Diary

R/V Pelagia Cruise ARCHIMEDES-1

Sunday – 27 November 2005
Nederlandse versie
We are now sailing in tropical waters with temperatures well above 25°C while we hear from the daily news service here on the Pelagia about the winter with snow over much of Europe. Over the last few days we have solved a major contamination problem we had in our high pressure samplers (HPS). These pressure sampling systems are essentially like a 50 ml syringe but can maintain a pressure of up to 800 bar, corresponding to a water depth of around 8000 m. With these pressure retaining systems made out of titanium, we can measure the activity of deep water microbes without changing their pressure conditions as mentioned in an earlier progress report of ARCHIMEDES-1.
The contamination came from the grease used for valves. On this grease there were also some bacteria growing in high numbers. These grease-eating bacteria were also responsible for the high activity rates we measured during the first week. A thorough cleaning protocol has now been developed starting with Herman - the master-mind of the high pressure samplers - putting apart each of the 72 high pressure samplers. Then, all the individual components are first put in an Ajax solution, then in a strong acid mixed with seawater and finally in distilled water. All these washing steps are done in a sonicator which helps to remove all the remains of oil and grease. After that, the individual components have to be assembled again by Herman. This through cleaning now has allowed us now finally to measure activity rates in the high pressure environment of the deep sea. Although it is a bit early to make firm statements, it appears that conventional sampling with the NOEX bottles of the deep ocean leads to a gross overestimation of the microbial activity. Over the next few days we will have a major focus on collecting more of this type of measurements. Besides this high tech part of the cruise, we also had a low-tech part planned. With the successful application now of the high pressure samplers, this low tech part is somewhat reduced in size. This low-tech part is collecting the sea surface micro-layer, the skin of the ocean. It is this layer which influences the exchange of gases and heat between the ocean and the atmosphere. This micro-layer is sampled with glass plates collecting the top 0.1 mm of the ocean. Today, Thomas and Karel set out with the inflatable boat of the Pelagia supported by Marco (first mate) and Hans (Second Engineer). After 2 hours of dipping a glass plate into the water, they came back with 4 liters of sea surface micro-layer water. This micro-layer is typically enriched in organic and inorganic phosphorus and in other organic and inorganic compounds. We will focus on the microbiology of this layer and the response of the microbes to the input of soot, also called 'black carbon'. This black carbon originates largely from incomplete combustion of fossil fuel burning or burning wood. We add a standardized amount of this soot to water and test how the microbes are reacting to it in the presence and absence of ultraviolet radiation. Apparently, bacteria are able to live on this soot if ultraviolet radiation helps them to break this soot down. We are now half way through the cruise and we start sailing north again. Before the temperatures drop making it less pleasant to enjoy warm nights, we had a mid-term BBQ last Saturday. Ger, Roel, Sjaak, Jose converted the aft deck first to a nice grill place with excellent food nicely arranged by John, the cook. This grill place slowly turned into a bar after sunset. People enjoyed a relaxing evening before we continued our sampling program on Sunday morning with a deep water cast and a micro-layer sampling.