Maria Włodarska-Kowalczuk

Global Patterns and Predictions of Seafloor Biomass Using Random Forests

A comprehensive seafloor biomass and abundance database has been constructed from 24 oceanographic institutions worldwide within the Census of Marine Life (CoML) field projects. The machine-learning algorithm, Random Forests, was employed to model and predict seafloor standing stocks from surface primary production, water-column integrated and export particulate organic matter (POM), seafloor relief, and bottom water properties. The predictive models explain 63% to 88% of stock variance among the major size groups. Individual and composite maps of predicted global seafloor biomass and abundance are generated for bacteria, meiofauna, macrofauna, and megafauna (invertebrates and fishes). Patterns of benthic standing stocks were positive functions of surface primary production and delivery of the particulate organic carbon (POC) flux to the seafloor. At a regional scale, the census maps illustrate that integrated biomass is highest at the poles, on continental margins associated with coastal upwelling and with broad zones associated with equatorial divergence. Lowest values are consistently encountered on the central abyssal plains of major ocean basins The shift of biomass dominance groups with depth is shown to be affected by the decrease in average body size rather than abundance, presumably due to decrease in quantity and quality of food supply. This biomass census and associated maps are vital components of mechanistic deep-sea food web models and global carbon cycling, and as such provide fundamental information that can be incorporated into evidence-based management.

Spitsbergen glacial bays macrobenthos – a comparative study

Abstract Macrobenthos was studied in seven glacial bays situated along the Spitsbergen coast between 77 and 79°N. The fauna was dominated by deposit-feeding or carnivorous polychaetes and bivalves. Only 4 of 118 species identified in the collected material occurred in all the west Spitsbergen localities examined (the polychaetes Chaetozone/Tharyx sp., Cossura longocirrata, Lumbrinereis fragilis s.l. (sensu lato), and the bivalve Thyasira flexuosa). Clustering of samples showed a difference between the faunas of east and west Spitsbergen; the latter formed two subgroups, localities open to Atlantic waters and those from inner fjord basins. The fauna in open basins was dominated by cosmopolitan species, whereas arctic elements shares were higher in inner basins and predominated in the fauna in Bettybukta (east Spitsbergen). This indicates arctic, relict character of the inner fjords sites. The biomass ranged from 6 to 310 g/m2 and Shannon diversities from 0.49 to 2.54.

Climate change effects on Arctic fjord and coastal macrobenthic diversity—observations and predictions

The pattern of occurrence and recent changes in the distribution of macrobenthic organisms in fjordic and coastal (nearshore) Arctic waters are reviewed and future changes are hypothesized. The biodiversity patterns observed are demonstrated to be contextual, depending on the specific region of the Arctic or habitat type. Two major areas of biotic advection are indicated (the North Atlantic Current along Scandinavia to Svalbard and the Bering Strait area) where larvae and adult animals are transported from the species-rich sub-Arctic areas to species-poor Arctic areas. In those Arctic areas, increased temperature associated with increased advection in recent decades brings more boreal-subarctic species, increasing the local biodiversity when local cold-water species may be suppressed. Two other large coastal areas are little influenced by advected waters; the Siberian shores and the coasts of the Canadian Archipelago. There, local Arctic fauna are exposed to increasing ocean temperature, decreasing salinity and a reduction in ice cover with unpredictable effect for biodiversity. One the one hand, benthic species in Arctic fjords are exposed to increased siltation (from glacial meltwater) and salinity decreases, which together may lead to habitat homogenization and a subsequent decrease in biodiversity. On the other hand, the innermost basins of Arctic fjords are able to maintain pockets of very cold, dense, saline water and thus may act as refugia for cold-water species.

Towards a pan-Arctic inventory of the species diversity of the macro- and megabenthic fauna of the Arctic shelf seas

Although knowledge of Arctic seas has increased tremendously in the past decade, benthic diversity was investigated at regional scales only, and no attempt had been made to examine it across the entire Arctic. We present a first pan-Arctic account of the species diversity of the macro- and megabenthic fauna of the Arctic marginal shelf seas. It is based on an analysis of 25 published and unpublished species-level data sets, together encompassing 14 of the 19 marine Arctic shelf ecoregions and comprising a total of 2,636 species, including 847 Arthropoda, 668 Annelida, 392 Mollusca, 228 Echinodermata, and 501 species of other phyla. For the four major phyla, we also analyze the differences in faunal composition and diversity among the ecoregions. Furthermore, we compute gross estimates of the expected species numbers of these phyla on a regional scale. Extrapolated to the entire fauna and study area, we arrive at the conservative estimate that 3,900–4,700 macro- and megabenthic species can be expected to occur on the Arctic shelves. These numbers are smaller than analogous estimates for the Antarctic shelf but the difference is on the order of about two and thus less pronounced than previously assumed. On a global scale, the Arctic shelves are characterized by intermediate macro- and megabenthic species numbers. Our preliminary pan-Arctic inventory provides an urgently needed assessment of current diversity patterns that can be used by future investigations for evaluating the effects of climate change and anthropogenic activities in the Arctic.

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.

Decadal change in macrobenthic soft-bottom community structure in a high Arctic fjord (Kongsfjorden, Svalbard)

Marine benthic macrofauna communities are considered a good indicator of subtle environmental long-term changes in an ecosystem. In 1997/1998 and 2006, soft-bottom fauna of an Arctic glacial fjord Kongsfjorden was extensively sampled and major communities were identified along the fjord axis, which were related to the diminishing influence of glacial activity. Spatial patterns in community structure and species diversity were significantly different in the central basin of Kongsfjorden between periods while there was no change in the inner part of the fjord. In 1997/98, three faunal associations were distinguished with significant differences in species richness and diversity (H′) while in 2006 only two faunal associations were identified and there were no differences any more between the two formerly distinct associations in the central fjord. The increased input of Atlantic water due to a stronger West Spitsbergen Current may be the reason for unification of previous clear faunal division. The faunal association in the inner, well separated glacial part of the fjord, characterized by strong glacier influence, was protected from Atlantic water inflow and, hence, the macrobenthic fauna essentially remained unaffected. Reduced abundance of species typical for glacial bays in the central part of the fjord in 2006 may result from the decreasing effect of Blomstrandbreen glacier, strong increase of input of Atlantic water into the fjord and increased temperature of West Spitsbergen Current. Higher values of POC in 2006 than in 1998 are likely the effect of increased primary production resulting from warmer water temperatures.

Unexpected Levels of Biological Activity during the Polar Night Offer New Perspectives on a Warming Arctic

The current understanding of Arctic ecosystems is deeply rooted in the classical view of a bottom-up controlled system with strong physical forcing and seasonality in primary-production regimes. Consequently, the Arctic polar night is commonly disregarded as a time of year when biological activities are reduced to a minimum due to a reduced food supply. Here, based upon a multidisciplinary ecosystem-scale study from the polar night at 79°N, we present an entirely different view. Instead of an ecosystem that has entered a resting state, we document a system with high activity levels and biological interactions across most trophic levels. In some habitats, biological diversity and presence of juvenile stages were elevated in winter months compared to the more productive and sunlit periods. Ultimately, our results suggest a different perspective regarding ecosystem function that will be of importance for future environmental management and decision making, especially at a time when Arctic regions are experiencing accelerated environmental change [1].

Molluscs in Kongsfjorden (Spitsbergen, Svalbard): a species list and patterns of distribution and diversity

This paper presents a survey of the mollusc fauna in Kongsfjorden, an Arctic glacial fjord in Spitsbergen, Svalbard, based on 197 samples collected with van Veen grabs, dredges, scuba-diving collections and baited traps at depths ranging from 5 to 390 m. Eighty-seven mollusc species were recorded. The species distribution accords well with the distribution of the main substrata: barren rock, kelp bed, gravel and soft bottom. For the most common substrate type, the soft bottom, the distribution and diversity of molluscs were analysed in relation to environmental factors. Glacial activity (particularly the inflow of glacial meltwater loaded with mineral solids) is responsible for the main gradients of environmental variables in the fjord. Silt concentration in sediments, the water temperature near the bottom and inorganic suspensions in the surface water best predict the species distribution of the soft bottom. Two faunal associations located in glacial bays and three faunal associations in the central basin of the fjord can be distinguished for the fauna of the soft bottom. Molluscs are much more abundant in glacial bays (200–300 individuals (ind.) 0.1 m2) than in the central basin assemblages (30–40 ind./0.1 m2). Yoldiid ( Yoldiella solidula , Y. lenticula and Yoldia hyperborea ) and thyasirid bivalves (Thyasira dunbari, T. gouldi and Axinopsida orbiculata) cope particularly well with glacial sedimentation and occur in high quantities in glacial bays. Although there is no effect of glacial disturbance on the molluscan sample species richness and species diversity, there are significant clines of evenness and taxonomic distinctness in areas near to the glacier. The patterns of molluscan diversity are not fully consistent with the patterns described for complete macrobenthic communities.

Data integration for European marine biodiversity research: creating a database on benthos and plankton to study large-scale patterns and long-term changes.

The general aim of setting up a central database on benthos and plankton was to integrate long-, medium- and short-term datasets on marine biodiversity. Such a database makes it possible to analyse species assemblages and their changes on spatial and temporal scales across Europe. Data collation lasted from early 2007 until August 2008, during which 67 datasets were collected covering three divergent habitats (rocky shores, soft bottoms and the pelagic environment). The database contains a total of 4,525 distinct taxa, 17,117 unique sampling locations and over 45,500 collected samples, representing almost 542,000 distribution records. The database geographically covers the North Sea (221,452 distribution records), the North-East Atlantic (98,796 distribution records) and furthermore the Baltic Sea, the Arctic and the Mediterranean. Data from 1858 to 2008 are presented in the database, with the longest time-series from the Baltic Sea soft bottom benthos. Each delivered dataset was subjected to certain quality control procedures, especially on the level of taxonomy. The standardisation procedure enables pan-European analyses without the hazard of taxonomic artefacts resulting from different determination skills. A case study on rocky shore and pelagic data in different geographical regions shows a general overestimation of biodiversity when making use of data before quality control compared to the same estimations after quality control. These results prove that the contribution of a misspelled name or the use of an obsolete synonym is comparable to the introduction of a rare species, having adverse effects on further diversity calculations. The quality checked data source is now ready to test geographical and temporal hypotheses on a large scale.

Factors influencing hydroids (Cnidaria: Hydrozoa) biodiversity and distribution in Arctic kelp forest

The biodiversity and distribution patterns of epiphytic hydroids were studied in kelp forests (composed of Laminaria digitata, Saccharina latissima and Alaria esculenta ) located in an Arctic glaciated fiord (Hornsund, west Spitsbergen). In total, twenty-eight species were found colonizing algae, stones connected to holdfast, and overgrowing the surface of other animals associated with kelps. The characteristics of the algal host (e.g. algae species, age, rhizoid volume or biomass) did not show any effect upon hydroid species richness or species composition. High hydroid biodiversity was strongly dependent on microsubstrate heterogeneity. The highest biodiversity as well as frequency of hydroid occurrence were noted at a site located furthest from the glacier and characterized by the lowest sediment concentration and sedimentation rate. Sexual reproduction also seemed to be inhibited by glacier-derived disturbance. Of ten fertile species found at the ‘clearest’ site only two were fertile at sites under the strong influence of such perturbations. Potential physical drivers of species occurrence were linked to the activity of tidal glaciers, particularly to high loads of mineral sedimentation and iceberg scouring.