Blue Carbon feasibility study project: a case study for kelp habitat restoration in Northern Ireland inshore waters.
 
Laminarian kelps in Northern Ireland (NI) and around the world represent highly productive ecosystems, that store vast quantities of carbon in their living biomass. However, due to their preference on growing on hard substrata, they have a limited capacity for developing their own organic-rich sediments, limiting their function as long-term carbon sinks. Significant amounts of carbon in the form of detritus that originate from the Laminaria forests reach neighboring sedimentary habitats, where the potential for sequestration of the kelp organic material depends on the burial efficiency of the receiver site. Assessing the contribution of NI Laminarian kelp in the coastal blue carbon budgets, was done in three steps. Initially, a literature review was conducted to identify relevant scientific information on net primary productivity rates, the fate of carbon and the rates of carbon storage. Then using GIS, information was gathered on the current distribution of kelp. Combining these two sources resulted in the calculation of the total amount of kelp net primary productivity, which was then used to estimate the amount of blue carbon burial. Another goal of the study was the identification of suitable areas for potential kelp restoration efforts, in order to increase their blue carbon capacity. A habitat suitability model developed by Strong et al. (2021), was employed to identify these areas and the extent measured using GIS. The final goal of the project was to review potential restoration options and evaluate the positive and negative aspects of investing on these projects. The three Laminaria species found in NI cover an area of 173 km2.The total amount of carbon currently being sequestered was calculated ranging from 695 t C y-1 to 1,051 t C y-1. The habitat suitability model revealed that the available habitat where kelps could expand can add up to 406 km2. That would increase the carbon sequestration to a range between 1,658 t C y-1 and 2,912 t C y-1. When compared to the annual carbon sequestration rates of saltmarshes and seagrass, the contribution of kelp to blue carbon is considered minimal and thus investing in restoration efforts is not advisable. However, kelps in NI offer an array of other ecosystem services of high value, leading to the conclusion that while as blue carbon habitats they offer little value, their ecological and economic importance derived from other services warrants their protection and restoration.