Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Data Files
• Related Datasets
• Parameters
• Instruments
• Project Information
• Funding

Seagrass biomass sampling was conducted in the Western Atlantic at the following locations: 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. 

Field collection procedures:
Haphazardly select 10 locations to sample with a PVC core. At each location, carefully place the PVC core (15cm diameter) on the sediment surface. It is extremely important to check both the inside and outside edges of the PVC ring to ensure that seagrass leaves are not trapped underneath. If there are leaves inside the ring that originate from shoots outside the PVC ring, carefully pull these leaves out. Conversely, if there are leaves outside the PVC ring that originate from shoots inside the ring, carefully pull these leaves inside. Only after this has been completed, insert the ring 10cm into the sediment while simultaneously twisting the core to sever belowground rhizomes. Carefully remove the core and place all captured aboveground and belowground vegetative biomass into a mesh bag. Gently shake the bag underwater to remove loosely attached sediment.

Lab processing procedures for morphometric data:
In the lab, take each mesh bag and carefully transfer its contents into a separate tub filled with freshwater. Gently agitate the seagrass material in the freshwater to further remove loosely attached sediment. Record the total number of Thalassia shoots, any evidence of grazing bite marks (number of grazing marks per shoot) and a visual estimate of epiphyte loading. Arrange all shoots on a smooth surface (e.g. glass plate) and record the length in mm of the longest leaf from each shoot.

BCO-DMO Processing:
version 1 (2021-05-24):
- converted date format to YYYY-MM-DD;
- replaced "NA" with "nd" to indicate "no data";
- added latitude, longitude, and site_name fields from the site coordinates data file;
- converted latitude and longitude to decimal degrees;
- removed commas from the notes and site_name columns.

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.