Week 12 - Physical (Flap Gates and LWD) and Chemical in Estuaries

Question 1

Tidal Gates - Salinity Gradient

Answer 1

Changes to estuary channel form will change salinity gradient

Additional salinity impacts due to tidal flap gates, primarily installed for agriculture, also flood control

Question 2

Tidal Flap Gates - Traditional

Answer 2

Tide gates are doors or flaps mounted on the downstream end of culverts in dikes or under roads, that allow upstream waters to drain while preventing inflows from tidal surges or flooding

Flap opens with positive hydraulic head

Flap closed most of the time

Fish passage?

Salinity/fluvial gradients?

Question 3

Tidal Flap Gates - Upgrade Options

Answer 3

The critical issue is fish passage. The secondary issue is circulation and restoring fluvial/salinity
gradient.

Tide gate has buoyant door which floats on the incoming tide and remains open until the water elevation reaches the floats, which closes the door.

The door is open most of the time

Question 4

Columbia River - Salmon Recovery

Answer 4

Example of jetty (levee) breach and removal of flap gate to restore fluvial/tidal gradients and connectivity to off-channel marsh habitat

Evaluation Criteria -
1, Opportunity/Access for salmon
2. Capacity/Complexity
3. Certainty of Success (self- maintaining, proven, subjective)

Question 5

Pitt-Addington Marsh

Answer 5

Four tidal gates, entirely diked marsh

Former floodplain of the Pitt River

Upper chinook (COSEWIC)

Widgeon Sockeye (endemic)

Incredible restoration opportunity!

Question 6

LWD in Estuaries - Where does it come from?

Answer 6

LWD is transported from the upper watershed to the estuary/ocean

Then ‘recycled’ by the actions of tides, wind and currents

The ocean is another source of wood

Winter storms blow wood into river mouths and onto
coastal beaches

Question 7

Where did all the LWD go?

Answer 7

Snags and driftwood presented obstacles for river traffic, fishers, etc.

US Army Corps of Engineers during the late 1800’s removed wood to improve and maintain the navigability of rivers

Snags removed from rivers by US Army Corps of Engineers, 1891-1917

Question 8

Woody debris in Restoration - Ecological functions

Answer 8

release organic carbon

provide habitat for fish and invertebrates

sediment accumulation

Question 9

Estuary Wood Dynamics

Answer 9

Wood-boring crustacea (gribbles)

Bivalve mollucs

Marine fungi

Bacteria

Question 10

Wood recycling - isopods

Answer 10

Wood-boring isopod crustacea (gribbles) of the genus Limnoria are major reducers of wood Pacific Northwest estuaries

Two species involved, L. lignorum, the endemic northern species, and L. tripunctata, the introduced species that is predominantly southern in distribution

Question 11

Wood Recycling - Wood-Boring mollucs

Answer 11

Other than gribbles, the only shallow-water, wood-boring animals in the Pacific Northwest are two species of shipworms.

The most important reducers of wood in estuarine and shallow marine waters of PN region

Question 12

Bankia setacea

Answer 12

most common species of shipworm, a coldwater native

the major marine, wood destroying animal in open ocean, embayments and estuaries

Terado nevalis - a smaller introduced warm water species of restricted distribution in PNW

Question 13

Wood Recycling - Fungi

Answer 13

Marine fungi degrade cellulosic materials, but their ability to rapidly or extensively degrade large pieces of wood appears to be much less than that of terrestrial fungi

Question 14

Wood Recycling - Bacteria

Answer 14

The role of cellulose-degrading bacteria in the sea is obscure, but many species of marine bacteria have been identified as active degraders of cellulose

Question 15

Log Booms in the Fraser Estuary

Answer 15

Legacy of historical forestry practices - convenient, slow decomposition

Regulations prohibit boom grounding, but no enforcement

Significant damage to marsh habitat from repeated grounding with mixed tidal cycle

Will require a govt policy shift and bold, courageous action to force industry change

Question 16

Campbell River Estuary

Answer 16

Heavy industry, dredging, infilling, log storage

1999 City, Nature Conservancy, Tula Found. Purchased Baikie Island

Land purchases

40,000 m3 of fill for habitat creation, shoreline restoration

Community stewardship with Greenways Land Trust provides funds for ongoing maintenance

Question 17

Final Note on Wood

Answer 17

In estuaries, fast carbon is eel grass decay; medium carbon is decaying salmon, and slow carbon is from decaying LWD

But decay of LWD in estuaries is many times faster than in freshwater, and in the forests

Fresh water – LWD decay is slow

Terrestrial forest – LWD decays is medium – but can still last 100+ years

Estuaries - LWD decay is relatively fast due to crustaceans and molluscs

Question 18

LWD for Estuary Restoration

Answer 18

1. Most people have no idea how much wood used to be in estuaries
2. The effects of LWD on fish growth, survival and production has not been demonstrated. Many pressing research questions.
3. Treat wood applications in estuaries as an experiment. Rigorous monitoring of hydrologic, geomorphic and fish community responses.
4. Use whole logs with root wads to ensure the wood remains in place, or attach logs to the ground using anchors or ballasted with boulders (this tech is going out of “fashion”)
5. Wood structures will not last long in an estuary so replacement required at ~10-15 year intervals

Question 19

Chemicals in Estuaries - Legacy Contaminants

Answer 19

Direct sewer outfalls and combined sewer overflows discharged into estuaries and industrial effluents were building a legacy of :

Metals - chromium, cadmium, copper, lead, zinc

pentachlorophenol (PCP), polychlorinated biphenyl (PCB), polycyclic aromatic hydrocarbons (PAH), halogenated hydrocarbon contamination

Question 20

Urban/Legacy Contaminants

Answer 20

Non-point source urban run-off continues to be a problem in restoring industrialized estuaries

Question 21

Mackay Creek Estuaries

Answer 21

stainless steel push corer to collect cores

cores extruded on site in 1 cm increments

Question 22

Source of copper

Answer 22

Brake pads - 5% copper, contributed 47%

Brick and wood siding - contributed 27%

Question 23

Copper and salmonids

Answer 23

high concentrations of copper can be toxic

lower concentrations can damage olfactory sensors (important to fish for feeding, predator avoidance, schooling, migration, recognition of natal spawning grounds and mating)

Question 24

Impacts of remediation

Answer 24

Restoration team must decide whether the site is suitable for restoration in its current state

Some sites might be so contaminated they cannot be restored without a site decontamination step or they cant be “restored” but rather “remediated” or “mitigated”

Question 25

Super-Fund sites in Washington

Answer 25

48 superfund sites, 17 others have been cleaned up and remove from the list

Question 26

Elliot Bay Action Plan

Answer 26

Pacific Sound Resources (PSR) site, 83 acres, 58 are which are tidal

wood treating facility released creosote and related hazardous contaminants 1990 - 1994

1. soil and sediment excavation
2. construction of upland slurry wall
3. a low permeability cap

Question 27

Restoration Challenges with chemicals

Answer 27

1. Restricted land access
2. Abandoned properties and mess
3. Established industry
4. Limited opportunities
5. Cost of restoration prohibitive
6. How to attract funding and resource for these projects?

Question 28

Change your template with restoration with chemicals

Answer 28

Rather than “use nature as your template”, you may need an entirely “new template”

Consider rehabilitation or mitigation as often the best that can be expected

Recognize that impaired ecosystems will always require active, long-term management of this new ecosystem, support native species, and at least emulate a naturally functioning system

Question 29

Human Element and Going forward

Answer 29

Public values can completely redefine urban restoration, where it is often valued more for its passive recreational uses than the less-defined concept of ecosystem function.

i.e. Make a canoe park, rather than restore natural function

need to counter humanistic, community-oriented, and recreational demands on an estuary with economic arguments based on natural capital and ecological services recovered by restoration

Question 30

Duwamish Estuary

Answer 30

Restoration actions in the Duwamish River estuary over the past decade have in aggregate, formed a landscape approach consisting of clusters of sites in strategic locations along the estuarine gradient that are perceived
to be critical for migrating juvenile salmon

Cumulative restoration projects may provide habitat linkages that create landscape-scale habitat function for migrating salmon that exceeds site-specific levels

Significant outcome in the Duwamish River estuary is not ecological or geochemical, but…

Citizen support, investment, and direct involvement in estuarine restoration has flourished. Citizens taking “ownership” will
then take care of it

Question 31

Final Lessons with Chemicals in Estuaries

Answer 31

1. Understand key processes that originate from the watershed and receiving coastal waters, as well as from within the estuary
2. Use landscape connectivity, both proximally and at regional scale, to maximize the constrained array of restoration options available.
3. Explore innovative and adaptive approaches
4. Plan for long-term stewardship, with small and many sites over the years
5. Expand social and cultural connections, institutional commitments
6. Document how and why estuary ecosystem function can persist, to change perceptions about whether it’s worthwhile investing in restoration
7. Promote ecologically functioning estuaries as a social, economic, and cultural investment