This dataset includes seagrass leaf morphometrics (Thalassia testudinum) from 650 experimental plots distributed across 13 sites in the Western Atlantic. Leaf morphology (average widths) were collected at two timepoints, once at the end of the 2018 summer growing season and again at the end of the 2019 winter season. Leaf width is reported as an average of all leaves across 4-6 harvested seagrass shoots in each experimental plot. Sites include: Bocas del Toro, Panama; Bonaire; Little Cayman, Cayman Islands; Carrie Bow, Belize; Puerto Morelos, Mexico; Andros, Bahamas; Eleuthera, Bahamas; Corpus Christi, Texas; Galveston, Texas; Naples, Florida; Crystal River, Florida; St. Joes, Florida; and Bermuda.

Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • BCO-DMO Curation Notes
  • Problem Description
• Data Files
• Related Datasets
• Parameters
• Project Information
• Funding

Sampling details

50 small seagrass plots (0.25m2, all comprised of one species, Thalassia testudinum) were established at 13 shallow sites in the Western Atlantic. Each plot was assigned to one of ten treatments comprising a factorial manipulation of caging, nutrient supply, and canopy clipping: (1) control (2) partial cage (3) full cage (4) added nutrients (5) added nutrients + partial cage (6) added nutrients + full cage (7) full cage + half canopy clip (8) full cage + full canopy clip (9) full cage + added nutrients + half canopy clip (10) full cage + added nutrients + full canopy clip. Leaf morphometrics (only leaf width) was measured at two time points (once at the end of summer 2018 and again at the end of winter 2019). The dataset reports average leaf width as measured across all leaves from 4-6 harvested seagrass shoots from each plot.

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)

Curation Actions Performed on Data
- Loaded Leaf_width.xlsx (sheet 1, xlsx format, floating point error adjustment applied, formatting preserved, missing values "" and "nd" set), named table 917968_v1_TEN_Leaf_morphometrics
- Renamed columns: "latitude (D,M,S)" to latitude, "longitude (D,M,S)" to longitude, "leaf.width (mm)" to leaf_width
- Converted latitude from degrees-minutes-seconds string format (with N directional) to decimal degrees, output column latitude_decimal_degrees
- Converted longitude from degrees-minutes-seconds string format (with W directional) to decimal degrees, output column longitude_decimal_degrees
- Reordered columns to: site, latitude, longitude, latitude_decimal_degrees, longitude_decimal_degrees, season, plot, clipping, nutrients, cage, leaf_width
- Split season column on space delimiter into season and year columns, deleted original season input column
- Reordered columns to: site, latitude, longitude, latitude_decimal_degrees, longitude_decimal_degrees, season, year, plot, clipping, nutrients, cage, leaf_width
- Set column types: cage, clipping, latitude, nutrients, longitude, season, site as string; latitude_decimal_degrees, leaf_width, longitude_decimal_degrees as number; plot, year as integer
- Rounded leaf_width to 1 decimal place, preserving trailing zeros
- Rounded latitude_decimal_degrees and longitude_decimal_degrees to 6 decimal places, preserving trailing zeros
- Deleted original latitude and longitude (D,M,S) string columns
- Renamed latitude_decimal_degrees to latitude and longitude_decimal_degrees to longitude
- Data file saved as 917968_v1_TEN_Leaf_morphometrics.csv

Curation Actions Performed on Metadata
- Standard FAIR metadata curation principles have been applied to the metadata associated with this dataset where possible.

Known Issues [Potentially Impacting Reuse]
- Data file and metadata as presented have not been validated by the dataset author.
- Supporting citations for papers associated with the methods used for the generation of this data have not been provided.

No issues related to this dataset have been disclosed by the dataset author.

Website: https://marinegeo.si.edu/research/research-in-action/underwater-meadows-and-resilient-seas

Coverage: Western Atlantic

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.