Epifaunal Habitat Associations on Mixed and Hard Bottom Substrates in Coastal Waters of Northern Norway

Katherine Dunlop,Liv Plassen,Astrid Harendza,Nigel Keeley

doi:10.3389/fmars.2020.568802

Abstract

Hard and mixed seafloor substrates are an important benthic habitat in coastal northern Norway and they are known to be colonized by relatively diverse communities of sessile epifauna. These assemblages are highly susceptible to physical damage and stresses imposed by organic material from industrial and municipal sources. However, despite increasing prevalence of stressors, the diversity and distribution of benthic substrates and biological communities in coastal Arctic and sub-Arctic regions remain poorly documented. In response, this study has characterized the composition of mixed and hard bottom substrates and associated sessile epifauna in fjords in Finnmark, northern Norway, using remote sensing and an innovation low-cost towed camera method. The study fjords supported a dense covering (0.1 to 0.68 individuals m–2) of sponge taxa common to deep-water ostur sponge habitats (Geodia sp., Mycale lingua, Polymastia sp., Phakellia ventilabrum, and Axinella infundibuliformis). In addition, aggregations of the soft coral (Duva florida), the tunicate (Ascidia sp.), the seastar (Ceramaster granularis) and anemone (Hormathia digitata) were prominent fauna. The small-scale spatial patterns of the epifaunal communities in this study were primarily influenced by the local hydrodynamic regime, depth, the topographical slope and the presence of hard bedrock substrates. This description of the composition, distribution and the identification of environmental drivers of epibenthic communities is valuable for the development of predictive habitat models to manage the benthic impact of multiple stressor on these ecological valuable and vulnerable Arctic habitats.

Highlights

Coastal Arctic and sub-Arctic regions are experiencing a combination of multiple stressors from industrial activities, municipal expansion and climatic change
these assemblages remain poorly mapped in Norwegian fjords
opening Arctic seas are contributing to an expansion in these maritime activities

Summary

INTRODUCTION

Coastal Arctic and sub-Arctic regions are experiencing a combination of multiple stressors from industrial activities (commercial fishing, aquaculture, marine shipping and mining), municipal expansion and climatic change. Low-cost drop cameras with reduced technical specification are effective for the fine-scale analysis of abundance, diversity and distribution of epifaunal communities in inshore coastal waters (Salvo et al, 2017, 2018) This method is limited in its spatial coverage, both in terms of the practicality of raising and lowering a camera over long distances and quadrat size (usually < 1 m2), which is inappropriate to survey sparsely distributed organisms (Magurran and McGill, 2011). In response to the lack of data on the diversity and spatial distribution of hard and mixed seafloor substrates and associated epifaunal communities, this study applied a novel towed video survey technique combined with remote sensing to effectively characterize: (1) the substrate composition of patchy mixed and hard bottom habitats and (2) the associated sessile epifauna communities in poorly mapped coastal northern Norway. This study presents a novel and cost-effective towed video camera technique and footage analysis method for the quantitative survey of epifaunal communities on complex hard and mixed topography in inshore coastal waters

MATERIALS AND METHODS

RESULTS

Key Findings

Summary and Conclusion

DATA AVAILABILITY STATEMENT