Comparison between Recent benthic foraminiferal faunas of the Porcupine Seabight and Western Approaches Continental Slope

Weston, Janice F.

doi:10.1144/jm.4.2.165

Cited by 34 publications

(17 citation statements)

References 17 publications

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“…The rather more inflated later chambers in A. weddellensis, and the smaller size of E, exigua, may indicate that the bathyal site is a stressful environment for these species, perhaps because it lies near the limit of their bathymetric ranges (Boltovskoy & Wnght 1976, p. 91, Wang & Lutze 1986. Weston (1985) found that E. exigua only became the dominant species in the dead foraminiferal assemblage in the Porcupine Seabight below about 2400 m. The occurrence, albeit occasionally, of the allogromiin Tinogullmia sp. nov. inside small crustacean (copepod) moults (Table4) is of interest.…”

Section: Phytodetritus Populationsmentioning

confidence: 96%

Influence of seasonally deposited phytodetritus on benthic foraminiferal populations in the bathyal northeast Atlantic. the species response

Gooday¹,

Lambshead²

1989

Mar. Ecol. Prog. Ser.

228

105

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Cores were obtained with a multiple corer at a bathyal site (1320 to 1360m depth) in the Porcupine Seabight during April and July 1982. In July (but not April) the sediment surface was overlain by a layer of phytodetritus, material rapidly sedlmented from the euphotik zone following the spring bloom. The phytodetrital fraction of samples (0 to 1 cm layer of subcores; 3.46 cm2 surface area) removed from the July cores harboured dense, low-diversity populations of benthic foraminifers which resembled the phytodetritus-dwelling assemblages already described from the much deeper (4550 m) BIOTRANS site in the northeast Atlantic. Our new observations consolidate the view that phytodetritus is a microhabitat for some deep-sea benthic foraminiferal species. The bathyal populations were dominated by Alabaminella weddellensis (75 '70 of total) and also included Episton~inella exigua and Tinogullmia sp. nov. These 3 species occurred also in the BIOTRANS phytodetrital assemblages. The April san~ples and the total July samples (phytodetritus plus sediment fractions) yielded diverse foraminiferal populations of similar density and species richness. However, there were some important taxonomic dfferences. In particular, the 8 species consistently present in the phytodetritus were significantly more abundant in the July san~ples, while the most common species in the April sanlples (01.dmrnina sp. nov. A ) was entirely absent during July. We argue that the infhtence of phytodetritus, rather than spatial variability (patchiness), was responsible for some of the differences in species abundances. Other species, however, maintain more stable populat~on densities. Our results suggest that deep-sea benthic foraminifers, like those living in shallow water, probably display a variety of life-history strategies and populdtion dynamics. INTRODUCTIONThe delivery of organic material to the food-limited deep-sea benthic ecosystem is a central topic in biological oceanography (Angel 1984, Fowler & Knauer 1986, Bruland et al. 1989) One potentially important pathway is provided by rapidly sedimented phytoplankton blooms (Takahashi 1986) which accumulate during the spring and early summer on the sea-floor as a layer of 'phytodetritus'. This material was first reported in sediment cores and bottom photographs taken at depths of 1000 to 4500m in the Porcupine Seabight (an area centred around 51°30'N; 13'00' W) and on the adjacent abyssal plain (Billett et al. 1983, Lampitt 1985, Rice et al. 1986). Elsewhere in the northeast Atlantic it has been observed in the Rockall Trough (Barnett et al. 1982), the northern Bay of Biscay (Sibuet 1984, p. (Gardner et al. 1984). Phytodetritus is known to be ingested by deposit-feeding echinoderms (Billett et al. 1988) and other inegabenthic animals (Thiel et al. in press). Evidence from the BIOTRANS site (4550m depth) indicates that it is also degraded rapidly by deep-sea bacterial populations (Lochte & Turley 1988) and colonised and eaten by small benthic foraminifers (Gooday 1988a). The presen...

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Section: Phytodetritus Populationsmentioning

confidence: 96%

Influence of seasonally deposited phytodetritus on benthic foraminiferal populations in the bathyal northeast Atlantic. the species response

Gooday¹,

Lambshead²

1989

Mar. Ecol. Prog. Ser.

228

105

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“…Early studies of benthic foraminifera from the Celtic Sea and western English Channel depicted a correlation between the faunal variations and water depth, sediment type, and tidal and current regimes (Le Calvez 1958;Le Calvez and Boillot 1967;Murray 1970;Murray 1979;Sturrock and Murray 1981;Murray et al 1982;Weston 1985;Scott et al 2003). Further investigations of suspended sediment samples showed that small, dead foraminiferal tests (<200 µm) were suspended and transported from areas with powerful vertical turbulences and mixing (e.g., English Channel) to areas with a thermally stratified water column (e.g., South…”

Section: Previous Workmentioning

confidence: 99%

“…Environmental parameters such as food supply and oxygen concentrations in pore and bottom waters are linked to seasonal stratification and vary from mixed to stratified waters. These parameters are the primary controlling factors on the distribution of benthic foraminiferal assemblages (Weston 1985;Scott et al 2003).…”

Section: Previous Workmentioning

confidence: 99%

“…Herein, we used the complete dataset of living and dead foraminiferal species. Foraminiferal data from Le Calvez (1958), Le Calvez and Boillot (1967), Murray (1970) and Weston (1985) from this area were also considered ( Fig. 1).…”

Section: Sample and Data Sourcesmentioning

confidence: 99%

“…This appendix can be found at OceanRep (GEOMAR_Publications Database; http://oceanrep.geomar.de/24635/). Sturrock and Murray (1981) and Murray et al (1982), triangles: stations of Schönfeld and Altenbach (2005), diamonds: stations of Le Calvez (1958), Le Calvez and Boillot (1967), Murray (1970) and Weston (1985) Sturrock and Murray (1981) and Murray et al (1982) …”

Section: Appendixmentioning

confidence: 99%

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Recent benthic foraminiferal assemblages from the Celtic Sea (South Western Approaches, NE Atlantic)

Dorst

Schönfeld

Walter³

2014

Paläontol Z

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The faunal composition and diversity pattern of Recent benthic foraminifera from the shelf and slope of the South Western Approaches (Celtic Sea) were assessed. The sampling stations cover a depth range from 100 to 500 m. A total number of 294 species was recorded, of which 89 were found exclusively in the living fauna and 118 only in the dead assemblage, whereas 87 species were found in both assemblages. The faunal composition revealed a distinct bisection of the living fauna on the shelf. While certain distribution patterns of living dominant species were recognized along a NE-SW trending transect towards the shelf edge, the living fauna changed within small depth intervals and geographic position on the slope.Causes for this structured slope assemblages were probably along-slope currents of varying strengths, as well as variations in topography and bottom sediments. Analyses of population densities and diversity patterns determined high densities along the shelf edge and at one slope station, as well as an increasing diversity with water depth. A comparison with literature data from the same area yields distinct differences in faunal composition on the shelf and slope. The diversity was similar on the shelf, but higher at corresponding stations on the slope. We conclude that the faunal composition was highly influenced by the time and methods of sampling. In order to obtain consistent results in regional studies, all samples 1 should be taken in a short time interval and by using the same sampling device. In addition, we depicted the influences of environmental parameters on dead faunal assemblages and their consequences for paleoenvironmental interpretations of fossil foraminiferal assemblages. Keynotes

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Water mass exchange between the Nordic seas and the Arctic Ocean on millennial timescale during MIS 4–MIS 2

Rasmussen

Thomsen

Nielsen

2014

Geochem Geophys Geosyst

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[1] The climate of the last glaciation circa 65,000-25,000 years ago was interrupted by about 15 abrupt temperature fluctuations, the so-called Dansgaard-Oeschger events consisting of warm interstadials and cold stadials recorded in Greenland ice cores. The largest fluctuations occur in the North Atlantic region, but they have been registered over the most of the world. The events are linked to changes in deep water formation in the Nordic seas and North Atlantic, disrupting the thermohaline circulation. Yet, Dansgaard-Oeschger events have so far not been recorded north of the convection areas in the central Nordic seas, and it is not known if they affected the water exchange between the Nordic seas and the Arctic Ocean. In this study, we analyze core JM05-31GC from the northern Fram Strait at the very entrance to the Arctic Ocean. The core contains sediments from marine isotope stages (MISs) 4-2. The results show millennial timescale shifts in all the investigated proxies including the distribution of planktonic and benthic foraminifera, planktonic and benthic oxygen and carbon isotopes, and several sedimentological parameters. In JM05-31GC, the interstadials are characterized by relatively high surface and low bottom water temperatures, low content of ice-rafted debris, and well-ventilated bottom water. Stadials are characterized by the presence of icebergs and decreasing surface water and increasing bottom water temperatures due to increased inflow of Atlantic subsurface water. Ventilation decreased during Heinrich events and most stadials. The results show that the DansgaardOeschger events strongly affected the water exchange between the Nordic seas and the Arctic Ocean.

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Comparison between Recent benthic foraminiferal faunas of the Porcupine Seabight and Western Approaches Continental Slope

Cited by 34 publications

References 17 publications

Influence of seasonally deposited phytodetritus on benthic foraminiferal populations in the bathyal northeast Atlantic. the species response

Influence of seasonally deposited phytodetritus on benthic foraminiferal populations in the bathyal northeast Atlantic. the species response

Recent benthic foraminiferal assemblages from the Celtic Sea (South Western Approaches, NE Atlantic)

Water mass exchange between the Nordic seas and the Arctic Ocean on millennial timescale during MIS 4–MIS 2

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