The brown seaweeds of Jersey: An intertidal blue carbon assessment

With expanding human populations and rising consumer demands driving the climate crisis, there has never been a greater need for innovative climate change mitigation and adaptation strategies. Although a relatively new science, blue carbon has become increasingly appealing as a marine-based solution. However, macroalgae are yet to be included in such assessments. This is a major detriment to European coastal areas and islands in particular as their marine habitats are often macroalgae-dominated. Jersey, in the Channel Islands, may utilise its sizeable intertidal zone to restore current macroalgal habitats, facilitate new growth or establish seaweed aquaculture. Approximately 1730 tonnes of organic carbon are currently stored in brown macroalgae biomass in Jersey’s intertidal zone. Length-biomass allometry was investigated and significant ratios were found for the majority of species. Additionally, sheltered areas of coastline contained significantly higher densities of carbon and habitats varied significantly in their carbon stock. The intertidal habitat map used in this study accurately represents the environmental ground conditions and presents a suitable method of remote monitoring for future, larger blue carbon projects. The general state of Jersey’s seaweeds and their potential use as a climate change mitigation or adaptation strategy are discussed.