Live foraminiferal assemblages, including soft-walled monothalamous taxa (organic-walled allogromiids, agglutinated saccamminids and psammosphaerids) in addition to hard-shelled polythalamous forms, were analyzed at nine sites (26-104 m water depth) in Tempelfjord on the west coast of Svalbard. Small volumes of sediments (1 ml) were split into 63-125, 125-300 and >300 pm size fractions and each fraction was sorted for all stained foraminifera. There was a marked contrast in foraminiferal assemblages between the inner and outer parts of the fjord. Monothalamous foraminifera (88-97% of the live assemblage >63 mu m) overwhelmingly dominated samples from the inner stations, located close to the glacier edge and, therefore, influenced by freshwater inputs. Multi-chambered agglutinated and calcareous taxa, on the other hand, were most common (77-82%) at the two outer stations. Many of the monothalamous foraminifera were organic-walled allogromiids. The dominant allogromiid was a tiny (30-60 mu m) undescribed species, often with a distinctive cover of sediment particles, which ensured its retention on the 63-mu m sieve. This species made up 31% of live foraminifera in all samples and 66% at one station near the glacier. Saccamminids and psammosphaerids were also common at some stations. A. total of 63 monothalamous morphospecies was recognized with numbers at each station ranging from 7 (station 0763) to 19 (station 0758). Saccamminids at station 0759 were particularly diverse (12 morphospecies). Forms assigned to the genus Gloiogullmia represented 5-10% of the assemblage along the fjord, while the percentage of the genera Psammosphaga, Tinogullmia, and Micrometula was fairly consistent at all stations. These results provide further evidence of the importance of soft-walled, monothalamous foraminifera in sublittoral, high-latitude and brackish-water settings.
Distribution and biodiversity of living benthic foraminifera, including monothalamous taxa, from Tempelfjord, Svalbard
MORIGI, CATERINA;
2007-01-01
Abstract
Live foraminiferal assemblages, including soft-walled monothalamous taxa (organic-walled allogromiids, agglutinated saccamminids and psammosphaerids) in addition to hard-shelled polythalamous forms, were analyzed at nine sites (26-104 m water depth) in Tempelfjord on the west coast of Svalbard. Small volumes of sediments (1 ml) were split into 63-125, 125-300 and >300 pm size fractions and each fraction was sorted for all stained foraminifera. There was a marked contrast in foraminiferal assemblages between the inner and outer parts of the fjord. Monothalamous foraminifera (88-97% of the live assemblage >63 mu m) overwhelmingly dominated samples from the inner stations, located close to the glacier edge and, therefore, influenced by freshwater inputs. Multi-chambered agglutinated and calcareous taxa, on the other hand, were most common (77-82%) at the two outer stations. Many of the monothalamous foraminifera were organic-walled allogromiids. The dominant allogromiid was a tiny (30-60 mu m) undescribed species, often with a distinctive cover of sediment particles, which ensured its retention on the 63-mu m sieve. This species made up 31% of live foraminifera in all samples and 66% at one station near the glacier. Saccamminids and psammosphaerids were also common at some stations. A. total of 63 monothalamous morphospecies was recognized with numbers at each station ranging from 7 (station 0763) to 19 (station 0758). Saccamminids at station 0759 were particularly diverse (12 morphospecies). Forms assigned to the genus Gloiogullmia represented 5-10% of the assemblage along the fjord, while the percentage of the genera Psammosphaga, Tinogullmia, and Micrometula was fairly consistent at all stations. These results provide further evidence of the importance of soft-walled, monothalamous foraminifera in sublittoral, high-latitude and brackish-water settings.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
