Benthic foraminifera in the surface sediments of the Beaufort Shelf and slope, Beaufort Sea, Canada: Applications and implications for past sea-ice conditions

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Journal of Marine Systems 74 (2008) 840 – 863 www.elsevier.com/locate/jmarsys

Benthic foraminifera in the surface sediments of the Beaufort Shelf and slope, Beaufort Sea, Canada: Applications and implications for past sea-ice conditions David B. Scott a,⁎, Trecia Schell a , André Rochon b , Steve Blasco c a

Centre for Environmental and Marine Geology, Dalhousie University, Halifax, Nova Scotia, Canada B3H3J5 b ISMER, Université d'Quebec á Rimouski, Rimouski, P.Q., Canada c Natural Resources, Canada, 1 Challenger Drive, Dartmouth, Nova Scotia, Canada B2Y4A2 Received 25 January 2008; accepted 30 January 2008 Available online 21 February 2008

Abstract This paper presents new data on distribution patterns of modern benthic foraminifera and other microfossils from the Canadian Arctic, specifically the Beaufort Shelf and slope. The material was collected in June to August of 2004 and is the first of its kind in this area to be collected since 1970. We examined the smaller sizes (45–63µm) as well as N 63µm and discovered that many species had been severely underrepresented in previous studies. Deep sea forms, that had been overlooked previously, were common on the shelf; two species (Elphidiella arctica and Ammotium cassis) appeared in preliminary results to be indicators of methane seepage; and it was possible to make determinations of sea-ice coverage using a combination of foraminifera and tintinnids (planktic ciliates). Our data indicated the presence of many of the same species as previous studies from this area, but improved techniques of sample processing greatly increased the number of specimens and species found (particularly the small deep sea arctic species Buliminella hensoni and Bolivina arctica) which provide much more reliable data for paleoceanographic determinations. One of the primary objectives for this work was to provide baseline data to help determine paleo-ice cover; these data cover a broad range of conditions on the Beaufort Shelf that make it possible to achieve this objective as well as improving what it is known about the assemblages on this shelf as compared to other arctic shelf areas, such as the Siberian Shelf). © 2008 Elsevier B.V. All rights reserved. Keywords: Foraminifera; Tintinnids; Beaufort Shelf; Ice cover; Size fractions; Methane release; Amundsen Gulf

1. Introduction The initiation of two large international projects (CASES, Canadian Arctic Shelf Exchange Study and ArcticNet) has begun to fill a 30 year gap in knowledge

⁎ Corresponding author. E-mail address: [email protected] (D.B. Scott). 0924-7963/$ - see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jmarsys.2008.01.008

regarding modern microfossil distributions on the Beaufort Shelf and slope. The data presented in this paper are the modern distributions of benthic foraminifera and other microfossils that provide us with proxies for the paleoceanographic conditions that characterize the Beaufort Shelf. Without these data it would be difficult to interpret changing foraminiferal assemblages at strategic piston core intervals that span the Holocene and into the last glaciation. The history of last few

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hundred years of sea-ice cover, which is one of the main concerns in the global warming scenario, is a major problem that these data allow us to address in much more robust manner. For one unique setting it appears that foraminiferal assemblages might also be associated with seeps, which may allow detection of areas of paleomethane seeps. The Canadian Arctic has not been investigated for distributions of modern benthic foraminifera since the late 1960's and early 1970's when the first sustained effort was made to sample the Beaufort Shelf and slope as well as many of the Arctic channels (Vilks, 1969, 1989; Iqbal, 1973). Some early work was done in the deep sea Arctic as part of the United States T-3 ice island project and ice stations LOREX, FRAM and CESAR (summarized in Scott and Vilks, 1991), however the deep sea areas have extremely slow sedimentation rates (1cm–10cm/10,000yrs; Backman et al., 2004). These areas cannot provide the high resolution records required to determine what conditions were in the last few centuries or decades in relation to the projected global warming. Cushman (1948) and Loeblich and Tappan (1953) established the taxonomy for many of the species discussed by later authors. Phleger (1952) was the first to examine the surficial distributions of Arctic shelf foraminiferal species. His work showed that many of the species that presently live on Canadian Arctic shelves are non-calcareous because of the lowered salinities and extreme cold water. Several studies followed Phleger's work into the Arctic Archipelago (Carsola, 1952; Iqbal, 1973; Marlowe and Vilks, 1963; Vilks, 1964, 1969, 1976). However Vilks (1989) provided the first comprehensive investigation of Beaufort Shelf benthic foraminfera resulting from the circum Americas cruise of the CCGS Hudson in 1969–70 which sampled many of the same stations as were sampled for the present study. Green (1960) and Lagoe (1977, 1979) established much of what we know about the deep water Arctic species from data collected from the T-3 ice island occupied by an international group of scientists for several years (Clark et al., 1980). These studies were added to by examination of material from the ice stations in the central Arctic (LOREX, FRAM, CESAR; Markussen et al., 1985; Scott and Vilks, 1991). Scott et al. (1989) provided the first detailed paleoclimatic and stratigraphic record from the central Arctic from the collection of cores from the Alpha Ridge but these cores only provide a broad framework with a low resolution of 10,000yrs per centimetre. However, many of these deep water species find their way onto the Beaufort Shelf and into the Arctic Archipelago. More recent work has been done by Poore et al. (1994), Polyak et al. (2002, 2004),

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Bergsten (1994), and Wollenburg et al. (2001, 2004); some of these are in shallower water as well as deep water and will be discussed in more detail below. In terms of techniques for detecting presence/absence of sea-ice several recent papers have used various microfossil proxies for paleo-ice conditions—chlorophycean algae from river runoff (Matthiessen et al., 2000); multi-proxy data from a thermokarst lake on Richards Island in the Beaufort Sea using a series of proxies that include pollen, dinoflagellates, foraminifera, thecamoebians and geochemistry (Solomon et al., 2000), and a study of paleo-ice conditions in the eastern Arctic using dinoflagellates (Mudie et al., 2005). Mudie et al. (2006) presented a multi-proxy record of cores from Jones Sound in the eastern Arctic to examine the ice history. In the present paper we use planktic/benthic foraminifera ratios and abundance of tintinnids (ciliates) for ice cover proxies. In an accompanying paper Richerol et al. (2008) discuss the palynology of the samples discussed here towards developing a multiproxy record for this area. Most recently Walsh (2006) completed a study on a mud volcano, and Moss (2006) and Schell et al. (in press) examined a transect (Line 400) from the Beaufort Shelf–Amundsen Gulf region. In these two studies short histories were obtained from box cores from the same locations as the surface samples in this paper. 2. Materials and methods 2.1. Physical characteristics of the area Fig. 1 shows the locations of all the stations that will be documented here for their foraminiferal assemblages. There were 51 box core stations ranging in depth from 33m to over 1000m (Table 1). The stations were taken in transects from shallow to deeper. Three transects were on the shelf and upper slope only (transects 600, 700, 800); these stations had soft, muddy sediments, but not high in organic content. Transects 200, 300 and 400 had stations running off the shelf across the Amundsen Gulf while transect 100 ran down the centre of the Gulf; the stations on the shelf were much like those in the other shelf transects but the ones in deeper water had very brownish organic sediments; one station (415) had cobbles which were relict from an old Holocene shoreline. The transect in the Mackenzie Trough (trans. 900) had the highest sedimentation rates (determined from 210Pb dates courtesy of D. Amiel and K. Cochran, SUNY) and also relatively little organic matter. The samples were collected along transects designated by the CASES project and all major

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Fig. 1. Areal map of the CASES sampling region with water depth and station locations. Ice edge positions at the time of sampling are shown with white lines.

measurements (CTD, seismics, multi-beam, some bottom photos, with various other measurements at selected stations) were done at each station which was useful to help us understand the population dynamics of the various organisms that were being studied. In the eastern shelf (lines 400, 600, 700) some parts of the shelf were not visited because of “pingo-like” features (PLF's) which were areas where there were features caused by permafrost expansion; the water depths were unpredictable and maps are unreliable in this area because of rapidly changing conditions; nonetheless we did get a few samples there but not as many as in other areas. Water property data were collected over the designated transects (Fig. 1) and are highly variable on the shelf with ice cover in the winter, opening in June–July and freezing over in October. The salinities are variable in the summer depending on wind direction, which can blow the freshwater plume from the Mackenzie river either east or west although the dominant direction seems to be to the east. In the winter the salinity and temperature are uniformly high and cold respectively except along the edge of the polynas. At the time of sampling on the shelf salinities were low in the surface water (b 30‰) but usually increased to N 35‰ at the seafloor. Temperatures were also often above 5°C at the surface but negative values even in the shallowest stations. Off the edge of the shelf, surface temperatures were less extreme and always − 2°C at the seafloor. In the Mackenzie Trough fluorometer and transmissometer readings were very high but in deep water were again

low. Lines in the Amundsen Gulf had more oceanic values than anywhere on the Beaufort Shelf. But in the summer all parameters are highly variable with depth as observed from the CTD data from several transects during CASES Leg 8 (June–Aug. 2004—a summary of all auxiliary data can be found at http://www.cases. quebec-ocean.ulaval.ca/fieldwork2003.asp). Sediments on the shelf were generally high in silt and clay content with little or no sand. Organic contents were highest in the areas where there is continual scouring of underlying permafrost by the shore fast ice and “stamuki zones”; we took very few samples in the nearshore because of pingos and the deep draft of the ship. However these areas are continually reworked by both ice and waves so are not suitable for long-term climate studies. Sedimentation rates on the shelf are relatively high-some Pb210 dates indicate 10–15cm of sedimentation in the last 100years, including one of the 1000m cores (from D. Amiel and K. Cochrane, CASES). On the other hand, box cores from the Amundsen Gulf indicate little or no sedimentation with glacial sediments directly underlying the thin Holocene. Some bottom photographs are included here to provide a visual appreciation of the seafloor; station 415 appears to be a relict shoreline with cobbles; station 406 is a typical muddy bottom on the shelf with numerous macro-invertebrates and station 403 is a shallow inshore station on the Beaufort Shelf, also very muddy but there are soft deep-sea corals in both 403 and 406—this is the first time these have been reported from the Beaufort Shelf (Plate 1).

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Table 1 List of stations sampled by date of collection and including water depth, type of sample and latitude/longitude Calendar date

Water depth (m)

Station no.

CASES sample #

Latitude

Longitude

Sampling device

Sampling type

26-June-04 27-June-04 28-June-04 01-July-04 01-July-04 02-July-04 03-July-04 04-July-04 05-July-04 06-July-04 07-July-04 09-July-04 10-July-04 11-July-04 12-July-04 17-July-04 18-July-04 18-July-04 19-July-04 20-July-04 21-July-04 22-July-04 23-July-04 23-July-04 24-July-04 25-July-04 26-July-04 26-July-04 28-July-04 29-July-04 30-July-04 31-July-04 31-July-04 31-July-04 01-Aug-04 01-Aug-04 09-Aug-04 10-Aug-04

330 44 1154 87 77 251 1071 281 169 54 42 1087 70 45 241 228 388 397 307 224 45 390 387 179 59 36 36 66 442 352 569 297 430 241 95 193 511 544

600 609 703 709 711 803 850 906 909 912 809 750 712 718 650 200 118 309 312 315 415 412 409 406 403 400 805A 805C 124 115 109 215 212 209 206 250 112 106

2004-804-600A 2004-804-609A 2004-804-703 2004-804-709 2004-804-711A 2004-804-803A 2004-804-850A 2004-804-906A 2004-804-909A 2004-804-912A 2004-804-809A 2004-804-750A 2004-804-712A 2004-804718A 2004-804-650A 2004-804-200A 2004-804-118A 2004-804-309A 2004-804-312A 2004-804-315A 2004-804-415A 2004-804-412A 2004-804-409A 2004-804-406A 2004-804-403A 2004-804-400A 2004-804-805A 2004-804-805C 2004-804-124A 2004-804-115A 2004-804-109A 2004-804-215A 2004-804-212A 2004-804-209A 2004-804-206A 2004-804-250A 2004-804-112A 2004-804-106A

71, 37.48N 70, 56.58N 70, 56.58N 70, 57.811N 70, 49.427N 70, 38.169N 70, 32.889N 70, 01.145N 69, 45.16N 69, 29.25N 70, 05.7N 71, 20.753N 70, 40.37N 70, 10.196N 71, 18.558N 70, 02.7N 70, 56.64N 71, 07.52N 71, 18.115N 71, 29.155N 71, 54.455N 71, 41.992N 71, 30.70N 71, 18.66N 71, 06.777N 70, 54.991N 70, 23.405N 70, 23.571N 71, 23.368N 70, 50.910N 70, 36.600N 70, 58.450N 70, 45.429N 70, 32.319N 70, 19.248N 70, 27.095N 70°45.2N 70°36.0N

130, 34.24W 130, 31.38W 130, 31.38W 133, 47.025W 133, 48.199W 135, 55.041W 137, 36.00W 138, 35.817W 138, 16.296W 137, 56.43W 135, 20.48W 134, 08.609W 133, 40.84W 133, 32.047W 131, 37.148W 126, 17.8W 125, 51.02W 125, 50.01W 125, 11.534W 124, 32.583W 125, 52.092W 126, 28.649W 127, 05.53W 127, 41.91W 128, 18.302W 128, 55.987W 135, 25.178W 135, 25.214W 126, 43.112W 125, 03.010W 123, 25.824W 123, 24.900W 123, 53.429W 124, 21.95W 124, 50.320W 125, 25.386W 124°13.9W 122°37.8W

Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core Box core

~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface ~Surface

(forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams) (forams)

Relative positions are shown in Fig. 1.

One station was of particular interest because of its unique nature-station 805. This was a Kopanoar mud volcano that was 40m high and almost 1km in diameter. Samples were taken from both the crest (805A) and the moat (805C). Sedimentation rates were extreme here— probably on the order of a few centimeters per year and in 2002 the Japanese ship R/V Mirai had measured methane release 5 times normal at the crest (Rochon et al., 2003). 2.2. Collection and processing of samples Surface sediments were collected from the surface of box cores (scraped from the upper .5cm with a spoon) and therefore known, undisturbed surfaces. Sur-

face samples were frozen soon after collection but not fixed because of perceived restrictions for use of formalin. We later discovered this was not a problem, much to our dismay, and we still have no living foraminiferal data from this area since the samples did not remain frozen. However because of the careful scraping with a spatula of the surface 0.5cm we are quite certain we have a good representation of the fauna and the sedimentation rates here are sufficiently high that we are not looking at relict faunas. We have also noted in previous work that the soft organic Komokiacean are not present below the upper surface (Schröder et al., 1989). Also it has been proven that total assemblages are the most reliable indicator of benthic environments

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Plate 1. Bottom photos of three different types of seafloor from the Amundsen Gulf and Beaufort Shelf. (a) bottom photo from station 415, 45m water depth (near Banks Island) which shows large cobbles which are probably the remnant of a Holocene water depth) at the edge of the eastern Mackenzie Shelf; (b) Station 406, 177m water depth just of f the Mackenzie Shelf with muddy bottom and abundant sea life, including soft deep-sea corals(arrows); (c) Station 403, 58m water depth, same muddy bottom but on the shelf (photos by P. Renaud during Leg 8, CASES at the same locations as the box cores).

because they integrate small seasonal and spatial changes (Scott and Medioli, 1978 and many subsequent papers). All cores and samples are stored in a cold room (4°C) to preserve the faunas. We have not observed deterioration of foraminifera under these conditions even after long storage periods. Tencm3 samples were sieved through 63µm sieves to retain the larger foraminifera and also through 45µm sieves to retain the 45–63µm fraction, which had not been done before, and this resulted to rather large numbers of certain species previously overlooked both by others and ourselves. The other factor that was different here from previous studies was that these samples were not dried and, since many of the smaller and fragile species are extremely difficult to examine when dried, this also is an important factor. In samples that contained large numbers of specimens we used a wet splitter to divide the sample into equal aliquots of 300–500 specimens (Scott and Hermelin, 1993). Photography of selected species was done with an ESEM (Plate 2) located at the Bedford Institute of Oceanography, Dartmouth, Nova Scotia; images were captured digitally. There is a limited taxonomy discussion at the end of this paper but the major taxonomy and plates will be in Scott et al. (in review to J. Foram. Res.). However some brief notes here are necessary to explain some of the “grouping” of species in this paper. For one of the most common deep-sea forms (Stetsonia arctica which also goes under the names S. horvathi, Epistominella arctica, and sometimes Epistominella vitrea), Scott and Vilks (1991) illustrated, using the intra-gradational series technique, that all these forms are junior synonyms of S. arctica (Green); coincidently Green also described S. horvathi which is also included with S. arctica. This technique was first used by Medioli and Scott, 1978 for foraminifera and suggested by Mayr et al., 1953 to be a valid technique for these highly variable types of populations, This technique was also used for the Islandiella teretis group, which will be illustrated in Scott et al. (in review to J. Foram. Res.). Elphidiella hannai was suggested to be the same as one from the Russian shelf—the species reported on the Russian shelf was Elphidiella groenlandicum (Polyak et al., 2002). Poor specimens of E. hannai may be confused with E. groenlandicum but pristine specimens of E. hannai are unmistakable as a different species. Lastly, this is the first finding of Komokiaceans in the Arctic (excluding Rhizammina algaeformis); the forms found here had organic tests and have not been reported before even though they have been reported in the Antarctic (e.g. Gooday et al., 1994, 2004). Unfortunately these are not preserved in cores.

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3. Results The samples provide a contrast between the low and high sedimentation/runoff areas and the high rates of change that occur between the shelf and the Amundsen Gulf for both the sediments and foraminiferal faunas present. Total numbers of individuals and percentages were done for both the N 63µm and 45–63µm fractions (Table 2) which show there were high abundances in both fractions but almost always different dominant species between them, illustrating once again why the small fractions must be examined, especially for some of the deep-sea calcareous forms. In the following sections each transect is discussed and the diagrammes contain graphs of abundance and percentage occurrences vs. depth for the most prominent species in each transect. For all the species, the total numbers and percentages for both size fractions are tabulated in Supplemental Table 1. We did not count allogromiids because they are very difficult to separate taxonomically, they do not preserve down cores so they are not helpful for paleoenvironmental interpretations. 3.1. Amundsen Gulf 3.1.1. Transect 100 Line runs 100 extended through the centre and deepest parts of the Amundsen Gulf (Table 2, Fig. 2, all stations N 200m water depth). Some of the depths in this transect are the deepest ever measured in this area (over 600m). The dominant species in the smaller (45–63µm) fraction were fundamentally different than the larger fraction with a high representation of calcareous deep sea Arctic species (S. arctica, and Buliminella hensoni, Table 2) together with many large deep sea agglutinated forms that are common in the deep ocean of the Atlantic and Pacific but not very common in the deep Central Arctic Ocean. There are also shelf calcareous species (I. teretis and Cassidulina reniforme) indicating some shelf influence here even though salinities were high and temperatures low. There are many planktic foraminifera indicating that open ocean surface water is present, with little of the lower salinity, Mackenzie River surface water. Number of specimens/10cm3 is high (800–4500/10cm3) and percentage in the b 63µm can be as high as 78% of the total. 3.1.2. Transect 200 Transect 200 had some shallow shelf depths but was not in the high runoff area of the Mackenzie Trough (Table 2, Fig. 3). Consequently it had a mixed fauna along its edges with some tintinnids (lowered

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salinity surface water indicator) together with planktonic foraminifera in the central part. There were high numbers of B. hensoni throughout the transect, including in the shallowest parts, that suggest the Arctic deep water is penetrating easily to the 100m depth. High numbers of planktonics occurred in the centre of the gulf where the influence of open arctic surface water is most evident. 3.1.3. Transect 300 Transect 300 was very similar to 200 but did not have the shelf stations present (Table 2, Fig. 4). In station 315, which is closest to Banks Island (Fig. 1), there are many I. teretis. Towards the centre there are more large agglutinates. 3.1.4. Transect 400 Transect 400 transversed the Amundsen Gulf with one shallow station on the edge of the Beaufort Shelf and the other on the shallow shelf off of Banks Island (Table 2, Fig. 5). Station 415 appeared to be on a former shoreline where there were large, rounded cobbles that were observed in a bottom photos taken at the time of sampling (Plate 1). The station depths here ranged from shallow (40m) to over 500m in the middle of the Gulf. The shallow stations were similar to those on the shelf but the deeper ones had a unique deep water agglutinated fauna with some of the largest foraminifera in the Arctic Ocean being present—i.e. Astrorhiza arenaria which is up to 1cm across and some very large R. algaeformis—these didn't show up in the counts as abundant but biomass wise these would almost be macrofossils. Together with the large species there was an abundance of the deep water calcareous species, which were largely 45–63µm. The presence of tintinnids on either side of the Gulf indicated some limited freshwater flow along the edges. Transects 200–400 were grouped together as Amundsen Gulf transects in Table 2 but separated between N 200m and b 200m water depth. Both sets had high total numbers of specimens of 500–8000 but the percentage of 45–63µm fraction was greater in the deeper stations. 3.2. Beaufort Shelf 3.2.1. Transect 600 Transect 600 was unique in the sense it had a station in the area of “pingo-like” features which usually suggested permafrost near the sediment surface (Table 2. Fig. 6). Significantly this was the only other station, besides the mud volcano site, to have the

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Table 2 Summary of all transects for relative presence of species (from the top down-most abundant to lesser abundance of main species, for both the above 45 and above 63 µm fractions Transects

Transects

Transects

Transect

Areas of methane

600–800, part of 200, 300, 400 (b200 m)

Parts of 200, 400 and all of 100 and 300(N200 m)

All stations in water depths greater than 300 m (except transects 100–300, 400

900

Stations 805, 711

N63 µm

N63 µm

N63 µm

N63 µm

N63 µm

Elphidium exc. clavatum Cassidulina reniforme

Trochammina spp I. teretis C. reniforme

Cassidulina reniforme Spiroplectammina biformis Textularia earlandi

Cassidulina reniforme Haynesina orbiculare

Spiroplectammina biformis

Islandiella teretis Cribrostomoides subglobosa Stetsonia arctica

Textularia earlandi

Planktonics Many small and large agglutinated species

Planktonics Assorted other agglutinated spp. Rare Oridorsalis umbonatus

N45 b 63 µm

N45 b 63 µm

N45 b 63 µm

N45 b 63 µm

N45 b 63 µm

Stetsonia arctica Buliminella hensoni

Stetsonia arctica Buliminella hensoni

Stetsonia arctica Buliminella hensoni

Discorbis squamata Buliminella hensoni

Bolivina arctica

Bolivina arctica

T. earlandi Reophax scottii Tintinnids

Tintinnids

Stetsonia arctica Buliminella hensoni Cassidulina reniforme Tintinnids

species Ammotium cassis and E. hannai present at station 609. The species E. hannai have not been reported north of Vancouver Island prior to this occurrence although Vilks may have seen some abraded specimens that he called Elphidium groenlandicum. The fauna at station 609 may be indicative of methane release associated with the “pingo” like features on the

Elphidium exc. clavatum Islandiella teretis Rare Elphidiella hannai and Ammotium cassis

Spiroplectammina biformis Tintinnids

inner shelf. Other than the two species mentioned above, the most the common agglutinated species were (Spiroplectammina biformis and Trochammina spp.) and calcareous species (C. reniforme, Elphidium excavatum f. clavatum) that had been noted on this shelf previously but not in the high numbers recovered with our box cores.

Plate 2. Dominant taxa of Foraminifera in the CASES study region. The name and date after each species name refers to the original author of each species and the complete references are listed in the bibliography. Mic = µm. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

Bolivina arctica Herman, 1974. Buliminella hensoni Lagoe, 1977. Cassidulina reniforme Nørvang, 1945. Elphidium excavatum (Terquem, 1876) f. clavatum Cushman 1930. Islandiella teretis (Tappan, 1951). Neogloboquadrina pachyderma (Ehrenberg, 1861). Reophax scottii Chaster, 1892. Reophax guttifer Brady, 1881. Rhizammina algaeformis Brady, 1879. Saccammina difflugiformis (Brady, 1879). Spiroplectammina biformis (Parker and Jones, 1865). Stetsonia arctica (Green, 1960). Textularia earlandi Parker, 1952. Trochammina globigeriniformis (Parker and Jones, 1865). Trochammina nana (Brady, 1881). Tintinnopsis rioplatensis Souto, 1973.

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Fig. 2. Percentages of selected species for the total assemblage as well as the 45–63µm fraction versus depth along transect 100, Amundsen Gulf.

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Fig. 3. Distribution of selected species versus depth along transect 200, Amundsen Gulf.

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Fig. 4. Distribution of selected species for the two size fractions versus depth along transect 300, Amundsen Gulf.

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Fig. 5. Distribution of selected species versus depth along transect 400, Amundsen Gulf.

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Fig. 6. Distribution of selected species versus depth along transect 600, Beaufort Shelf. Same format as Fig. 2.

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Fig. 7. Distribution of selected species versus depth along transect 700, Beaufort Shelf.

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Fig. 8. Distribution of selected species for the two size fractions versus depth along transect 800, Beaufort Shelf.

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Fig. 9. Distribution of selected species for the two size fractions versus depth along transect 900, Mackenzie Trough.

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3.2.2. Transect 700 Transect 700 covered a wide depth range from 30m to over 1000m (Table 2, Fig. 7). The shallow stations (718–712) had a fauna similar to transect 600 but this changed dramatically when the slope was reached; starting at station 703 and ending at 750 (N 1000m) planktics become a significant component and tintinnids almost disappeared as a result of being at the ice edge where there was little meltwater or freshwater from the shelf. The smaller species (45–63µm, B. hensoni, S. arctica) became much more prominent at the 1000m depth, reflecting the deep Arctic Ocean water. This transect had two of the deeper stations off the shelf edge and was listed in a separate column in Table 2—these are the only two stations that had a significant presence of Oridorsalis umbonatus, a North Atlantic deep water indicator. 3.2.3. Transect 800 Transect 800 covered the full depth range of this study from 33 to 1056m (Table 2, Fig. 8) as in transect 700. As in the adjacent transect 700, there were significant changes between the stations in this transect with depth. However this transect also sampled the moat and crest of the Kopanoar mud volcano (station 805) where the A. cassis and E. hannai fauna were again encountered. Along the remainder of the transect there were common calcareous species such as Haynesina orbiculare, E. excavatum, and C. reniforme together with several agglutinated species (Trochammina spp., Textularia earlandi, and S. biformis). At the two deeper stations (803 and 850) some deep water Arctic species appeared but mostly in the size fraction 45–63µm—S. arctica, B. hensoni, and Bolivina arctica. These species also occurred at the other stations but here they were dominant in the smaller size fraction. Tintinnids were also common suggesting that significant amounts of low salinity surface water reached offshore at this location close to the Mackenzie Trough. These transects had high numbers of specimens (1600–6700/ 10cm3): 20–74% in the 45–63µm fraction. 3.2.4. Transect 900 Although transect 900 only had only 3 stations, it was in the Mackenzie Trough where sedimentation rates were highest and it covered a depth range of 56m to 280m (Table 2, Fig. 9). The surface sediments here contained a largely agglutinated fauna consisting of Trochammina, Textularia, and Reophax species in relatively low numbers (100's). There were a few calcareous species such as I. teretis and C. reniforme. In the 45–63µm fractions there were extremely high populations of the deep water calcareous species B. hensoni

and S. arctica and the highest numbers of tintinnids observed anywhere on the shelf as a result of the high freshwater component from the Mackenzie River. This transect had the lowest total number (210) to the highest total number (10,800)/10cm3 of all the transects with 30–60% in the 45–63µm fraction. 4. Discussion 4.1. Comparison with previous data from the Canadian Arctic Vilks (1989) reported far fewer specimens from the 1969/70 Hudson samples on the Beaufort Shelf. There are some likely reasons for this, which were beyond the control of methods used in the 1970's. First of all they were not using box cores but grab samplers and piston core tops so the uppermost surface may have been lost; we know from our own sampling that even just the top of the short cores from the box cores where we took the upper 1cm, there were lower abundances than in material from the upper 0.5cm 10cm3 sample we used for our surface distributions; this was useful information because it indicates that just in the upper 1cm considerable degradation takes place—we knew this for the Komokiacea but not some of the other species. Second, not keeping the samples in liquid would have affected some of the more fragile agglutinated species. Finally not looking at the smaller b 63µm fraction precluded seeing some entire species groups however it should noted that no one was looking at the smaller size fraction including ourselves until recently. Vilks did look at the N 63µm fraction which was more than many others who have worked in the Arctic and who found few benthic species by examining only the N 125 or N 150µm fractions. Our new data usually indicates numbers in the 1000's rather than 100's per unit volumes that Vilks reported from the same locations. We found fundamentally the same calcareous species in similar percentages to Vilks but he found far fewer agglutinated species because of drying the samples and to some extent size fraction although this not as much a factor for agglutinated species as for the smaller deep-sea Arctic species such as S. arctica, B. arctica and B. hensoni. Taxonomically most of the names are the same except that Vilks divided the Islandiella's into several species, which we group into I. teretis; this problem is discussed briefly in the taxonomy section later but more comprehensively in Scott et al. (in review to J. Foram. Res). Vilks' papers are the most comprehensive and most useful to the present study because he studied the shelf area. However other papers have provided

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complementary information, particularly those of Lagoe (1977, 1979) who was the first to use % species abundances although he did not do the total number from a standard unit volume. He did, however, illustrate his material exceptionally well. Green (1960) described some of the key species that are prominent Arctic species. Markussen et al. (1985) surprisingly looked at N 63µm for the planktonics but only N 125µm for the benthics—the benthic species they found were the large Atlantic species but none of the most common Arctic species such as S. arctica, B. arctica or B. hensoni. Because of their methods Markussen et al. (1985) got the mistaken impression that those deep water Arctic stations were “planktonic ooze”. Scott and Vilks, (1991) looked at the same stations and found an almost one to one ratio of benthics to planktics—a fundamentally different result which shows that a one to one ratio of benthics/planktics indicates permanent ice cover, and other stations in the same group where there was some seasonally open water had a 10:1 planktic to benthic ratio while typical open ocean deep sea sediments will have up to a 100:1 ratio. Iqbal (1973) and Vilks (1989) examined grab samples from M'Clure Strait just north of Banks Island which is the widest opening to the NW Passage—their data appear to be the only data from this important area. These stations ranged in depth from 250 to 450m and the faunas found were very similar to what we found in the Amundsen Gulf. As with Amundsen Gulf there are few sources of freshwater or fine sediments—there are few cores here but it could be assumed that sedimentation rates in M'Clure Strait are also low as they are in Amundsen Sound and that oceanographic conditions are similar. The best documented data set is that of Iqbal using 40 grab samples—overall he saw largely agglutinated faunas, often 100% of the fauna being agglutinated. Both Iqbal and Vilks observed high numbers of planktonic species both in sediments and in samples taken in the water column. The main benthic calcareous species were the same as we see in Amundsen Sound— Islandiella spp. and C. reniforme. They also observed many species of Lagena spp. which occurred rarely in our material. Iqbal, as with Vilks, examined his material dry but found much larger total numbers than Vilks— sometimes over 200 specimens/dry weight gram of sediment which may correspond to as much as 2000 specimens/10cm3 wet sediment although it is very difficult to make the total number comparison between dry and wet sample volumes. Vilks (1969) also looked at many of the channels in the Canadian Archipelago where he found a largely agglutinated fauna, similar to M'Clure Strait and similar

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to what Phleger had reported in 1952. Schröder-Adams et al. (1990b) examined foraminifera in the N 63µm fraction from samples taken from an ice island occupied by the Geological Survey of Canada that was grounded off of Axel Hieberg Island in 1985/1986. This area had perennial ice cover and Schröder-Adams et al. (1990a) compared benthic foraminiferal faunas from Lancaster Sound/Baffin Bay, which is seasonally open, to the same ice island samples. These data provide a contrast between perennially ice covered and seasonally open shelf areas, a condition somewhere between what is occurring on the Beaufort Shelf. Unlike most other Arctic studies, in this study they were able to preserve the samples in formalin and use Rose Bengal to distinguish living and dead specimens in the Lancaster Sound/Baffin Bay sample set but not the Ice Island set. In the ice island samples there were extremely high total numbers from 10,000/10cm3 to over 100,000 benthics in some samples, similar to what Scott et al. (1989) saw on Alpha Ridge. This adds to the conclusion made by Scott et al. (1989) and Scott and Vilks (1991) that almost equal numbers of planktic vs. benthic can be inferred to mean permanent ice cover as opposed to seasonal ice cover where the P/B ratio is 10:1. The Lancaster Sound samples were examined in liquid suspension, which enabled the living specimens to be detected. In these samples there were some stations that had living percentages that appeared to be as high as 10%. The ice island samples were examined dry and not stained. The differences between perennially ice covered areas and those that are seasonally open are readily apparent from these data. Because there is little or no freshwater input to perennially ice covered areas, there is low surface productivity and the salinity is always high which allows calcareous species to be preserved in the sediments as well as reducing organic carbon input to the seafloor which adds to carbonate dissolution (e.g. Wollenburg and Kuhnt, 2000). The water depths under the ice island varied from about 100m to over 300m. The dominant species were a series of calcareous species: S. arctica (E. arctica and Stetsonia horvathi in Schröder-Adams et al., 1990a,b), Buliminella borealis (= B. hensoni) and many more calcareous species, including some exceptionally large (1–2cm width) Cyclogyra involvens which were also found on the Beaufort Shelf, not in our box cores but in benthic dredge samples taken at the same time. 4.2. Comparison with other arctic margins Probably the most analogous area to the Beaufort Shelf is the Siberian Shelf where there are several large rivers flowing into the Arctic Ocean adding 1/3 of the

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total freshwater to the Arctic (Polyak et al., 2002). Polyak et al. (2002) presented a large data set for benthic foraminifera from the Kara Sea, which is a large estuarine-like area adjacent to the Barents Sea. Polyak et al. (2002) assembled not only their own data but combined theirs with previous work for a comprehensive study; the only drawback was that the size fractions used were not always consistent but they were usually using 100µm mesh size so most species were detected except the small deep sea forms. Depths sampled ranged from 9 to 500m but were mostly less than 100m. Salinities and temperatures are quite different with bottom water temperatures, even in the summer, being b − 1°C and salinities even in the winter seldom above 34‰ except in the deepest stations. The foraminiferal fauna is quite distinct from that observed on the Beaufort Shelf. In particular they observed far more calcareous material than occurs on the Beaufort Shelf. Although the same species are on the Beaufort Shelf they are not as common as in the Kara Sea. Specifically H. orbiculare, Elphidium exc. f. clavatum, and C. reniforme, which occur sporadically on the Beaufort Shelf, but are not the dominant species, appear to be common in the Kara Sea. Islandiella spp. are the only calcareous species that are common in both areas. The increased presence of calcareous species in the Kara Sea, however, appears to be concentrated in areas where the bottom salinity exceeds 30‰. Also, except for a few stations, the foraminiferal numbers are much less than 100/dry gram of sediment. One possible factor influencing the prevalence of calcareous species might be the proximity of the North Atlantic to this area; this would provide warmer, higher salinity water to Northern Europe than that available in the Beaufort Sea. The only other study close to the present one was by Poore et al. (1994) who examined cores from the Northwind Ridge into the Canada Basin. This study examined piston cores in water depths of 945 to 3500m so it barely overlaps with our deepest station. In the core at 950m a few benthic foraminifera were observed but since they examined only the fraction N 150µm they did not see most of the dominant species. Scott has however looked at surface samples from near the same region and did see much the same fauna as we see at 1000m off the Beaufort Shelf as well as the central Arctic so in this case size does matter. Most of the rest of the more recent papers are on deepsea regions. One of the first papers to make the distinction between living and total was Bergsten (1994) who examined areas in the Amundsen Basin; this study examined areas similar in physiography to those of Scott and Vilks (1991). Her samples ranged in water depth from 1074 to 4375m and the faunas she observed were similar in many

ways to those of Scott and Vilks (1991) with higher percentage's of agglutinated species in the slope areas where there was seasonally open water and few agglutinated species in the deeper, perennially ice covered areas that were dominated largely by the calcareous species S. arctica—very similar to what was observed before. However what is the most interesting are the numbers of living specimens. In the shallower stations, where there were more agglutinated species, there were substantial percentage's of living specimens (.6–25% out of total populations of 700–7000) but in the deeper stations where S. arctica was dominant living %'s rarely exceeded 1%. However in the shallower stations, where S. arctica was also common, living specimens were often also dominated by this species as well as agglutinated species. However there was little consistency—at station 2200 which was in 1074m water depth, there was a total population of over 23,000 with only .5% living and no living S. arctica. These results confirmed a belief by some (including the senior author of this paper) that although total populations are very high in the central Arctic Ocean, there are few living specimens in the deep sea Arctic and the high total population numbers are due to the exceedingly slow sedimentation rates. Wollenburg and Mackensen (1998) and Wollenburg and Kuhnt (2000) also looked at living faunas in reference to primary production. They found the highest numbers of living foraminifera associated with high productivity zones, which generally occurred in seasonally ice-free areas (in this case some of the same areas as reported by Bergsten, 1994 and Schröder-Adams et al., 1990b). They also noted that preservation of calcareous foraminifera in the high productivity zone was poor compared with the perennial ice area—another factor noted by Scott and Vilks (1991) and Schröder-Adams et al. (1990a,b) in an area close to this one. Wollenburg and Mackensen (1998) also examined infaunal living species and found more infaunal living specimens in seasonally open areas but they did not make the comparison to determine if these infaunal living species affected the total populations—in a similar type of study (Tobin et al., 2005) it was determined that even though there might be significant living populations below the upper 1cm, these living foraminifera do not affect the total populations determinations— i.e. the upper 1cm is the best analogue to use for characterizing modern environment. In two related papers, Wollenburg et al. (2001, 2004) looked at paleoproductivity in cores from the same area and were able to see reduced productivities during glacial periods when areas, now only seasonally ice covered, were covered perennially. They examined the 24,000ybp interval and the 145,000ybp intervals respectively. We hope to be able to

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do much the same type of inferences from cores on the Beaufort Shelf/slope area. 4.3. Implications of faunal parameters in relation to paleo-sea-ice cover In addition to the studies mentioned above we have also found some faunal parameters useful especially in a brackish Arctic environment such as the Beaufort Shelf. A number of findings provide us with much more specific data with which to interpret our downcore data and in turn provide much better perspective of paleo-ice cover and paleoceanographic conditions. First tintinnids occur in many samples and these indicate some freshwater input as well as high amounts of suspended particulates (SPM, Scott et al., 1995)— their presence precludes significant permanent ice cover since ice cover usually means little runoff or freshwater in the water column. The presence of abundant agglutinated species also suggests significant freshwater and/ or high productivity since perennial sea-ice inhibits both. Conversely if there is significant freshwater input there are fewer planktic foraminifera. It has been shown in this study and several others mentioned above that if the P/B ratio is close to 1:1 there is probably permanent ice cover so if that is observed in cores then those intervals suggest perennial ice. None of the stations we sampled (see Table 2, Figs. 2–9) were in the perennial ice cover and hence no samples had a 1:1 P/B ratio, unlike the Central Arctic where that is the normal condition throughout the Quaternary (Scott et al., 1989). The closest condition to perennial ice cover was in the Amundsen Gulf where there is little affect from freshwater. There, mostly in the centre, planktics ranged from 16 to 50% especially on line 100 which ran down the centre of the Gulf. In the slope stations at 1000m (703a, 750, 850) planktics ranged 20–25% except in station 850 which is on the edge of the Mackenzie Trough; there planktics were only 11% and there were abundant tintinnids, reflecting the influence of the Mackenzie River even in this deep water station on the outer edge of the Mackenzie Trough. The Central Arctic (Alpha Ridge) has no tintinnids and very few agglutinated species unlike either the Gulf or various Arctic slope areas (e.g. Wollenburg and Mackensen, 1998; Wollenburg and Kuhnt, 2000) which have relatively abundant agglutinated faunas. These data combined with palynological data (Richerol and Rochon, in review to J. Marine Sci.) being generated independently should allow us to reconstruct a robust paleo-ice cover picture with resolution depending on sedimentation rates.

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The work of Wollenburg and Kuhnt (2000) and Wollenburg et al. (2004) can also provide us with some comparative data on previous transitions from 24 to 145kybp which were transitions between interstadials and glacials which may be similar to what we will see in our cores. In particular, areas off the Barents Sea Slope where they see higher productivity are similar to the slope of the Beaufort Shelf (stations 703, 750, 850), which are at the present ice edge and open for a short period of the year. The faunas observed by both Wollenburg and others as well as by Scott and Vilks (1991) in similar areas are very similar to our slope stations— fairly high percentages of planktics, many agglutinated species as well as many deep-sea calcareous species (b 63µm fraction) and high numbers of I. teretis and few O. umbonatus. The main differences between Beaufort sites and the deep-sea sites are the presence of agglutinated species and lower total numbers that are almost certainly the result of higher sedimentation rates at the Beaufort and Barents Sea slope sites. At the core surface of the CESAR cores, O. umbonatus was apparently more abundant but that 1cm was accumulated over 10,000yrs so its resolution is not sufficient to differentiate Atlantic influence over the Holocene time frame. 4.4. Foraminiferal data in relation to other environmental parameters Apart from the paleo-ice records, there are some other findings indirectly related to climate change—the presence of species that appear to react to methane and/ or suspended particulates (SPM). The occurrence of E. hannai is the first report of this species in the Arctic (although it appears that some people may have confused this species with another one—there is a short discussion at the end of this section). This species is dominant in some parts of San Francisco Bay and has been reported in high numbers from a small mudflat in Washington State (Scott, 1974, Jones and Ross, 1979). What is significant about this species is that it appears to tolerate high amounts of pollution which may include sulfur or methane and that could account for this species presence atop the mud volcano and in the pingo area where methane discharge has been measured (Walsh, 2006). A. cassis is another species that occurred with E. hannai and this one is known to prefer areas of high SPM which could also be expected around pingos and mud volcanoes (Scott et al., 1977, Wefer, 1976). Hence not only will we be able to detect sea-ice cover changes but also paleo-pingo and mud volcano sites where methane has been released in the past. Additionally, although very rare, the marsh species, Trochammina

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macrescens, is found in a one station (711, 77m); although rare it is notable because samples from marshes onshore near Inuvik contained this species but in low numbers (b 100 spec./10cm3) so that for the specimens to appear offshore indicates substantial movement by land fast ice to the shelf. This species was also found in some mud volcano sediments on the inner shelf (Walsh, 2006). The presence of Komokiacea (not counting the many reports of R. algaeformis), although the first report from the western Arctic, is not particularly surprising since they are found in deep waters around the world (e.g. Gooday et al., 1994, 2004). There are also large numbers of smaller agglutinates on the shelf. This is mildly surprising since large numbers of agglutinated species are reported in only few previous studies except in the Canadian Archipelago (Phleger, 1952 and Vilks, 1969; Iqbal, 1973; Schröder-Adams et al., 1990a,b). The presence of species such as B. arctica, S. arctica, and B. hensoni in the shallow water shelf sediments suggests that some deep Arctic water is penetrating into the shallow shelf areas. This is borne out by the physical characteristics of the water below 30m and also during the winter there is certainly more of deep water penetrating onto the shelf as the freshwater supply is diminished. The Amundsen Gulf is a unique deep-sea environment where there is a mixture of deep-sea agglutinated species that might be expected in abyssal depths together with a collection of deep-sea calcareous as well as slope Arctic species. But in the deep-sea Arctic there are very few agglutinated species (Scott and Vilks, 1991). We now have surface baseline data in all the core locations, which will be valuable as a starting point for our present and future studies of Western Arctic paleoceanography. These data allow us to determine if there are migrations of faunas by depth or if the entire assemblage is altered by changing ice conditions with new species coming in from a different part of the ocean; if the latter happens there is sufficient data from ours and other studies mentioned above to accurately interpret the paleoenvironment. Presently the only Atlantic deep water species observed in this study (only in the deepest stations) is O. umbonatus and this only in low percentages although it does occur more abundantly in the eastern Arctic (Scott and Vilks, 1991, Bergsten, 1994). Since we have very good physio-chemical data for each station we know the parameters at the time of collection. Combining these data with future palynological data we are confident we can build a strong picture of past seaice and paleoceanographic conditions, which can then be compared with present day conditions.

4.5. Taxonomic notes This paper is not intended to be taxonomic in nature as the taxonomy for all these species is being published in a micropaleontology journal. However there are a few issues raised by reviewers regarding the grouping of some of the more common species. As with many foraminiferal species there has been some over splitting of some of the more common species that occur in this study. For one of the most common deep-sea forms, (S. arctica, which also goes under the names S. horvathi, E. arctica, and sometimes E. vitrea), Scott and Vilks (1991) illustrated, using the intra-gradational series technique (this technique was first used by Medioli and Scott, 1978 for foraminifera and suggested by Mayr et al., 1953 to be a valid technique for these highly variable types of populations), that all these forms are junior synonyms of S. arctica (Green); coincidently Green also described S. horvathi which is also included with S. arctica. The aperture grades from a slit to almost a loop but there are many intermediate forms—this becomes obvious after looking at many thousands of specimens as we did in our central Arctic studies. The same is true for the I. teretis group, which will be illustrated in Scott et al. (in review to J. Foram. Res.). One other species that was questioned was E. hannai— it was suggested that this species was also found on the Russian shelf—the species reported on the Russian shelf was E. groenlandicum (Polyak et al., 2002). Poor specimens of E. hannai may be confused with E. groenlandicum (as was the case here with the first few specimens we found of E. hannai) but pristine specimens of E. hannai are unmistakable is as a different species; E. hannai has not been reported anywhere in the Atlantic which appears to be where most of the species reported by Polyak and others are coming from. Lastly we discussed the first finding of Komokiaceans in the Arctic—if you consider R. algaeformis to be Komokiacean then they certainly have been reported in the Arctic before, both by ourselves and others but the forms with the completely organic tests have not been reported before even though they have been reported in the Antarctic (e.g. Gooday et al., 1994, 2004). 5. Conclusions The new data presented here illustrate the importance of the small (45–63µm) fraction of the benthic foraminiferal populations, most specifically showing that the smaller deep-sea arctic species penetrate into the Beaufort Shelf and Amundsen Gulf. This suggests that Arctic Deep-Water does seep onto to the shelf

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areas at least on the Beaufort Shelf. This is the first study on the Beaufort Shelf to look at the combined abundance of tintinnids and foraminifera and tintinnids provide a direct proxy of lowered salinity and high suspended particulate matter. The combined use of benthic and planktic foraminifera together with tintinnids provides us with a means to detect freshwater influence, sea-ice cover, and perhaps methane release as well as overall paleoceanographic conditions. Data from this study in combination with others from high productivity zones can be linked to lower sea-ice cover. Acknowledgements We thank the captain and crew of the NGC Amundsen and many others from CASES Legs 8 and 9 for their help in obtaining the samples for this study. Specifically R. Bennett, (NRCan), B. Hill, (Dalhousie) and A. Aitken (U. Sask.). R. Murphy and W. Rainie (NRCan) supplied us with the needed parts and instruction for the use of the box corer and data management respectively. F. Thomas (Bedford Institute) kindly and painstakingly took all the ESEM photographs presented here. J. Bartlett, C. Lywelln, J. Beaudoin and J.H. Clarke from the Ocean Mapping Group at University of New Brunswick provided us with high quality subbottom seismics and multi-beam imagery, which helped in selecting sample sites. D. Amiel and K. Cochrane (NYU–Stonybrook) supplied us with Pb210 dates which helped in determining sedimentation rates. Tony Walker collected the salt marsh samples from the Mackenzie Delta for the authors during the 2004 field season. P. Renaud (U. Connecticut) took bottom photos, some of which are in this paper. Funding for this project was primarily from the CASES NSERC network and Canada Fund for Innovation grants to Laval University led by Louis Fortier and Martin Fortier with supplements from the Natural Sciences and Engineering Research Council (Canada) Discovery grants to DBS and AR. Additional logistical support and maps were supplied by S. Blasco. This study was carried out as part of the Canadian Arctic Shelf Exchange Study (CASES). Many helpful comments and papers were received from L. Polyak and J. Wollenburg. Last but certainly not least all present researchers in the North owe a debt of gratitude to those scientists in the 1970's who worked under very difficult conditions. We in particular, are indebted to those Canadian micropaleontologists who pioneered many of the early studies using helicopters and cutting holes in the ice to obtain bottom samples. DBS in particular would like to acknowledge the help and guidance of Gus Vilks who unfortunately is no

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longer with us. He was a great mentor and friend as well as a very thoughtful and pioneering scientist. We also thank the 3 reviewers who spent considerable time and effort to help improve this paper. Appendix A. Supplementary data Supplementary data associated with this article can be found, in the online version, at doi:10.1016/j.jmarsys. 2008.01.008. References Backman, J., Jakobsson, M., LØvlie, R., Polyak, L., Febo, L.A., 2004. Is the central Arctic Ocean a sediment starved basin? Quaternary Science Reviews 23, 1435–1454. Bergsten, H., 1994. Recent benthic foraminifera of a transect from the North Pole to Yermak Plateau, eastern central Arctic Ocean. Marine Geology 119, 252–267. Brady, H.B., 1879. Notes on some of the reticularian Rhizopoda of the Challenger Expedition. Quarterly journal of microscopical science 19, 20–62. Brady, H.B., 1881. Über einige arktische tiefsee-Foraminiferen gesammelt während der österreichisch-ungarischen NordpolExpedition den Jahren 1872–74. Denkschriften der Kaiserlichen. Akademie der Wissenschaften Wien Mathematisch-naturwissenschaften Classe, vol. 43, pp. 9–110. Carsola, A.J., 1952. Marine Geology of the Arctic Ocean and adjacent seas off Alaska and Northwest Canada. University of California, unpublished PH.D thesis, 221p. Chaster, G.W., 1892. Foraminifera. First Report of the Southport Society of Natural Science, 1890–91, pp. 54–72. Clark, D.L., Whitman, R.R., Morgan, K.A., MacKay, S.D., 1980. Stratigraphy and glacial-marine sediments of the Amerasian Basin, Central Arctic Ocean. Geological Society of America. Paper 180, 57p. Cushman, J.A., 1930. The foraminifera of the Atlantic Ocean. Part 7. Nonionidae, Camerinidae, Peneroplidae and Alveolinellidae. United States National Museum Bulletin, vol. 104, pp. 1–79. pls. 1–18. Cushman, J.A., 1948. Arctic Foraminifera. Cushman Laboratory for Foraminiferal Research. Special Publication 23, 79p. Ehrenberg, G.C., 1861. Elemente des tiefen Meeresgrundes in Mexikansichen Golfstrome bei Florida; uber die TeifgrundVerhaltnisse des Oceans am Eingange der Davisstrasse und bei Island. Monatsbericht der Königlichen Preussischen Akademie der Wissenshaften zu Berlin (1861), pp. 275–315. Gooday, A.J., Bowser, S.S., Bernard, J.M., 1994. The foraminifera of Explorers Cove, Antarctica: a deep-sea assemblage in shallow water? Antarctic Journal, 149–151. Review. Gooday, A.J., Holzmann, M., Guiard, J., Cornelius, N., Pawlowski, J., 2004. A new monothalamous foraminiferan from 1000 to 6300m water depth in the Weddell Sea: morphological and molecular characterisation. Deep-Sea Research II 51, 1603–1616. Green, K.E., 1960. Ecology of some Arctic foraminifera. Micropaleontology 6, 57–78. Herman, Y., 1974. Arctic Ocean sediments, microfauna, and the climatic record in Late Cenozoic time. In: Herman, Y. (Ed.), Marine Geology and Oceanography of the Arctic Seas. SpringerVerlag, New York, pp. 283–348.

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