This study evaluated the impact of pumping fresh water into Biscayne Bay near the Deering Estate to address rising salinity levels. Macroalgae and seagrass communities were monitored as indicators of ecological change. After fresh water flooding, sites separated into distinct pre- and post-flooding clusters. Relative frequencies suggested a shift toward more brackish-tolerant species and decline in marine species. Nutrient analysis found higher nitrogen levels in macroalgae like Ulva ohnoi and in seagrasses near fresh water sources, indicating flooding increased nutrient availability. Continued monitoring will compare results to previous studies to further assess flooding impacts.

1. Fernandez, C.| Montenegro, K. | Collado-Vides, L. | Florida International University
Introduction
Methods
Conclusions
Acknowledgements
This project had help and contribution from Tiany Hernandez, Lowell Iporac, Christian
Lopes, Madison Machado, and Ligia Collado-Vides.
Work Cited-
Juanes, J. A., Guinda, X., Puente, A., and Revilla, J.A. (2007) Macroalgae, a Suitable Indicator of the Ecological Status of Coastal Rocky Communities in the NE
Atlantic.
Lirman, D., Thyberg, T., Santos, R., Schopmeye, S., Drury, C., Collado-Vides, L., Bellmund, S., Serafy, J. (2014) SAV Communities of Western Biscayne Bay, Miami,
Florida, USA: Human and Natural Drivers of Seagrass and Macroalgae Abundance and Distribution Along a Continuous Shoreline
Lirman, D., Bellmund, S., Browder, J., Serafy, J. (2016) 4th Annual Report: IBBEAM – Integrated Biscayne Bay Ecological Assessment and Monitoring
Results
Nutrient Analysis
15cm x 15cm Quadrat randomly placed at Site 7. Top and bottom photo were
taken in January 2016 and April 2016, respectively.
•
The construction of the Deering Estate Flow Way is a pilot study to evaluate the impact of pumping
more fresh water into the bay in the Biscayne Bay coastal environment at Deering Estate in
response to rising levels of salinity and marine conditions.
•
Macroalgae and seagrasses can be effective tools to assess ecological quality based on community
assemblages (Juanes et al. 2007)
•
Seagrass and macroalgae assemblages will be able to represent changing ecological effects on the
coastal environment near Deering due to the pulse flooding events from the Flow Way experiment.
•
Dominance of Batophora, Acetabularia, Caulerpa, Laurencia, Halodule, and other brackish-tolerant
species are characteristics of estuarine, brackish waters (D. Lirman et al. 2014).
•
By comparing current findings to a similar study conducted before the construction, data will
demonstrate the difference that salinity has on community assemblages and nutrient availability
through tissue content.
•
As freshwater is flooded, an increase in nutrients and a decrease in salinity is expected in our
coastal sites. A shift from a combination of marine and brackish water species towards a
dominance of brackish-water tolerant species is expected, and a signature with high nutrients
compared with years before the flooding.
•
The MMRL has a collection of data for the Deering Estate
that serves as a reference to evaluate the impact of the
flooding experiment conducted in Deering Estate.
•
Each site (18 for 2009-2010 survey and 9 for 2015-2016
survey) was selected to represent different coastal habitats.
•
20 random pictures were taking at each site and the best 10
were analyzed for the diversity of algae present.
•
Cluster analysis followed by a MDS (Multidimensional
Similarity) were applied to the relative frequency data.
•
Data was normalized to the number of sites.
•
Macroalgae and seagrass samples were collected at each
site for identification to the lowest taxon..
•
Salinity data was provided by Biscayne National Park.
•
Seagrass and algae samples were collected, cleaned form
epiphytes, dried, and ground. Tissue nutrient content was
analyzed for N and δ15N‰ at the Isotope analysis lab at
Florida International University.
•
Information from this study is essential to
determine the effectiveness and impact of
freshwater pulse flooding tactic in sites close to
shore in Biscayne Bay.
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Figure 1: Relative Frequencies of Seagrass Species. The dominant
Thalassia testudinum shows a drop after the flooding
Figure 3: Cluster analysis displaying hierarchal levels of similarity
using relative frequencies of algal species per time sampled. 2009-
2010 sampling periods are separate from 2015-2016.
Map of sites at Deering Estate. Site 5 (N 25° 36.650’, W 080° 18.417’)
is located at the mouth of the C-100 Canal. Site 9 (N 25° 36.063’, W
080°18.087’) is located at the mouth of Cutler Creek.
represent sites in region used by previous study.
Figure 4: MDS of relative frequencies of algal species, comparing algal
composition across time. All seasons from 2009-2010 form another
group. November 2015 is isolated.
Figure 5: Average Salinity on site D62 (BNP).
Simpson’s Diversity Index was calculated to measure diversity
between the species found in the 2009-2010 time period and
the 2015-2016 time period.
The diversity values for the two periods were 0.925 and 0.918.
•
Salinity did not change in the Deering Estate area. However, Lirman et al. (2016) show that the rest
of sites along the coast of the Bay have suffered an increase in salinity due to a strong drought.
The flooding kept salinity in brackish levels at Deering Estate.
•
Sites before and after the flooding experiment were clearly clustered separately .
•
The relative frequency of macroalgae and seagrass found suggest a community shift towards a
greater dominance of estuarine species and a decline in marine species in the area.
•
The overall pattern found for species values was maintained along the three seasons analyzed.
Ulva ohnoi, or Ulva (Enteromorpha form) are the species with the highest values of δ 15N
compared with the rest of the other species.
•
Following seagrass data, site 7 localized at the exit of the rehydration creek show the highest
values δ 15N in the tissue of both Thalassia and Halodule. The values are extremely high
compared with other sites using the same species. Site 7 has a clear input of nutrients with a
strong anthropogenic signature.
•
As more data is collected, nutrient content will be compared to data in previous study. Based on
this study, Ulva species nutrient content should be gathered as it is potential massive growing alga
and can be used as an indicator for high nutrient discharge.
Monitoring Algal and Seagrass Species Diversity Changes in a Freshwater-Flooded,
Coastal Wetland
Figure 2: Relative Frequencies of Seagrass Species.
Halimeda incrassata shows a drop after the flooding
Figure 6 Seasonal Variability of Nutrient Content. N and δ15N%
values are high, particularly for species such as Ulva ohnoi.
Figure 7: Spatial Variability of Nutrient Content