This document summarizes a study that aims to characterize the microorganisms associated with the sea grass Thalassia testudinum in Puerto Rico and evaluate how fecal pollution impacts the microbial composition and sea grass health. The study will collect sea grass leaf samples from sites with varying levels of contamination to analyze the epiphytic microbial communities through DNA sequencing and metabarcoding. Microbial composition will be compared between sites and related to fecal coliform levels. Sea grass productivity will also be assessed and compared between sites. The results could provide insights into new plant-microbe interactions and identify bioindicators of sea grass ecosystem health.

1. Characterization of the associated
microorganisms of Thalassia
testudinum as an indicator of sea grass
ecosystem health in Puerto Rico
By:
Manoj Saxena
Laura L Fidalgo
Ingrid Venero Vélez
Coastal Environments
Loretta Roberson, Ph.D.

2. Introduction
 SEA GRASS ECOSYSTEMS
 Primary producer
 Important for nutrient cycling Sea Grass- microbes
interaction
 Habitats of many other species
 Bio indicators of environmental conditions

3. Sea Grass Ecosystems are under threat
Global map indicating changes in sea grass area plotted by coastline regions.
RED = Rapidly decreasing
Waycott M et al. PNAS 2009;106:12377-12381
©2009 by National Academy of Sciences

4. Goals and Objectives
Hypothesis: Fecal pollution has an impact on the composition and
diversity of the epiphytic microorganisms on Thalassia testudinum leaves
effecting its growth.
Specific objectives:
a) Characterize the composition and diversity of Thalassia testudinum
associated microorganisms in three different sites that range from minimal
to heavy contamination.
b) Evaluate the relation between degree of fecal pollution and
concentration of epiphytic coliform bacteria.
c) Evaluate the biological productivity of Thalassia testudinum in each study
site.

5. Methodology
Study sites
 Water quality gradient along San Juan Estuary (PEBSJ)
 Condado Lagoon (B +quality)
 San Juan Bay (B quality)
 San Jose (C quality)
 Control area: Jobos Bay (Natural Pristine System)

6. Methodology
Microbial community structure Sea grass productivity
Data Source Data Source
 DNA from epiphytic microbial  Morphometry of blades - Leaf
communities on Thalassia leaves Area Index (LAI)
Sequencing – Meta genomics  Standing Crop Biomass - Blade
production and turnover.
Analysis Analysis
Turnover will be calculated by
Dendrogram cluster analysis- comparison
dividing standing crop by production
of microorganism community value.
composition by sea grass bed area

7. Methodology
A

8. Results and Potential Benefits
Direct
 Defines microbial community of sea grass Thalassia testudinum
 Pollution effects on microbiota composition
 Knowledge of new plant- microbe interactions
 Bio-indicator
Indirect
 Opens new research areas
 Potential discovery of new microbes species

9. Questions

10. Reference
 Celdrán, D., Espinosa, E., Sánchez-Amat, A., & Marín, A. (2012). Effects of
epibiotic bacteria on leaf growth and epiphytes of the seagrass posidonia
oceanica. Marine Ecology Progress Series, 456, 21-27. doi:
10.3354/meps09672
 Merina, M., Lipton , A. P., & Godwin Wesley, S. (2011). Isolation,
characterization and growth response of biofilm forming bacteria bacillus
pumilus from the sea grass, halodule pinifolia off kanyakumari coast. Indian
Journal of Marine Sciences, 40(3), 443-448.
 Mass mortality of the tropical seagrass Thalassia testudinum
in Florida Bay (USA) MARINE ECOLOGY PROGRESS SERIES,Vol. 71:
297-299, 1991
 Waycott M, et al. Accelerating loss of seagrasses across the globe threatens
coastal ecosystems. Proc Natl Acad Sci USA 2009;106:12377–12381
 Teena S. Michael, et al. A review of epiphyte community development:
Surface interactions and settlement on seagrass,Journal of Environmental
Biology, July 2008, 29(4) 629-638 (2008)

11. Time table
Activity Year 1 Year 2
Semester 1 Semester 2 Semester 1 Semester2
Sampling of sea X
grass leaves
Water sampling X
Water quality X
analysis
DNA extraction X
from sea grass
samples
PCR X
amplification
Sequencing X
Statistical X X
Analysis
Writing X
Manuscript