The abundance of benthic calcareous foraminifera and other meiofauna at a time series station in the Northeast Water Polynya, Greenland

Abstract

Abundance and vertical distribution of living calcareous Foraminifera and associated meiofauna have been estimated during the ice‐free period in 1992 and 1993 at a time series station in the Northeast Water Polynya off eastern Greenland. Calcareous forams (>150 μm) represented on average 28–39% of the meiofaunal size class. The mean abundance for both years was 574 individuals/100 cm2, and the variability of the estimates (Standard deviation = ±140) was relatively modest for benthic samples (Standard error=8.7% of the mean, number of samples=8). The abundance in 1992 was lower than in 1993 (probability <0.05), reflecting a smaller polynya, with less surface water productivity. While 41% of the variation in abundance in 1993 could be explained as a function of time (the estimated mean doubled between May 30 (387 ind/100 cm2) and July 24 (734 ind/100 cm2)), supporting earlier observations elsewhere that Foraminifera respond rapidly to seasonal or pulsed food inputs, the relationship was not statistically significant. The number of species present was low, a characteristic observed in other foram biofacies associated with open water shelf regions of the Arctic. This assemblage was dominated by a few calcareous forms: Elphidium excavatum, Melonis barleeanum, Nonionella labradorica, and Bucella frigida. Green and brown material, which we suspect was freshly settled phytodetritus, was found in numerous individuals of the dominant calcareous species located as deep as 6 cm within the sediment. The dominant species, including those containing “pigments,” were encountered at specific, fairly narrow depth ranges within the sediment, with maximum abundances being common below, rather than at the sediment surface. Other meiofauna (nematodes, agglutinated forams, and ostracods) occurred to depths as great as 10 cm in all cores, but their greatest densities were generally confined to surface sediments.