Geo log i cal Quar terly, 2013, 57 (2): 335–342 DOI: http://dx.doi.org/10.7306/gq.1087
Plio cene ag glu ti nated ben thic Foraminifera from Site U1341 in the Be ring Sea (IODP Ex pe di tion 323)
Mi chael A. KAMINSKI1, 2, *, Sev KENDER3, Agnieszka CIUREJ4, Ramona BÃLC5 and Eiichi SETOYAMA1
1 Earth Sci ences De part ment, King Fahd Uni ver sity of Pe tro leum and Min er als, PO Box 701, Dhahran, 21361, Saudi Ara bia
2 De part ment of Earth Sci ences, UCL, Gower Street, Lon don, WC1E 6BT, United King dom
3 Brit ish Geo log i cal Sur vey, Keyworth, Nottingham, NG12 5GG, United King dom
4 In sti tute of Geo log i cal Sci ences, Pol ish Acad emy of Sci ences, Senacka 1, 31-002 Kraków, Po land
5 Fac ulty of En vi ron men tal Sci ence, Babeº-Bolyai Uni ver sity, Fântânele 30, 400294, Cluj-Napoca, Ro ma nia
Kaminski M.A., Kender S., Ciurej A., Bãlc R. and Setoyama E. (2013) Plio cene ag glu ti nated ben thic Foraminifera from Site U1341 in the Be ring Sea (IODP Ex pe di tion 323). Geo log i cal Quar terly, 57 (2): 335–342, doi: 10.7306/gq.1087
We pres ent the first re cord of ben thic foraminiferal as sem blages from 92 sam ples col lected at approx. 3 m res o lu tion in the bot tom part of Hole U1341B drilled in the south ern Be ring Sea dur ing In te grated Ocean Drill ing Pro gram (IODP) Ex pe di tion 323. Plio cene ag glu ti nated foraminiferal are gen er ally rare within highly diatomaceous claystones oc cur ring from the base of the hole at 601.87 m be low sea floor (mbsf) to ~320 mbfs. The ag glu ti nated foraminiferal as sem blages are strongly dom i - nated by the infaunal gen era Eggerella, Karreriella, Martinotiella, and Spirosigmoilina. The cal car e ous-ce mented Eggerella and Martinottiella are canaliculated with pores that are open to the test sur face. Tu bu lar ag glu ti nated foraminifera are rare and are only found in iso lated sam ples. The eco log i cal in for ma tion gained from this as sem blage sup ports other proxy in for - ma tion in di cat ing high lev els of or ganic pro duc tiv ity and se verely hypoxic con di tions in the Be ring Sea deep wa ter dur ing the Plio cene.
Key words: Ben thic Foraminifera, Plio cene, tax on omy, Be ring Sea, hypoxia.
INTRODUCTION
The Be ring Sea is the third larg est mar ginal sea in the world sur passed only by the Med i ter ra nean and South China seas (Hood, 1983). The north ern half of the Be ring Sea con sists of a shal low (0–200 m) neritic en vi ron ment that is cov ered sea son - ally by sea ice whereas the south ern half is a much deeper silled basinal set ting, with lit tle sea sonal ice. IODP Ex pe di tion 323 drilled two sites on the Bow ers Ridge in the south west ern part of the Be ring Sea, an ex tinct arc sys tem that ex tends 300 km north from the Aleu tian Is land arc (Fig. 1). Drill ing at Site U1341 lo cated at a wa ter depth of 2,177 m re cov ered nearly 600 m of diatomaceous sed i ment, and pro vides a geo log i cal re - cord of past in ter me di ate wa ter con di tions in the Be ring Sea.
The site is lo cated just be low the mod ern ox y gen min i mum zone (OMZ), which causes the oc ca sional for ma tion of lam i - nated sed i ments. Fluc tu a tions in the in ten sity or depth of the
OMZ on a va ri ety of timescales should be re flected by ben thic fora miniferal re cords at this site and can be com pared to shal - lower sites (Takahashi et al., 2005).
The pri mary ob jec tive of drill ing at Site U1341 was to study high-res o lu tion “Plio cene–Pleis to cene” palaeoceanography in the south ern part of the Be ring Sea at a west ern flank lo ca tion of Bow ers Ridge. Pre vi ous DSDP cor ing (at Site 188) and sub se - quent pis ton core stud ies in the re gion doc u mented high sed i - men ta tion rates of >100 m/my and the pres ence of ap pro pri ate microfossils for palaeoceanographic stud ies (Takahashi et al., 2005). The age model for Hole 1341B is con strained by the pres ence of stratigraphically im por tant di a toms, silico flagel - lates, and ebridians (Ex pe di tion 323 sci en tists, 2009). The in ter - val con sid ered in this study is as signed a Plio cene age based on the last oc cur rence of the ebridian Ebriopsis antiqua antiqua in Cores U1341B-37H, and the last oc cur rence da tum of the silicoflagellate Distephanus jimlingii in Cores U1341B-38H, in - dict ing the whole of the stud ied in ter val is older than ca. 2.47 Ma. The base of the cored in ter val in Hole 1314B is as signed to the lower Plio cene based on the last oc cur rence of the radio - larian Dictyophimus bullatus (3.8–4.0 Ma) in Core U1341B- 71X.
The pur pose of this pa per is to re port the tax on omy and biostratigraphy of the Plio cene ag glu ti nated foraminifera from
* Corresponding author, e-mail: kaminski@kfupm.edu.sa Received: March 8, 2013; accepted: April 3, 2013; first published online: April 12, 2013
this highly pro duc tive part of the north ern Pa cific Ocean. The ul - ti mate goal is to es tab lish ben thic foraminiferal re cords from IODP holes in the Be ring Sea at a range of timescales, for use as prox ies of ox y gen a tion and pro duc tiv ity.
MATERIAL AND METHODS
IODP Ex pe di tion 323 suc cess fully drilled seven sites whose sed i ments cap ture the spa tial and tem po ral evo lu tion of the Be -
ring Sea through the Plio cene and Pleis to cene. This study fo - cuses on the old est strati graphic re cord re cov ered dur ing IODP Ex pe di tion 323. The cores re cov ered on IODP Ex pe di tion 323 con sti tute the only con tin u ously-cored high-lat i tude re cord of
“Plio cene–Pleis to cene” bi otic and cli ma tic change avail able for study in the north ern Pa cific re cov ered thus far by the Ocean Drill ing Pro gram. Sam ples (approx. 20 cm3) were col lected from the work ing halves of Site U1341B cores dur ing the postcruise sam pling meet ing us ing a metal spat ula. Sam ples were gently sieved over a 63 mm screen, us ing just a wa ter spray. Sam ple Fig. 1. Lo ca tion of Site U1341 and other IODP sites (grey dots) near Bow ers Ridge,
south ern Be ring Sea
res i dues were then air-dried and ben thic foraminifera were picked into card board microslides us ing a fine brush. Spec i mens were im aged us ing a JSM-5900LV SEM at KFUPM in Dhahran.
RESULTS
Ag glu ti nated foraminifera were found to be a mi nor com po - nent in the richly diatomaceous claystones re cov ered in Hole U1341B, and some sam ples were bar ren of foraminifera. The ma jor ity of sam ples ex am ined are noncalcareous and con tain only a few spec i mens of ag glu ti nated foraminifera. The sam - ples from Core U1341B-71X (the base of the hole) un til the lower part of Core U1341B, 63X con tain only ag glu ti nated foraminifera. Cal car e ous ben thic foraminifera were found in iso lated sam ples in the up per part of the stud ied sec tion. These are gen er ally less abun dant than the ag glu ti nated spe cies, mostly con sist of nodosariids, buliminids, Uvigerina and Melo - nis, and will be de scribed sep a rately. Plank tonic foraminifera, con sist ing of rare Neogloboquadrina and Globigerina were only found in three sam ples in the stud ied in ter val (U1341B, 61X-5, 115–117 cm; 61X, CC; 47H, CC).
The abun dance of ag glu ti nated foraminifera in the non - calcareous sed i ments var ies from 0 to 224 spec i mens per sam - ple. A to tal of nine spe cies were found in the stud ied in ter val:
these are (in de scend ing or der of abun dance), Martinot tiella sp.
1, Eggerella sp. 1, Kar reriella sp. 1, Spirosigmoilinella com - pressa Matsunaga, Psam mo siphonella sp., Eggerella bradyi (Cushman), Martinottiella sp. 2, Rhabdamminella sp. and Bathysiphon sp. 1 (Figs. 2–4). The abun dances of in di vid ual spe cies are given in Ap pen dix 1*. Be cause the com mon spe - cies of ag glu ti nated foraminifera ex tend through the whole Plio - cene in ter val in Hole U1341B, the in ter val is not fur ther sub di - vided.
SYSTEMATIC PALAEONTOLOGY
Tax o nomic iden ti fi ca tions are based largely on the pub - lished mono graphs of Mio cene foraminifera, in clud ing Cicha et al. (1998), van Morkhoven et al. (1986), and Kender et al.
(2008). The sys tem atic clas si fi ca tion of the ag glu ti nated fora - minifera fol lows Kaminski (2004).
Ge nus Bathysiphon Sars, 1872 Bathysiphon sp. 1
(Fig. 2Ca, Cb)
D e s c r i p t i o n. – Test a straight un branched elon gate tube, open at both ends, nonseptate. Wall ag glu ti nated, thick, of silt-sized grains with clay par ti cles, sev eral grains thick, with very smooth in ner and outer sur faces, with out sponge spicules.
Ap er ture at the open end of the tube.
R e m a r k s. – This spe cies dif fers from the type spe cies of Bathysiphon in lack ing any ob vi ous biogenic si li ceous par ti - cles such as sponge spicules em bed ded within the wall. In - stead, the wall is com prised of par ti cles of fine silt and clay. The test has a brown ish col our, likely re sult ing from the pres ence of clay par ti cles. Very rare in Hole U1341B.
Ge nus Rhabdamminella de Folin, 1887 Rhabdamminella sp.
(Fig. 2B)
D e s c r i p t i o n. – A ro bust tube with abun dant sponge spicules ori ented par al lel to the long axis of the test.
R e m a r k s. – Only found in a sin gle sam ple (U1341B- 70X-5, 146–148 cm).
Ge nus Psammosiphonella Avnimelich, 1952 Psammosiphonella cf. cylindrica (Glaessner)
(Fig. 2A, D)
cf. Rhabdammina cylindrica Glaessner, 1937, p. 354, pl. 1, fig.1.
D e s c r i p t i o n. – Test tu bu lar, monothalamous, round in cross sec tion, straight, of even di am e ter or slightly ta per ing in one di rec tion with out any dis tinct swell ing or "cen tre of or gani - sa tion". The in ner sur face of the tube is even, not con stricted.
Wall thick, com posed of equidimensional min eral grains, mostly quartz, ce mented with or ganic ma te rial.
R e m a r k s. – This spe cies most closely re sem bles Psam mosiphonella cylindrica (Glaessner), which is known from Paleogene and Up per Cre ta ceous flysch-type de pos its in Eu - rope (Kaminski and Gradstein, 2005), dif fer ing only in its larger di men sions. Rare in Hole U1341B.
Ge nus Spirosigmoilinella Matsunaga, 1955 Spirosigmoilinella compressa Matsunaga, 1955
(Fig. 2E–G)
Spirosigmoilinella compressa n.sp. – Matsunaga, 1955, p. 50, figs. 1, 2.
Spirosigmoilinella compressa Matsunaga, 1955 – Kaminski and Gradstein, 2005, p. 218, text-fig. 36, pl. 36, figs. 1–7.
D e s c r i p t i o n. – Cham bers nearly planispirally en - rolled, two per whorl, plane of coil ing in early stage chang ing slightly to show a sig moid curve in cross sec tion, later with coil - ing in a sin gle plane. Wall finely ag glu ti nated, grey in col our. Ap - er ture rounded, at the end of a short neck with out a tooth.
R e m a r k s. – This spe cies is char ac ter ized by ini tial por - tion that is coiled in a sigmoidal curve. Kaminski and Gradstein (2005) dis cussed the syn on ymy of the type spe cies. The spe - cies is known from the Mio cene of the Ja pan Sea and Sakhalin Is land. The spe cies is re stricted to the Mio cene in the Sea of Ja - pan (Hanagata et al., 2001). This the first re port of the spe cies in sed i ments of Early Plio cene age.
Ge nus Eggerella Cushman, 1935 Eggerella bradyi (Cushman)
(Fig. 2I)
Verneuilina bradyi n.sp. – Cushman, 1911, p. 54, text-figs. 87a, b.
Eggerella bradyi (Cushman) – Cushman, 1933, p. 33, pl. 4, fig. 1.
Eggerella bradyi (Cushman) – Cushman, 1937, p. 52, pl. 5, fig. 19.
Eggerella bradyi (Cushman) – Szarek, 2001, p. 93, pl. 8, figs. 3, 4 (with syn - onyms).
R e m a r k s. – This is a widely dis trib uted spe cies that is known from the Arc tic (Cushman, 1937). Szarek (2001) reported the spe cies from up per most bathyal to lower bathyal depths in the west ern Pa cific (Sunda and Viet nam ese shelves).
In the stud ied in ter val it is found only in sam ple U1341B-61X-5, 115–117 cm, in as so ci a tion with cal car e ous ben thic foraminifera.
Pliocene agglutinated benthic Foraminifera from Site U1341 in the Bering Sea (IODP Expedition 323) 337
* Supplementary data associated with this article can be found, in the online version, at doi: 10.7306/gq.1087
Eggerella sp. 1 (Fig. 2Ha, Hb)
D e s c r i p t i o n. – Test small, subconical, early stage in trochospiral coil of five in flated cham bers per whorl, at least in the microspheric gen er a tion, quickly re duc ing to three cham - bers per whorl. Wall finely ag glu ti nated, with much cal car e ous ce ment, coarsely canaliculate, the pores with an or ganic lin ing.
Ap er ture a round to oval open ing near the base of the ap er tural face, pro duced, and bor dered by a nar row lip.
R e m a r k s. – This spe cies dif fers from the type spe cies Eggerella bradyi (Cushman) in its smaller di men sions and in pos sess ing an ap er ture that is more rounded and pro duced.
Ad di tion ally, spec i mens in ves ti gated in the SEM are ob served to have canaliculae that are open to the test sur face in the lower part of the cham ber wall (Fig. 2Ha). The spec i mens do not ap - Fig. 2A – Psammosiphonella cf. cylindrica (Glaessner), U1341B-70X-5, 146–148 cm; B – Rhabdamminella sp.
U1341B-70X-5, 146–148 cm; Ca – Bathysiphon sp. U1341B-70X, CC; Cb – de tail of wall; D – Psammosiphonella cf.
cylindrica (Glaessner), U1341B-70X, CC, top view; E–G – Spirosigmoilinella compressa Matsunaga; E – U1341B-61X-3, 146–148 cm; F – U1341B-53H, CC; G – U1341B-61X-3, 146–148 cm; Ha – Eggerella sp. 1.
U1341B-63X-3, 146–148 cm; Hb – de tail of wall show ing open pores; I – Eggerella bradyi (Cushman), U1341B-61X-5, 115–117 cm
pear to be abraded, so this fea ture ap pears to be pri mary. In the type spe cies E. bradyi the test sur face ap pears to be smoothly fin ished, and canaliculae are closed at the sur face by a thin im - per fo rate layer of ag glu ti nated grains. This spe cies, by pos - sess ing open canaliculae in the outer wall of the test (but not in the intercameral septa), has ap par ently de vel oped a phys i o log - i cal re sponse to sur vive the low-ox y gen con di tions pres ent in the deep Be ring Sea.
Ge nus Karreriella Cushman, 1933 Karreriella sp. 1
(Fig. 3A–F)
D e s c r i p t i o n. – Test free, elon gate, ini tially trocho - spiral with up to five cham bers per whorl, later re duced to twisted triserial and fi nally be com ing biserial in just the fi nal one or two pairs of cham bers. Cham bers in the ter mi nal biserial part Pliocene agglutinated benthic Foraminifera from Site U1341 in the Bering Sea (IODP Expedition 323) 339
Fig. 3Aa–F – Karreriella sp.1; Aa – ju ve nile in di vid ual show ing open canaliculae on the bot tom half of the cham - bers, U1341B-70X, CC; Ab – de tail of ap er ture show ing finely ag glu ti nated lip and ter razzo sur face of ag glu ti - nated grains; B – larger spec i men with ap er ture be com ing oval, U1341B-70X, CC; C – spec i men with a pair of biserial cham bers, U1341B-52H-2, 130–132 cm; Da – spec i men be com ing biserial, U1341B-53H, CC; Db – de tail of wall show ing evenly-spaced open canaliculae, some of which are sur rounded by a rim of ag glu ti nated grains; Ea – bro ken spec i men, U1341B-53H, CC; Eb – de tail of wall; F – larger spec i men with two pairs of biserial cham bers, U1341B-61X-5, 115–117 cm
are glob u lar, with de pressed su tures. Wall finely ag glu ti nated, with cal car e ous ce ment, canaliculated, a smooth outer sur face, with pseudopores open to the sur face. Ap er ture ar eal, a roun - ded open ing slightly above the base of the ap er tural face in the triserial stage, be com ing more ar eal and in creas ingly oval in the biserial adult stage, pro duced, and sur rounded by a dis tinct lip.
R e m a r k s. – This spe cies can be dis tin guished from Eggerella sp. 1 in pos sess ing a ter mi nal biserial stage with an oval ap er ture. The spe cies bears some re sem blance to Meida - monella novangliae (= Gaudryina baccata var. novangliae Cushman, 1922), but dif fers in pos sess ing a much re duced biserial part and an oval (rather than slit-like) ap er ture. The ag - Fig. 4A, B – Martinottiella sp. 2. U1341B-63X-3, 146–148 cm: A – adult spec i men, B – ju ve nile in di vid ual; C–Hb –
Martinottiella sp. 1. U1341B-70X, CC; C–G – lat eral views of adult and ju ve nile spec i mens; Ga, Gb – bro ken spec i men show ing de tails of ap er ture and sin u ous pseudopores; Ha, Hb – top view of a bro ken uniserial frag - ment, show ing de tails of the wall struc ture
glu ti nated wall is sev eral grains thick, with a ter razzo outer sur - face (con sist ing of grains in the 5–10 mm size range the flat sides ori ented nor mal to the test sur face). Grains are sur - rounded by canaliculae sev eral mm in di am e ter that are open at the test sur face. At higher mag ni fi ca tion some of the open ings ap pear to be sur rounded by el e vated rims of fine ag glu ti nated grains.
Ge nus Martinottiella Cushman, 1933 Martinottiella sp. 1
(Fig. 4C–H)
Martinottiella communis (d’Orbigny). – Szarek, 2001, p. 93, pl. 8, fig. 10 (cf. fig. 9).
Martinottiella communis (d’Orbigny). – Hanagata, 2006, pl. 2, figs. 5, 6.
D e s c r i p t i o n. – Test free, elon gate, cy lin dri cal, early trochospiral coil with four to five cham bers per whorl, later re - duced to triserial, biserial, and a rel a tively long fi nal uniserial stage. Wall finely ag glu ti nated, canaliculate, with an in ner or - ganic lin ing. Ap er ture ter mi nal, round, pro duced on a short tu - bu lar neck in the cen ter of the flat tened ter mi nal face.
R e m a r k s. – This spe cies dif fers from the type spe cies Martinottiella communis from the (Badenian) of the Vi enna Ba - sin in its much smaller di men sions (the type spec i mens from Baden il lus trated by Papp and Schmidt, 1985, are over 2 mm in length) and thin finely ag glu ti nated wall that pos sesses coarse, me an der ing pseudopores (Fig. 4Gb). The wall is grey in col our, but at high mag ni fi ca tion has a “salt and pep per” ap pear ance ow ing to the pres ence of some mafic grains. Ad di tion ally, the ap er ture is round and pro duced, rather than in the form of an oval or cres cen tic slit (see Papp and Schmidt, 1985: pl. 66, figs.
6–8). Our spec i mens cor re spond well to one of the spec i mens from the west ern Pa cific il lus trated by Szarek (2001: pl. 8, fig.
10) as Martinottiella communis. Sim i lar small (<300 µm) smooth-walled spec i mens of this spe cies were il lus trated by Hanagata (2006) from up per Mio cene dysoxic sed i ments in north ern Ja pan. This spe cies is likely the one re ported by Echols (1973) as Martinottiella communis from the Up per Mio - cene and Lower Plio cene of DSDP Leg 19 sites in the Be ring Sea. This spe cies has been re corded from within low ox y gen in - ter me di ate wa ters off the Pa cific coast of Ja pan (Kaiho and Hasegawa, 1986), where ox y gen lev els are some what higher than in the mod ern Be ring Sea bot tom wa ter.
Martinottiella sp. 2 (Fig. 4A, B)
D e s c r i p t i o n. – Test free, elon gate, cy lin dri cal, early trochospiral coil with four to five cham bers per whorl, later re - duced to triserial, biserial, and a short uniserial stage. Wall coarsely ag glu ti nated, thick, canaliculate, with an in ner or ganic lin ing. Ap er ture ter mi nal, round, pro duced on a short tu bu lar neck in the cen ter of the flat tened ter mi nal face.
R e m a r k s. – Dif fers from Martinottiella sp. 1 in its larger di men sions and in pos sess ing a thick ag glu ti nated wall. It has a very short uniserial stage. Very rare.
DISCUSSION
The Be ring Sea re gion is one of the most highly bi o log i cal pro duc tive re gions in the world (Sambrotto et al., 1984), and has only lim ited deep ma rine con nec tions with the North Pa - cific. Con se quently the ox y gen min i mum zone ex tends to deeper lev els in the Be ring Sea than in the open ocean. The
stud ied lo ca tion at 2,177 m depth on Bow ers Ridge is cur rently af fected by the lower por tion of the OMZ, where mod ern-day ox y gen val ues are be low 1.5 ml/l (Ex pe di tion 323 Sci en tists, 2009). The site is there fore sen si tive to changes in the depth of the OMZ that would be caused by height ened pro duc tiv ity and/or re duced ven ti la tion of the bot tom wa ters. The sed i ment re cord of the south ern Be ring Sea in cludes in ter vals of lam i - nated diato maceous sed i ment that were de pos ited when con di - tions be came anoxic.
The ag glu ti nated foraminiferal as sem blage in the Plio cene of Hole U1341B is dom i nated by infaunal ta pered elon gated forms that would be best placed within Morphotype 4b of Kaminski and Gradstein (2005). This morphotype is known to be the dom i nant one in hypoxic con di tions such as in the mod - ern Cal i for nia Bor der lands Bas ins (Kaminski et al., 1995), un - der the OMZ off West Af rica (Kender et al., 2008a, b; 2009), or in as so ci a tion with Up per Cre ta ceous dysoxic shales (B¹k, 2006; Cetean et al., 2008). The dom i nant spe cies (Martinotiella sp. 1) has been iden ti fied as Martinotiella communis (d’Orbigny) in pre vi ous stud ies of “Mio cene–Plio cene” foraminiferal as sem - blages in NW Pa cific re gion (Echols, 1971; Szarek, 2001;
Hanagata, 2006), but its true tax o nomic af fin ity to the much larger and coarsely-ag glu ti nated “Med i ter ra nean–Paratethyan”
spe cies re mains to be de ter mined. Hanagata (2006) re ported an as sem blage dom i nated by “M. communis” [=Martinottiella sp. 1] with rare Spirosigmoilinella compressa in the up per Mio - cene–Plio cene of the north ern Ja pan Sea, and con cluded that the dom i nance of Martinottiella was re lated to “high lev els of or - ganic mat ter flux, which were pres ent in the late Mio cene–Plio - cene”.
The ag glu ti nated foraminifera re cov ered from Hole U1341B dis play ad di tional mor pho log i cal fea tures that can be as so ci - ated with hypoxic en vi ron ments: these in clude small test size and a thin wall, and the pres ence of a highly per fo rate test (Bernhard, 1986). In the case of ag glu ti nated taxa, per fo ra tions are in the form of canaliculae that are nor mally closed at the sur - face by a thin im per fo rate layer of ag glu ti nated grains. In the case of two of the in ves ti gated spe cies, the canaliculae are open at the test sur face. The test sur face does not ap pear to be dam aged by abra sion or dis so lu tion, which leads to the con clu - sion that this is a pri mary fea ture. Al though open canaliculae have been ob served pre vi ously (Mikhalevich, 2011), our find ing is the clear est ex am ple of such a fea ture that has been de - scribed thus far in an ag glu ti nated foraminifer. Such a fea ture in an ag glu ti nated spe cies re calls the per fo rate wall struc ture of a cal car e ous ben thic foraminifer, and is likely to be an ad ap ta tion for sur vival in se verely hypoxic con di tions.
CONCLUSIONS
Nine spe cies of ag glu ti nated foraminifera were found in the Plio cene of Hole 1341B in the south ern Be ring Sea. The re cov - ered as sem blage dis plays low abun dance and di ver sity, and con sists mainly of infaunal taxa dom i nated by a spe cies Martinottiella. The as sem blage strongly re sem bles the “Marti - nottiella communis as sem blage” of the north ern Ja pan Sea de - scribed by Hanagata (2006). Two of the taxa as signed to Eggerella and Karreriella dis play a po rous wall tex ture with canaliculae that are open to the sur face of the test, which is likely an ad ap ta tion to the se verely hypoxic con di tions pres ent in the deep Be ring Sea dur ing the Plio cene.
Pliocene agglutinated benthic Foraminifera from Site U1341 in the Bering Sea (IODP Expedition 323) 341
Ac knowl edge ments. We thank Prof. K. Takahashi for the op por tu nity to par tic i pate in the Ex pe di tion 323 sci en tific party.
This study was spon sored by a Fast-Track Grant (SB1010001) from the Dean ship of Sci en tific Re search, King Fahd Uni ver sity of Pe tro leum & Min er als. SK pub lishes with per mis sion of the
Ex ec u tive Di rec tor of the Brit ish Geo log i cal Sur vey (NERC).
The jour nal re view ers S. Filipescu, M. Gonera and D. Peryt are kindly ac knowl edged for their help ful com ments. This is con tri - bu tion nr. 100 of the Deep-Wa ter Ben thic Foraminiferal Pro ject.
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