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We evaluated the downward Particulate Organic Carbon (POC) export fluxes in the Subtropical Frontal zone (STF) of the Southern Ocean. The site is characterized by enhanced primary productivity which has been suggested to be stimulated through so-called natural iron fertilization processes at its northern boundary where iron-depleted subantarctic water (SAW) mixes with oligotrophic, iron-replete subtropical water (STW). We adopted the small-volume 234Th method to achieve highest spatial sampling resolution as possible based on a cruise to the STF to the east New Zealand in austral late autumn-early winter, May-June 2008. The inventories of fluorescence, particulate 234Th and POC observed in the upper 100 m were all elevated in the mid-salinity part of the water type (34.5 < S < 34.8), compared with low (S < 34.5) and high (S > 34.8) salinity waters. However, Steady-State 234Th fluxes were similar cross all of the salinity gradient being 1484 in the mid-salinity, and 1761 and 1304 dpm m-2 d-1 in the high and low salinity zones respectively. Bottle POC/Th ratios at the depth of 100 m were used to convert the Th fluxes into POC export flux. The POC flux was again not enhanced in the mid-salinity range where the primary production was highest, being 7.4 mmol C m-2 d-1 as compared to 9.9 mmol C m-2 d-1 in high salinity waters, and 5.9 mmol C m-2 d-1 in low salinity waters. This study implied that natural iron fertilization does not necessarily lead to the enhancement of POC export in STF regions. [ABSTRACT FROM AUTHOR]

Carbonate system variables were measured in the South Atlantic sector of the Southern Ocean along a transect from South Africa to the southern limit of the Antarctic Circumpolar Current (ACC) in February-March 2008. Eddies detach from retroflection of the Agulhas Current located north of the Subantarctic Front (SAF). The eddies increase the gradients observed at the fronts so that minima in fCO2 and maxima in pH in situ on either side of the frontal zone are observed, while within the frontal zone fCO2 reached maximum values and pH in situ was a minimum. Mixing at the frontal zones, in particular where cyclonic rings were located, brought up CO2-rich water (low pH and high nutrient) that spread out the fronts where recent biological production favored by the nutrient input increases the pH in situ and decreases the fCO2 levels. Vertical distributions of water masses were described by their carbonate system properties and their relationship to CFC concentrations. Upper Circumpolar Deep Water (UCDW) and Lower Circumpolar DeepWater (LCDW) had pHT.25 values of 7.56 and 7.61, respectively. UCDW also had higher concentrations of CFC-12 (> 0.2 pmol kg-1) as compared to deeper waters, revealing the mixing with recently ventilated waters. Calcite and aragonite saturation states (Ω) were also affected by the presence of these two water masses with high carbonate concentration. Ωarag =1 was observed at 1000m in the subtropical area and north of the SAF. At the position of the Polar front and under the influence of UCDW and LCDW Ωarag =1 deepen from 600m to 1500m at 50.37° S, and it reaches to 700m south of 57.5° S. High latitudes are the most sensitive areas under future anthropogenic carbon increase. Buffer coefficients related to changes in [CO2], [H+] and Ω with changes in CT and AT showed the minimum values are found in the Antarctic Intermediate Water (AAIW), and UCDW layers. These coefficients suggest that a small increase in CT will sharply decrease the pH and the carbonate saturation states. Here we present data that are used to suggest that south of 55° S by the year 2045 surface water will be undersaturated in aragonite. [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented in which the editor discusses the theme of the issue, which is the archaeology and anthropology of the world's subarctic and subantarctic regions.

For thousands of years, hunter-gatherer societies from southern and central Patagonia inhabited a Subantarctic landscape. In this paper, we argue against the traditional assumption that these were simple societies. We examine population diversity from ecological, archaeological, and ethno-historical data sources, emphasizing the economic and social variability while considering social change through time. We end by analyzing processes of the development of social complexity and hierarchy in recent times, when the industrial world violently disarticulated those societies. All this evidence suggests levels of social variability and complexity archaeologists have not expected. The paper critically reviews traditional archaeological approaches and suggests new research lines that allow for a better understanding of social dynamics. [ABSTRACT FROM AUTHOR]

Based on an eddy permitting ocean general circulation model, the response of water masses to two distinct climate scenarios in the South Pacific is assessed in this paper. Under annually repeating atmospheric forcing that is characterized by different westerlies and associated heat flux, the response of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) is quantitatively estimated. Both SAMW and AAIW are found to be warmer, saltier and denser under intensified westerlies and increased heat loss. The increase in the subduction volume of SAMW and AAIW is about 19.8 Sv (1 Sv = 10 m s). The lateral induction term plays a dominant role in the changes in the subduction volume due to the deepening of the mixed layer depth (MLD). Furthermore, analysis of the buoyancy budget is used to quantitatively diagnose the reason for the changes in the MLD. The deepening of the MLD is found to be primarily caused by the strengthening of heat loss from the ocean to the atmosphere in the formation region of SAMW and AAIW. [ABSTRACT FROM AUTHOR]

Some holoplanktonic species are cosmopolitan and have continuous distribution in the world’s oceans. For most of these species it is not clear whether there is unhampered gene flow between far distant populations or they represent a complex of cryptic species. In the present study we investigated genetic diversity of the cosmopolitan chaetognath Eukrohnia hamata in order to identify its spatial structure. DNA-barcode fragment of the mitochondrial COI gene was determined and analyzed for E. hamata specimens collected in the Arctic Ocean, Atlantic Ocean, and Atlantic sector of the Southern Ocean. Five lineages were determined by the phylogenetic analysis with robust statistical support. Three lineages: Antarctic (Eh-1), Subantarctic (Eh-2), and Arctic (Eh-3) had significant genetic differences and were geographically separated. Two other lineages: Eh-4 and Eh-5, that had the smallest genetic difference, were observed together in tropical waters, but they were geographically separated from the other lineages. We suppose that geographical distribution of most of the E. hamata lineages is shaped by the large-scale oceanic fronts, considered as biogeographic boundaries for numerous zooplankton species. Genetic homogeneity of Arctic, Subantarctic, and Antarctic lineages was also shown, each within its regions of inhabit. [ABSTRACT FROM AUTHOR]

Ocean acidification is expected to have detrimental consequences for the most abundant calcifying phytoplankton species Emiliania huxleyi. However, this assumption is mainly based on laboratory manipulations that are unable to reproduce the complexity of natural ecosystems. Here, E. huxleyi coccolith assemblages collected over a year by an autonomous water sampler and sediment traps in the Subantarctic Zone were analysed. The combination of taxonomic and morphometric analyses together with in situ measurements of surface-water properties allowed us to monitor, with unprecedented detail, the seasonal cycle of E. huxleyi at two Subantarctic stations. E. huxleyi subantarctic assemblages were composed of a mixture of, at least, four different morphotypes. Heavier morphotypes exhibited their maximum relative abundances during winter, coinciding with peak annual TCO2 and nutrient concentrations, while lighter morphotypes dominated during summer, coinciding with lowest TCO2 and nutrients levels. The similar seasonality observed in both time-series suggests that it may be a circumpolar feature of the Subantarctic zone. Our results challenge the view that ocean acidification will necessarily lead to a replacement of heavily-calcified coccolithophores by lightly-calcified ones in subpolar ecosystems, and emphasize the need to consider the cumulative effect of multiple stressors on the probable succession of morphotypes. [ABSTRACT FROM AUTHOR]

Background and aims - During a survey of the soil diatom flora of the sub-Antarctic islands in the southern Indian Ocean, an unknown small-celled naviculoid taxon was discovered living in small cracks in cliffs bordering the ocean. The taxon showed a set of morphological features only found in the genus Microcostatus. However, the unknown taxon could not be identified using the currently available literature. Methods - Using both light microscopical and scanning electron microscopical techniques, the morphology of the unknown Microcostatus taxon was documented. The new taxon is described, illustrated and compared with all other similar Microcostatus taxa worldwide. Key results - Microcostatus elisabethianus possesses a unique combination of morphological features that excludes conspecificity with all other members of the genus. It is characterized by a lanceolate valve outline with protracted, elongate apices, a very large, porous conopeum reaching the valve margins and uniseriate striae composed of only one macroareola and mantle areolae restricted to the valve apices. The morphological features of the genus Microcostatus are evaluated and discussed. Notes on the occurrence and ecology of the new taxon are added. [ABSTRACT FROM AUTHOR]

Cocconeis subantarctica sp. nov., a small monoraphid marine diatom, previously described as C. scutellum cf. var. parva Grunow, is reported from the Kerguelen Archipelago. Based on the careful re-examination of the material using SEM (scanning electron microscopy), both valves and the cingulum were described, which enabled a better classification of this small Subantarctic taxon. The shape of the frustule is widely rounded to subdiscoid, with uniseriate and radiate striae on both valves. The SV (sternum valve) areolae have rota-like hymenate pore occlusions, with larger marginal areolae separated by a hyaline rim. The RV (raphe valve) areolae are more complex than those of the SV, with several reniform concentric hymenate occlusions. This taxon has no real stauros, only one virga, which is larger on one side of each valve. The species is not a member of the Cocconeis scutellum 'complex', but is closely related to C. stauroneiformis despite several morphological differences. [ABSTRACT FROM AUTHOR]

Intercomparisons between altimeter sea surface height (SSH) and open-ocean in situ observations have been limited owing to sparse available datasets. Here, SSH anomaly (SSHA) determined from current and pressure recording inverted echo sounders (CPIES) from the cDrake experiment were compared with an up-to-date AVISO-mapped product. Meandering Antarctic Circumpolar Current (ACC) fronts in the passage interior elevated SSHA variance; south of the Shackleton Fracture Zone and along the northern continental slope, the variance decreased by factors between 6 and 10. In situ analysis focused on the two constituents of SSHA, SSHAref determined from bottom pressure and SSHAbcb calculated from geopotential height referenced to the bottom. The peak variance of both SSHAbcb and SSHAref occurred in the energetic region between the Subantarctic Front and the Polar Front. The contribution of SSHAbcb to total SSHA variance was greater than 40% at all sites and averaged over all sites it was 73%. For most sites, high-frequency (>1/20 cpd) SSHAbcb signals dominated total high-frequency variance. Aliasing of high-frequency signals resulting from 10-day altimeter sampling was assessed. The fraction of aliased energy at frequencies longer than 1/50 cpd for sites at and north of the Shackleton Fracture Zone approached 0.25 and approached 0.50 for southern sites. CPIES and mapped altimeter SSHA agreed well. The mean correlation coefficient was 0.82 and the mean RMS difference was 0.075 m. Correlations between CPIES and AVISO were notably poorer at the northern and southern boundaries. RMS differences increased as a function of CPIES high-frequency SSHA variance because the mapped altimetry product does not resolve these frequencies. [ABSTRACT FROM AUTHOR]

Argo profiling floats initiated a revolution in observational physical oceanography by providing numerous, high-quality, global, year-round, in situ (0-2000 dbar) temperature and salinity observations. This study uses Argo's unprecedented sampling of the Southern Ocean during 2006-13 to describe the position of the Antarctic Circumpolar Current's Subantarctic and Polar Fronts, comparing and contrasting two different methods for locating fronts using the same dataset. The first method locates three fronts along dynamic height contours, each corresponding to a local maximum in vertically integrated shear. The second approach locates the fronts using specific features in the potential temperature field, following Orsi et al. Results from the analysis of Argo data are compared to those from Orsi et al. and other more recent studies. Argo spatial resolution is not adequate to resolve annual and interannual movements of the fronts on a circumpolar scale since they are on the order of 1° latitude (Kim and Orsi), which is smaller than the resolution of the gridded product analyzed. Argo's four-dimensional coverage of the Southern Ocean equatorward of ~60°S is used to quantify variations in heat and freshwater content there with respect to the time-mean front locations. These variations are described during 2006-13, considering both pressure and potential density ranges (within different water masses) and relations to wind forcing (Ekman upwelling and downwelling). [ABSTRACT FROM AUTHOR]

Remote tissue biopsy sampling and satellite tagging are becoming widely used in large marine vertebrate studies because they allow the collection of a diverse suite of otherwise difficult-to-obtain data which are critical in understanding the ecology of these species and to their conservation and management. Researchers must carefully consider their methods not only from an animal welfare perspective, but also to ensure the scientific rigour and validity of their results. We report methods for shore-based, remote biopsy sampling and satellite tagging of killer whales Orcinus orca at Subantarctic Marion Island. The performance of these methods is critically assessed using 1) the attachment duration of low-impact minimally percutaneous satellite tags; 2) the immediate behavioural reactions of animals to biopsy sampling and satellite tagging; 3) the effect of researcher experience on biopsy sampling and satellite tagging; and 4) the mid- (1 month) and long- (24 month) term behavioural consequences. To study mid- and long-term behavioural changes we used multievent capture-recapture models that accommodate imperfect detection and individual heterogeneity. We made 72 biopsy sampling attempts (resulting in 32 tissue samples) and 37 satellite tagging attempts (deploying 19 tags). Biopsy sampling success rates were low (43%), but tagging rates were high with improved tag designs (86%). The improved tags remained attached for 26±14 days (mean ± SD). Individuals most often showed no reaction when attempts missed (66%) and a slight reaction–defined as a slight flinch, slight shake, short acceleration, or immediate dive–when hit (54%). Severe immediate reactions were never observed. Hit or miss and age-sex class were important predictors of the reaction, but the method (tag or biopsy) was unimportant. Multievent trap-dependence modelling revealed considerable variation in individual sighting patterns; however, there were no significant mid- or long-term changes following biopsy sampling or tagging. [ABSTRACT FROM AUTHOR]

Presented here is an objective approach to identify, characterize, and track Southern Hemisphere mobile fronts in hemispheric analyses of relatively modest resolution, such as reanalyses. Among the principles in its design were that it should be based on broadscale synoptic considerations and be as simple and easily understood as possible. The resulting Eulerian scheme has been applied to the European Centre for Medium-Range Weather Forecasts (ECMWF) Re-Analysis (ERA)-Interim and a climatology of frontal characteristics, at both the 10-m and 850-hPa levels, derived for the period 1 January 1989-28 February 2009. The knowledge of the character of these features is central to understanding weather and climate over the hemisphere. In both summer and winter the latitude belt 40°-60°S hosts the highest frequency of frontal points, but there are significant zonal asymmetries within this band. The climatology reveals that the longest fronts are in the Indian Ocean where mean lengths exceed 2000 km. The mean frontal intensity over the hemisphere tends to be greater at 850 hPa than at 10 m, and greater in winter than in summer. The frontal intensity also shows its maximum in the Indian Ocean. In the mean, the meridional tilt of these fronts is northwest-southeast over much of the midlatitudes and subtropics, and increases with latitude toward the equator. The tilts are of overwhelmingly opposite sign in the coastal Antarctic and subantarctic regions. Broadly speaking, the number of fronts and their mean length and mean intensity exhibit maxima in winter in the midlatitudes (30°-50°S), but show a sizeable semiannual variation (maxima in fall and spring) during the year at higher latitudes. [ABSTRACT FROM AUTHOR]

The ocean-atmosphere flux of carbon dioxide in subantarctic surface water (SASW) east of New Zealand has been determined using data from bi-monthly cruises on a time series transect for 8 years. The 60 km long transect extends from the coast (45.770°S 170.720°E) to a station at 45.833°S 171.500°E. Sea surface temperature, salinity, nutrient concentrations and pCO have been measured at a frequency of about once every 2 months from January 1998 until December 2005. Measured pCO exhibits a seasonal cycle with a maximum in late winter/spring, and a minimum in late summer/autumn, a mean 356 μatm, and an amplitude of 9 μatm. The magnitude of ΔpCO (the air-sea concentration gradient) has increased over the 8 years, primarily due to the increase in atmospheric CO concentration. The air-sea flux of CO was determined from wind speed data and ΔpCO. The uptake of atmospheric CO by SASW in the study area changed from + 1 and +82 mmol m in 1998 and 1999 respectively (ocean as source) to −870 and −510 mmol m in 2004 and 2005 (ocean as sink). These values are substantially less in magnitude than the value obtained from the Takahashi et al. (Deep-Sea Res II, ) flux climatology. [ABSTRACT FROM AUTHOR]

We explored the relationship between mixing dynamics in the surface mixed layer and the photoprotective response of phytoplankton. The distribution of photoprotective pigments was determined at 15 stations in subantarctic waters southeast of New Zealand during austral autumn. The first-order kinetics of the phytoplankton photoprotective response to both light and dark was determined using in situ simulated (deck) incubations. The vertical mixing regime was deduced from two physical parameterizations based on CTD and ADCP profiles. A photophysiological index based on the vertical profile of de-epoxidation state (DES) of the diadinoxanthin-cycle to changes in light intensity was compared with the two physical estimates of vertical eddy diffusivity. For short time scales (<12 h) and within a similar water mass, the DES index provides within one order of magnitude an estimate of average vertical velocity representative of the bulk vertical eddy diffusivity. From the results, a conceptual model is presented of the quantitative relationship between vertical mixing and phytoplankton photoprotection in the water column. This relationship can provide additional insights into the effects of changes in vertical eddy diffusivity in the surface mixed layer on the photoprotective response of phytoplankton. [ABSTRACT FROM PUBLISHER]

Aim The aim here was to assess whether the present-day assemblage of subantarctic flowering plants is the result of a rapid post-Last Glacial Maximum (LGM) colonization or whether subantarctic flowering plants survived on the islands in glacial refugia throughout the LGM. Location The circumpolar subantarctic region, comprising six remote islands and island groups between latitudes 46° and 55° S, including South Georgia in the South Atlantic Ocean, the Prince Edward Islands, Îles Crozet, Îles Kerguelen, the Heard Island group in the South Indian Ocean and Macquarie Island in the South Pacific Ocean. Methods Floristic affinities between the subantarctic islands were assessed by cluster analysis applied to an up-to-date dataset of the phanerogamic flora in order to test for the existence of provincialism within the subantarctic. A review of the primary literature on the palaeobotany, geology and glacial history of the subantarctic islands was carried out and supplemented with additional palaeobotanical data and new field observations from South Georgia, Île de la Possession (Îles Crozet) and Îles Kerguelen. Results First, a strong regionalism was observed, with different floras characterizing the islands in each of the ocean basins, and endemic species being present in the South Indian Ocean and South Pacific Ocean provinces. Second, the majority of the plant species were present at the onset of accumulation of post-glacial organic sediment and there is no evidence for the natural arrival of new immigrants during the subsequent period. Third, a review of geomorphological data suggested that the ice cover was incomplete during the LGM on the majority of the islands, and ice-free biological refugia were probably present even on the most glaciated islands. Main conclusions Several independent lines of evidence favour the survival of a native subantarctic phanerogamic flora in local refugia during the LGM rather than a post-LGM colonization from more distant temperate landmasses in the Southern Hemisphere. [ABSTRACT FROM AUTHOR]

Two limpet species occur intertidally on subantarctic South Georgia, the patellid Nacella concinna and the siphonarlid Kerguelenella lateralis. N. concinna is confined to the lower shore close to LWS; K. lateralis occurs in middle shore pools, so their distributions do not overlap. N. concinna has a much narrower thermal niche (−12.9°C to +15.6°C) than K. lateralis (−17.8°C to +31.8°C). Environmental data are presented to show that the upper lethal temperature of N. concinna is low enough to prevent the limpet living higher on the shore. Both limpet species are slow-moving, but K. lateralis shows increasing speed with rising temperature, peaking at 15–20°C. In contrast, N. concinna moves actively down to −1.9°C (when sea water freezes), but there is a steady decrease in speed of locomotion above +2°C. Locomotion ceases at 14°C in N. concinna (c.f. 30°C in K. lateralis). Both species exhibit very low tenacities, but in N. concinna tenacity decreases with increasing shell length. In K. lateralis there is no effect of temperature on tenacity. Both species show a positive allometric relationship between foot area and shell length. N. concinna feeds upon microbial films and microepiflora, but K. lateralis eats colonial diatoms and Enteromorpha bulbosa. Observations on shell middens of the kelp gull Larus dominicanus showed that the gulls did not eat K. lateralis, though they ate great quantities of the less accessible N. concinna. Gulls ate N. concinna as small as 11 mm shell length (within the size range of K. lateralis). Experiments on gulls demonstrated an unwillingness to eat K. lateralis, probably because the siphonariid extrudes a viscid white mucus when the foot is touched. [ABSTRACT FROM AUTHOR]

The authors discuss the impact of ontogeny on the plant-plant interactions along the environmental stress gradients. They relate the study by P. C. le Roux and colleagues which examines the interactions between Azorella selago and Agrostis magellanica in a subantarctic island ecosystem. They note that the study shows that the outcome of plant-plant interactions along stress gradients can be affected by ontogeny.