Do realignment sites restore microbial biodiversity-driven nutrient cycling and trace gas fluxes comparable to natural coastal ecosystems?

Dr Kelly Redeker, Dr Thorunn Helgason, Mr Richard Garbutt, Dr Alexander Dumbrell, Dr Katie Fenn. University of York, University of Essex and CEH.

Interesting biogeochemistry in salt marsh sediments revealed by footprint, Kelly-Redeker

Realigned salt marshes (restored salt marshes on previously developed land) play a substantial and growing role in coastal management practices within the UK. These managed ecosystems have different above- and below-ground biodiversity and community structures, relative to their natural salt marsh counterparts, which leads to differences in ecosystem processes. Saltmarshes play a large role in global climate, nutrient cycling and regional biodiversity, especially given their relatively small area (<0.1%of the planet’s surface). They are purported to be significant carbon sinks, although upper marshes can be substantial sources of methane (CH4) and nitrous oxide (N2O).

Kelly Redeker with the ‘love your saltmarsh’ activity at the YorNight event.

Saltmarshes may therefore have multiple, potentially conflicting, effects upon global warming through greenhouse gas fluxes. Saltmarsh communities also affect climate by producing significant amounts of halogenated, nitrogen- and sulphur-bearing compounds, which affect ozone in the lower atmosphere and the stratosphere as well as acting as aerosol precursors. The biological and abiotic drivers of these climate-influencing processes within natural saltmarshes remain poorly understood and/or quantified. This lack of knowledge reduces our capacity to effectively model future climate, nor can we accurately assess the implications of various feedback mechanisms (e.g. global warming on saltmarsh carbon storage potential) upon these processes. Our prior research has found plant and microbial community compositional differences between natural and realigned sites.