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In recent decades populations of native submerged aquatic vegetation (SAV) have declined in Florida spring runs due to sharp increases in benthic filamentous algae and a suite of other anthropogenic changes. Though managers are attempting to revegetate many degraded spring runs, sediments in these sites are often highly reduced due to high sediment organic matter content and thick mats of benthic algae. In these reduced conditions, phytotoxic compounds such as hydrogen sulfide can potentially hinder plant establishment and growth.
In this study we compared three different methods for planting eelgrass (Vallisneria americana) in a formerly vegetated section of a Florida spring run: seed broadcasting, ramet planting, and sod installation. For each planting method, we established plots in organic sediments covered in benthic algae, in mineral sediments free of benthic algae, and in sediments where benthic algae and organic matter had been recently removed via hand dredging (n=3). To determine which management approach was best for reestablishing eelgrass, we monitored sediment redox potential and plant growth for four months. Preliminary results show that biomass in both ramet and sod plots had increased after one month in both the mineral sediment treatments and in treatments where benthic algae was removed. Conversely, many ramets planted in benthic algae/organic treatments have senesced after only a few weeks. When planting eelgrass in sites high in organic matter, managers can increase planting success by first dredging and/or removing benthic algae from sediments. In sites where this is not possible, installation of eelgrass sod with an established root system may act as a viable planting alternative.
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