First year of practical experiences of the new Arctic AWIPEV-COSYNA cabled Underwater Observatory in Kongsfjorden, Spitsbergen

Philipp Fischer,Max Schwanitz,Markus Brand,Uwe Posner,Friedhelm Schröder,Reiner Loth

doi:10.5194/os-13-259-2017

Abstract

Abstract. A combined year-round assessment of selected oceanographic data and a macrobiotic community assessment was performed from October 2013 to November 2014 in the littoral zone of the Kongsfjorden polar fjord system on the western coast of Svalbard (Norway). State of the art remote controlled cabled underwater observatory technology was used for daily vertical profiles of temperature, salinity, and turbidity together with a stereo-optical assessment of the macrobiotic community, including fish. The results reveal a distinct seasonal cycle in total species abundances, with a significantly higher total abundance and species richness during the polar winter when no light is available underwater compared to the summer months when 24 h light is available. During the winter months, a temporally highly segmented community was observed with respect to species occurrence, with single species dominating the winter community for restricted times. In contrast, the summer community showed an overall lower total abundance as well as a significantly lower number of species. The study clearly demonstrates the high potential of cable connected remote controlled digital sampling devices, especially in remote areas, such as polar fjord systems, with harsh environmental conditions and limited accessibility. A smart combination of such new digital sampling methods with classic sampling procedures can provide a possibility to significantly extend the sampling time and frequency, especially in remote and difficult to access areas. This can help to provide a sufficient data density and therefore statistical power for a sound scientific analysis without increasing the invasive sampling pressure in ecologically sensitive environments.

Highlights

Kongsfjorden (78◦55 N, 11◦56 E) on the western coast of Spitsbergen (Fig. 1) is described as one of the best studied polar fjord systems in the Arctic (Wiencke, 2004)
The Kongsfjorden shallow water ecosystem is characterized by large kelp beds of different species of macroalgae between 0 and approximately 12–15 m water depth (Bartsch et al, 2016)
Similar temporal patterns were observed in salinity (Fig. 4), which indicates that the overall patterns in the water temperature in the shallow littoral zone of the fjord system were significantly determined by a fast exchange of water masses that brought either colder and lower saline Arctic water or warmer higher saline water masses even to the shallow fjord areas

Summary

Introduction

Kongsfjorden (78◦55 N, 11◦56 E) on the western coast of Spitsbergen (Fig. 1) is described as one of the best studied polar fjord systems in the Arctic (Wiencke, 2004). The 20 km long ecosystem opens without a sill in a westerly direction toward the Fram straight (Hop et al, 2002) and is alternatively penetrated by warm saline Atlantic water masses from the West Spitsbergen Current, by cold less saline Arctic water from the East Spitsbergen Current, or a mixture of both (Cottier et al, 2005). This bi-modal hydrographic situation leads to a complex spatio-temporal pattern in the fjord hydrography with an occasionally more Atlantic and in other instances more Arctic characteristic with respect to the water masses, even in the inner fjord system (Svendsen et al, 2002). Important knowledge gaps such as a lack of quantitative data on production, abundance of key prey species, and the role of advection in the biological communities in the fjord still exist (Hop et al, 2002)

Methods

Results

Conclusion