1. Seagrass and Salt Marsh: Critical Coastal Habitats
South Slough National
Estuarine Research Reserve

2. What is a Salt Marsh?
Salt marshes are transitional areas between land and water, occurring along the intertidal shore of estuaries and sounds where salinity (salt content) ranges from near ocean strength to near fresh in upriver marshes.

3. What is a Seagrass Bed?
Seagrasses are flowering plants that have adapted to living in salt water. Seagrasses are found mostly on soft sediment in estuaries and shallow coastal waters and are frequently found growing in dense beds.
In Pacific Northwest estuaries, the common species of seagrass is called eelgrass (Zostera marina), which grows in soft sediments of intertidal and subtidal zones.

4. Where are seagrass and salt marsh communities located?
Salt marshes

5. Estuarine Habitats:
Salt marshes
Tidal channels:

6. Estuarine Habitats: 1. Open Water- Subtidal Salt marshes
Tidal channels:
Eelgrass beds

7. Estuarine Habitats: 1. Open Water- Subtidal 2. Intertidal mudflat
Salt marshes
Tidal channels:
Intertidal mudflat
Eelgrass beds

8. Elevation is a primary determinant of seagrass and salt marsh location
Transitional Zone
Extreme High Tide
Mudflat and/or Seagrass
Low and Mid Salt Marsh
High Salt Marsh
High Tide MHHW
Low Tide MLLW
Mainstem Tidal Channel
Tidal Inundation Period:
High Marsh- Short
Low Marsh- Long

9. Why are seagrass and salt marsh communities important
Why are seagrass and salt marsh communities important? What roles do they play in the coastal ecosystem?

10. In ecological and economic value, they rival tropical rainforests and the world’s richest farmlands!

11. Seagrass and Salt Marsh Functions
Primary Production
Fish and Wildlife Habitat (including “nursery” role)
Sediment sink
Shoreline protection
Water Quality

12. Primary Production
Eelgrass and Salt Marsh provide the critical foundation to the “detrital food web”
Production
Shredding
Colonization/decomposition
Consumption by small organisms (“grazers”)
Consumption by larger organisms (“predators”)
Defecation/Nutrient transformation
The entire estuary ecosystem depends on the primary producers in the water and in the salt marsh. The primary source of food for the estuary originates in the thick salt marsh vegetation. Only a small amount is consumed directly; most is eaten after it dies. Upon its death, it is partially decomposed by bacteria and fungi into minute particles called detritus. These decaying plants and micro-organisms are then eaten by fish, worms, and crustaceans, furthering the cycle of decomposition. The plentiful insects provide food for birds and fish.

13. Fish and Wildlife Habitat Example
Juvenile Salmon rearing habitat
Foraging
Physiological transitions
Refuge from predators

14. Fish and Wildlife Habitat Example
Resident and migratory bird habitat
Shorebirds – feed on insects, fish, invertebrates
Ducks and geese graze on vegetation – Ex. Black Brant / eelgrass

15. Water Quality Nutrient uptake
Sediment trapping and baffling of wave energy
Oxygen production

16. Natural Variability of Salt Marsh and Seagrass Habitats
Plant distribution, species diversity, and density can vary substantially over seasons and years in response to:
Precipitation, water table
Light availability
Temperature
Nutrient availability
Plant competition/succession
Sediment characteristics
Oceanic cycles (El NIÑO, PDO)
Sea level rise

17. Human Impacts on Salt Marsh and Seagrass
Direct Impacts:
Dredging
Diking
Draining
Filling
Indirect Impacts:
Pollution – toxics,
nutrients, sediments
Water diversions
Shading – i.e. docks,
piers, bridges, boats,
high water turbidity
Invasive species

18. HISTORIC CHANGES OF COOS BAY TIDAL WETLANDS, FILLED AGRICULTURAL LANDS, AND RESIDENTIAL COMMUNITIES ( )
ACRES
Loss of salt marshes has been extensive throughout the world, as well as locally.
YEAR

19. Blue shaded areas represent tidal wetlands converted to other uses
Blue shaded areas represent tidal wetlands converted to other uses. Loss of eelgrass habitat is not as well documented, but is also widespread.
Coos Bay 1900

20. Why Monitor Salt Marsh and Seagrass Habitat?
To further our understanding of coastal ecology
To document changes over time as an indicator of estuarine health
To assess changes in sensitive estuarine habitats from long term trends in sea level rise and climate change
To alert us to declines in key habitats and guide corrective action
To motivate the public to protect existing habitat, restore degraded habitat, and improve upstream land use practices

21. South Slough’s Monitoring Strategy
South Slough National Estuarine Research Reserve (SSNERR) currently monitors a variety of physical and chemical measures as part of a nationwide effort to track the status and trends of estuarine resources in the United States.
Monitoring of eelgrass and salt marsh serve as biological indicators of ecosystem health.

22. A key advantage of biological indicators of estuary health is that they respond to a broad variety of environmental variables (temperature, salinity, light, pollution, etc), and therefore provide an integrated measure of how the ecosystem is functioning.
Note: this same fact also makes it hard to discriminate the exact environmental variables responsible for changes in these habitats. Hard to pinpoint exact causes of changes.

23. The “Big Picture” Questions:
Within salt marshes and eelgrass beds, how are species composition, abundance, and distribution changing over time?
What might be causing these changes?

24. Questions about short-term variability in these habitats:
How closely linked are the seasonal ecological characteristics of these habitats along the estuarine gradient?
How does the location of a habitat along the estuarine gradient affect species diversity, spatial cover, and biomass?

25. Questions about long-term variability in these habitats:
How are changes in eelgrass and salt marsh habitats related to longer-term changes in the nearshore Pacific Ocean and/or freshwater inputs from the local watershed?

26. Guiding Concepts of Our Monitoring Approach:
Establish monitoring sites along estuarine gradient (marine  freshwater)
Conduct representative sampling using transects and plots
Repeatable measures
Measure both plant community attributes and environmental variables
Testing both national (NERRS) and International (SeagrassNet) protocols
Sample quarterly (4x per year) to assess seasonal variability
SHOW BIOMONITORING SITES ON LAMINATED POSTER

27. Transects and Plots

28. What do we measure at each site?
Water depth
Water salinity (salt content)
Water Table Height
Sediment elevation changes
Sediment grain size
Light using loggers
Water temperature using loggers

29. What do we measure at each quadrat plot?
Canopy height / Blade width
Shoot density
Flowers & fruits
Sediment description
Biomass core (0.0035m2)
Seagrass % cover
Species composition
Photograph

30. Monitoring sediment elevation changes

31. SeagrassNet Sites

32. Current project status?
First year of project – 3 seasons of data collected
Data analysis this Fall
Ongoing long term monitoring to reveal trends