64PE370 - Diary 3

I was thrilled to hear that I could join a scientific cruise organised by the NIOZ and participate to the GEOTRACES programme. This would be an excellent opportunity and wonderful experience for a marine biologist at the University of Groningen. And, of course, an additional extra was that this cruise would take place in the (warm) Mediterranean Sea. However, the weather could not really meet the high expectations during the beginning, until recently, since now a bright flat blue sea and a blue cloudless sky are visible till the horizon.

I already joined the RV Pelagia at Texel in order to 'grow my sea legs', which turned out to be a real necessity. During a number of storms with waves sounding like a whirlpool in the port holes, I had to pay the toilet multiple visits of which I sometimes did not made it in time. I also had to get used to the continuous shaking of the ship since this is my first cruise. Despite - as I have been told - the relative busy cruise schedule with many sampling stations, there is always a moment to enjoy the sunshine on the deck. And at arrival in the port of Lisbon, almost the all crew members and scientists went to the city centre for some sightseeing in this beautiful city.

The unlucky flying fish that hit the deck of the RV Pelagia and subsequently died from suffocation and dehydration. One of the enlarged pectoral fins which is used for gliding in the air and acts as wing to provide lift is clearly visible. Moreover, the extended lower lobe of the caudal fin enables the fish to continue forward force generation when most of the body has already left the water for a maximal jump distance. (Photo: Nicholas Sanchez)

For a marine biologist, a ship is of course one of the best locations to observe the avifauna and sea life from up close. Multiple dolphin pods have been spotted as well as whales, sea turtles and various patrolling seabird species. At night, squid and fish, attracted by the lights, gather near the RV Pelagia. Moreover, an unlucky flying fish has been found on deck after a miscalculated leap out of the water (see picture 1.). My presence on the RV Pelagia is to 'catch' smaller life forms from the water. I filtrate ten litres of seawater from four different depths, namely just below the chlorophyll maximum, at the chlorophyll maximum, just above the chlorophyll maximum and from the surface (ten metres). These filters will subsequently be used for HPLC analyses and absorption analyses at the University of Groningen which can tell us the pigment composition and chlorophyll-a specific absorptions. This can be used, together with other CTD measurements such as PAR irradiance and fluorescence data, to determine algae biomass, algae community structure and algae group specific primary production. These data can be used to investigate how the distribution of trace metals and nutrients may affect the algae community and/or how the algae community may affect the distribution of trace metals and nutrients.

Furthermore, I assist where necessary. I change the three filters on top of the bridge that collect aerosols every day. These aerosols might be dust carried away from the Sahara desert and might give extra input of trace metals and nutrients in the Mediterranean Sea. Moreover, I am responsible for the tapping of water from the 25 litres high volume CTD for oxygen measurements. These are required since the measurements from the sensor on the CTD frame can be unreliable.

Time flies and 22 more stations will have to be sampled in the next two weeks. Extra busy times are upon us. However, if the weather continues to be this magnificent, the 'gezelligheid' remains and more marine life is spotted, the second half of this cruise will be over too soon. So enjoy the cruise for as long as it lasts!

Pim Boute