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Marine Ecology Progress Series

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MEPS 427:233-246 (2011)  -  DOI:

Quantifying freshwater-induced fragmentation of submerged aquatic vegetation communities using a multi-scale landscape ecology approach

Rolando O. Santos1,*, Diego Lirman1, Joseph E. Serafy1,2

1Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, Florida 33149, USA
2NOAA, National Marine Fisheries Service, Southeast Fisheries Science Center, 75 Virginia Beach Drive, Miami, Florida 33149, USA

ABSTRACT: Species composition and abundance of nearshore submerged aquatic vegetation (SAV) of Biscayne Bay, Florida, USA, are influenced by pulsed delivery of fresh water from canals that drain the Everglades and adjacent urban and agricultural areas. In the present study, we evaluated whether freshwater inflows were correlated with the spatial structure (e.g. patchiness, fragmentation, spatial heterogeneity) of SAV. SAV patches were delineated using aerial photographs and object-based classification, and the SAV seascape structure was characterized at different spatial scales (200 m to 1 km from shore) using landscape metrics. The area closest to shore (200 m buffer) was identified as the area with the highest heterogeneity in SAV seascape structure; areas beyond this buffer did not differ significantly in landscape metrics. Within the 200 m buffer, SAV seascapes clustered into continuous SAV structures (CSS) and fragmented SAV structures (FSS). CSS had a higher proportion of the benthos covered by larger SAV patches with simpler boundaries. FSS had a higher density of smaller SAV patches with complex shapes and a lower proportion of the substrate covered by SAV patches. Neither structure type was distributed randomly along the shoreline. CSS were prevalent in areas with high and stable salinity. FSS were prevalent in areas influenced by freshwater discharges where salinity is low and variable, highlighting how the pulsed release of fresh water may adversely influence the structure of SAV seascapes, potentially resulting in fragmentation of the benthic community. Thus, this seascape approach provides a tool to assess the influences and effectiveness of the ­Everglades Restoration Project in Biscayne Bay.

KEY WORDS: Submerged aquatic vegetation · Seagrass · Landscape ecology · Seascape structure · Salinity patterns · Water-quality influences · Habitat fragmentation · Everglades restoration

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Cite this article as: Santos RO, Lirman D, Serafy JE (2011) Quantifying freshwater-induced fragmentation of submerged aquatic vegetation communities using a multi-scale landscape ecology approach. Mar Ecol Prog Ser 427:233-246.

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