Carbon preservation in salt marshes in relation to vegetation zonation and response to climate change

It is estimated that biological carbon storage and sequestration in highly productive coastal ecosystems, such as salt marshes and mangroves (also known as Blue Forests), accounts for 30-40% of carbon that is captured by all marine life (Blue Carbon) despite covering only 0.5% of seabed. Salt marshes in particular are now recognised as some of the most important carbon sinks on the planet. Preliminary estimates suggest that in terms of global Carbon burial they may be superior to rainforests and it is suggested that they bury Carbon up to 55 times faster than terrestrial ecosystems (Macreadie et al., 2013). However questions remain; these relate to the specific characteristics of salt marshes regarding vegetable zonation, inundation frequencies and supply of allochthonous material and their effects on the sequestration process of organic carbon. Carbon burial processes are an interplay of origin and type of organic matter, which relates to dominant vegetation, mineral type and grain size, oxygen exposure time (in salt marshes this largely relates to inundation frequency) and a range of microbially mediated biogeochemical processes in the sediments (Wang et al., 2003; Volkman et al., 2008; De la Rosa et al., 2012). The composition of buried organic matter, originating from different plant species, affects its preservation potential, and therefore it is expected that salt marsh areas with distinct vegetation zonation will bury different amounts of carbon and may respond differently to environmental change. In addition salt marsh vegetation zones trap sediments with different grain sizes, affecting carbon preservation by differing degrees organic matter and mineral association (e.g. Mayer, 1994; Hedges and Keil, 1995). The need for a careful examination of carbon preservation of distinct salt marsh vegetation zones is therefore paramount in fine tuning the quantitative assessment of carbon sequestration of these systems. This is particularly pressing now as the ongoing sea level rise is forecasted to affect these ecosystems, by changing the inundation frequency thus affecting oxygen supply as well as supply of allochthonous material (Macreadie et al., 2013). The successful student will embark in spatial and temporal field sampling from distinct vegetation zones of selected salt marshes in North West England. Vegetation surveys coupled with elemental (Carbon content) molecular (lipid biomarkers) techniques will be carried out with the view to gain understanding of the preservation of Carbon in these environments. At a later stage a spatial assessment of carbon preservation potential will be attempted using GIS. Based on that, modelling techniques will help to estimate the response of different preservation zones to ongoing climate change. The student will benefit from the expertise and the wide range of facilities available in the School of Natural Sciences and Psychology in Liverpool John Moores University. The student will acquire an excellent range of skills, from analytical, ecological, GIS, to modelling, and will be proficient in an area of environmental science that is highly topical and thus important for environmental policymaking.