By Camela Haddad. Wednesday 05/06/2019, at approximately noon, was the start of a great journey. After hours of driving, a short ferry trip and airport picking up, we all finally arrived to Vesterålen. The full team was constituted of Joost Raeymaekers, Thijs Bal, Jørgen Hetzler and myself (from Nord University, Bodø campus), Trond Amundsen and Ioanna Gavriilidi (from NTNU in Trondheim) and Neal Sheraga (from Alfred Wegener Institute, Germany). Within this whole team, two "mini" teams were formed: team stickleback (targeting the three-spined stickleback, Gasterosteus aculeatus), and team goby (targeting the two-spotted goby, Pomatoschistus flavescens).
On the first day, both teams went on checking for sticklebacks and gobies on some pre-selected sites, which looked like suitable habitats for the fish species. Three-spined stickleback occurs in both marine and freshwater environments, but for this campaign we were after the marine (or tidal) ones. We anticipated that, at this time of the year when sticklebacks breed, we could find those near river mouths or in harbours. The two-spotted goby is very common along the Norwegian coastline, but the highest densities can be found in kelp beds. So, for both species, sites were pre-selected with the help of the satellite view on Google Maps, which clearly shows harbours and river mouths, and which also give a hint where large patches of kelp can be found.
Team stickleback drove from site to site by car, and used waders, hand nets and minnow traps to check on the presence or absence of the fish. Team goby used a boat to reach the sites. To check the presence of gobies, someone in a dry suit jumped in the water to snorkel along the shore. Once a suitable place was found, a large net (a 60 meter beach seine) was used to trawl from the shore. Different strategies for different species!
After an unsatisfactory morning, perseverance (and some luck) resulted in good news for both mini teams, hurray!
The next day was for processing the fish. Team goby needed to measure and weigh about 100 fish, including, at least, 25 males. The sex ratio for each goby catch was determined too. The gobies will be used to study how climate (sea temperature) affects life history and sexual selection, and to test if life history variation represents local adaptation to temperature regimes.
Team stickleback worked on dissecting 24 to 30 fish collected from each site. From each individual, gonads, pelvic muscles, skin, brain and gills were taken and preserved in RNAlater (stabilizing reagent) for epigenetic studies. Later on, sequencing technologies will be used on these tissues in order to study if ocean warming has any effect on the expression of certain genes, as has been suggested by experimental studies.
It was a very fruitful and fun fieldwork trip for all, we're looking forward to more of this kind :)
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