Ecological aspects of aggregates.

PAMATMAT, M., RIEBESELL, U., SCHIEL, S. AND SCHLOSS, I.R.

Berichte zur Polarforschung Reports on Polar Research

Alfred-Wegener-Institut

Año: 1989 p. 93 - 100

Fragile aggregated particles, or ´marine snow´, are a common feature of the pelagic ecosystern. These aggregates, ranging in size from a few hundred rnicrometres to several centimetres in diameter, are very diverse in structure and cornposition. They offen include both organic and inorganic components. The processes leading to the formation of aggregates are still poorly understood. The study of marine aggregates is of considerable value to several oceanographic disciplines. The aggregation of microscopic particles to rnacroscopic conglomerations leads to an alteration of particle sinking rate which can result in a substantial increase of vertical flux. Chemical conditions within aggregates can differ significantly from the surrounding water, resulting in chemical heterogeneity and small-scale patchiness in the pelagic System. The aggregation of small particles to larger ones can also be of importance to the pelagic food web. Conventional oceanographic sampling methods (such as nets or water bottles) have failed to collect the fragile aggregates without disrupting them. In this study, we used an experimental apparatus (roller table, See later for details) which has been shown to reform disrupted aggregates and maintain them in the laboratory (Shanks and Edmondson, in press). Consequently, aggregated material obtained by this method can be interpreted as marine Snow which was present in the water column before sampling. Applying this method to melted brown-ice will create new aggregates which have not necessarily existed in the ice. Therefore, aggregates produced under these conditions will be interpreted as aggregates that potentially would have been forrned during and after ice-melting.