Practical applications derived from three growing seasons estuary rehabilitation project : adopt a beach

[From the U.S. Government Printing Office, www.gpo.gov]

PRACTICAL APPLICATIONS DERIVED
FROM THREE GROWING SEASONS

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ESTUARY REHABILITATION PROJECT
ADOPT A BEACH
Qr JUNE 1989 REPORT

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.P73
1989
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The preparation of this report was financially aided through a grant from the
Washington State Department of Ecology with funds obtained from the National
Oceanic and Atmospheric Administration, and appropriated for Section 306 of
the Coastal Zone Management Act of 1972.

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INTRODUCTION

This report provides practical information on the planting intertidal species
cornmon to Puget Sound estuaries. The information is based on several Adopt a
Beach projects that have been monitored during two and three monitoring
season starting in the spring of 1987. Some of the information is also based on
field observations collected by the author and volunteers who have assisted
with the project as well as on conversations with scientists specializing in

wetlands. Obviously, it is not meant to be a compendium of the state of the art
on planting projects in Puget Sound, it merely adds information to this body of
knowledge which is in great need of being compiled in a document.

PART ONE: PRACTICAL ASPECTS OF PLANNING AND DEVELOPING A PROJECT is
broadly applicable to planting a variety of estuarine species with the exception
of eelgrass which is treated separately in PART TW0.

PART TWO: PLANTING BULLRUSH, GRASS AND EELGRASS is based on the
experience of planting Scirpus Validus (Softsiem Bullrush), Scirpus Martitimus
(Maritime Bullrush), Distichlis spicata (Saltarass) and Zostera marina
(eelgrass). The information concerning the first three species is applicable
but not verified to some of the other common emeracrit intertidal species of
Puget Sound. The information on eelgrass is obviously limited to the unique
growing conditions of that species.

This report begins with a summary of the projects that serve as source
information.

DESCRIPTION OF THE PROJECTS THAT SER -V7 ED AS SOURCE
INFORMATION FOR THIS REPORT

JETTY ISLAND, EVERETT
The coal of this project is to study the colonization by Distichlis spicata of
newly created sites that duplicate the tidal elevations and soil salinity levels
tolerated by this species. Specifically:

1. To compare the colonization rate of plots planted in different
densities.

2. To compare the colonization rate. of plots using different
transplanting treatments.

3. To compare the colonization rate of plots by observing the interaction
between densities and treatments.

n 1, 11 C q C s:

For anv single treatment, the greater the density, the more rapid the
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colonization of plots, as measured bv cover.

2. For any single treatment, the less disturbed the root mass of the transplants,
the more rapid @he colonization of plots, as measured by cover.

I
For any single treatment, the laraer the root mass of transplants, the. more
rapid the colonization of plots, as measured by cover.

PADILLA BAY EELGRASS NURSERY
This project, located in the Padilla Bay eelgrass meadows, compares eelgrass
recovery patterns in donor plots and growth patterns in recipient plots, both
types of plots being replicates of one another. Without a simple way to
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quantify the recovery rate of a harvested eelgrass bed, it is difficult to know
the extent of dama,,e that harvestina has on the bed. The project also
compareS harvesting methods in order to identify the least damaging, one.
Finally, eelgrass has been planted in pots to see if 1)potted eelgrass grows and
2) it can 6 transplanted successfully.

SMITH COVE EELGRASS PROJECT, SEATTLE
The Smith Cove eelgrass project involves the establishment of an eelgrass bed
in an urban environment usincy a small hi<,h ran-incy Zosteria marina
ecotype (up to +3 ft above mean lower low water) transplanted from a West
Seattle beach. The project is located on a tideflat adjoining a slip for deep draft
vessels (Pier 91) in the Magnolia section of Seattle.

The project has the following objectives: 1) to improve the low intertidal
habitat of a tideflat adjoining a mitigation project of the Port of Seattle and to
monitor the effectivess of planted eel-rass in att.ractin- marine organisms, 22)
to test the effectiveness of different methods of harvesting and planting (plugs
and bare roots, anchored and non anchored plants) and 3) to monitor the
dynamics of a planted eelgrass bed.

TERMINAL 108, DUWANIISH WATERWAY, SEATTLE
The goal of this project is to establish afringe marsh of intertidal species that
are compatible with the area, and to observe its trends over several growing
seasons. The results will help determine the success of transplanting plugs of
Scirpus validus from an adjacent area as a means of propagatine this species.
The measure of success will be the comparison of plant charactaristics of the
project plot with those of the donor site over several growing seasons.

ROUTE 509 MARSH, DUNN7 AMISH WATERWAY, SEATTLE
The -Loal of this project is to reve-getate plots in a damaged area having no
veaetation cover with a species indigenous to this marsh (Scirpus maritimus)
an@ to compare the experimentally vegetated plots with adjacent control plots
that are allowed to colonize naturafly.

PART ONE: PRACTICAL ASPECTS OF PLANNING, DEVELOPING
AND MONITORING A PROJECT

Gro,@@,in- Intertidal species serves a variety of purposes: mitigation, restoration,
creation or enhancement of a habitat. Whatever the purpose, no project
should be undertaken without first deciding the functions and values it
attemps to create, replace or compensate for. This report assumes that the
purpose of the project and its functions and values have been well established
and that suitable candidate sites have been selected.

DETERNUNING SITE SUITABILITY
Elevation
Tidal elevation is key to the success of emergent plai-its. There is a tendency to
plant to low. A rule of thumb is to plant between the Mean Higher High Water
mark (1\4HHW) and the Mean Lower High Water mark (MLHW). Establishing
these elevations is relative]), easy: Check the tide tables and observe the site
when there is a hi2h tide of 11.5 ft and again when there is a tide of 9.5 ft.
Mark the reach for both tides. Plants will usually grow within one vertical
foot of these two elevations but not as well. So the acceptable range is four
vertical feet and the optimal range is two vertical feet.

Substrates
With the exception of Salicornia, intertidal plants do not grow well in rocky,
gravelly and hard substrates and combinations thereof. Suitable sites often
@ave these bottoms. The r-ule of thumb to duplicate the growing conditions of
the reference site or of the donor site is poorly applicable here because these
areas. are usually rich in organic substrates. For information on soil
conditions, please refer to PART TWO.

Exposure
It t'he site is exposed to a long fetch, it will be swept by waves; this is probably
why not much is growing there: it is simply too exposed. Intertidal species
need to be protected from waves. One of the greatest causes of project failure is
wave exposure.

Salinitv
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It is important to understand intertidal emergent species as fresh water plants
that are salt tolerant. The rule of thumb is that plants that are found both in
fresh water and salt water will usually tolerate salt concentrations no greater
than 5ppm while those that are only found in Puget Sound will tolerate 20ppm.

It is important to record two salinities: surface water salinity and ground
water salinity. The later is more crucial since it is the one that irrigates the
roots. Donor site salinity should be roughly identical to recipient site salinity.
If plants are grown from seed and irrigated with fresh water, plant a few
pioneers first to assess their adaptability.

SITE PREPARATION
Soil 12renaraiion
As indicated earlier, project site soils are often poor. Fertilizing soils with
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or2anic matter has been attempted on one Adopt a Beach project at
considerable effort. Glacial till was broken up and mixed with pea gravel and

sandy loam. The pea gravel layer helped the sandy loam-silt mixture from
washing out. Salicornia planted in this mix thrived more than salcornia
planted in brokcn-up till. It is important to break up hardened substrate and to
remove rubble, especially rubble burried in the root zone. Bullrushes
smothered by a laver of gravel will be stunted. Bullrushes and grasses will
usually find enough nutrients in sand and sand-silt mixtures without the need
to add organic soils. Too much silt will cause irrigation problems (see below).

Irrigation
Flat intertidal marshes have elaborate dendritic drainages that prevent the
pooling of water. Site preparation for non-sloping sites should include proper
drainage. The site cannot be even slightly lower than the surrounding area,
otherwise the digging of drainage channels will drain the site poorly. If the
site is scalloped, channels should drain the depressions. Standing water that is
left unflushed by one or more tide cycles will form Salt pannes with salinities
as high as 100ppm and hard crusts that barely suitable for such hardy non-
natives as Fathen and Brass Buttons. Standing water that is reauglarly flushed
will thrive with microorganisms that decay into thick azoic muds. Plants
growing in this environment remain stunted. Highly saturated soils such as
those with high silt concentrations (greater than 1/3) are also a poor growing
medium. If the boot sinks above the ankle, the soil is too soft.

Sloping
It is best to grade a site at a slope no greater than I vertical foot for each six
horizontal feet. Sloughing occurs with greater slopes, often resulting in root
exposure. See also SITE PROTECTION.

SITE PROTECTION
Browsing
Projects occuring in estuaries, more especially urban ones, will be visited by
Canada Geese. These birds are aggressive browsers and will decimate a project
rapidly. They are especially fond of grasses and will also chomp on the tender
shoots of bullrushes. This is more of a problem between March and June. If
geese regulary visit the project, fencing it in its first years will help ensure its
survival. The project is especially vulnerable when the plugs are isolated.
When the plants start joining the stand is less penetrable.

Debris

Fencing also helps keep out the debris. It can also trap debris washing over

the top inside. Leave a gap under the fence to allow small debris to escape.
Large debris is the most troublesome for it will roll and crush the vegetation
(and even a fence!) A log boom placed outside to deflect the debris off the site.

Wakes
While usually protected from waves, estuary shores are racked by boat wake.
Boat wake will scour the substrate, expose roots and wash away plants. There is
little that can be done to attenuate this problem other than to place log booms
on the periphery of the project.

Sloughing
The best remedy against sloughing is to grade the project site into a gentle
slope. Protection from wake and waves will also reduce sloughing. Sloughing

that occurs downslope from the plants will expose their roots while sloughing

that occurs upslope from the plants will tend to smother them. Upslope
sloughing can be reduced by planting transitional intertidal-upland species,
such as Dcschampsia or Distichlis spicata, to help hold down the soil behind the
more emergent species.

DONOR SITES
Careless harvesting can damage a donor site, especially if the demand for
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plants is large. Techniques for minimizing damage are described in PART TWO.
Whenever possible, grow plants from seeds.

PLANTING
Planting- mvith plucs: larger plugs (25cm3) are less likely to "vash awav Or M31,C
the plant topple. Planting seedlings in intertidal areas requires some form of
temporary anchoring such as biodegradable jute mat or large U shaped
anchors that strap down the roots. For more information, please refer to PART
TWO.

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.PART TWO: PLANTING BULLRUSH, GRASS AND EELGRASS

SPECIES: Scirpus validus (Softstern Bullrush)

SOURCE IINTORMATION
Terminal 108 fringe marsh construction, Duwamish Waterway, Seattle, Route
509 marsh, Seattle and AAB interil'dal species nursery.

GENERAL PROPAGATION CHARACTERISTICS
S. validus is a resilient pereni3l with a low transplanting mortality rate.

DONOR SITE IINFORINIATION
Donor Site Selection
As for most intertidal species, it is best to select a donor site with similar
characteristics to the recipient site. S. validus is at home in fresh and brackish
waters (at least 15 ppm for surface -,vatcr and 5ppm for ground water). Salt
tolerance may be an adaptive trait of ecotypes and may not be universal for the
species.

Donor Siie Tm@;i2ct
There is no information on donor site recovery since the plants were
harvested from an area that was to be dredQed. The large, deep and dense roots
would leave deep scars, especially if plugs were excavatcd contiguously.

METHOD OF COLLECTION
In February, larae plugs (at least 25 cm3) of adult plants (+/-Im) were dug up
at the Terminal 108'site. Cuttina throuah the root mass -,vas very difficult.

ALTERNATIVE PROPAGATION
S. validus is a slow zenninator but can be grown from seeds and can be
irrie-ated with fresh water. First year plants survive radical root subdivision.

STORAGE
Terminal 108 plants were stored for two months in sand near the project site.
In April they were transplanted to their permanent site. Despite two
transplantings during active root growth, first growing season survival was
very high.

PLANTING
Plugs were planted in predominantly sand in two or three rows, almost
contiguousIv, and at the +10 ft from Mean Lower Low Water mark. S. validus is
also a pioneer species .vhere silt constitutes 25% of the substrates.

ESTABLISHMENT
Comnarison with nearbv reference @ite
1987 1988 1989
Seasonal -reening late on par early
Stalk density I ow, e r lower on par
Shoot heizht shorter shorter taller
Flowering density lower lower greater
Rate of (lie back earlier on par NA

It should be noted that in 1989 thee reference site is under stress due to erosion.
Nevertheless, the project site has shoots nearing 2 m which is considerably

higher than the previous year (1.3m) and taller than for the reference site for
any given year.

Cover
1989 is the first vear where significant lateral growth is occuring both upslope
and downslope from "mother" plugs. Interval planting of plugs would result in
very patchy cover for several years unless mixed with compatible co-dominant
plants such as typha and Scirpus maritimus.

OTHER INFORMATION
Volunteer plants propagated from seeds grow to 1.5m in their second year.
Seedling started in pots and transplanted in the same environment would

probably attain a comparable height.

SPECIES: Scirpus maritimus (Maritime Bullrush)

SOURCE INFORMATION
Route 509 marsh, Seattle, AAB intertidal species nursery

GENERAL PROPAGATION CHARACTERISTICS
Scirpus maritimus has a low mortality rate when transplanted to a similar
environment.

DONOR SITE INFORMATION
Donor Site Selection
Scirpus maritimus is found in brackish situations. In Seattle, it can be found in
places where the surface water and ground water salinity is 17 ppm.

Donor Site Impact
This plant is a deep rooter (20 cm and more). Excavating large open areas
creates ponds that are poorly colonized by lateral growth of surrounding
vegetation and by volunteers. An alternative is to remove plugs along narrow

bands in the pattern of channels flowing toward low areas. The method that
was finally adopted at the Route 509 marsh was to extract plugs from the
margin of the marsh along a broad front; this method left the least visible
damage to the marsh.

METHOD OF COLLECTION
Twenty five cubic centimer and slighly smaller plugs of mature plants (+/-
1m) were dug up in February, March and April, during a period of
accelerating root growth but before stalk greening. The month of harvest had
no measurable impact on subsequent plant establishment.

ALTERNATIVE PROPAGATION
S. maritimus germinates readily and proliferates in seed bed that are watered
with fresh water. First year plants survive well severe root subdivision.
Second year plants grown in pots and watered with fresh water grow to about
two thirds the height of plants found in the wild and flowering is significant.

STORAGE
No information on storage or multiple transplanting.

PLANTING
Plugs were planted roughly on 75cm centers in soils with a roughly 2/3-1/3
ratio of sand and silt mixed with small gravel and with only traces of visible
organic matter. Plants prefer well drained areas to those that are poorly
drained. Plants planted above the Mean Higher High Water mark do well as
long as the soil at root level remains moist (see below).

ESTABLISHMENT
Comparison with nearby reference site
1987 1988 1989
Seasonal greening later later later
Stalk density lower lower lower
Shoot height shorter shorter shorter
Flowering density lower lower lower
Rate of die back NA later NA

Cover
Cover is greater in dryer parts of the plots than in areas where the soil is
wetter. By the second growing season, plants on 75 cm centers were merging
in the dryer areas but plants remained small and isolated in the wetter areas.
Furhtermore, the wetter the soil, the greater the mortality between the first
and the second season.

OTHER INFORMATION
The cause of poor plant growth in poorly drained areas needs to be researched.
In the spring of 1989 the plants in all three plots, except for those on high

spots, suffered a reversal: mortality, stunted and late growth. It is possible that
a thick laver of azoic mud may be starving roots from oxygen or that the soil is
being depleted of nutrients.

SPECIES: Distichlis Spicata

SOURCE INFORMATION
Jetty Island density project, Terminal 108, Route 509 marsh and AAB intcrtidal
species nursery.

GENTERAL PROPAGATION CHARACTERISTICS
Distichlis behaves unpredictably. Though it is one of the toughest plants, its
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propagation from seeds or plugs is not guaranteed.

DONOR SITE INFOR-M-ATION
Donor Site Selection
D. spicata tolerates a wide range of salinity and can live upland
undistinizuishablv from other 1z rasses. Plants accustomed to fresh water or to
dry environments readily' adapt to wet saline soils. At Jetty Island, the donor
site was sli-hly upland from the recipient site and the soil consisted of sand
with traces of silt and no visible organic matter.

Donor Site Imliact
Plants were removed from rectangles, 1.5 m by I m in plugs roughly 25 cm3l.
By April of the follow-ing year, the excavated areas were still quite visible. The
impact to the donor site can be lessened by diar-ing out shallower plugs since
the root mass is often layered and the upper laver is sufficient to nourish the
plant (however, thin plugs may wash away if not anchored).

N=HOD OF COLLECTION
Plants grow readily from 25 cm3 plugs either whole or subdivided into 8cm3.
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To save transporting weight, the sand can be removed from the roots.
41

ALTERNATINTE PROPAGATION
Transplanting plugs will not necessarily guarantee propagation. PI U L's
transplanted from Kellogg Island across from terminal 108 in Seattle failed to
survive two seasons while potted plants and mats of D. spicata are groNving
readily at the same location. D. spicata is very tenacious: root fragments that
have anchored themselves accidentally have become fully grown plants.
Uprooted plugs landing face down send shoots under-round that re-emerge as
new shoots. Plant. propagation from seed can be prolific or fail altoLether. D.
spicata's rapid growth rn@k_es it an excellent candidate for pot or ma-t
propagation whereby seeds are sown on a prepared surface and slices of
"lawn" are transplanted to the project site.

STORAGE
There is no experience @vith storing D. spicata though the resilience of its roots
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make a it a good candidate for warehousing in moist sand.

PLANTING
The planting at Jetty Island was meant to test the rate of propagation from

planting centers at different intervals and for diffrcnt size plugs. The
treatment was as follows:

.Planting Intervals: .75m. 1m and 1.5m
.Plant size: 25cm3, 8cm3 (with soil matrix), 8cm3 with relatively bare
roots.

The planting medium is dredge sand with traces of silt from the Snohomish
river.

ESTABLISHMENT
It is still too early to tell which treatment yields the best and fastest cover.
Whole plugs tend to grow into larger tufts and smaller planting intervals
obviously yield the highest cover. Over what period of time does it all even
out? data are insufficient at this time. However, there is significant
underground growth radiating from approximately one third of the surviving
plugs. As branching continues, it is possible that some of the plots planted at
.75m intervals will experience some merging of cover by the end of the second
growing season.

A number of small plugs had been torn out from Jetty, Island plots. For
practical reasons, harvesting heavier plugs will ensure less wash-out. Plots
with plants below the Mean Lower High Water have suffered high mortality
while those located at Mean Higher High water have shown virtually no
mortality between spring 88 and spring 89.

Comparison with nearby reference site
1987 1988 1989
Seasonal greening late
Stalk density NA
Shoot height on par
Flowering density NA
Rate of die back NA

Cover
See Plant Establishment above

OTHER INFORMATION
None

SPECIES: Zostera Marina (Eelgrass)

SOURCE INFORMATION
Padilla Bay nursery project, Smith Cove experimental celgrass project, Seacrest
Park project in Seattle.

GENERAL PROPAGATION CHARACTERIS TICS
Z. marina is a difficult species to transplant. Its survival rate is low and its
establishment is unpredictable.

DONOR SITE INFORMATION
Donor Sii@ Selection
There are several ecotype@s in Puget Sound. Roughly speaking, there is subildal
Z. marina (longer, wider blades) and intertidal Z. marina (shorter thinner
blades). To be on the safe side it is best to select the appropriate ecotype for
transplanting to the project site.
I

Donor Sii-, TmT.)act
Int-,rtidal donor site impact 'IS MOSL pronounced when digging up pluE:s with
shovels from mudilats and less pronounced when plugs are removed from
sand), substrates. Hand harvesting is least damaging to both mud flats and
sandy bottoms.

The Padilla Bay project measured the rate of recovery of donor plots when
han,ested in different patterns. Harvesting was done by hand. It %vas assumed
that removinz eel-rass turions (cluster of blades) contiguously would remove
approximately 80% of the root mass. The results one year after harvest are as
fO I 10 'A? S:

-Total removal of cover (2m x 2m plot): lowest recovery
-Checkerboard removal (Im squares): good recovery, some patchiness
-Checkerboard removal (.5m. squares): almost total recovery
-50% thinnina (2m. x 2m. plot): cover in distin guish able from reference
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plot.

Donor sites where Z. japonica occurs along with Z. marina will vield Z. japonica
at the recipient site, particularly if it is at the upper range of the intertidal Z.
marina ecotype. Z. japonica is a hardy and prolific propagator that will
outcompete Z. marina.

N4ETHOD OF C0=C`FION
Plua collection: Plugs crumble when dug up and need to be placed in pots
immediately. To prevent dissication of blades (,which happens rapidly when
the blades no longer rest on a wet surface) the pots need to be sprayed with sea
water. This method of removal from a donor site is cumbersome.

Turion collection: Turions can be harvested by hand, making sure to snap root
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sections no shorter than 12cm. In many cases two turions per root section are
harvested,

ALTERNATIVE PROPAGATION
Seed propagation has not been attempted with these projects. Propagation by
subdividing potted celgrass will be attempted in the near future (see STORAGE
below).

STORAGE
Short term storage
As mentioned earlier, it is essential.to keep the blades wet. When harvesting
turions, they should be placed in buckets filled with sea water. Turions can
keep several days (turions kept five days are still -viable). It is essential to
cban2e the water twice a day or to provide continuous flushing, othcrNvisc the
rapid decay of epiphiies and incidentally harvested organisms will affect the
turions.

Lon(2 term sloraze
Harvested celzrass can grow in pots provided that the storage, site conditions
duplicate the conditions of the donor site. Pot size and dens1tv affects survival
rate. Such an experiment at Padilla Bay ).,icldcd the following results one year
after potting:

-1 gal. pot planted with 3 turions: 17% survival
-2 gal. pot planted with 6 turions: 44% survival
-4 -al. pot planted with 9 turions: 100% survival
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PLANTING
All harvestina and planting took place in May (1987 for Smith Cove and 1988
for Padilla liay and Seac-rest Park).

Iniertidal l2lanting:
Plug planting
Di- holes deep enough to accept the plug. Ensure that the plant is flushed with
the ground; a small rise will affect its proper irrigation. There is no
information on the relative success of plug planting. The plug plot at Smith
Cove was mostly unsuccessful by the end of the first growing season. Since the
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treatment was not randomized it is impossible to know whetber the cause was
due to local conditions, to the dissication of many of the plants during
transportation or to the method of harvesting.

Turion planting
To tie or not to tie down: Turions can wash away easily especially in mud flats
where the tide rushes in. An easy method of anchoring is to hold down the
root with a 10cm piece of coat hanger bent in an "S." The recurved bottom
helps anchor the coat hanger. A method that should not be attempted is to
plant eelgrass in a trench and bold down the roots with stretched twine then
backfill. The twine will float up to the surface, snag the eelgrass and uproot it.
Planting the eelgrass roots 5cm deep without anchoring works well in low
energy areas. 'furion survival at the Smith Cove pT0jJ`ct was unrelated to
anchored vs. non-anchored treatment. In Padilla Bay, where turions were not
anchored, there \vas strong evidence of plants washing away from the
recipient plots. Turions where the mud matrix around the roots served as an
anchor were dragged outside of the plot in the direction of the flood and had
replanted themselves.

Pattern of planting: At Padilla Bay, recipient plots were "mirror images" of the
donor plots. Plots were planted in 1m checkerboard pattern, .5m checkerboard
pattern and 50% density of the donor plot. Survival one year later does not
exceed 20% of the plot and for most plot is less than 5% of the cover. With this
experiment it is impossible to say which planting pattern works best.

Site selection
Recipient sites need to be irrigated by seeps at low tide. If the surface is
merely wet but not saturated, dissication will occur and the plants will die. A
well developed intertidal bed will act as a sponge and retain enough water to
irrigate itself. Z. japonica occurs at the upper range of Z. marina. The
presence of Z. japonica at a recipient site will cause Z. Japonica to outcompete Z.
marina. This may be one of the contributing failures at the Padilla Bay project.

Subtidal planting
Subtidal planting has been attempted in Puget Sound usually with not much
success. Adopt a Beach did a subtidal project at the Seacrest Park in Seattle. At
this date there is no information on the success of the project.

Cedar boxes 50cm x 50cm x 15 cm were built with biodegradable burlap bottoms,
filled with sand and silt from the recipient site and planted with four turions.
The boxes were fitted with rebar to serve as anchor and floated to their resting
place at -5 and -6 ft from Mean Lower Low Water.

ESTABLISHMENT
The only Adopt a Beach project with sufficient data to observe establishment
trends is the Smith Cove project. Unfortunately, the project suffered almost a
complete loss during the winter of 1988-1989. The cause of the loss is
speculative. A nearby fill project caused heavy siltation to occur and a silt film
covered the eelgrass. Sand from the project also drifted in throughout the fall.
It is possible that a combination of turbidity and smothering destroyed the
plants.

Turions were planted roughly 50cm apart. As noted earlier, anchoring was not

a factor in survival. The pattern of growth as observed in the fall of the first
growing season, the following spring and the following fall is a s follows:

OVERALL PLOT COVER AVTERAGE DENSITY
(Relative to the previous survey) (Relative to the previous survey)

SPRING 87 (planting)
FALL 87 Lo sing Lo sing

SPRING 88 Lo sing Gaining

FALL 88 Gaining Gaining

By Fall 88, there were more turions growing than the number planted; but

rather than growing throughout the plot, they were growing in three clusters
distributed in the cast central, south central and southwest section of the plot,
leaving large areas with light density or no surviving plants at all. This
pattern of growth has implications on plot design: eelgrass planted on an
interval pattern will not grow uniformly throughout the plot. To measure plot
success on the uniformity of cover would be misleading. It should be expected

that eelgrass planted at regular intervals will undergo a decline in cover; but
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over time, prolific clusters will appear at random.

OTHER 111,TFORMATION
One method of planting eel 'grass that should be attempted is to replicate the
pattern of natural beds in low density areas. Eelgrass beds are dynamic;
eelgrass clusters in those areas seems to migrate along a front and the cover
for a fixed area changes from year to year. In transplanting , a boundary
should be drawn around the project and eelgrass would be planted in random
clusters within the boundary. Endoubtedly some clusters would not survive;
but many clusters would contract, expand and migrate within the boundary
throu2hout the seasons.

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