How will pioneer salt marsh plants respond to rising CO₂?
In the VAL Lab, a new experiment is underway using the PGC20 Growth Chambers. Over the next six months, Jenny Clarke – a second-year PhD researcher co-supervised by Iris Moller (Geography) and Jennifer McElwain (Botany) – will use the chambers to investigate the potential impacts of climate change on two species of pioneer salt marsh plants.
Jenny is growing Spartina anglica and Salicornia europaea under two scenarios: current climate conditions and a potential future, high-CO₂ climate. By comparing the two, she aims to determine how rising atmospheric CO₂ concentrations may affect the germination, establishment, and biophysical properties of each species.
To recreate a working salt marsh inside each chamber, Jenny uses a two-tank system. One tank represents the marsh itself, holding pots of tidal flat mud sown with seeds of one or both species collected from her field site on North Bull Island in Dublin Bay; the other supplies a reservoir of artificial seawater that floods the marsh semi-diurnally, reproducing the twice-daily tidal rhythm experienced by the pioneer zone at North Bull Island.
The ‘current’ climate conditions simulated by the chambers are informed directly by data collected at a monitoring station set up at her field site on North Bull Island. The raised-CO₂ conditions mirror these current settings in every respect except atmospheric CO₂, which is elevated to 820 ppm, in line with the IPCC’s SSP3-7.0 projection for the year 2100.
Salt marshes are among the most valuable habitats on our coastlines: they sequester large amounts of carbon, buffer the shore against storms and erosion, and support rich communities of plants, birds, and invertebrates. They are also highly sensitive to environmental change. By focusing on the pioneer species that first colonise the bare tidal flat, allowing marshes to establish and expand, Jenny’s work should help clarify how these critical ecosystems might respond as the climate continues to change over the coming century.
