The main objectives of the biological sampling in ACUSAT are:

a) To verify information from satellite and acoustic recordings of mesoscale eddies

b) To provide data for model evaluation and improvement

Sampling design: The sampling will be designed to resolve species composition according to the density structure observed by acoustics at frequencies from 18 kHz to 360 kHz. Samples will be collected both day and night along transects through the centre of the eddy. This will reveal the density structure of biomass in relation to the physical structure of the eddy.

Sampling methods:

· Data on hydrography and fluorescence will be obtained from CTD casts with water bottles. Water samples will be taken from selected depths for nutrient and chlorophyll analysis.

The sampling program will involve several opening and closing nets to study the distribution and vertical dynamics of individual species or groups.;

· Mocness (180 μm, 1 m2, 7 nets), oblique hauls

· Macro zooplankton trawl (3000 μm, 36 m2), equipped with a multisampler and 5 cod-ends (Wenneck et al. 2008).

Data obtained:

· Hydrography (Salinity, Temperature)

· Nutrients (Phosphate, Nitrate, Silicate)

· Phytoplankton biomass (Chlorophyll-a, Fluorescence)

· Zooplankton biomass: Fractionated into the following size spectra: 180-1000µm; 1000-2000µm; >20000µm

· Biomass and numbers of main groups of micronekton/macrozooplankton: euphausiids, amphipods, shrimps, gelatinous zooplankton.

Sampling with Mocness net	Examples of biological samples