Post-Fiona: Wetland to Sand Dune

Hurricane Fiona brought many changes to our Island landscape: some dramatic, others subtle, and a few that are – paradoxically – both. Here’s one in that last category, a dramatic change that may be hard to notice unless you know what to look for. Can you see what is very out of place in Photo 1?

Photo 1: Can you spot what's wrong in this picture? Hint: those are Cat-tail (Typha latifolia) seed heads peeking out of fresh sand.

In the centre of the photo are some Cat-tail (Typha latifolia) seed heads, rising out of pure sand like Ozymandias in the desert. Around those sentinels are more Cat-tail stalks, partially buried. This is a plant of freshwater wetlands, so what is it doing in this dry, sandy, salty spot? The answer is clear nearby, where a wave of newly deposited sand meets a freshwater wetland (Photo 2). Fiona didn’t just peel sand away from PEI’s coast, it also pushed sand inland, in this case burying a wetland.

Photo 2: The mystery of the Cat-tails in sand is solved nearby: Hurricane Fiona pushed tons of fresh sand from the shore inland, partially burying this freshwater wetland.

The volume of sand deposited here is amazing. Although it may be hard to see from the photo, the top of that new sand is a good metre (three feet) above the wetland, and the edge is more than 10 metres (30 feet) inland from where the dune and wetland used to meet. In a short period of time, Fiona moved the equivalent of one dump-truckload of sand into *every metre* of this part of the wetland, hundreds of loads in total.

Photo 3: Cat-tails aren't the only evidence of habitat change at this site. Common Reed (Phragmites australis) is another plant of wetlands on PEI, but found growing in pure sand thanks to Hurricane Fiona.

Cat-tails aren’t the only evidence of where the wetland used to be. Although Common Reed (Phragmites australis) is known to be able to adapt to desert-like environments, on PEI it’s more commonly seen in wet soil than dry sand; it looks out of place towering above pure sand at this site (Photo 3). This is a fast-growing plant that sends out specialized stems (called stolons) capable of growing as much as 10 centimetres (four inches) in one day! Here, they are marching across the sand towards the remaining wetland like aliens heading back to the mothership (Photo 4). Everything you see on top of the sand is new growth this year.

Photo 4: Common Reed sends out fast-growing specialized stems called stolons. Here, you can see them working their way back to the wetland like aliens returning to the mothership.

On PEI, sand dunes and wetlands go hand in hand. Our coastal dunes often block drainage from low-lying areas behind them, impounding water from springs, streams, precipitation, and snowmelt. The interplay between these two habitats is like a dance: sometimes the wetland breaks though the dune and expands its footprint, at other times the dune moves inland and buries the wetland.

It will be interesting to watch what happens at this site in Western PEI over the coming years. I predict the new sand will become vegetated and stable while water continues to slowly accumulate in the wetland behind. The wetland will expand into adjacent low-lying areas and – when enough water builds – breach the dune at its lowest point.

Our coastal dunes and wetlands are dynamic and adaptable environments where the only constant is change. That’s what makes them fascinating parts of PEI untamed!