âYealm Intertidal Habitat [and their supported wildlife communities] Improvementsâ
Our estuary, the final tidal part of our river where the fresh meets saltwater
The intertidal wildlife can be subject to the extremes of whatever the weather is doing at low tide extremes of salinity, drying, heat and cold
Freshwater floating over saltwater
Settlement of catchment sediment: freshwater right saltwater left
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âFlocculationâ
Physical factors driving estuarine ecology
The estuarine ecosystem is highly productive â being âfedâ by the organic detritus from the catchment and tidal waters
⊠organic detritus from the catchment and tidal waters
https://www.yucatanalamano.com/destacado/egresada-de-uam-disena-nano-molecula-que-elimina-bacterias-y-virus/
Mudflat bacteria break the organic detritus down releasing nutrients (8 billion per egg cup of mud so many they deplete the mud of oxygen making the mud anoxic just 1cm down ⊠why itâs black!)
Single celled seaweeds, diatoms, use these nutrients, carbon dioxide and solar energy to photosynthesise ⊠these diatoms migrate within the mud surface with daylight and tides
Saltmarsh
Dominant estuarine ecosystems:
Tidal reedbeds
Seagrass meadows
All are hugely important for the carbon they sequester, trap and store
Mudflats
were commissioned to survey the condition of the saltmarshes by funding partners (right) resulting in
In general, the saltmarshes of the Yealm Estuary are in as good and healthy natural condition as could be expected for a ria-type estuary
A number of issues were identified around the Puslinch marsh area where there may be options to restore and enhance the saltmarsh
Erosion of the historic âcausewayâ is likely leading to the erosion of the saltmarsh behind â potential to build âpoldersâ to encourage sediment build up and saltmarsh restoration
Paddling and grazing by Canada geese may be causing and maintaining the âpitsâ within the saltmarsh proposal to monitor geese behaviour to test this
Restoration of saltmarsh at Kitley Quay being considered but may not be cost:effort effective
Restoration of River Yealm bank â considering use of woody material to repair the bank âwork with natureâ
Polders being placed across the mudflat
â made from local coppiced posts and brashings. Dampen waves & slows the flow, and designed to encourage sediment build up behind to raise the height into the âsaltmarsh zoneâ Fish passes are a must
Example of polders being placed within the Dart Estuary
An additional possibility could be to plant hardy pioneer saltmarsh species to help establish/reinforce a saltmarsh
Species shown is common cordgrass â once considered an invasive
All aspects of the restoration need careful liaison with the regulatory authorities and of course the landowners
Example of possible local saltmarsh interpretation
However, saltmarsh is very vulnerable to disturbance, so we need to encourage an enjoy â donât touch approach There may be places where a closer look may be managed
Dwarf seagrass meadow restoration â these are naturally floating plants collected from Kingsbridge creeks â complete with roots, leaves & seedheads â possibly float as a seed dispersal mechanism?
Carefully washed and checked for âcling-onâ aliens â the plants are replanted in similar conditions within Cofflete Creek Dwarf seagrasses tend to dieback over winter so success may not be evident, if at all, in the spring/summer.
Even if replanting is unsuccessful, they may still grow from the seeds
What successful dwarf seagrass restoration could look like in several years â seen here growing with the channel and below midtide on the mudbanks
There is also some interest in the possibility of restoring native oyster reefs on the bed of the estuary â they would naturally filter the waters âcleanâ
There is historic evidence that shows that there was once a native oyster fishery within the Yealm
Screengrab https://emrprojects.files.wordpress.com/2016/03/fig port
The majority of marine nature conservation is about prevention rather than cure; due to the costs and physical difficulties of working within the marine environment, only time can effectively heal many wounds and this can be considerable.
The subtidal seagrass meadows in the mouth of the Yealm are reported to be healthy but we should ideally be discussing how we ensure its resilience and potential for ensuring it can spread
There is some evidence that the nutrients level flowing into the estuary are too high â areas of green blanket weed over the mudflats and streaks of âred-tideâ.
Photo from a Kingsbridge mudflat shows what can happen when the blanket weed builds up and starts to breakdown, turning the conditions anoxic (black areas) and inhibiting the natural mudflat ecology
Nutrients are from all fragments of our community â most are usually from agriculture but the onus is to reduce the inputs from horticulture, households, industry and âroadsâ too as the inputs are cumulative
Wastewater treatment may cope with our organic waste inputs but often just break them down into a readily available plant growth fertiliser that add to the algal blooms within our watercourses ⊠they could be removed with further cost to the bill payer
Where development occurs, it is important to work with nature and design & build in a diversity and complexity of semi-natural habitats for wildlife
Other issues being highlighted within the Estuaries Management Plan, presently being reviewed, are disturbance and cumulative loses of foreshore through development. Disturbance includes light pollution over tidal waters.
Biosecurity is a growing issue â we are seeing many more invasive and non-native marine species across our estuaries, and we all need to be taking more care not to spread them
Photos show the âworm wart weedâ, a new arrival within the Yealm
