Benthic foraminiferal colonisation of phytodetritus during spring bloom within the marginal sea ice zone off Northern Svalbard continental margin

Phytodetritus is transient organic material derived from phytoplankton blooms that sinks to the seafloor. Benthic foraminifera act as primary consumers of this nutrient-rich material, yet their distribution patterns in phytodetritus and underlying associated surface sediment in Arctic regions remain poorly understood. This study investigates the distribution of living benthic foraminifera in phytodetritus and underlying associated surface sediment during the spring bloom, examining their density, relative abundances, and microhabitat preferences. Distribution patterns were analysed in relation to water depth, bottom water conditions, and organic matter availability. At the highly productive Barents Sea slope station, Alabaminella weddellensis, Adercotryma glomeratum, and Cassidulina neoteretis occupied freshly deposited phytodetrital material, whilst Melonis zaandami dominated the sediment. At the moderately productive Yermak Plateau site, both layers hosted Cassidulina reniforme and C. neoteretis, with Lagenammina arenulata preferring the phytodetrital layer. At the Phaeocystis bloom site in Sophia Basin, Epistominella arctica and Quinqueloculina akneriana were abundant in phytodetritus, whilst Ioanella tumidula and Hormosinelloides guttifer inhabited the sediment. Our findings emphasise the significant role of environmental factors in shaping remarkably distinct foraminiferal communities within the phytodetrital layer and the associated surface sediment, as reflected in faunal composition, density, and relative abundances.