Hi Noah,
It’s great that you are thinking about what local materials could be used for your design and any potential environmental impacts the use of these materials might have.
With regards to both mangroves and coral reefs, I would suggest avoiding these as alternative materials. As you’ve already acknowledged, these sources are already threatened and both provide critical ecological services to Saibai Island’s coastline.
During the design process, it is okay for you to make some reasonable assumptions based on your own research. Have a look through the interactives and photo galleries to see if you can see any other materials that might be better suited.
Cheers,
Anthony
Anthony Brady