Tuesday, 9 January 2018

EFFECTS Cruise December 2017

EFFECTS (Examining the Role of Fish-Falls on Ecosystem processes)

The EFFECTS Cruise took place in December 2017 with Andrew Sweetman and Robert Harbour (Heriot-Watt University, Edinburgh), Kathy Dunlop and Paul Renaud (Akvaplan-Niva, Tromsø) and Daniel Jones (National Oceanography Center, Southampton).

The team boarded the RV Johan Hjort (Institute of Marine Research). The destination was Kaldfjorden, a fjord system off the island of Kvaløya, close to Tromsø, Northern Norway.

RV Johan Hjort in Kaldfjorden, Troms

In recent years, Kaldfjorden has been a winter stopover site for a large proportion of the migrating Norwegian spawning herring stock.  The herring have been followed to Kvaløya and Kaldfjorden by killer and humpback whales, made famous in the recent BBC Blue Planet II documentary.

Killer whales in Kladfjorden.(image from bbc.co.uk)

Feeding by whales are suspected to result in high herring mortality and the occurrence of high numbers of herring carcasses on the seafloor. Such a large input of organic material to the seafloor has the potential to significantly impact benthic community functioning.  However, carcasses can be removed by the local scavenging community, reducing the effect of  herring decomposition on seafloor processes.  Knowledge of the scavenging communities in Kaldfjorden is very limited and one of the aims of the EFFECTS project was to assess scavenging rates on herring carcasses.

The Anonyx baited camera lander and a yo-yo camera system were used on the cruise to examine what scavenging communities were feeding on herring carcasses and how quickly.  The yo-yo camera system was used to collect images of the seafloor habitat and to quantify the density of herring carcasses on the seafloor. 

Images of the "Anonyx" camera lander being deployed in the dark waters of Kaldfjorden and the Yo-Yo camera being prepared for deployment.  

5 baited lander camera deployments were made in the Kaldfjorden (3 in the outer fjord and 2 in the inner fjord region).  2 yo-yo camera transects were also conducted in each of the outer and inner fjord regions.  

Ships track during EFFECTS cruise. 

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