North Hampton salt marsh study assessment of Little River marsh and Bass Beach marsh

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

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NORTH HAMPTON SALT MARSH STUDY

Part I: Assessment of Little River Marsh and Bass Beach Marsh

Part II: The problem, recamiended solutions, and projected outcames

Frederick T. Short, Ph.D.
Jackson Estuarine Laboratory
Univexsity of New Hampshire
RED #2 Adams Point Road
Durham, New Hampshire 03824

October 31, 1984

The preparation of this document was financed in part by the Coastal Zone
Management Act of 1972, as amended, administered by the Office of Ocean and
Coastal Resource Management, National Oceanic and Atmospheric Administration
through a cwant provided by the New Hampshire Office of State Planning.

U.S. DEPARTMENT OF COMVER@@
COASTAL SERVICES CENTER
-2234 SOUTH HOBSON AVENUI.
f,W1 CHARLESTON SC

77- Aw@ - *maw

low,

.41

Coastline of North Hampton, New Hampshire, showing the two salt marshes;
Bass Beach Marsh on the right and Little River Marsh on the left.

PART I: Assessment of Little River Marsh and Bass Beach Marsh

INIRODUCTION

All salt marsh is intertidal. That is, at scffe time during the year, salt

marsh is f looded with salty ocean water. Little River Marsh and Bass Beach

Marsh are both examples of "high marsh," marsh area that forms between mean high

water and the upper limits of the high spring tides. Much of the classic work

on marshes f ocused on 1 ow, regu 1 ar 1 y f 1 ooded marsh areas, but recent authors

have recognized the importance of the high marsh to understanding and managing

marshland ecosystems generally.

New Hampshire tidal marshes, including those in North Hampton, are typical

of what is called the "New England type." These marshes developed during post-

glacial submergence of land and concurrent rise in sea level. Sediments,

primarily of marine origin, were deposited in tidal lagoons and built up because

of protection by sand bars or barrier beaches from direct' impact by the sea.

The sediments increased in depth until they reached the mid-tide level. At that

point, the marsh area was free of tidal waters for approximately half the day

and vegetation was established in the form of salt water cordgrass (Spartina

alterniflora).

As stands of cordgrass spread and thickened, the plants themselves trapped

sediments and the level of the marsh rose as these trapped particles ccubined

with decaying plant material to form marsh peat. This process, which began

approximately 10,000 years ago after the last glaciation, continues today.

When the marsh reaches the level of mean high tide, cordgrass is replaced

by salt meadow grass (Spartina patens , the familiar salt hay of North Hampton's

marshes that was so valuable to the early settlers. Salt hay is the dcminant

plant of the high salt marsh. High marsh may, as noticeably in North Hampton's

Little River Marsh, take over all the marsh area until the entire lagoon

consists of high marsh except for the channels carrying fresh upland water and

tidal ocean water.

Salt marshes of the New England type comprise only 2% of the marshland

along the Atlantic coast of the United States. High marsh accounts for at most

50% of that 2%, or 1% of the total marsh area of the eastern seaboard. of the

approximately 7500 acres of marsh in New Hampshire, North Hampton's marshes

represent about 200 acres. New England type marsh represents the highest ratio

of people to marshland area in the United States, and the pressure on these

marshes is therefore arguably the greatest.

"In the 17th century, these marshes were so va 1 uab 1 e that armed men f rom

Massachusetts cam to take hay from the New Hampshire marshes, about which the
New Hampshire citizens complained bitterly."i But the obvious value of the

marshland to the colonists as cattle fodder no longer exists. No direct

commercial use is made of New Hampshire's saltmarsh today.

However, the marsh that remains has great value, economic and otherwise, to

the towns it occupies and to the vitality of the land/sea margin as a whole.

Primary production, the conversion of light energy and mineral elements into

plant material, occurs abundantly in marshes. It is estimated that tidal marsh

ecosystems may produce 10 tons of organic matter per acre per year, comparing

favorably with modern wheat production, and providing a basis for the entire

marsh-related ecosystem including off-shore fisheries.

This plant material decomposes and is then available directly as food both

within the marsh and offshore. The marsh is a hatchery and a nursery for

oysters, crabs, snails, shrimp, commercially valuable fish, and insects. (These

last, especially mosquitoes, have been the object of man's attention and the

1. Teal, J. & M. 1969. Life and death of the salt marsh. p. 240.

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Li7tie Ri :ver Marsh (top) and Bass Beach Marsh (bottom).

cause of considerable alteration of the marsh because of ditching to drain

mosquito breeding poo 1 s. However, insects remain a crucia I part of the f ood

web.) The creatures in the marsh are attracted to it by its abundant f ood

supply and the protection it affords.

Marshes provide a nesting ground and feeding ground for marine and other

birds. Wildlife is drawn to the marsh to browse or to hunt the smal 1 manumls

and reptiles that thrive there.

Marshes absorb f lood waters, trap sediments, and inprove water quality by

assimilating nutrients of upland origin, whether agricultural or industrial.

Lastly, marshes provide open space in crowded seashore environments, an asset

that cannot be measured perhaps, but one that benefits residents and passers-by

alike.

PHYSICAL DESCRIPTION

Little River Marsh

Little River marsh represents the drainage of a post-glacial valley cut off

at the mouth by a barrier beach. The major freshwater inflow to the marsh is

the Little River, which derives its drainage from swamps and upland ponds in the

tam of North Haupton. The upper extent of the tidal, or saltwater, influence

is a concrete dam located east of Woodland Road and behind the Fuller Farm

The drainage of the Little River Marsh to the ocean is blocked with sand at

the bridge on U.S. Rt. 1A on the Hampton-North Hampton line. The only open

connection between the marsh and the ocean is a culvert under Rt. 1A at the

northeast end of the marsh. Both the flood of tidal water and the flow fran the

Little River are restricted to this culvert.

NORTH HAMPTON

BASS BEACH'
Salinity at. High Tide
MARSH

SVI
Atlantic Ave*

J* PPT

"'30
LITTLE
RIVER Atlantic Ocean
MARSH

Salinity distribution at high tide (parts per thousand) in the two North
Hanpton marshes. Ocean water extends into the marsh, pushing the fresh upland
water back, and mixing with it in the upper reaches. The dam on the Little
River and the blocked channel under Rt. IA are the upper extents of tidal
effects in the Little River Marsh. At the Bass Beach Marsh, ocean water extends
into the salt pond, elevating the salinity.

NORTH HAMPTON
V..
Salinity at Low Tide BASS BEA 'CH
MARSH

Atlantic Ave.

0 PPT

to
got

LITTLE
RIVER
MARSH Atlantic. Ocean

Salinity distribution at low tide (parts per thousand) in the two North
Hanpton marshes. At low tide, ocean water drains from the marsh and fresh creek
water reinvades the lower reaches. Note that the scales of the low tide and
high tide figures are different. At low tide, significant portions of the
creeks and pannes are not saline. At both marshes, salt water is left behind on
the marsh surface as the tide drains, leaving saline pockets, while fresh water
from the upland creeks mixes with the receding tidal water in the main channels,
diluting the outflow.

The main channel into the marsh parallels Sea Road, doglegs to the south

and continues west to join the Little River at a major bend in the stream The

channel of the Little River continues south around Fifield Island where it

terminates in stagnant pools at the closed breachway at the Hampton-North

Hampton 1 ine.

Bass Beach Marsh

The marsh at Bass Beach represents the area of conf luence of several smal 1

drainage brooks from North Hampton. Four to five brooks, including Chapel

Brook, empty into the southwest end of Philbrick Pond, a salt pond at the center

of Bass Beach Marsh. The brook running through the adjacent golf course no

longer drains into the Bass Beach Marsh, but has been diverted to a point

further north.

Philbrick Pond has an outflow at its southern end connected to the ocean by

its flowing through a culvert under the old electric railway bed, continuing as

a stretch of open water, and then flowing through a culvert under Rt. 1A. The

latter culvert has had a floodgate, or clapper valve, employed in previous

years.

Vegetation

The dominant salt marsh plant in the Little River Marsh is salt meadow

grass, or salt hay (Spartina patens). Salt water cordgrass (Spartina

alternif lora) occurs in only one patch. Broadleaf and narrowleaf cattail (Typha

latifolia and Typha angustifolia) and phragmites (Phragmites communis), all

indicators of fresh water, grow around the margins of Little River Marsh.

Purple loosestrife (LythrLun salicaria), an introduced plant which has invaded

many freshwater and terrestrial areas of New England, is now the most abundant

plant in the Little River Marsh, covering 60% of the marsh surface area.

SALINITY OF SEDIMENTS, ppt

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Healthy Salt Marsh 5 22 P-6 28 26 23 29 29 29 30

Little River Marsh 8 8 28 21 33
90% OF MARSH

Bass Beach Marsh 26-47
80% OF MARSH

Generalized cross-section of a New England salt rrarsh. Typical salt content of sediment water for a healthy
salt marsh with salinity value indicated for specific points across the marsh. Salinity values at the Little
River marsh a lower throughout the Transition Zone and High Marsh, allowing invasion of loosestrife, phragmites
17
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and cattail. At Bass Beach Marsh, sediment water salinity values in the predcauxiant pannes are as high or higher
than the hea 1 thy marsh. P 1 ant identif ication: SP - Spartina patens, SA - Spartina a 1 ternif 1 ora, M - Myrica
pensylvanica, Juncus spp., SPE - Spartina pectin@ta, Ss - Solidago sempervirens, Z - Zostera marinaf TY
TVpha spp., J2 ger rdii, MF - Mixed f orbs, SSa - Stunted Sa, Ru - Ruppia maritima, Cr - SeTg-es(mostly
scirpus spp.), Ph Phragmites cmw-inis, Ls - Lythrum salicaria, SAL - Salicornia. spP., DS - Distichlis spicata

Decreased salt content in the sediments of Little River Marsh has greatly

reduced the area of high marsh and allows an invasion of Transition Zone

(f reshwater/terrestrial) plants.

Both forms of S artina occur at the Bass Beach Marsh. Cordgrass (S.

alternif lora.) is found along sone channel edges, at the upper end of the pond,

and typically, in its short form is found in the dead pannes of standing water.

When all of Bass Beach Marsh was true high marsh, its predominant plant was salt

hay (S. patens). But as the dead pannes formed, cordgrass, which is more salt

tolerant, re-invaded. Salt hay (S. patens) renains along the higher channel and

ditch edges and as high marsh meadow al ong the outf 1 ow f rom Phi 1 brick Pond.

Phragmites occurs at the marsh margins. Samphire (Salicornia europaea) is found

in the pannes, as is blue-green algae.

HISTORY OF NORTH HAMPTON KWHES

The marshes in North Hampton have a long history of alteration by man.

Ditching, diking, road construction, dredging, and development of upland areas

have al 1 played their part in changing marsh hydrology. Human intervention

ccupounded itself: to improve drainage of the Little River Marsh without the

botherscm dredging of the channel to the ocean at the southern end of town, a

29" culvert was installed under the fish houses. And when the 29" culvert

proved too smal 1 to do much good, it was replaced with a 4811 culvert early in

1948.

Conversations about the marshes with residents of North Hmpton were useful

for gaining perspective on changes taking place over the course of many years.

Wi 1 liam Fowler said that in 1850 and again in 1870, ditches were opened into

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Photos of Little River Marsh and the 48" culvert installed under the
fish houses in 19 48. Photo at upper right shows the marsh under f 1 ood
conditions. Photos fran the New Hampshire Departaent of Public Wbrks and
Highways -

Little River Marsh. And in 1950, approximately, the trunk, or culvert, was

installed at the north end of Little River Marsh. He first noticed purple

loosestrife growing in the marsh about 20 years ago.

Morris Lamprey has seen fox and deer on the marsh. His father mowed salt

hay on Little River Marsh until 1915. According to Mr. Lamprey, the dam on the

Little River that is the limit of salt water inflow was installed before 1950.

He first saw purple loosestrife 10-15 years ago.

Vivian Brown's father plowed out the channel at the Hampton/North Hampton

line with his horses every spring from 1920 to 1950. Until 1960, Leonard

Knowles reditched and oiled the Little River Marsh for mosquito control.

Vivian Brown remembers bobbing for eels and ice skating on the pond that formed

over Litt 1 e River Marsh in winter, but not being a 11 owed on the main ditch or

the opening to the trunk. She thinks purple loosestrife has came in within the

last 10 years or 15 at most.

Vince and Lucy Palmer say that the Little River Marsh floods "to look like

a lake" about 3 times a year, mostly in winter and spring.

Mary Russell remembers rafting on Philbrick Pond at Bass Beach Marsh, and

says that the area of open water has grown smaller. She says that several

people, including William Fowler, experimented with aquaculture by seeding clams

in the area between the trunk to the ocean and the trunk under the old electric

railway. There is less sanphire now, she says, and sane loosestrife has came in

on her land, upland from the marsh, during the past 5 years.

Frank Richardson, scientist with the New Hampshire State Wetlands Board,

says that the excellent birding in Bass Beach marsh is related to the extensive

open water areas. And he confirms that in the last 10 years there has been a

dramatic invasion of purple loosestrife in Little River marsh, especially at the

southern end.

These conversations confirm that the marshes used to flood with tidal water

more extensively and more often than they do now, and that purple loosestrife is

a relatively new phenomenon of the last 10 to 15 years.

PART II: The problem, recommended solutions, and projected outcomes

THE PROBLEM

Both of the salt marshes in the town of North Hampton are in serious

trouble. And in both cases, the cause of these problems is hydrological. That

is, the changes in the Little River Marsh and Bass Beach Marsh are caused by and

related to the way water, both fresh and salt, interacts with the surface of the

marsh. In both marshes, these changes are tending toward a loss of true salt

marsh and the substitution of something else. Hydrological changes are typical

causes of marsh loss along the East Coast of the United States. And in most

cases, the changes in the water/land interface are caused by van. This is the

case in North Ha:mpton.

It would be a mistake, however, to think that the same process is occurring

in Little River Marsh and Bass Beach Marsh. Despite their common root in

hydrology, the changes leading to loss of high salt marsh are quite different in

the two marshes and must be explained separately. This report will do that and

will then recomTend solutions and predict the results that can be anticipated if

the solutions are instituted.

The town of North Hampton is outstanding in its interest in the salt

marshes within its borders. A significant portion of New Hampshire's marshland

has disappeared over the past few years with very little concern or even notice

on the part of the locales involved. It must be understood that the study

presented here to the Selectmen of North Hampton is not long-term or intensive

scientific research, but rather a broad overview of conditions familiar to the

author from work in similar areas, backed up with two months of research and

NORTH HAMPTON

Areas of BASS BEACH
Present Day Salt Marsh MARSH

AtlantIc Ave.

LITTLE
RIVER
Atlantic Ocean
MARSH

Extent of. old* salt marsh

Hatched areas represent the extent of present day salt marsh at Little
River Marsh and Bass Beach Marsh in North Hampton,'New Hampshire. Actual salt
marsh at Little River Marsh is reduced 70% from its former extent. At Bass
Beach the salt marsh remains the same size as previously, although 80% of the
marsh is dead panne.

investigation of local conditions plus a literature review. Other, more

detailed, work could be done to document current conditions and to track the

changes that will occur if and when efforts are made to restore the hydrology of

both marshes. From what I now know, I make the f ol lowing assessment of the

North Hampton marshes.

Little River Marsh

The problem at the Little River Marsh is that there is not enough flushing

of saline tidal ocean water up into and then back out of the marsh. During a

normal tidal cycle of 12 hours, ocean water cannot reach the far end of Little

River Marsh and drain back out. It is this flooding and draining of salt water

that creates the characteristic salt marsh flora and fauna, from the smallest

benthic alga and crustacea to the more noticeable cordgrass and racoon. At

Little River Marsh, the single culvert under the fish houses at the north end of

the marsh currently carries all the salt water it can into the marsh. It is

fu 11 of inf lowing water throughout f I ood tide.

The lack of tidal flushing is exacerbated by the channel under the bridge

on Route 1A being blocked. It is doubtful whether this channel carriedmuch

ocean water into the marsh except when newly reditched, as it was annually

before 1950. But it certainly drained the freshwater frcm the Little River into

the ocean, thereby allowing more salt water originating at the culvert under the

fish houses to penetrate the upper reaches of the marsh by simple displacement.

There are other culverts and bridges within the marsh that restrict

flushing. The development of Fifield Island and the associated roads have al I

wrought hydrological changes. Each of these culverts and other "improvements"

must, at the time it was built, have seemed to be a minor undertaking unlikely

to have any significant impact. But the long-term cumulative effect is great.

23 AUGUST I .91S.34 26 AUG"UST 19184
10.

Tide in Marsh
EBB --JRZ@- EBB
6 e at Ocean
CD

01
6 8 10 12 Z 4 6 8 10 6 8 10 I'z ?- 4 8 10
NOON NOON.
TIMEhr TIME. hr

Tide sequences for two days of varying tidal amplitude, showing tide height
at the ocean (above mean low water) and in the marsh. Tide heights are always
much reduced inside the marsh because of the restricted inf low. Ocean tide
height strongly affects the amount of ocean water entering the marsh.
Additionally, ebb from the marsh lasts longer than flood because of the relation
EBB
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of the culvert to ocean water level.

As exp 1 ained in the f irst part of my report, sa I t marsh f orms preci se I y

because land areas are f looded during the tidal cycle with salt water. If an

area no longer receives this periodic flushing, "the resulting loss of tidal

energy, an essential driving force in salt-imrsh ecosysterm, alters the role of
these coastal wetlands.,'2 This is what has happened, and what continues to

happen, in the Little River Marsh.

Since much of what was formerly true marsh in the Little River Marsh is now

no longer subject to tidal flushing, terrestrial and freshwater marsh plants

have begun to invade. The most obvious and aggressive of these is purple

loosestrife (Lythrum salicaria) which now covers approximately 60% of former

marsh area. Loosestrife is not productive of the detrital material so essential

to the food web of the marsh. It doesn't attract birds or animals since it

constitutes a barrier rather than a protective habitat for wildlife. The

invasion of purple loosestrife is a sure indicator of degradation and loss of

salt marsh area.

Bass Beach Marsh

The Bass Beach Marsh has, to explain it in simplest terms, the opposite

problem from the Little River Marsh. That is, too much water sits on the marsh

surface and doesn't drain out. Because large areas of the marsh are permanently

covered with saline water, the typical marsh plants have died out and dead panne

areas have formed. The dead pannes represent an area of dead saltwater hay

(Spartina patens) covered by a thick mat of blue/green algae.

2Roman, C.T., W.A. Niering and R.S. Warren. 1984. P. 141. Salt Marsh

Vegetation Change in Response to Tidal Restriction. Environwental Managerent.

Vol. 8, No. 2, pp. 141-150.

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L tie River Marsh showing the invading non-saltmarsh plants.

It is hard to say in retrospect exactly what the cause of the dead

pannes might have been. However, it seems certain that it is related to the

mosquito ditches which rib the marsh surface, creating high margins along the

ditches where the earth was thrown when the ditches were dug. These levees may

have trapped water between the ditches and made it hard for it to drain. There

is some indication in the literature that standing water on the marsh peat

causes the peat itself to rot, campact, and subside. That process would tend to

speed up the formation of dead pannes. Or the ditch margins, like dikes, may

have simply held the tidal water in the salt hay areas longer than the plants

could handle, and the stress eventually caused the death and decay of the

typical high marsh meadow vegetation. Salt marsh plants can tolerate a twice
M daily saltwater bath, but not a continual soaking in salt water. Purple

loosestrife has not invaded the Bass Beach Marsh because the soil there is too

salty and too constantly submerged. It exists only along some of the upper

margins of the marsh and is not abundant.

The dead pannes are not tota 11 y dead. As mentioned above, they support

thriving colonies of blue/green algae and also many insects and, at least in the

deeper ones, crustaceans and sma 11 f ish. The f ish and insects attract many

shore birds making Bass Beach Marsh one of the best birding marshes along the

New Hampshire coast.

Because Bass Beach Marsh is full of birds and free of purple loosestrife,

it is possible to conclude that the marsh is healthy. This is simply not the

case. First, Bass Beach Marsh is no longer true high marsh any more than much

of Little River Marsh is. Second, Bass Beach Marsh is not a stable ecosystEm

The size and extent of the dead pannes has increased rapidly in the past 10

years and, without intervention, can be expected to continue to expand. If the

process of dead panne formation goes unchecked, the marsh will eventually

degrade and become inhospitable to birds and animals. In other words, the

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Bass Beach Marsh showing extensive nonproductive dead Danne areas-

current abundance of birds and fish at the Bass Beach Marsh represents a step in

the gradual decline of the marsh into a stable but non-ecologically productive

flooded area.

RBOOMMENDED SOLUTIONS

Given that both Little River and Bass Beach Marshes are seriously disrupted

high marsh ecosystems, what, if anything, can be done to restore them to true

marsh? The solution, like the problem, lies in hydrology. To revitalize each

marsh, more movement of both fresh and salt water across the marshes' surfaces

is required. But just as the two marshes have rather dif f erent problems, so

their cures , though hydrological, will occur quite differently and must be

looked at separately.

Little River Marsh

My recommendation for increasing water flow in the Little River Marsh is to

install a 48" culvert under Route 1A, running from the Little River as it passes

the north side of Fifield Island, under Route IA and the beach beyond it, out

into the ocean, and terminating on the rock ledge found of f the beach at that

point.

What wi 11 this cul vert do? First, it wi 11 increase f low in the Litt I e

River and allow it to drain. Draining the Little River will permit increased

salt water flow into the marsh from the northern culvert under the fish houses

by displacement. Draining the Little River will flush accumulated sediment now

deposited on the river and marsh channel bottoms out to the ocean. As the

sediment is flushed, the various channels within the marsh will become deeper

NORTH HAMPTON

BASS BEACH
Projected Salinity at High Tide MARSH

AtIantIc Ave.

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,ell

io PPT
X)30

LITTLE
RIVER 'FIIIELD Atlantic Ocean
MARSH

Salt Water Intrusion Af ter Recommended Changes

Projected salinity distributions at the Little'River Marsh and Bass Beach
Marsh af ter remnukended changes in hydrology are instituted. Note the extension
of high salinity water into the southern and northern ends of Little River
Marsh, the projected result of a second culvert installed near Fifield Island.
At Bass Beach Marsh the extent and level of salinity is projected to increase
throughout the marsh.

and the tidal flooding and draining of the marsh all the more effective.

Seawater will circulate around Fifield Island once again. Salinity of the water

on the marsh surface and the water in its sediments wi 11 increase.

It should be noted also that installation of the recummended culvert will

not increase the winter and spring flooding of Little River Marsh. If anything,

flooding will decrease because of better drainage of the marsh. Placing the

ocean end of the culvert on the rock ledge off the beach should circumvent

another potential problem, the filling of the seaward end of the culvert with

sand.

In sum, the proposed additional culvert at the south end of the marsh will

help, over time, to create more truly high marsh conditions. Saline tidal water

and fresh upland water will be exchanged over the marsh surface twice daily, and

sanething near to the hydrological pattern of the nAllenia before major roads,

dams, and their consequent water restrictions were installed will occur. The

ebb and flow of salt water, a virtual necessity for the existence of true salt

marsh, wil 1 exist again at the Little River Marsh in North Hampton, and wil I

permit the re-establishment of genuine salt marsh flora and fauna.

There is another possible, but less desirable, alternative to the

construction of a culvert under Route 1A near the North Hampton/Hampton line as

a way of improving the situation at the Little River Marsh. This second

alternative would involve running a ditch from near the fish house culvert

approximately parallel to the shore and over to the Little River at the north

side of Fif ield Island. Such a ditch would improve the f low of salt water to

the far reaches of the marsh currently being invaded by purple loosestrife. To

be effective, however, I think this method would require a second culvert, or

trunk, out to the ocean under the fish houses. Otherwise, the single trunk now

in place would probably operate as a barrier to the sufficient tidal flushing

that is the ultimate aim of these changes.

Bass Beach Marsh

At the Bass Beach Marsh, rather than installing a culvert, a culvert needs

to be removed. The culvert under the old electric railway bed, along with the

bridge running over it, creates too great a restriction of water flow and will

have to be disassembled if the Bass Beach Marsh is to be restored. Instead of

the culvert/bridge under the old electric railway, an open channel should be

established. The culvert under Route 1A appears to allow an adequate flow of

water and does not require any changes, except that use of the floodgate should

be discontinued.

Additionally, ditching should be done to drain some of the dead panne areas

of standing water. Although the ditches are the probable cause of the dead

pannes, only breaking through their higher rims with drainage ditches wil I

alleviate the conditions that have produced these dead panne areas. Such

ditching, when combined with the creation of an open channel, except under Route

1A, should provide enough flooding and drainage of the Bass Beach Marsh to

restore it to high marsh over a period of time.

Since the excellent birding at Bass Beach Marsh is related to the dead

pannes, some dead panne areas can be maintained by not ditching and draining

them. The birds will continue to be attracted by these pannes' insect and fish

populations.

To reduce the mosquito population currently breeding in the dead pannes,

deep center areas, or pot holes, should be dug in the pannes. Then, at low

tide, the small larvae--eating fish that live in the pannes will congregate in

these pot holes and survive to eat more larvae. Currently, during particularly

low tides, the entire panne probably becanes dry enough or saline enough so that

fish do not survive, leaving mosquito and other insect larvae to thrive. This

and other methods of Open Marsh Water Management show great potential for

controlling mosquitoes in New Hampshire marshes.

PROJE= OUTCCHES

The eventual results of implementing the above reccmmendations would be

great, if not carplete, restoration of the Little River Marsh and the Bass Beach

Marsh to true New England salt marsh, or high marsh, ecology. It is impossible

to give a time frame for these changes. I have been able to find only one

follow-up study on marsh restoration, and it covered a period of only two years

after changes were made to the marsh. To examine the specifics, let me once

again talk about the marshes separately.

At Little River Marsh, adding a culvert under Route 1A at the south end of

the marsh is, as I said, the preferred solution. Doubling culvert access to the

marsh will double the amount of salt water flowing onto the marsh. Currently,

salt water flows through the culvert under the fish houses at near maximum

capacity during the two hours that f lood tide occurs on the marsh. Ebb tide

lasts for 10 hours on the marsh. Its flow is determined by the volume of water

on the marsh at high tide. If more salt water enters the marsh, more will leave

during ebb tide. The present culvert does not restrict ebb f low. An additional

culvert will not, either; it wil I drain the marsh more campletely.

The increased ebb and flow in the marsh channels and the Little River will

have an imTediate self-dredging effect on these waterways. And the increased

intrusion of ocean water into former marsh areas will allow a gradual return to

the high marsh environment. Salt hay (Spartina patens) will grow in and purple

loosestrife (Lythrum salicaria), phragmites (Phragmites ccnyminis.), and cattail

(Typha latifolia) will retreat. It should be understood that increasing the

salinity of the water f lowing in the channels of the Little River Marsh also

increases the salinity of the water held in the marsh peat, or interstitial

water. The salt water bath to the roots of loosestrife, phragmites, and cattail

is what will cause their retreat and eventual demise.

I cannot say exactly what the effects would be of the second solution, an

additiona 1 ditch from the main ditch at the north end of the marsh and over to

Fifield Island, would be. There would be same increased salinity at the far end

of the rrarsh, but it would not be accompanied by increased f low overa 11.

At Bass Beach Marsh, improved hydrology will improve marsh health.

Removing the bridge and culvert will allow more ocean water into the marsh, and,

nust importantly, will allow better drainage of the marsh. The same sediment

flushing mechanism will apply and will self-dredge the channels and ditches.

Sal t hay (Spartina patens) wi 11 regrow over ditched dead pannes, and up into

areas now covered by phragmites.

As mentioned before, same dead panne areas could be kept to attract birds.

Bass Beach Marsh wil 1 probably always have some dead panne areas, and as the

currently preserved areas grow in, others will occur through natural flooding

and subsiding of marsh peat. These new pannes should then be pot-holed.

Eventua 11 y, most of the marsh wi 11 be high marsh, with a few dead pannes in 1 ow,

frequently flooded places.

I can find only one report of marsh restoration in the literature. The

effort was undertaken by the Fairfield Conservation Commission in 1974, to

restore salt marshes in Connecticut that had been invaded by phragmites. 'With

this reintroduction of tidal exchange, significant reduction in Phragmites. were
noted within one growing season.0 The report does not constitute a scientific

follow@up of marsh restoration procedures. It merely mentions word-of-mouth

reports that measures to improve tidal f low seem to have reduced phragmites

populations.

3 Roman, C.T., W.A. Niering, and R.S. Warren. 1984. P. 149. "Salt Marsh

Vegetation Change in Response to Tidal Restriction." Environmental Management

Vol. 8, No. 2, pp. 141-150.

If the Town of North Hampton undertakes the restoration of its marshes by

instituting the recommendations made above, it will be exemplary in its

environmental concern. If the town additionally undertakes to document and

scientifically monitor the changes in the marshes, it would establish itself as

a unique textbook example of marsh restoration certain to be of interest to

scientists, coastal wetlands managers, and students of ecology throughout the

United States.

ACKNOWLEDGMENTS

Thanks to the Jackson Estuarine Laboratory of the University of New

Hampshire for partial funding and support during this study. The Selectmen of

the Town of North Hampton, as well as many private citizens of the town,

provided me with much cooperation and many insights, f or which I am grateful.

Ruth Hannett and Carol Leaharat monitored a tide gauge, and I appreciate their

attention to detail. And the nembers of the Marine Ecology course taught by Dr.

Arthur C. Mathieson at UNH assisted me with collecting baseline data. Finally,

thanks to Catherine A. Short for writing and editing.

BIBLIOG@APHY

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Hampshire tidal marshes. N.H. Agricultural Experiment Station, UNH.
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