light interact with grazer effects on the dominant tropical seagrass, Thalassia testudinum. Sites have been selected along a latitudinal gradient (from Bermuda to Panama), such that light and temperature vary, allowing the investigators to test for the effects of abiotic factors on the ecological effects of increased grazing (tropicalization simulated via artificial leaf clipping). At each of the 15 marine sites, grazing treatments will be crossed with nutrient manipulations in a factorial design for 18 weeks, after which seagrass structure and functioning will be assessed via measurements of areal productivity, shoot density, aboveground biomass, and carbohydrate storage. Experiments will be conducted both in the summer and winter seasons, when abiotic gradients are at their weakest and strongest, respectively. Emerging statistical techniques in hierarchical mixed modeling and structural equation modeling will further allow for integration of experimental and observational data.