Benthic Surveys in Culebra, Puerto Rico: comprehensive assessment of seagrass community structure and demography from transect surveys conducted in 2014 and 2022

This record provides seagrass habitat metrics collected in 2014 and 2022 at 13 monitoring stations in Ensenada Honda and Puerto Manglar in the island of Culebra, Puerto Rico, as part of Culebra's Ridge-to-Reef Monitoring and Evaluation Framework to assess the effectiveness of the NOAA strategies and actions in priority watersheds to reduce land-based sources of pollution (LBSP) impacts to the nearshore marine ecosystems of the island. Metrics include benthic cover of: total seagrasses, seagrasses by species, macroalgae, coralline algae, scleractinian corals, sponges, and sand/sediments, short shoot densities, and epiphyte relative abundance.

At each monitoring station, three replicate 30 meter transects were set up, oriented perpendicular to shoreline and extending offshore. A 0.25 m2 PVC sampling quadrat (50 cm x 50 cm) divided into 25 grid units (10 cm x 10 cm each) was used to estimate attributes of the seagrass community within each of 30 quadrats sampled contiguously (one at each meter mark) along each 30 m transect. Transect #2 was extended to the edge of the bed and seagrass community attributes were recorded within four quadrats placed equidistant from the 30 meter mark to the edge of the bed. Within each 0.25 m2 quadrat. seagrass community attributes were recorded implementing visually estimated Braun Blanquet (1932) index scores. Seagrass habitat metrics recorded included:

1- Total seagrass cover by species (i.e., Thalassia testudinum, Syringodium filiforme, Halodule wrightii, and Halophila stipulacea). Halophila was recorded as an individual seagrass species, but not considered in the total seagrass cover score.

2) Total cover of macroalgae, calcareous algae, sponge, corals, and sediment and/or rubble.

3) Epiphytic load index.

4) Short shoot densities (# shoots/100 cm2); collected within a single randomized 100 cm2 (10 cm x 10 cm) grid box within each quadrat along the 30 m transect.

These data addresses biological response endpoint monitoring; specifically, seagrass monitoring to establish baseline data with which to evaluate the proximal effects of LBSP management actions to address increased terrigenous sediment transport to Ensenada Honda and associated nearshore waters of Culebra. Seagrass is viewed as a sentinel indicator of the effects of management actions because they are located more closely to the source of pollution than the coral reef track which is ultimately the key biological response endpoint of NOAA LBSP management goals and outcomes on Culebra.

-Braun-Blanquet J (1932) Plant sociology: the study of plant communities. Authorized English translation of Pflanzensoziologie. Translated, revised, and edited by George D. Fuller and Henry S. Conard, 1st ed. McGraw-Hill, New York, NY. 439pp.

-Culebra land-based sources of pollution dashboard. Available at: https://esassoc.shinyapps.io/culebra/

Raw data include individual Braun-Blanquet index scores for seagrass community attributes within each 0.25m2 survey quadrat with the corresponding physical data which reflect the description of the site.

Genus/species identification is provided for seagrass taxa only.

The physical data for the survey quadrats include site name, latitude (decimal degrees), longitude (decimal degrees), transect, transect position (meters), and depth (feet).

While every effort has been made to ensure that these data are accurate and reliable within the limits of the current state of the art, NOAA cannot assume liability for any damages caused by errors or omissions in the data, nor as a result of the failure of the data to function on a particular system. NOAA makes no warranty, expressed or implied, nor does the fact of distribution constitute such a warranty.

We welcome the opportunity to collaborate on research issues contributing to the scientific basis for better management of marine ecosystems.

The following recommendations are for your consideration as you use this data:

1) Data analyses should take all field exigencies into account. The most effective way to do this would be active collaboration with principal investigators.

2) In all presentations, product releases, or publications using these data proper acknowledgement the individuals responsible for data collection is expected. Citing the DOI (if available) is preferred, a non-DOI example is listed below.

3) If you collect or generate data for the same study areas, CREP requests that you share relevant information on complimentary data collections.

Data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

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Observations were made by experienced benthic survey personnel who met a set of minimum standards for the community assessment and taxon identification in each region. Prior to the initiation of data collection, the divers checked and calibrated their mutual Braun-Blanquet index scores for each species of seagrass present in the quadrat.

Handheld GPS units were used to locate sites and mark site locations.

Within monitoring stations, the 2014 and 2022 survey transects were not exactly collocated.

Complete. All planned benthic cover and demographic data were collected.

Within monitoring stations, the 2014 and 2022 survey transects were not exactly collocated.

Survey methods were consistent across all sites.

The quality control occurred at two major stages - 1) data entry and 2) data management. Data entry quality control included both review and manual error correction steps.

Visually estimated benthic cover was quantified implementing the Braun-Blanquet Index scores