After a few days of bad weather (Force 10) slowing the steam to the working area the weather has finally improved. The forecast appears to be good and full activities have begun.
Today a sub-surface mooring was deployed at the PAP site by the team of scientists and engineers onboard. The mooring will stay out for a couple of weeks before being recovered before the end of the cruise. The mooring is equipped with sensors (instruments) measuring the biological activities in the ocean. For example, a sensor called the Deep-IODA will measure the oxygen consumption in the ocean interior (>200m). Another sensor called the ZPS (Zooplankton Sampler) is fixed at 50m and will collect samples of zooplankton (marine animals near the base of the food chain). The ZPS works by filtering water at a rate of 25 Litres per minute. Zooplankton are caught on a mesh and the samples are preserved in a sealed container to analyse back in the laboratory. Sampling will occur every 12 hrs at midday and midnight. These times have been chosen because zooplankton tend to spend the daylight hours in the dark depths of the ocean (~ 200 m) to avoid being eaten by predators. However the food is more abundant in shallower waters so they move upwards to feed once it is dark and then retreat to deeper waters to avoid predation in the daytime. Comparing samples collected in the light and dark will provide information on the level of migration occurring at this time of the year and the abundance and diversity of zooplankton populations at 50m. A microcat (temperature and conductivity/salinity sensor) has also been deployed just above the zooplankton sampler to gain information on the physical properties of the ocean which is intimately linked with the biology.