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# In Portsmouth, the marsh floats
- URL: https://www.earthtoseanews.com/floating-saltmarsh/
- Published: 2026-08-29T06:04:15.000Z
- Updated: 2026-09-05T04:43:24.000Z
- Description: Marine scientists in England are launching pontoons planted with living saltmarsh, bringing shoreline habitat back to harbours that were long ago walled in concrete, and the same thinking is stirring in Sydney.
- Author: Nicole McMahon
- Tags: Innovations, All stories

Saltmarsh is one of those quiet ecosystems that does everything at once: it shelters young fish, feeds wading birds, filters the water and tucks away carbon in its muddy roots. The trouble is that it needs a soft, gently sloping shore, and busy harbours replaced most of theirs with seawalls generations ago. At the University of Portsmouth, Dr Ian Hendy of the Institute of Marine Sciences has an answer that skips the shore entirely: purpose built floating pontoons, engineered to carry living saltmarsh vegetation, moored where the habitat once grew. The first are going in at a watersports park on Portsmouth's harbour edge with the water company Southern Water as partner, and Dr Hendy describes it as reintroducing habitat into spaces where it had been completely lost to development. The project runs as a long term study, with careful before and after monitoring of the fish, invertebrates and pollinators that move in.

The idea travels beautifully, because nearly every harbour city in the world has the same hard edges. Southern Water's Joff Edevane calls the pilot a wonderful opportunity to improve water quality while rebuilding natural capital, and if the floating marsh performs, versions of it could soften seawalls from Southampton to Singapore. Closer to home, the same current is moving in Sydney: Blue Green Australia, led by Colin Finn of the University of Sydney, is drawing up a plan to rewild Rushcutters Bay with restored oyster reefs and mangroves, part of a bigger vision for a living harbour foreshore. The water, it turns out, is ready to come back the moment we make it a little room, even room that floats.

### Questions you might have

**What exactly is saltmarsh?**

The community of salt tolerant plants that grows where the tide meets soft ground. It is a nursery for young fish, a dining table for shorebirds, a natural water filter and one of the best carbon keepers on any coast.

**Why put it on pontoons instead of the shore?**

Because in a working harbour the soft shore is gone, replaced by vertical walls where marsh cannot grow. A floating platform gives the plants the tidal water they need without moving a single wall.

**Could floating habitat work in Sydney?**

The conditions that suit it, calm walled bays that once held marsh and mangroves, describe much of Sydney Harbour. Planning is already under way to rewild Rushcutters Bay with oyster reefs and mangroves, and we will be following where that leads.

*Our short take: the project was announced by the University of Portsmouth, 9 April 2026\. Sydney planning reported by OnImpact.*