A comparative study of the biomass and density of seagrass beds in Jersey, Channel Islands

Seagrasses provide a variety of ecosystem functions within the marine environment. Recently, an increasing
interest has been shown in the Blue Carbon potential of seagrass meadows. As these plants sequester more
carbon than they omit, they are classed as carbon sinks and can be used within Blue Carbon strategies to
mitigate climate change. It was hypothesised that older seagrass beds would contain higher levels of carbon
sequestration; therefore, these older beds should be prioritised for conservation. An old and a young Zostera
marina seagrass bed was studied from two sample sites; Anne Port and St Catherine’s Bay. The above-ground
biomass (AGB), below-ground biomass (BGB), blade lengths and the number of blades per plant were
compared using generalised linear models between the different aged beds in both locations. The results found
that while some variables were statistically significant, there was too much variability between the two sites.
Therefore, it was concluded that older beds should not be prioritised for conservation. Instead, the value of
seagrass beds should be analysed on an individual basis.