by Adrian C. Newton
Foraminifera (forams) are single-celled protozoans that have been used extensively as indicators of paleoclimates by geologists and oceanographers. Only recently have more biologically oriented investigations of their life history and ecology been conducted. As part of the Northeast Water Polynya Project (NEWP) I investigated the distribution and ecology of benthic forams, and their relation to other oceanographic parameters. NEWP was an international project working in the Northeast Water Polynya - a seasonally ice-free region off the northeast coast of Greenland. During two summers of field work aboard the USCGC Polar Sea, I collected sediment samples at every available opportunity in order to acquire temporal and spatial data on the foram population.
Spatial data showed that foram abundance and biomass were greater where overlying water was ice-free rather than ice-covered, suggesting that both factors are coupled to primary productivity in the photic zone. Such coupling will lead to good long-term records of polynya productivity, as higher numbers of preserved forams in the geologic record will indicate periods of greater productivity. Interestingly, diversity within the foram population was lower in ice-free regions, dominated by only a few species. Therefore low-diversity fossil assemblages may also indicate periods of high productivity in the polynya.
Temporal data collected at a time-series station suggest that foram abundance increases considerably in response to pulsed food inputs. This response by forams has been noted previously where appreciable reworking of food in the water column does not take place. It has been suggested that cold arctic conditions suppress bacterial production in the water column and sediments. Therefore, if benthic forams feed and reproduce in an opportunistic fashion upon food reaching the sea floor then they will play an important role in arctic food webs, making newly settled detritus available to other benthic organisms. My recovery of forams packed full of a green material supports this proposition. I hypothesize that the material is settled phytodetritus which the forams ingested. Interestingly, these living individuals were found up to 6 cm deep in the sediment, suggesting high rates of mixing by larger animals such as worms, in response to food input during spring and summer.
This research sheds light on the wealth of information that living forams hold, and identifies their importance in benthic food webs in the Arctic Sea. They form a valuable resource for biological oceanographers, in addition to the significance they already hold for geological oceanographers.
Editor's Note: Adrian graduated in August 1994 and returned to his home in the UK, where he presently seeks employment in environmental policy.
Oceanography, Texas A&M University
Updated July 24, 1995