Northeast Water Research Articles

Contribution of waters of Atlantic and Pacific origin in the Northeast Water Polynya

Measurements of nitrate and phosphate taken in the Northeast Water Polynya (NEWP) during the summer of 1993 have been used to identify the contribution of waters of Atlantic and Pacific origin in the polynya. Since waters from the northern Pacific exhibit a deficit in nitrate relative to phosphate due to denitrification in low oxygen waters, the relationship between nitrate and phosphate can be used to distinguish between oceanic waters of Pacific and Atlantic origin. The Pacific Water enters the Arctic Ocean through Bering Strait and flows along the northern coasts of Alaska and Canada. Some of this water exits through Fram Strait and may therefore enter the polynya which is situated above the continental shelf off the north-eastern coast of Greenland. Compared to data from the Greenland Sea, which only show a N–P relationship of typical Atlantic Water, the data from the Northeast Water Polynya show that the upper waters of the polynya bear a clear signal of waters of Pacific origin. In the surface mixed layer an average of about 90 % is found to have Pacific N–P characteristics. Below the surface mixed layer the amount of Pacific derived water decreases through the halocline and from about 150 m to the bottom only typical Atlantic Water is found.

Physiological variation among native and exotic winter annual plants associated with microbiotic crusts in the Mojave Desert

Microbiotic crusts are important components of many aridland soils. Research on crusts typically focuses on the increase in soil fertility due to N-fixing micro-organisms, the stabilization of soils against water and wind erosion and the impact of disturbance on N-cycling. The effect of microbiotic crusts on the associated plant community has received little attention. We quantified the influence of crusts on the production, species diversity, nutrient content and water relations of winter annual plant species associated with microbiotic soil crusts in the northeast Mojave Desert. Shoot biomass of winter annuals was 37% greater and plant density was 77% greater on crusts than were biomass and density on soils lacking crust cover (=bare soils). This greater production of annuals on crusts was likely due to enhanced soil conditions including an almost two-fold increase in soil organic matter and inorganic N compared to bare soils. Crusted soils also had 53% greater volumetric water content than bare soils during November and December, the time when winter annuals become established. As plant development progressed into spring, however, soil water availability decreased: More negative plant xylem water potentials were associated with greater plant biomass on crusted soils. Plants associated with microbiotic soil crusts had lower concentrations of N in shoots (mg N g−1 dry mass). However, total shoot N (mg N m−2) was the same in plants growing on the different soil types when biomass production peaked in April. Shoots had similar patterns in their concentration and content of P. Species diversity of annuals was not statistically different between the two soil types. Yet, while native annuals comprised the greatest proportion of shoot biomass on bare soils, exotic forbs and grasses produced more biomass on crusts. Total shoot nutrient content (biomass×concentration) of the two exotic annual species examined was dramatically greater on crusts than bare soils; only one native species had greater shoot content of N and P when growing on crusts than bare soils. Microbiotic crusts appear to increase site fertility in the northeast Mojave Desert, but nutrients and water distributed within a greater biomass of annual plants growing on microbiotic crusts likely resulted in lower concentrations of nutrients in plant tissue and lower xylem pressure potentials than plants growing on bare soils. Exotic annuals growing on crusts appear to respond to the higher N availability by growing faster, potentially outcompeting native annual species.

Northeast Water Polynya 1993: construction and modelling of a time series representative of the summer anticyclonic gyre pelagic ecosystem

A multidisciplinary international oceanographic expedition was conducted in the Northeast Water Polynya (NEW, northeast of Greenland) from May to August 1993, to understand the formation of the polynya and its influence on the pelagic ecosystem. The residual circulation in the polynya is characterized by an anticyclonic gyre, which follows a system of troughs. The numerous data acquired during the expedition and the resulting publications provide the background for an ecological modelling study. Since the sampling scheme during this expedition was not appropriate for implementing ecological models, the first objective of the present study was to build up a multivariate time series. Stations in the time series were selected by taking into account the residual circulation in the anticyclonic gyre. Model outputs were compared to data along the time series. From the time series alone, it was not possible to fully understand the development of a second phytoplankton bloom, so that we formulated three hypotheses on the functioning of the ecosystem during that period: (H1) horizontal supply of nitrate from waters located to the north; (H2) vertical diffusion of nitrate; (H3) local remineralization processes in the surface layer. H2 and H3 are evaluated using two ecological models, in which the same components are simulated, but the first considers only the nitrogen cycle and the second simulates both the carbon and nitrogen cycles. Comparing the chemical and biological variables simulated by the models to the observed time series data by reference to the three hypotheses lead to the conclusion that H2 is the most likely hypothesis. This also means that the summer pelagic ecosystem in the anticyclonic gyre was perhaps dominated by a short food chain that mostly comprised large phytoplankton, copepods and appendicularians. However, because the parameterization of vertical mixing used to test hypothesis H2 may be an oversimplification of field conditions, the hypothesis cannot be fully tested.

The subglacial cavity and implied dynamics under Nioghalvfjerdsfjorden Glacier, NE‐Greenland

Seismic depth soundings on Nioghalvfjerdsfjorden Glacier (NFG), NE Greenland, reveal an overdeepened trough under the floating glacier. The maximum depth of the trough reaches more than 900 m below sea level. Mass balance calculations indicate considerable ice loss due to strong subglacial melting with a mean melt rate of 8 m a−1. The geometry of the cavity and water mass characteristics from CTD measurements suggest the existence of a well defined regional circulation system. Warm, saline and rather dense water follows the inward inclining basal slope through the deep valley of Dijmphna Sund towards the grounding line. Shallow ridges at the eastern glacier front prevent this water mass entering from that direction. The comparatively cold, fresh and less dense melt water follows the subglacial ice topography leaving the cavity through the gaps towards the east. The abundance of subglacial melt water east of NFG is most probably one of the main reasons for the semi permanent sea ice cover in this region. Cold water masses upwelling in the Northeast Water Polynia and detected by satellite remote sensing are very likely influenced and modified by the subglacial melt water production.

Pathways of carbon cycling in marine surface waters: the fate of small-sized phytoplankton in the Northeast Water Polynya

The fate of small-sized phytoplankton ( 70%). Downward export would have occurred infrequently, as a result of intense grazing by appendicularians. Size-differential pathways of carbon cycling in planktonic food webs are discussed.

Airborne line scanner measurements for ERS-1 SAR interpretation of sea ice

A new method is presented for interpretation of Synthetic Aperture Radar (SAR) images recorded with the first European Remote Sensing Satellite (ERS-1) with respect to classification of sea ice. Conventional interpretation of spaceborne radar images is often based on subjective classification of radar signatures. Themost promising approach is a region-based segmentation with subsequent interpretation of the segments. The definition of regions with common properties enables a characterisation by texture parameters besides backscatter coefficients. The major drawback of this method is the subjective selection and characterisation of the training segments on which the classification is based. To avoid this subjective influence, an attempt is made of an independent classification by the use of two airborne line scanner systems, one for the visible and the other for the infrared spectral range. The systems were installed on research aircraft (aeroplane and helicopter) during an experiment covering the marginal ice zone north of Spitsbergen in late winter 1993 and in the North East Water Polynya in summer 1993. Several underflights of ERS-1 were carried out during the SAR mode. Typical areal coverage of the line scanner images during a flight is 1.5% of a SAR scene. The line scanner images are classified using a two-dimensional feature space. By this procedure various ice types are identified. After matching the locations of the line scanner and the segmented SAR images, it is then possible to derive the characteristics of different ice types with respect to radar signatures. Backscatter coefficient and texture parameters are used for the discrimination of ice types. Texture parameters used are moments of the grey-level distribution and values of the co-occurrence matrices. The results of this work show, that the common method of a subjective characterisation of training regions runs into difficulties. SAR signatures are essentially dependent on the conditions during ice development. Regions with different ice types can have the same SAR signatures and different SAR signatures may be found for the same ice type. With the presented method it is possible to achieve classification accuracies up to 78% with a discrimination of young ice, first-year ice and old ice during winter situations. In summer, it is difficult to discriminate wind exposed water and sea ice. In this case, the classification of SAR images is derived exclusively by means of texture parameters since the backscatter coefficient is of little use. With the discrimination of water, snow-covered ice, and brash ice an accuracy of 73% is achieved under summer conditions.

Estimation of the surface heat budget and the thickness of thin sea-ice in Arctic polynyas with Landsat 5 TM

A method was developed to relate the thickness of sea-ice to its surface temperature and other meteorological parameters controlling the surface heat exchange between sea-ice and the atmosphere. The method was based on a one-dimensional thermodynamic sea-ice model, allowing an optional snow cover. The surface temperature and the albedoof sea-ice were derived from radiance measurements of the Thematic Mapper. The method was applied to the NorthEast Water polynya in winter (East of Greenland) to estimate the polynya's ice thickness and its surface energy exchange. The results were compared with the pack-ice zone surrounding the polynya. The polynya is covered by thin ice surrounded by thicker multi-year ice. The surface heat exchange in the polynya (-150Wm-2) was significantly larger than above Arctic pack-ice (-25Wm-2 to -50Wm-2).

The Influence of Solar Zenith Angle and Cloud Type on Cloud Radiative Forcing at the Surface in the Arctic

Abstract Measurements of the long- and shortwave incident radiation taken from the USCGC Polar Sea during a research cruise to the Northeast Water Polynya during the summer of 1993 are analyzed together with observations of cloud type and amount to determine the effects of summertime Arctic clouds on the surface radiation budget. It is found that the solar zenith angle is critical in determining whether clouds heat or cool the surface. For large solar zenith angles (>∼80°) the infrared heating effect of clouds is greater than the reduction in insolation caused by clouds, and the surface is heated by the presence of cloud. For smaller zenith angles, cloud cover cools the surface, and for intermediate zenith angles, the surface radiation budget is insensitive to the presence of, or changes in, cloud cover.

In situ ingestion rates of appendicularian tunicates in the Northeast Water Polynya (NE Greenland)

We report in situ ingestion rates of individual oikopleurid appendicularians from the Northeast water Polynya (NEW) determined by a modification of the gut pigment technique. Appendicularians were most abundant at ice edge stations and were rare at open water stations in the centre of the polynya. Gut passage time (GPT), which was determined in experiments onboard ship, was not related to body size (mean ± SD = 74 ± 23 min). Gut chlorophyll content (GCC) excluding phaeopigments (i.e. GCC = chlorophyll a + b + c), averaged 4.06 ng ind.-1, with quartiles of 1.20 to 4.73 ng ind.-1. There was no evidence of a diel feeding rhythm. GCC was higher and more variable at non-bloom (i.e. at chlorophyll concentrations 5 μm in size. This suggests inhibition of ingestion rates at ice edge stations with diatom blooms. The ingestion rate (IR, ng chlorophyll ind.-1 d-1) of individual appendicularians in the NEW can be predicted by IR = 2.5 BL:BT-0.41 TL2.14 (r2 = 0.43) where BL:BT is the ratio of chlorophyll a in particles >5 μm in diameter to the total chlorophyll biomass, and TL (mm) is the trunk length.

Body size, sex ratio and diet composition of Arctogadus glacialis (Peters, 1874) (Pisces: Gadidae) in the Northeast Water Polynya (Greenland)

Little is known about the biology and feeding ecology of Arctogadus glacialis (Peters, 1874), an endemic gadid fish species occurring circumpolarly in both ice-free and ice-covered Arctic seas. In this study we analysed specimens sampled from bottom trawl and Agassiz trawl catches conducted at eight stations in water depths from 115 to 490 m in the Northeast Water Polynya off Greenland in August 1990. Size composition and sex ratios were assessed for 585 fish with standard lengths ranging from 7.8 to 34.5 cm. Median fish sizes at the stations ranged between 8.6 and 18.8 cm. Quantitative stomach content analyses of a subsample of 175 specimens revealed that in the Northeast Water A. glacialis fed almost exclusively on pelagic prey. Truly benthic organisms were not found in the stomachs, and sympagic species were rarely recorded. Overall, calanoid copepods were the major prey in terms of numbers. However, stomach contents varied considerably between fish size groups. In terms of prey biomass, copepods dominated the diet of small fish ( 16 cm), which dominated the catches at deep stations (360–480 m). The broad variety of diet composition indicated an opportunistic pelagic feeding pattern.

Comparative studies in biochemical composition of benthic invertebrates (bivalves, ophiuroids) from the Northeast Water (NEW) Polynya

Two species of ophiuroids (Ophiopleura borealis and Ophiacanthabidentata) and bivalves (Astarte crenata and Arctinulagroenlandica) were collected within and adjacent to the Northeast Water Polynya off the northeast coast of Greenland, and analyzed for total moisture, protein, lipid, and ash content. Body composition varied significantly among stations within species. Lipid and protein contents of Astarte crenata were higher in clams collected from the eastern Westwind Trough stations compared to those collected from the western Westwind Trough stations. However, the mean lipid and protein contents were significantly higher in Ophiopleura borealis sampled from the western Westwind Trough compared to the eastern Westwind Trough. Ophiopleura borealis are mobile deposit feeders and scavengers and may not be as directly dependent on sedimentary biogenic material as Astarte crenata and Ophiacanthabidentata. Samples of both Ophiopleura borealis and Ophiacantha bidentata from the Belgica Trough had lower protein and lipid contents compared to those sampled in the western Westwind Trough. Samples of Arctinula groenlandica from two locations on the Ob Bank had significantly different protein levels from each other. These data support previous work, indicating that biogenic materials resulting from primary production in the ice-free western area of the Northeast Water Polynya are advected eastward down the western Westwind Trough and that the Belgica Trough has lower organic input compared to the Westwind Trough.

Pathways of carbon cycling in the euphotic zone: the fate of largesized phytoplankton in the Northeast Water Polynya

The fate of large-sized phytoplankton and pathways of carbon cycling in surface waters, i.e. recycling within or export out of the euphotic zone, were investigated in the Northeast Water (NEW) Polynya (77-81 °N) from 23 May to 17 August 1993. Sampling represented a wide range of ice, hydrographic and nutrient conditions. Phytoplankton and zooplankton abundances, and phytoplankton production rates were determined in the field, whereas potential rates of grazing by copepods, dinoflagellates and appendicularians were calculated from abundances and temperature, using assumptions from the literature. The potential downward and lateral export of phytoplankton was also calculated by resolving a carbon budget for the euphotic zone. The present study suggests that, in the NEW, different pathways for the cycling of carbon existed in seasonally ice-free (in the polynya) and continuously ice-covered areas (outside the polynya). Outside the polynya, the fate of large-sized phytoplankton could not be assessed because the heterotrophic community presumably grazed on a variety of food items, including ice algae, microzooplankton and large-sized phytoplankton. In the polynya, the fate of large-sized phytoplankton production was to be mostly recycled at the beginning of sampling and to be mostly exported downward or laterally as the bloom of large-sized phytoplankton developed. Generally, copepods mostly contributed to recycling, but sometimes dinoflagellates or appendicularians alone recycled most of the large-sized phytoplankton production.

The modelling of sea ice melt-water ponds for the High Arctic using an Airborne line scan camera, and applied to the Satellite Special Sensor Microwave/Imager (SSM/I)

Melt-water ponds on sea ice in the Northeast Water Polynya (77-82 N, 1-18 W) were mapped using a line scan camera (LSC) mounted on a helicopter. Passive microwave satellite data from the Special Sensor Microwave/ Imager (SSM/I) were employed to analyse the temporal trend of radiances of shorefast ice for 1993 and sea ice during sixteen flights of the LSC (June-July). A simple, linear algorithm tailored to accommodate the summer ice regime, was developed. The LSC measurements of ice (50.9 12.5%), water and melt-water pond fractions compared very well with the SSM/I derived mean ice concentrations (50.9 12.8%). The comparison resulted in a correlation coefficient of 0.953. Combining the LSC melt-water pond fraction data with other data available from the literature provided the basis to construct a second degree polynomial function of a melt-water empirical model to correct the under estimation of SSM/I derived sea ice concentration due to the effect of melt-water ponds.

Historical and present distribution, abundance and exploitation of Atlantic walruses (Odobenus rosmarus rosmarus L.) in eastern Greenland

The status of the Atlantic walrus (Odobenus rosmarus rosmarus L in eastern Greenland is reviewed on the basis of several historical and recent sources of information on distribution, numbers and catch. Walruses occur in small groups along the east coast of Greenland from approximately 63° N to approximately 81° N. Their largest abundance is, however, north of approximately 73° 30' N. The sexes are generally segregated during summer: During August and September, about 50 males are found at each of two terrestrial haulouts Sandøen (74° 15' N) and Lille Snenæs (76° 52' N).
 Movement of walruses that could be identified from natural marks indicates that there is a connection between the two groups. During summer, the majority of mature females and subadults of both sexes are distributed further north, between about 80° N and about 81° N. Walruses winter in the Northeast Water Polynya, in leads and cracks in the offshore pack ice in the Fram Strait and Greenland Sea between about 78° N and about 81° N, further south in smaller recurring polynyas, and in the shear zone between fast ice and the pack ice along the east coast of Greenland. Although a connection between walruses in eastern Greenland and Svalbard has been demonstrated, the extent to which the eastern Greenland population is geographically isolated from groups further east has not been determined.
 A total kill of about I 680 walruses (including walruses killed-but-lost) by European sealers and hunters between 1889 and 1955 severely reduced the walrus population in eastern Greenland. Back-calculations based on estimates of the present population size of between 500 and 1000 walruses indicate that this population numbered between 700 and 1900 individuals in 1889, and most likely about 900 individuals.
 It is estimated that Greenlanders removed 20 to 30 walruses (primarily males) annually during the 198Os and 199Os (23% killed-but lost animals included). This appears to be a sustainable catch.

Summer distribution of seabirds in the North-East Water polynya, Greenland

The distribution at sea of seabirds was studied in the North-East Water (NEW) polynya, Greenland, during transect counts in the summers of 1991, 1992 and 1993 on board the ice-breaking RVs Polarstern and Polar Sea. Data collected within the polynya ‘box’ (78–82°N; 5–18°W) concern observations of 8000 birds counted during 1350 half-hour counts. Distribution is presented as density (N/km 2) and calculated daily food intake. Five bird species were selected for discussion, representing more than 95% of the total numbers encountered: Fulmar ( Fulmarus glacialis), Ivory Gull ( Pagophila eburnea), Kittiwake ( Rissa tridactyla), Glaucous Gull ( Larus hyperboreus) and Ross's Gull ( Rhodostethia rosea). For these species, densities are comparable in the NE Greenland polynya and in other European Arctic seas. The main difference is the absence in NEW of the species playing the main role in Arctic seas: Brünnich's Guillemot ( Uria lomvia) and Little Auk ( Alle alle). In the absence of fish-eating birds and of birds consuming zooplankton in the water column, the NEW polynya ecosystem is thus dominated by surface feeders and, closer to the coast, by benthic feeders like eiders, Somateria mollissima and S. spectabilis, and walrus, Odobenus rosmarus. The density and daily food intake for all seabirds are one order of magnitude lower in the polynya than in the Arctic seas. The distribution and abundance of seabirds in the NEW polynya seems to reflect a very low density of pelagic fish and Zooplankton in the water column, while Zooplankton must be present at ‘normal’ concentrations in the upper layer.

Floristical and ecological characterization of the polar desert zone of Greenland

Abstract. Species composition and biomass of four plant communities were investigated in two coastal polar desert areas in eastern North Greenland, bordering the North East Water Polynya ‐ an ice‐free sea area kept open by upwelling ‐ and compared with inland areas in North Greenland. Herb barren, the poorest type, has a species richness of 6 species/m2, a cover of 0.7 %, and an aboveground biomass of 0.6 g/m2 (vascular plants). The richest type, Saxifraga oppositifolia snowbed, has 10 species/m2, 5.0 % cover, and 11.2 g/m2 biomass.A floristic and vegetation boundary exists a few kilometres from the coast. The coastal areas bordering the North East Water Polynya had an impoverished flora and vegetation compared to areas near the ice‐covered sea, possibly caused by very low summer temperatures and high frequency of clouds.A new delimitation of the polar deserts of Greenland is proposed on the basis of the number of vascular plant species, the occurrence of species with a specific inland distribution in North Greenland and the dominating life forms. At present the polar desert zone includes only areas within a zone up to ca. 15 km from the outer coast of high arctic Greenland ‐ north of ca. 80° N. Large areas formerly classified as polar deserts in eastern North Greenland, as well as in Washington Land in western North Greenland, are excluded. New floristic data confirm that Greenland is correctly included in the Canadian province of the arctic polar deserts, whereas there is no reason for subdividing the polar deserts of the Canadian province.

Streamwater nitrate concentrations in six agricultural catchments in Scotland

The concentrations of nitrate-N (NO 3N) in catchment inputs and outputs have been compared and contrasted between 6 farm catchments in Scotland, 3 in the West and 3 in the North-East. Forms of intensive animal farming ranging between beef and dairy cattle, sheep and poultry give different sources for potential NO 3N leakage from the systems. While stream reaches bordered by intensive cereal production give rise to the largest inputs to surface waters, climatic influences result in the more-efficient use of fertilizer- and farm waste-N in the West, and an enhanced potential for N-loss to waters in the cooler North-East, regardless of the N-inputs being considerably lower in the latter region. Although the EC Nitrate Directive limit of 11.3 mg NO 3N l −1 was not exceeded, peak values occurring during summer baseflows and autumn soil rewetting were commonly larger than the ‘target’ maximum concentration of 5.65 mg NO 3N l −1.

Potential radionuclide transport pathways from seafloor dumpsites: Kamchatka region of the North Pacific Ocean

Encapsulated nuclear waste materials, dumped by Russia, are present at two deepwater seafloor locations in the offshore north-west Pacific Ocean, south-east of the Kamchatka Peninsula. This paper assesses potential pathways by which these wastes might, if released from their containers, disperse away from the dumpsites and through the surrounding ocean. A review of large-scale ocean circulation theory and of field and model results suggests that mean abyssal currents are north-eastward to eastward from the dumpsite locations and would advect leaking materials toward the north-eastern Pacific. Results of advective and diffusive horizontal plume transport models are consistent with this sense of flow. Trajectory speeds are, however, subject to considerable uncertainty. Our results suggest that as little as 5 years or as long as 100 years might be required for material to be transported from the dump sites to the north-east Pacific. Dilution by 4 or 5 orders of magnitude is predicted during this transit. Vertical mixing or upwelling are necessary in order to transport contaminants upward from north-east Pacific abyssal waters to the near-surface layers before they can potentially impact productive coastal regions, such as those off Alaska. Information concerning such upwelling mechanisms is inadequate for estimation of rates or to identify geographical areas that might be at risk.

Choanoflagellates (acanthoecidae, choanoflagellida) from the Weddell Sea, Antarctica, Taxonomy and community structure with particular emphasis on the ice biota; with preliminary remarks on choanoflagellates from Arctic sea ice (Northeast Water Polynya, Greenland)

Summary Ice biota studies in the Antarctic region, Weddell Sea, have focused on an examination of single cells and an analysis of community structure of the flagellate assemblage from sea ice and comparisons with planktonic assemblages. Based on extensive light microscopical analysis of 40 samples ranging from open water to “brown-ice” habitats, it became evident through clustering of the data, that the mature choanoflagellate community from ice is significantly different from both the water column community and those encountered in samples derived from newly formed ice (i.e. grease ice, platelet ice, nilas and thin pancakes). The choanoflagellates from sea ice encompasses a range of previously undescribed loricate taxa ( Acanthocorbis nana sp. nov., A. weddellensis sp. nov., A. prolongata sp. nov., Apheloecion antarctica sp. nov., A. glacialis sp. nov., A. conicoides sp. nov., Calliacantha frigida sp. nov., C. ankyra sp. nov., Diaphanoeca multiannulata subsp. nov. glacialis, Parvicorbicula corynocostata sp. nov., P. pachycostata sp. nov.). These taxa have been investigated using a combination of light, and electron microscopy. A preliminary investigation of samples from the Arctic (NE Greenland) indicates that the loricate choanoflagellate diversity is significantly lower in Arctic sea ice.

Breeding ecology of the FulmarFulmarus glacialisand the KittiwakeRissa tridactylain high‐arctic northeastern Greenland, 1993

The breeding ecology of the FulmarFulmarus glacialisand the KittiwakeRissa tridactylain the high Arctic was studied in relation to the occurrence of the northeast water polynya in northeasternmost Greenland (80d̀N). Mean laying dates were 31 May in the Fulmar and 18 June in the Kittiwake; the total nesting season for the Fulmar just matched the time window of the polynya opening period. Fulmar colony attendance fluctuated within a period of 11.6 days because of variation in nonbreeding prospectors but showed no clear diurnal variation. Fulmar incubation shifts, on average, lasted 6.1 days (range 1–13 days), which is significantly longer than elsewhere, and the average chick‐guard period of 10.9 days (range 1–17 days) was significantly shorter than in other studies. Egg neglect occurred in 18% of Fulmar nests or 0.7% of nests per day. Overall breeding success (chicks fledged per egg laid) was 0.56 in the Fulmar and 0.67 in the Kittiwake; the latter produced 1.4 young per active nest or 1.2 per completed nest. Mean Kittiwake clutch size was 2.03; larger clutches were laid early. Nest site characteristics (presumably reflecting nest predation risk) and breeding behaviour affected breeding success. in the Fulmar, hatching success was negatively correlated with laying date and the proportion of egg neglect, while overall breeding success was correlated negatively with distance to nearest neighbouring site and positively with the length of the chick‐guard period. Kittiwake breeding success was negatively correlated with laying date. Using seabirds as indicators of marine food supply, breeding success in both species suggested moderate to good food supply in the northeast water polynya in 1993, although at least in the Fulmar the high reproductive output appeared partly maintained by behavioural buffering; long incubation shifts, egg neglect and short chick‐guard periods were symptoms of foraging constraints.