U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2016–3042

June 2016

ISSN 2327-6916 (print) ISSN 2327-6932 (online)

http://dx.doi.org/10.3133/fs20163042

Assessing Wildlife Benefits and Carbon Storage from Restored 

and Natural Coastal Marshes in the Nisqually River Delta:

Determining Marsh Net Ecosystem Carbon Balance

A

B

C

A) Reference marsh during high tide in the spring. Water levels are just a few 

centimeters above the coastal plain, but can be up to a meter deep during 

particularly high tides in the winter. B) Reference marsh during low tide in the 

summer. C) Restoration marsh during low tide in the summer. High tides in the 

marsh being restored can be more than a meter above the marsh plain because, 

historically, these areas were previously isolated from tidal influence and had 

subsided following drainage for agricultural use.

Working in partnership since 1996, the U.S. Fish and 

Wildlife Service and the Nisqually Indian Tribe have restored 

902 acres of tidally influenced coastal marsh in the Nisqually 

River Delta (NRD), making it the largest estuary-restoration project in the Pacific Northwest to date. Marsh restoration increases 

the capacity of the estuary to support a diversity of wildlife 

species. Restoration also increases carbon (C) production of 

marsh plant communities that support food webs for wildlife and 

can help mitigate climate change through long-term C storage in 

marsh soils. 

In 2015, an interdisciplinary team of U.S. Geological Survey 

(USGS) researchers began to study the benefits of carbon for 

wetland wildlife and storage in the NRD. Our primary goals 

are (1) to identify the relative importance of the different 

carbon sources that support juvenile chinook (Oncorhynchus 

tshawytscha) food webs and contribute to current and historic 

peat formation, (2) to determine the net ecosystem carbon 

balance (NECB) in a reference marsh and a restoration marsh 

site, and (3) to model the sustainability of the reference and 

restoration marshes under projected sea-level rise conditions 

along with historical vegetation change. In this fact sheet, 

we focus on the main C sources and exchanges to determine 

NECB, including carbon dioxide (CO2

) uptake through plant 

photosynthesis, the loss of CO2

 through plant and soil respiration, 

emissions of methane (CH4

), and the lateral movement or 

leaching loss of C in tidal waters. 

Restoring and Preserving Coastal Marshes Could Help 

Reduce Atmospheric Carbon Concentrations 

Increasing concentrations of CO2 in the Earth’s atmosphere 

are linked to changes in weather and climate around the 

globe. One way to mitigate these changes is to preserve, 

restore, and create ecosystems that remove large amounts of 

C from the atmosphere and sequester it in soil organic matter. 

Coastal marshes have the potential to be effective at storing 

C, because fast-growing marsh plants extract C from the 

atmosphere through photosynthesis and store it in leaves and 

stems aboveground and roots belowground. Although much 

of the aboveground and some of the belowground material 

decomposes over time, enough organic material is preserved 

by the waterlogged conditions to have a build-up of C in most 

marshes. Under the right conditions, this build-up of C can 

create organic “peat” soils and store C for hundreds to thousands 

of years. Preventing marsh loss, as well as restoring coastal 

marshes, maximizes long-term C storage and provides additional 

ecosystem benefits, which are of great concern to naturalresource managers and policymakers.

How Do You Measure Carbon Uptake in Tidal Marshes?

Measurements at the Nisqually River Delta 

For an accurate assessment of C uptake from the 

atmosphere and its storage above- and belowground in the NRD, 

it is necessary to collect data under a range of environmental 

conditions. To accomplish this, the USGS plans to establish 

two meteorological stations in the NRD to continuously measure atmospheric C exchange. One station is to be placed in 

a natural, undisturbed, or “reference” marsh, and the other in 

a “restoration” marsh, a historical marsh that was diked for 

agricultural use and then restored to tidal influence in 2009. The 

NECB from both marshes provides a means to compare carbon 

uptake rates, as well as quantify potential carbon stocks and storage for carbon markets. 
CO2

CH4

CO2

CO2

CO2

CH4

CH4

diffusion

respiration

methanogenesis

DOC

DOC

Bacteria

Net ecosystem carbon balance (NECB) is the net balance between carbon (C) 

inputs, such as carbon dioxide (CO2) uptake through plant photosynthesis, and 

CO2 losses through plant and soil respiration; methane (CH4) emissions; and the 

exchange of dissolved organic carbon (DOC), dissolved inorganic carbon (DIC), 

and sediment with tidal waters. 

Measuring Atmospheric Carbon Exchanges

In order to determine the atmospheric component of the 

NECB, we plan to deploy a suite of instrumentation at each site 

to measure CO2 uptake by plant photosynthesis, losses of CO2

by plant and soil respiration, and CH4 emissions. These instruments use continuous (10 times a second) measurements of 

Differences in plant type,

hydrology, salinity, and seasonality

affect carbon exchanges.

Puget

Sound

122°44' 122°42' 122°40'

47°

07'

47°

06'

47°

05'

47°

04'

0 0.5 1 Mile

0 0.5 1 Kilometer

Historical marsh

Restoration

marsh

Nisqually River

Delta (NRD)

5

Billy Frank Jr.

Nisqually National

Wildlife Refuge

Location of the Nisqually River Delta (NRD). The green-shaded area 

represents the historical coastal marsh, and the gray-shaded area 

represents the marsh undergoing restoration.

Meteorological tower: instrumentation includes 

carbon dioxide and methane analyzers; a 

wind anemometer; temperature, humidity, and 

radiation sensors; and a field camera. 

CO2 and CH4 concentrations along with measurements of wind 

speed, which transports the gases, to quantify net atmospheric 

C exchanges. This information can help us understand how 

productivity differs between natural and recently restored coastal 

marshes, as well as how differences in plant type, hydrology, 

salinity, and seasonality 

affect atmospheric C 

exchanges. 

Locations of 

meteorological stations 

are to be coordinated 

with the Billy Frank 

Jr. Nisqually National 

Wildlife Refuge 

management and the 

Nisqually Indian Tribe 

to minimize effects on 

the surrounding landscape. Necessary power 

systems, including solar 

panels and batteries, can 

be deployed in such a 

way to minimize marsh 

disturbance and preserve the scenic quality 

of the sites. 

The Effects of Tides

One difficulty in measuring net C uptake in coastal marshes 

is the effect of tides. Exchange of tidal waters can result in 

appreciable C loss, particularly when C taken up by plants 

through photosynthesis is exported as litter or dissolved organic 

carbon (DOC) to outflowing tidal waters. All such losses through 

the tidal exchange, and all gains from the delivery and settlement 

of DOC and dissolved inorganic carbon (DIC) in litter and sediments, must be quantified to estimate the NECB for each marsh.

To account for the tidal exchange of C, two hydrology 

stations are planned to be established on the edge of the coastal 

marsh channel, next to the meteorological stations. These are 

needed to continuously measure the major forms of dissolved C 

and particulates in the volume of water exchanged. Together, the 

gaseous C measurements from the meteorological stations and 

the C measurements from the hydrologic stations can be used to 

estimate the net amount of C stored at the natural and restoration 

marsh sites. 

USGS Fact Sheet Authors:

Frank Anderson, Brian Bergamaschi, Lisamarie Windham-Myers, Isa Woo,

Susan De La Cruz, Judith Drexler, Kristin Byrd, and Karen Thorne

Funding Provided By:

This project is funded by the United States Geological Survey Land Carbon 

Program and United States Fish and Wildlife Service, and leverages existing 

research from the National Aeronautics and Space Administration-Carbon 

Monitoring System program (Project #: NNH14AY67I) and the Estuary and 

Salmon Restoration Program (Project #: 13-1583P).

For more information:

Visit: http://www.werc.usgs.gov/nisquallycarbon or contact: 

Lisamarie Windham-Myers: lwindham-myers@usgs.gov

Partners: 

Billy Frank Jr. Nisqually National Wildlife Refuge:

http://www.fws.gov/refuge/nisqually/