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Conserving Posidonia Australis

Posidonia-australis.jpg

The endemic & threatened species (IUCN), Posidonia australis, is declining at a rate of 1.8% annually (Orth & Dennison 2007). 
 
The meadows formed by Posidonia australis provide the habitat for highly productive ecosystems, providing shelter for sea horses, crustaceans, cephalopods and act as an important nursery for fish. It is also a critical food source for species in the Sirenia order such as Dugongs. Posidonia is very slow to reproduce and very slow growing, meaning it has a slow ability to recover from disturbances. 
This species is highly important in reducing the impacts of global warming as it has an 80% rate of carbon sequestration in sediment (gC m-2  year). 
 
When this species is threatened, whole ecosystems are put at risk. 

Anthropogenic activities that threaten Posidonia include the following: 
- climate change & sea level rise
- increased frequency of storm events
- eutrophication
- dredging/ increasing turbidity
- scaring from propellers
-habitat loss due to mooring- causes scarring
- cattle grazing, runoff
- runoff from river/ urban areas, changing nutrient & salinity levels
- commercial trawling
- urban development 
 
Groups such as Operation Posidonia provide individuals with the opportunity to partake in citizen science programs aimed at restoring habitats that have been lost or disturbed, particularly by traditional chain & block moorings that cause scarring. 
 
"Operation Posidonia has come up with an exciting solution to this problem, but it relies on getting help from local communities.

We are asking 'citizen scientists' to collect donor shoots from their local beach.

Living, green Posidonia shoots often wash ashore after storms, where they will soon perish unless returned underwater. Citizen scientists can collect these detached seagrass shoots and bring them to one of our collection spots. We will then use these shoots to restore seagrass populations without damaging existing Posidonia meadows." 

You can find out more and how to volunteer here: https://www.operationposidonia.com


Written by Kristen McSpadden

Image credited to Dave Harasti & DPI ©