The proposed study concentrates on the life-history characteristics and feeding of Microsetlla norwegica and on its role in degradation of marine snow. We will produce quantitative information on the production (reproduction and growth), feeding (ingestion rates and selectivity) and mortality of M. norwegica, none of which are presently available. In addition, we will study the ability of M. norwegica to find, colonize and consume different types of aggregates, and quantify the abundance of M. norwegica in different types of aggregates from different areas. The specific hypothesis include:
1 . M. norwegica maintains high abundance in the ocean by compensating low growth and fecundity by long reproductive time and low mortality
2. M. norwegica is able to feed and produce on a number of food organisms, including ones that are considered as low quality food for copepods. M. norwegica feeds on aggregates; the production of M. norwegica on aggregates depends on the aggregate quality.
3. M. norwegica is associated with aggregates, using them both as a substrate and as a food source, and is therefore likely to contribute to the degradation of marine snow.
4. Since M. norwegica is regularly observed in marine snow aggregates, it must frequently encounter an aggregate and colonize it. The encounter frequency is dependent on the swimming speed and motility pattern of M. norwegica as well as on its ability to remotely detect aggregates. Theoretical arguments suggest that chemical rather than hydro mechanical cues are used in remote detection. Based on the results, it will be possible to reveal the role of M norwegica in remineralisation and degradation of marine snow and therefore in retarding the vertical flux.