Trait-based analysis of meiobenthic foraminifera in a glacier-influenced fjord: Krossfjord, Svalbard

Habitat heterogeneity can influence functional diversity in Arctic benthic ecosystems, but its effects on meiobenthic Foraminifera remain poorly understood. This study hypothesised that the fjord gradient selects distinct trait profiles, with agglutinated tests in the inner fjord and calcareous tests in the outer fjord (H1), that functional richness peaks in the outer fjord (H2), and that trait–environment links are strongest for test material (H3). The study quantified key foraminiferan traits, tested trait–environment relationships, and compared functional diversity (FRic, FDis, RaoQ), redundancy, and vulnerability across the inner, middle, and outer zones of Krossfjord using RLQ and fourth-corner analyses. Trait analysis of 43 species showed that communities were dominated by infaunal strategies, calcareous tests, muddy-sand substrates, suboxic affinities, and fresh food preferences, with only weak shifts among zones. Functional diversity was broadly similar across the fjord gradient, with a tendency for slightly higher functional richness in the outer fjord and slightly higher functional dispersion and Rao's quadratic entropy in the inner fjord. Test material was the only trait significantly associated with environmental gradients, with agglutinated forms more common in the inner fjord and calcareous forms prevailing in the outer fjord. The study identified 35 functional entities, of which 37 % were represented by a single species, indicating potential functional vulnerability. Overall, these findings suggest weak environmental filtering of foraminiferan traits along the fjord gradient, while possible effects of climate-driven change require further investigation.