Seabirds and seals as drivers of plant succession on Surtsey

Seabirds and seals are key drivers of plant succession on Surtsey, accelerating vegetation development through nutrient transfer from sea to land. Since 1965, 75 vascular plant species have colonized the island, with 40 establishing viable populations. Recent decades show slowed colonization, but dense vegetation (2 ha in 2018) has emerged on the northern spit due to seagull breeding and grey seal haul-outs. A 2019 survey revealed overlapping seal distribution and dense vegetation, suggesting seals contribute 9-13 kg N/ha annually, comparable to seagulls' 5-30 kg N/ha input. Plant biomass measurements indicate the spit's development mirrors that of an older gull colony in the south, highlighting the combined role of seabirds and seals in shaping Surtsey's ecosystem. Further research is recommended to quantify seal impacts on nutrient cycling.

Magnússon, B., Gudmundsson, G. A., Metúsalemsson, S., & Granquist, S. M. (2020). Seabirds and seals as drivers of plant succession on Surtsey. Surtsey Research, 14, 115–130. https://doi.org/10.33112/surtsey.14.10