Plankton analysis with the PAMAS S4031 GO

Plankton analysis with the PAMAS S4031 GO

By means of the PAMAS S4031 GO particle counter, the Norwegian Institute of Marine Research (IMR) in Bergen has been able to gain new insights in the field of marine biology. The measured values have successfully proven the theory that the feeding behaviour of mussels is not constant and fluctuates. Furthermore, the previous assumption that the energy supply of the mussels is a purely mechanical sieving process has been shown to be incorrect. Instead, the blue mussel adapts its food intake to the prevailing plankton population in the seawater.

The Norwegian Institute for Marine Research IMR in Bergen has been successfully using the portable particle counter PAMAS S4031 GO for many years in scientific research and for the exploration of marine biology. In this example, the institute is studying the feeding behaviour of the blue mussel (Mytilus edulis), which is cultivated in aquacultures in the seawater in eastern Stavanger, in the Norwegian Lysefjord. The mussel feeds on plankton, which it filters out of the water through its gills.

In one study, plankton was analyzed in seawater. The aim of the study was to investigate the energy supply of the blue mussel and to detect possible factors that play a role in dietary variations. For this purpose, the plankton population and the retention efficiency of the blue mussel were analyzed at two measuring locations. From May to August, several blue mussels were fixed at the measuring locations using lantern nets at a sea depth of 7 meters. Water samples were taken at the same depth. The plankton particles in the seawater were counted using the PAMAS S4031 GO particle counter. The research team started with the water samples and measured the particle quantity and the particle size distribution within the range of 1 to 35 µm. By means of seawater analysis via particle counting, seasonal variations of the plankton concentration could be identified. With this analysis, the marine biologists proved that the plankton population increases and that the size distribution changes with the increase in water temperature from 8 °C to 16 °C during the analysis period.

In addition to the plankton population in seawater, the marine research team also analyzed the retention efficiency of the blue mussel. For this purpose, several mussels were removed from the net for a certain period of time and placed in feeding chambers. The retention capacity of the mussel was determined using the flow-through method, i.e. the plankton population at the entrance of the feeding chamber was compared with the particle concentration at the exit of the chamber. The findings were that the mussels mainly consumed larger plankton particles in the range of 20 to 35 µm in May and June. The seawater analysis had shown a well-balanced particle size distribution for this period of early summer. However, in late July and August the mussels filtered smaller plankton particles of 6 to 16 µm from the seawater. For the late summer period, the particle counter had detected an increased plankton concentration of smaller particle sizes in the seawater.

In a second study, the IMR used the PAMAS S4031 GO to successfully demonstrate that controlled upwelling of deep feedwater in higher, oligotrophic seawater levels has a significant impact on mussel production, as plankton biomass can be largely increased by upwelling. As a result, mussel production yields can be tripled by upwelling.

The success of these studies has contributed to the fact that the portable particle counter PAMAS S4031 GO is now used worldwide by numerous marine research institutes and is valued as an accurate and reliable measuring instrument. Thanks to the 32 freely adjustable size channels, the particle counter enables a highly differentiated analysis of the particle size in the lower micron range.

https://www.pamas.de/particle-counters/products-by-name/pamas-s4031-go