Exploratory data analysis of the interactions among physics, food web structure, and function in two Arctic polynyas

Abstract

Polynyas are areas of open water in ice-covered seas, characterized by high biological productivity. The NEW (Northeast Water) and NOW (North Water) polynyas, located off the east and west coasts of Greenland, were extensively sampled in 1993 and 1998, respectively. We used principal component analysis to explore the seasonal covariations among physical, chemical, and ecological characteristics in these polynyas. In both polynyas, the most explanatory eigenvector revealed the expected seasonal development of the bloom (nutrient consumption and biomass increases) associated with declining ice cover, warming, and mixed-layer shallowing. This seasonal pattern, however, was much weaker in NEW than in NOW. No connections between the structure of the food web and recycling processes were apparent in either polynya. The analysis points to much stronger and richer interactions between the mesoplankton (i.e., diatoms–zooplankton) and microbial food webs in NOW than in NEW. The differences between the polynyas may be explained in part by differences in their longevity, with the longer-lived NOW polynya having more time to develop complex trophic interactions. The results also indicate that the connections between food web structure and ecosystem function (i.e., new production versus recycling), at least at the seasonal scale, are weaker than expected.