Between 1984 and 1990, SAV were
planted or transplanted into 65 sites in the upper Chesapeake
Bay and the Elk, Sassafras, and Susquehanna Rivers. Whole plants,
turions, cuttings, and rootstocks of seven different species
were evaluated during all four seasons. Transplanting locally
growing whole plants on the same day that they were collected
was overwhelmingly the most successful procedure, when conducted
between May and early August. Vallisneria americana, Heteranthera
dubia, and Ceratophyllum demersum were the species with which
we had the greatest success. Myriophyllum spicatum was employed
successfully at several sites to provide shelter for the native
transplants. It was never introduced to an area in which it didn't
already exist. Vallisneria americana was the most frequently
and successfully employed spec
ies.
Of the 65 sites, SAV survival and expansion was moderate at 12,
and excellent at 9. From these sites three main criteria were
derived for optimal restoration site selection; a mean water
depth of 0.75 to 1.2 meter, sediments of sandy loams or loams
(organic matter of 1%-5%), and some form of sheltering influence.
The shelter may be in the form of an existing shoal, spit or
breakwater, or it may be installed (snow fence, chicken wire,
relocated course plants such as milfoil, etc.). The purpose of
protection is energy reduction and/or protection from herbivory.
The ideal transplant configuration was found to be high density
meter square plots, alternating with bare plots. High density
is defined as from 60 to 160 plants per square meter. The range
exists because of the harvest and transplant methodology. When
plants are collected, they are removed by inserting the hands
into the sediments and lifting while rapidly shaking the sediments.
This allows for the removal of whole plants and intact stolons,
which may have ten or more plants attached. These are not separated
until planting, when they are divided into stolons of from one
to five plants or plantlets, depending on their size. Each stolon
group is then gently wrapped in a circle and carefully inserted
into the sediments, 20 cm on center. While the larger plants
were found to survive and reproduce well, smaller plants were
found to be more viable when remaining connected at the stolon.
The high planting densities provide increased survival and the
open spaces allow for space to grow into. The open areas usually
closed up in two to three years. Time release fertilizers were
found to benefit plants in sandier substrates, and only for the
first year.