Biogeographical patterns among deep sea megabenthic communities across the Drake Passage

AbstractBiogeographical patterns among deep sea benthic communities in the Drake Passage remain poorly understood as a consequence of poor sampling resolution and the spatial remoteness of many sea floor features. Hard-bottom features, including at least 20 seamounts, remain uncharacterized with respect to their benthic megafaunal community assemblages. Here, we present community assemblage patterns from several locations across the Drake Passage to better understand the faunal relationships between deep sea floor communities in the region. Towed camera surveys were conducted on nine topographical features ranging from shelf environments on the southern Chilean Margin, the western Antarctic Peninsula shelf and seamounts in the central Drake Passage. These are the first quantitative measurements of megafaunal abundance at two seamount complexes in the central Drake Passage and multivariate analyses are used to examine the factors influencing species distributions. Three biogeographical groupings were identified based on species assemblages and environmental variables specific to major water mass boundaries in the region: sub-Antarctic Mode Water (318–523 m), Antarctic Intermediate Water (504–1128 m) and Circumpolar Deep Water (1837–3034 m). Further examination of megafaunal associations between sea floor structures may provide clues as to how sub-Antarctic communities are connected throughout the greater Southern Ocean.

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Seasonal deposition of phytodetritus to the deep-sea floor

Proceedings of the Royal Society of Edinburgh Section B Biological Sciences ◽

10.1017/s0269727000004590 ◽

1986 ◽

Vol 88 ◽

pp. 265-279 ◽

Cited By ~ 24

Author(s):

A. L. Rice ◽

D. S. M. Billett ◽

J. Fry ◽

A. W. G. John ◽

R. S. Lampitt ◽

...

Keyword(s):

Deep Sea ◽

Benthic Communities ◽

Time Lapse ◽

Sediment Traps ◽

Temporal Variations ◽

Sea Floor ◽

Porcupine Seabight ◽

The Past ◽

Sea Bed ◽

Seasonal Deposition

SynopsisEvidence has accumulated over the past twenty years to suggest that the deep-sea environment is not as constant as was at one time thought, but exhibits temporal variations related to the seasonally in the overlying surface waters. Recent results from deep-moored sediment traps suggest that this coupling is mediated through the sedimentation of organic material, while observations in the Porcupine Seabight indicate that in this region, at least, there is a major and rapid seasonal deposition of aggregated phytodetritus to the sea-floor at slope and abyssal depths.This paper summarises the results of the Porcupine Seabight studies over the past five years or so, using time-lapse sea-bed photography and microscopic, microbiological and chemical analyses of samples of phytodetritus and of the underlying sediment. The data are to some extent equivocal, but they suggest that the seasonal deposition is a regular and dramatic phenomenon and that the material undergoes relatively little degradation during its passage through the water column. The mechanisms leading to the aggregation of the phytodetritus have not been identified, and it is not yet known whether the phenomenon is geographically widespread nor whether it is of significance to the deep-living mid-water and benthic communities.

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Variability of Subantarctic Mode Water and Antarctic Intermediate Water in the Drake Passage during the Late-Twentieth and Early-Twenty-First Centuries

Journal of Climate ◽

10.1175/2009jcli2621.1 ◽

2009 ◽

Vol 22 (13) ◽

pp. 3661-3688 ◽

Cited By ~ 75

Author(s):

Alberto C. Naveira Garabato ◽

Loïc Jullion ◽

David P. Stevens ◽

Karen J. Heywood ◽

Brian A. King

Keyword(s):

Sea Ice ◽

Drake Passage ◽

Heat Fluxes ◽

Turbulent Heat ◽

Intermediate Water ◽

The West ◽

Mode Water ◽

Subantarctic Mode Water ◽

Turbulent Heat Fluxes ◽

The Antarctic

Abstract A time series of the physical and biogeochemical properties of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) in the Drake Passage between 1969 and 2005 is constructed using 24 transects of measurements across the passage. Both water masses have experienced substantial variability on interannual to interdecadal time scales. SAMW is formed by winter overturning on the equatorward flank of the Antarctic Circumpolar Current (ACC) in and to the west of the Drake Passage. Its interannual variability is primarily driven by variations in wintertime air–sea turbulent heat fluxes and net evaporation modulated by the El Niño–Southern Oscillation (ENSO). Despite their spatial proximity, the AAIW in the Drake Passage has a very different source than that of the SAMW because it is ventilated by the northward subduction of Winter Water originating in the Bellingshausen Sea. Changes in AAIW are mainly forced by variability in Winter Water properties resulting from fluctuations in wintertime air–sea turbulent heat fluxes and spring sea ice melting, both of which are linked to predominantly ENSO-driven variations in the intensity of meridional winds to the west of the Antarctic Peninsula. A prominent exception to the prevalent modes of SAMW and AAIW formation occurred in 1998, when strong wind forcing associated with constructive interference between ENSO and the southern annular mode (SAM) triggered a transitory shift to an Ekman-dominated mode of SAMW ventilation and a 1–2-yr shutdown of AAIW production. The interdecadal evolutions of SAMW and AAIW in the Drake Passage are distinct and driven by different processes. SAMW warmed (by ∼0.3°C) and salinified (by ∼0.04) during the 1970s and experienced the reverse trends between 1990 and 2005, when the coldest and freshest SAMW on record was observed. In contrast, AAIW underwent a net freshening (by ∼0.05) between the 1970s and the twenty-first century. Although the reversing changes in SAMW were chiefly forced by a ∼30-yr oscillation in regional air–sea turbulent heat fluxes and precipitation associated with the interdecadal Pacific oscillation, with a SAM-driven intensification of the Ekman supply of Antarctic surface waters from the south contributing significantly too, the freshening of AAIW was linked to the extreme climate change that occurred to the west of the Antarctic Peninsula in recent decades. There, a freshening of the Winter Water ventilating AAIW was brought about by increased precipitation and a retreat of the winter sea ice edge, which were seemingly forced by an interdecadal trend in the SAM and regional positive feedbacks in the air–sea ice coupled climate system. All in all, these findings highlight the role of the major modes of Southern Hemisphere climate variability in driving the evolution of SAMW and AAIW in the Drake Passage region and the wider South Atlantic and suggest that these modes may have contributed significantly to the hemispheric-scale changes undergone by those waters in recent decades.

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Control of Mode and Intermediate Water Mass Properties in Drake Passage by the Amundsen Sea Low

Journal of Climate ◽

10.1175/jcli-d-12-00346.1 ◽

2013 ◽

Vol 26 (14) ◽

pp. 5102-5123 ◽

Cited By ~ 15

Author(s):

Sally E. Close ◽

Alberto C. Naveira Garabato ◽

Elaine L. McDonagh ◽

Brian A. King ◽

Martin Biuw ◽

...

Keyword(s):

Water Mass ◽

Drake Passage ◽

Heat Fluxes ◽

Ekman Transport ◽

Turbulent Heat ◽

Intermediate Water ◽

Mode Water ◽

Amundsen Sea ◽

Turbulent Heat Fluxes ◽

Intermediate Water Mass

Abstract The evolution of the physical properties of Subantarctic Mode Water (SAMW) and Antarctic Intermediate Water (AAIW) in the Drake Passage region is examined on time scales down to intraseasonal, within the 1969–2009 period. Both SAMW and AAIW experience substantial interannual to interdecadal variability, significantly linked to the action of the Amundsen Sea low (ASL) in their formation areas. Observations suggest that the interdecadal freshening tendency evident in SAMW over the past three decades has recently abated, while AAIW has warmed significantly since the early 2000s. The two water masses have also experienced a substantial lightening since the start of the record. Examination of the mechanisms underpinning water mass property variability shows that SAMW characteristics are controlled predominantly by a combination of air–sea turbulent heat fluxes, cross-frontal Ekman transport of Antarctic surface waters, and the evaporation–precipitation balance in the Subantarctic zone of the southeast Pacific and Drake Passage, while AAIW properties reflect air–sea turbulent heat fluxes and sea ice formation in the Bellingshausen Sea. The recent interdecadal evolution of the ASL is consistent with both the dominance of the processes described here and the response of SAMW and AAIW on that time scale.

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The First Cut Is the Deepest: Trawl Effects on a Deep-Sea Sponge Ground Are Pronounced Four Years on

Frontiers in Marine Science ◽

10.3389/fmars.2020.605281 ◽

2020 ◽

Vol 7 ◽

Author(s):

Katelin M. Morrison ◽

Heidi Kristina Meyer ◽

Emyr Martyn Roberts ◽

Hans Tore Rapp ◽

Ana Colaço ◽

...

Keyword(s):

Arctic Ocean ◽

Deep Sea ◽

Multivariate Analyses ◽

Benthic Communities ◽

Bottom Trawl ◽

Physical Disturbance ◽

Remotely Operated Vehicle ◽

The Status ◽

And Control ◽

Distinct Separation

Few studies have described the effects of physical disturbance and post-recovery of deep-sea benthic communities. Here, we explore the status of deep-sea sponge ground communities four years after being impacted by an experimental bottom trawl. The diversity and abundance of epibenthic megafauna of two distinct benthic communities in disturbed versus control areas were surveyed using a remotely operated vehicle on the Schulz Bank, Arctic Ocean. Four years after disturbance, megafaunal densities of the shallow (∼600 m depth) and deep (∼1,400 m depth) sites were significantly lower on the disturbed patches compared to the control areas. Multivariate analyses revealed a distinct separation between disturbed and control communities for both sites, with trawling causing 29–58% of the variation. Many epibenthic morphotypes were significantly impacted by the trawl, including ascidians, Geodia parva, Hexactinellida spp., Craniella infrequens, Lissodendoryx complicata, Haliclonia sp. Stylocordyla borealis, Gersemia rubiformis and Actiniaria sp. However, we found some smaller morphospecies to be equally abundant with control transects, including Polymastia thielei, Geodia hentscheli, and Stelletta rhaphidiophora, reflecting lower trawl impact for these morphotypes. Overall, our results suggest that these are fragile ecosystems that require much more time than four years to recover from physical disturbance typical of trawling activities.

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Frontal Circulation and Submesoscale Variability during the Formation of a Southern Ocean Mesoscale Eddy

Journal of Physical Oceanography ◽

10.1175/jpo-d-16-0266.1 ◽

2017 ◽

Vol 47 (7) ◽

pp. 1737-1753 ◽

Cited By ~ 18

Author(s):

Katherine A. Adams ◽

Philip Hosegood ◽

John R. Taylor ◽

Jean-Baptiste Sallée ◽

Scott Bachman ◽

...

Keyword(s):

Mixed Layer ◽

Mesoscale Eddy ◽

Drake Passage ◽

Mathematical Framework ◽

Intermediate Water ◽

Surface Mixed Layer ◽

Mode Water ◽

Scotia Sea ◽

Simplifying Assumptions ◽

Circumpolar Current

AbstractObservations made in the Scotia Sea during the May 2015 Surface Mixed Layer Evolution at Submesoscales (SMILES) research cruise captured submesoscale, O(1–10) km, variability along the periphery of a mesoscale O(10–100) km meander precisely as it separated from the Antarctic Circumpolar Current (ACC) and formed a cyclonic eddy ~120 km in diameter. The meander developed in the Scotia Sea, an eddy-rich region east of the Drake Passage where the Subantarctic and Polar Fronts converge and modifications of Subantarctic Mode Water (SAMW) occur. In situ measurements reveal a rich submesoscale structure of temperature and salinity and a loss of frontal integrity along the newly formed southern sector of the eddy. A mathematical framework is developed to estimate vertical velocity from collocated drifter and horizontal water velocity time series, under certain simplifying assumptions appropriate for the current dataset. Upwelling (downwelling) rates of O(100) m day−1 are found in the northern (southern) eddy sector. Favorable conditions for submesoscale instabilities are found in the mixed layer, particularly at the beginning of the survey in the vicinity of density fronts. Shallower mixed layer depths and increased stratification are observed later in the survey on the inner edge of the front. Evolution in temperature–salinity (T–S) space indicates modification of water mass properties in the upper 200 m over 2 days. Modifications along σθ = 27–27.2 kg m−3 have climate-related implications for mode and intermediate water transformation in the Scotia Sea on finer spatiotemporal scales than observed previously.

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Large Plastic Debris Dumps: New Biodiversity Hot Spots Emerging on the Deep-Sea Floor

Environmental Science & Technology Letters ◽

10.1021/acs.estlett.0c00967 ◽

2021 ◽

Author(s):

Xikun Song ◽

Mingxin Lyu ◽

Xiaodi Zhang ◽

Bernhard Ruthensteiner ◽

In-Young Ahn ◽

...

Keyword(s):

Deep Sea ◽

Hot Spots ◽

Plastic Debris ◽

Sea Floor

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Gametogenesis and the reproductive cycle in the deep-sea anemone Paracalliactis stephensoni (Cnidaria: Actiniaria)

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315400034287 ◽

1990 ◽

Vol 70 (1) ◽

pp. 163-172 ◽

Cited By ~ 13

Author(s):

Michel Praet-Van

Keyword(s):

Organic Matter ◽

Shallow Water ◽

Deep Sea ◽

Phytoplankton Bloom ◽

Sea Anemone ◽

Bay Of Biscay ◽

Sea Anemones ◽

Spring Phytoplankton Bloom ◽

Sea Floor ◽

Ultrastructural Investigation

This ultrastructural investigation of gametogenesis in a deep-sea anemone of the Bay of Biscay trawled around 2000 m depth, contributes to the knowledge of biology and strategy of reproduction of deep-sea benthos.This sea anemone is dioecious. The sperm appears very similar to those of shallow water sea anemones of the genus, Calliactis. The ultrastructural investigation of oogenesis allows the characteristics of the stages of previtellogenesis and vitellogenesis to be defined. The latter begins with a period of lipogenesis correlated with the formation of a trophonema. Mature oocytes measure up to 180 (im in diameter. Study of spermatogenesis and oogenesis reveals that spawning occurs in April/May. In males, the main area of testicular cysts, full of sperm, reaches maximal development from March to May and, in females, the percentage of mature oocytes decreases from 33% in April to 1% in May.Spawning may be induced by the advent in the deep-sea of the products of the spring phytoplankton bloom. This period of spawning, during the increased deposition of organic matter to the deep-sea floor, may be an advantageous strategy for early development of Paracalliactis.

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Spatio-temporal variability of zoobenthic communities in a tectonic lagoon (Lake Vouliagmeni, Attika, Greece)

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315408001823 ◽

2008 ◽

Vol 88 (5) ◽

pp. 873-881 ◽

Cited By ~ 3

Author(s):

Chariton Chintiroglou ◽

Chryssanthi Antoniadou ◽

Panagiotis Damianidis

Keyword(s):

Multivariate Analyses ◽

Benthic Communities ◽

Marine Species ◽

Trophic Group ◽

Spatial And Temporal Scales ◽

Mediterranean Lagoons ◽

Deposit Feeders ◽

Spatio Temporal ◽

Lagoon Lake ◽

Hard Substrata

Lake Vouliagmeni (Attica, Greece) is a lagoon of great scientific interest due to its endemic fauna, widely used for recreational activities. Understanding the dynamics of this peculiar ecosystem is essential for its conservation. An ecological survey of the benthic communities was carried out, in both spatial and temporal scales. Material was collected with SCUBA diving, by taking off samples from the principal habitats of the lagoon, i.e. meadows, soft and hard substrata. The identification of the collected 61,975 living specimens revealed the presence of 12 floral and 20 faunal species. Multivariate analyses separated the sampling sites according to the four different habitats of the lagoon, whereas no temporal patterns came up. Micrograzers were the dominant trophic group, followed by deposit feeders regardless of the habitat studied. Lake Vouliagmeni is among the less diverse Mediterranean lagoons, mostly due to its isolation from the sea that hinders the entrance of marine species.

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