Børge Holte

Some macrofaunal effects of local pollution and glacier-induced sedimentation, with indicative chemical analyses, in the sediments of two Arctic fjords

Macrofaunal (>1 mm) and chemical sediment sampling was carried out in August 1992 close to the garbage dumping sites of the coal-mining industrialised settlements Longyearbyen (Adventfjord) and Barentsburg (Grønfjord), located in the Isfjord system, Svalbard. Six stations were sampled with respect to chemical parameters and fauna, while three stations were sampled with respect to only chemical parameters that comprised total organic carbon, total nitrogen, heavy metals (Hg, Cd, Pb, Cu), polycyclic aromatic hydrocarbons (PAH) and chlorinated hydrocarbons (5-CB, HCB, γ-HCH, DDT, PCB7). The concentrations of PCB7, PAH and HCB were, respectively, up to 5, 16 and 30 times higher than assumed background concentrations, presumably as a result of terrestrial water drainage of coal particles originating from local coal-stores and industrial activities in general. The faunal diversities across the sampled areas were relatively low (e.g. Shannon-Wiener indices between 2.0 and 3.2), probably mainly as a result of glacier-induced fine-particulated inorganic impacts. A relatively high faunal abundance, and a quantitative dominance of the opportunistic polychaete taxaCapitella capitata and Chaetozone/Tharyx sp. in the Adventfjord indicated an additional source of perturbation, which was related to the untreated local sewage effluents and/or drainage water from the garbage dumping sites.

Multidecadal stability of benthic community structure in a high-Arctic glacial fjord (van Mijenfjord, Spitsbergen)

Long-term change in benthic community structure may have significant impact on ecosystem functions. Accelerating climate change and increased human activity in the Arctic suggest that benthic communities in this region may be expected to exhibit change over time scales coinciding with these potential stressors. In 2000 and 2001, we resampled the soft-sediment communities of van Mijenfjord, a semi-closed (silled) fjord system on the west coast of Spitsbergen, following initial surveys in 1980. Multivariate community analyses and biodiversity indices identified distinct regions within the fjord. The communities characteristic of two regions were very similar to those sampled 20 years earlier. Regions corresponded with fjord basins and to community patterns and diversity gradients identified for many other Arctic fjords. Benthic communities in open (unsilled) fjords in the area have recently been shown to respond to decadal scale climatic fluctuation. We suggest that semi-closed fjords may be less susceptible to this type of environmental variability, and that communities are shaped by an interaction of impacts from local topography, glacial runoff, local circulation patterns, and faunal life-history traits. Open and closed fjords may respond to climatic warming trends in different ways, resulting in a subsequent divergence in spatial patterns of resident communities.

The macrofauna and main functional interactions in the sill basin sediments of the pristine holandsfjord, Northern Norway, with autecological reviews for some key-species

Abstract In order to study the sediment macrofauna (> 1 mm) in a pristine sill fjord system, baseline investigations were carried out in 1991, 1992 and 1994 in the 30 km long triple-basined Holandsfjord, Northern Norway. Three sampling stations were located in the deepest part of each basin and one in the outer margin of the fjord just outside the outer basin. The innermost basin has relatively high inorganic sedimentation rates caused by glacier-derived melt water run-off. The bottom sediments were generally clay-silt dominated with an organic carbon content between 7 and 11 mg g−1 in the sill basins and between 21 and 22 mg g−1 in the outer margin of the fjord. The Shannon-Wiener diversity index ranged between 3.0 and 4.2, the number of individuals between 373 and 4910 indo m−2 and the number oftaxa per station between 23 and 45. The highest diversity was found at the outer margin of the fjord while the highest number of taxa, in two of three sampling years, occurred at the fjord head. The fauna at the ...

The MAREANO programme – A full coverage mapping of the Norwegian off-shore benthic environment and fauna

Abstract Information about the distribution, composition and status of the benthic environment and communities is important for the implementation of ecosystem-based management involving assessment of the effects of human activities. The MAREANO programme (Marine Areal Database for Norwegian Coasts and Sea Areas) conducts seabed mapping in order to fill knowledge gaps in relation to the implementation of management plans for the Norwegian EEZ. This paper describes the experience from the mapping strategy used by MAREANO. By using a variety of sampling gears the benthic environment and communities from all types of seabed are thoroughly documented. This involves the mapping of bottom topography, seabed substratum, pollutants, species composition, biomass and habitat forming vulnerable biota in a varied marine landscape. The area mapped from 2006 to 2013 is 131,000 km2, spans depths ranging from 40 to 2700 m and covers a variety of topographic features including canyons, cold seeps and coral reefs. The information gained by this broad mapping approach has offered a unique insight into the diversity of benthic species and habitats. Through interpretation and classification of the information gained MAREANO scientists produce a database and detailed maps of seabed surficial geology, marine landscapes, biotopes and particularly sensitive and threatened habitats. Indicators of human impact, such as pollutants, trawl marks and marine litter are also presented on maps. Experience from 8 years of detailed mapping shows the necessity of thorough mapping for informed management decision-making.

Depth‐related benthic macrofaunal biodiversity patterns in three undisturbed north Norwegian fjords

Soft‐bottom macrofauna were sampled quantitatively in August 1994 in three undisturbed north Norwegian fjords. Samples were taken at 10, 25, 50 and 90 m depth in each fjord. The total number of taxa recorded was 399 and the number of specimens 22,017, inclusive of ten juvenile taxa with 1265 specimens, collected from a total sampling area of 4.8 m . The number of taxa per station varied from 75 to 171, the density from 1790 to 8723 individuals m , and the faunal diversity (Shannon‐Wiener H′) from 4.4 to 6.4. In general, the number of taxa increased with depth, whereas the highest densities were recorded at 10 and 25 m. The species richness was generally high at both small (alpha diversity) and larger (gamma diversity) spatial scales compared with other northern and off‐shore shelf areas. Species turnover (beta diversity) was greater across depths within fjords than within depths across fjords. Species community patterns were related to depth and sediment grain size. Statistical analyses undertaken indicated that the juveniles did not affect community structure very much. Among the polychaetes and molluscs the proportion of surface deposit feeders – inclusive of the both surface‐feeding and suspensivorous Spionidae and Oweniidae – and the deep subsurface deposit feeders (Maldanidae and the capitellid Heteromastus filiformis) largely increased with depth. The lowest proportion of other subsurface deposit feeders and the suspensivores occurred at the deepest stations. The study may provide useful reference data for sub‐Arctic fjord environments.

Benthic communities and their physical environment in relation to urban pollution from the city of Tromsö, Norway: 2. Soft-bottom communities

Six sampling stations with relatively similar soft-bottom substrates and current regimes were investigated to find out if there were qualitative and quantitative differences between the macrobenthos near the city of Tromso compared to that closer to the open sea, and if possible faunal differences could be due to sewage from the city. Diversity was highest and dominance lowest at the sampling stations furthest from Tromso (c. 15 km), which were considered unaffected by pollution. The sampling stations nearest to the sewage outfalls were considered moderately exposed to pollution. Analysis of similarity between the stations and log-normal distributions of species/abundance supported these assumptions. Total biomass was an unsuitable variable for evaluating the effects of pollution, due to irregular occurrences of large bivalves and prosobranchs. When the 16 most frequent taxa were considered, the following ten: Nemertinea indet., Harmothoe imbricata, Eteone longa, Anaitides maculata, Typosyllis sp...

Benthic communities and their physical environment in relation to urban pollution from the city of Tromsö, Norway

Abstract Six sampling stations with relatively similar soft-bottom substrates and current regimes were investigated to find out if there were qualitative and quantitative differences between the macrobenthos near the city of Tromso compared to that closer to the open sea, and if possible faunal differences could be due to sewage from the city. Diversity was highest and dominance lowest at the sampling stations furthest from Tromso (c. 15 km), which were considered unaffected by pollution. The sampling stations nearest to the sewage outfalls were considered moderately exposed to pollution. Analysis of similarity between the stations and log-normal distributions of species/abundance supported these assumptions. Total biomass was an unsuitable variable for evaluating the effects of pollution, due to irregular occurrences of large bivalves and prosobranchs. When the 16 most frequent taxa were considered, the following ten: Nemertinea indet., Harmothoe imbricata, Eteone longa, Anaitides maculata, Typosyllis sp...

Soft-bottom fauna and oxygen minima in sub-arctic north Norwegian marine sill basins

Marine sill basins are generally characterized by vertically stratified water masses. During periods of water stagnation, the bottom fauna may be severely affected by the depletion of oxygen. In northern Norway, stratification is less and water exchange processes stronger than in topographically similar boreal basins, which would generally imply better oxygen conditions. In this study the soft-bottom macrofauna (>1 mm) of three northern Norwegian sill basins was examined with respect to species diversity, abundance and functional relationships. Simultaneous data for hydrographical parameters (salinity, temperature, dissolved oxygen) and sediments (total organic carbon, fine fraction) were recorded. All basins were subject to discharges of municipal wastewater. In the basins, the water masses were stratified from spring to late autumn, but apparently freely circulating in winter. During stratification the oxygen content fell to 22–55% saturation in the bottom water. The fauna was generally species rich and diverse, but the number of species was lower than outside the basins. Polychaetes feeding at or just above the sediment surface were numerically dominant. The proportion of detrivorous polychaetes feeding below the sediment surface decreased in relation to oxygen minimum levels. The study suggests that, due to relatively strong water exchange dynamics, northern sill fjords are less vulnerable to organic discharges than more southerly located sill fjords.