Soft bottom species richness and diversity as a function of depth and iceberg scour in Arctic glacial Kongsfjorden (Svalbard)

Abstract

Macrozoobenthic soft-sediment communities of central Arctic Kongsfjorden inhabiting six depth zones between 5 and 30 m were sampled using SCUBA-diving during June-August 2003 and analysed comparatively. About 63 taxa were found, nine of which had not been reported for Kongsfjorden and four for Svalbard. Suspension feeding or surface and sub-surface detritivorous polychaetes and deposit-feeding amphipods were dominant. Only 11 of the 63 taxa (45 species and additional 18 families not further identiWed) inhabited the complete depth range. Biomass ranged from 3.5 to 25.0 g ash free dry mass m ¡2 and mean Shannon diversity (Log e) was 2.06. Similarity clustering from abundance and biomass data showed a signiWcant diVerence between the shallow station (5 m) and the rest. The latter formed two sub-groups (10-20 and 25-30 m). Depth is irrevocably correlated with icescouring. Thus the diVerences in diversity together with the predicted iceberg scour intensity support the 'intermediate disturbance hypothesis' indicating that habitats impacted by moderate iceberg scouring enable higher diversity. In contrast, biotopes frequently aVected only host pioneer communities, while mature, less diverse assemblages dominate depths of low impact.

Meiobenthic colonisation of soft sediments in arctic glacial Kongsfjorden (Svalbard)

“…Iceberg scouring is likely to be one of the most common disturbances in those benthic habitats. In fact, Laudien et al (2007) related macrobenthic community differences of the same habitat to scouring. The only existing study recording shallow water meiofauna recovery after iceberg impact stems from the Antarctic (Lee et al, 2001).…”

“…Physical disturbances both on spatial and temporal scales are thus highly variable. Laudien et al (2007) assume that for macrobenthic infaunal communities at Kongsfjorden iceberg scouring may be the main structuring force, capable of producing up to 5 m deep plough marks (pers. observ.…”

Disturbance effects of kelp thalli on structure and diversity of a coastal Arctic marine soft-bottom assemblage

“…The average tidal amplitude in Kongsfjorden is 1.8 m (Svendsen et al 2002). The soft-bottom community of the study site is dominated by polychaetes, molluscs and crustaceans (Laudien et al 2007). Stones (B 0.3 m in diameter) covered mainly with kelp (primarily Saccharina latissima (L.) C.E.Lane, C.Mayes, Druehl and G.W.Saunders, but also with Alaria esculenta (L.) Greville and Desmarestia sp.)…”

“…To avoid edge effects, each sample was taken at a minimum distance of 10 cm from plot margins by pushing a sediment corer of 5.2 cm diameter five centimetres deep into the sediment. This method (adopted from Petrowski et al 2015) was shown to generate representative samples of the soft-bottom fauna at the study site and produced a comparable taxon list to that compiled by Laudien et al (2007) who used larger corers (20 cm ø) that were pushed deeper (20 cm) into the sediment than in this study. Samples were transported within 2 h to the Marine Laboratory in Ny-Å lesund and stored in a cooler at 5°C.…”

“…The reported evidence about the ecological effects of disturbance in polar ecosystems comes, however, mainly from mensurative studies and is to our knowledge exclusively based on the role of physical factors like ice scour (e.g. Conlan and Kvitek 2005;reviewed in Gutt 2001;Laudien et al 2007) and boulder movements (Konar 2013). From rocky shores in the This article belongs to the special issue on the ''Kongsfjorden ecosystem -new views after more than a decade of research'', coordinated by Christian Wiencke and Haakon Hop.…”