Macroalgae and Blue Carbon: Understanding the Impact of Environmental Variables on the Rate of Growth and Carbon Content in Kelp (Laminaria digitata and Laminaria hyperborea)

The growing threat of climate change has resulted in the need for new and innovative
strategies to limit global emissions. One approach involves the conservation and
restoration of coastal vegetated ecosystems that naturally sequester and store atmospheric
carbon, termed Blue Carbon ecosystems. Research has demonstrated that macroalgae
have the potential to sequester and store significant amounts of carbon. However, when
considering the conservation and restoration of macroalgal habitat, it is necessary to
understand the most effective ways to manage these ecosystems and how the carbon
standing stock is likely to be impacted in the future. This study investigates the impact that
the location and age of kelp beds has on the carbon content of Laminaria digitata
populations on Jersey, with older ages and non-artificial environments found to result in
higher carbon contents. The monthly rates of growth and attrition are also compared
between two species of kelp, L.digitata and Laminaria hyperborea, at different locations
around Jersey. Growth rates are found to change seasonally, with a correlation between
declines in L.digitata growth rates and increasing sea surface temperatures (°C). This may
indicate that as temperatures rise in the future due to climate change, growth rates in kelp
populations on Jersey will be negatively impacted. The results of this study suggest that
when selecting sites for the conservation or restoration of kelp communities, locations
should be chosen with environmental characteristics that allow individuals to reach older
ages and higher biomasses in order to increase the carbon standing stock of populations.
Further research, quantifying the impact that specific environmental factors have on
carbon contents of kelp populations on Jersey, would be beneficial in future Blue Carbon
initiatives