| Popis: |
Nothing is homogenous, neither the oceans, nor the distribution pattern of particles and plankton, both in the water column and within their patches. Here we analyse and map the spatio-temporal distribution patterns and the internal structure of 94 patches of various size fractions of particles and plankton studied in two Arctic fjords over six summer seasons. Observed patches generally occupied only the minor part of the studied upper water column (on average 12 %), and frequently occurred as multi-fraction forms. They varied among years and regions in terms of their position in a water column, size, shape, and structure. Consequently, we propose completely novel insight into their internal structure, by classifying them according to their shapes and the location of their cores. We distinguished seven types of patches: Belt, Triangle, Diamond, Flare, Fingers, Flag, and Rosette. The observed increasing role of the smallest size fractions (steepening size spectra slopes) over years implies that Atlantic water advection played the crucial role on compositional dynamics on temporal scale. The recurring feature of the elevated concentrations of particles and plankton near glacier fronts suggest that it, together with local biological production, is the strongest mechanism generating patchiness on the local scale. Even though we significantly extended our comprehension of the phenomenon of patchiness, it still remains an ambiguous matter, when, why, and if the mechanistic or ecological forcing prevails in shaping the patterns of particles and plankton distribution. Regardless of the mechanism, our results show that particles and plankton are not purely dye-like passive objects and that the type of their structuring in a water column may have only short term and local validity. |
