Week 8- Habitat Restoration

What were habitats generally engineered by

Oyster/mussel species

Why are oyster/mussel beds key

• Fisheries resource

• Excellent filters (important for water quality)

What % of oyster reefs were lost globally and oyster reefs were functionally extinct

85%

What were the main reasons for habitat loss

Overfishing, eutrophication, coastal development, sewage inputs, sedimentation, habitat destruction

What are the benefits of habitat restoration

More fishing

Improves water quality

Protects shorelines by reducing coastal erosion

Improves estuary condition

Particles drawn from water column

How much water can a single oyster filter

200 litres

How are bivalves important

Habitat builders

When and why were bivalves reintroduced on a high scale

Between 1894 and 1930

Restore beds for commercial foshing

What issues arose from reintroducing bivalves

Exotic diseases, competitors, predators

Name an oyster project

Solent oyster restoration projext

Describe the solent oyster restoration briefly

1978- 15 million oysters removed by 15 million vessels

2013- fishery collapsed oyster fishing bannes

Native oyster is classified as apriority

How does an oyster hatchery work

Uses local oysteers at correct temp and diet

Natural water

In close confinement will breed

Allow larvae to settle on old oysters

Placed mature brood stock oysters at high densities in cages hung in water beneath pontoons

Why are the oysters in the solent oyster restoration project positive

Filter water column

Remove nitrogen

Sequester carbon

Provide habitats

Feed on algae and gills act as sieve to remove contaminants

How many larvae were released from solent oyster nurseries in 2017 alone

Over one billion

How many oysters were restored into nurseries/onto seabed

105,000

Where else is there an oyster project but on a significantly larger scale

Chesapeake Bay (US)

What led to the decline at Chesapeake Bay

Overfishing and pollution

What was the target planting density of Chesapeake Bay

12.5 million seed per hectare

What did they believe a successfully restored reef should have (metrics)

Min threshold of 15 oysters and 15g dry weight covering 30% of target restoration 6 years post

Target of 50 oysters and 50g/dry weight covering 30% 6 years post

2+ oyster year classes present

Stable/increasing spatial extent

What do they define a successfully restored tributary as

50-100% of currently restorable oyster habitat has oyster reefs that meet reef-level metrics

What has the success of bivalve restoration looked like

Social and ecological benefits

Future growth relies on promotion of natural/human benefits derived from bivalve habitat recovery

What % of the solent is the solent seascape project hoping to protect and restore

30

What are some of the numbers for solent seascape project

Restores 8Ha saltmarsh, 7Ha seagrass, 4Ha oysters, 10 seabird nesting sites

Increase habitat extent and catalyse recovery

Uses sediment dredged from harbour to rebuild degraded shoreline

58% of natural england salt marshes lost since 1946