Particulate matter and phytoplankton and bacterial biomass distributions in the Northeast Water Polynya during summer 1992

Abstract

The patterns of particulate matter distribution (chlorophyll, phytoplankton pigmentation, biogenic silica, particulate carbon, and nitrogen, bacterial and phytoplankton abundance, and optical particle concentration) in the Northeast Water Polynya off the northern coast of Greenland are described, and their relationships to environmental conditions (hydrography, nutrients, and ice cover) are analyzed. Particulate matter concentrations were substantial in the euphotic zone, with the largest fraction consisting of phytoplankton material. Most of this phytoplanktonic material was diatomaceous during the study period (late summer). Surface chlorophyll concentrations were inversely correlated with nitrate concentrations, which were often undetectable in the surface layer, suggesting that phytoplankton standing stocks were controlled by nitrogen availability. The particulate carbon to particulate nitrogen ratio was unusual, in that elevated (approximately nine by weight) mean values were observed near the surface and reduced values (near 6 by weight) occurred at the base of the euphotic zone. These elevated C/N ratios apparently resulted from adaptation to low nutrient conditions. Other elemental ratios (particulate carbon to chlorophyll, biogenic silica to particulate carbon) appear similar to other Arctic systems. Bacterial numbers were greatest in waters with intermediate ice concentrations but in all cases contributed a small fraction (approximately 3%) of organic carbon in the particulate pool. Though variable in spatial distribution, the polynya was a source of substantial quantities of particles; resolving the fate of this material requires further analysis of these data in conjunction with rate measurements and coupled physical‐biological models.

Peracarid fauna (Crustacea, Malacostraca) of the Northeast Water Polynya off Greenland:documenting close benthic-pelagic coupling in the Westwind Trough

“…They attributed this to grazing of herbivorous copepods, which is about 3 times higher in the south (Ashjian et al 1995). Ambrose & Renaud (1995) found no relationship between water-column and benthic pigment concentration (the most important predictor of infaunal density and polychaete biomass) in the Southern Trough, although phytoplankton standing crops were similar to those in the Northern Trough (Smith et al 1995) In their opinion this might indlcate that water column and benthos were decoupled in the south, possibly due to the abundance of grazing phytoplankton. Pomeroy (1974) and Jumars et al (1989) suggested that grazers are needed to stimulate bacterial activity (by providing substrate of high quality); the grazers should enhance the role and importance of the microbial loop in processing carbon.…”

“…The incongruence in our findings concerning the lower abundance of peracarids in the south, where the chlorophyll incorporation and biological activity (ATP measurements) are not strikingly lower, might indicate a greater abundance of smaller meiobenthic organisms in the south, which could lead to a most rapid incorporation of organic matter into the sediment by bioturbation processes. On the other hand, Ambrose & Renard (1995) implicate a possible grazing effect of copepods for the lower densities of polychaetes in the southern trough (Ashjian et al 1995, Smith et al 1995. Grazing would also affect the availability of food for peracarids.…”

“…) indicates high productivity of this area during summer months. Both abundance and biodiversity of peracarid communities in the NEW Polynya are influenced mainly by productivity (particularly ice algae) (Ritzrau 1994, Ambrose & Renaud 1995, Ashjian et al 1995, Smith et al 1995 and hydrography (lateral advection) (Ritzrau 1994, Schneider & Budeus 1994) during summer months. In winter, when the polynya is closed, biological processes of interspecies relationships (such a s competition and predation) likely control the composition of peracarids.…”

Fluxes of carbon in the upper ocean: regulation by food-web control nodes

“…9) ranges between -74 and -44 mmol C m Bacterial production was computed as the product of bacterial biomass and growth rates. Data from Smith et al (1995), Yager (1996) and Yager & Deming (1999) Th disequilibrium (E TH ), and computed bacterial respiration (BR, Eq. 14) and export (E T = P T -R, Eq.…”

“…In addition, because there are no published PB data for the Peruvian upwelling system, we used instead those for the Chilean upwelling (McManus & Peterson 1988, Ducklow & Carlson 1992. BP in the NEW was computed from published bacterial growth rates and bacterial biomass (Smith et al 1995, Yager 1996, Yager & Deming 1999. Values of E TH are from Buesseler (1998), Charrette et al (1999) and Buesseler et al (2001).…”