ABSTRACTS

Oral Session 5 | Tuesday, October 4, 16:40–17:00 | Abstract 560

Detecting Zooplankton from Space

The zooplankton Calanus finmarchicus is a keystone species that is commercially harvested and critical in sustaining many important fisheries in the Arctic. However, due to their patchy and ephemeral population distributions, they are notoriously difficult to map using traditional ship- based techniques. This research involves the use of a combined approach of globally consistent ocean colour imagery and radiative transfer modelling to identify reflectance anomalies potentially caused by surface swarms of Calanus. Results show that ‘patches’ of red pixels within the Lofoten- Vesteralen region of Norway (where in situ measurements indicate the presence of high concentrations of Calanus at the surface) are not well described by varying concentration combinations of chlorophyll, sediment and dissolved organic matter alone. A greater degree of closure between modelled and satellite derived reflectance signals is only achieved in these patches through the addition of Calanus absorption. Further, visual similarity in the RGB colour values of the satellite and modelled spectra were quantified using the Delta E metric and utilised to produce anomaly maps. These maps show a relatively high degree of anomaly within the patches compared to the surrounding waters, indicating the presence of something other than the material traditionally thought to drive the optical properties of the water column. This provides further evidence for the potential of surface swarms to influence remote sensing reflectance signals, and as a result they can be identified through satellite imagery. The methods described have the potential to be applied to other key groups of zooplankton, such as krill. 

*Cait McCarry, University of Strathclyde, 0000-0001-9051-3907

Sünnje Basedow, The Arctic University of Norway

David McKee, University of Strathclyde

Emlyn Davies, SINTEF Ocean