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We examine the main drivers that may elevate biomass and biodiversity of non-chemosynthetic benthic megafauna of the lower bathyal (800-3500m depth) of the Mid-Atlantic Ridge in the North Atlantic Ocean (MAR). Specifically: 1. Primary production in surface waters (10°-48°N) from remote sensing data 2002-2020 over the MAR was not significantly different from abyssal regions to the east and west. We reject the hypothesis that presence of a mid ocean ridge may enhance surface primary production. 2. The quantity of particulate organic matter reaching the sea floor was estimated as a proportion of surface export production scaled by bathymetry. Flux was 1.3 to 3.0 times greater on the MAR as a function of shorter vertical transport distance from the surface than on adjacent abyssal regions. 3. Depth variation effect on species richness. Demersal fishes living between 41° and 60°N showed a maximum of species richness at 2000 m depth and linear increase in regional (Gamma) diversity of 32 species per 1,000 m elevation of the MAR above the abyss. Elevated topography provides niches for species that cannot otherwise survive. 4. Substrate heterogeneity. The MAR >95% covered with soft sediment with frequent hard rocky patches spaced at a mean nearest neighbour distance of

The benthic foraminiferal assemblages from the upper Albian-lower Cenomanian interval of the Scaglia Bianca Formation in the Monte Petrano (MP) and Le Brecce (LB) sections (Umbria–Marche Basin; Italy) provide a detailed record of the faunal changes across the Oceanic Anoxic Event 1d (OAE 1d). Fluctuations in abundance, diversity, and species composition reflect variations in bottom-water oxygenation and organic carbon fluxes. Benthic foraminifera are integrated with planktonic foraminifera, calcareous nannofossils, and geochemical proxies to reconstruct the bottom and surface water conditions across the OAE 1d in the Umbria–Marche Basin. The pre-OAE 1d interval was characterized by benthic foraminifera that thrived under stable mesotrophic condition in bottom waters. In surface waters, planktonic foraminifera indicate dominant mesotrophic conditions in agreement with calcareous nannofossil assemblages suggesting a regime of higher fertility under cooler conditions. During the OAE 1d interval, benthic foraminifera display an increase in the abundance of infaunal taxa, suggesting mesotrophic conditions in bottom waters. Nevertheless, within the Pialli Level, the six laminated black-to-dark grey shale horizons (MP1/LB1 to MP6/LB6), benthic foraminifera are absent or highly impoverished (MP1, MP2, MP4, MP6, LB5, LB6), suggesting hypoxic/anoxic conditions in bottom waters. Planktonic foraminifera in this interval reflect mesotrophic to oligotrophic conditions under the presence of an expanded mixed layer and deeper thermocline in the surface waters. Calcareous nannofossils record warm conditions and lower fertility starting just prior to and across the OAE 1d. However, higher values of fertility are recorded in the black-to-dark grey shales MP3/LB3, MP4/LB4 and MP5/LB5 of the Pialli Level. The post-OAE 1d interval is marked by an increase in the diversity of benthic foraminifera, indicating a restoration of the oxygen conditions in a continuous mesotrophic regime in bottom waters. The surface waters experienced oligotrophic conditions based on the planktonic and calcareous nannofossils. A minor discrepancy between benthic foraminifera and geochemical reconstruction of oxygenation levels of bottom waters was recorded, especially in the Pialli Level. The benthic microfaunas appear to be very sensitive to very short-term oxygen depletion at the seafloor when geochemical proxies suggest temporary suboxia. This might indicate that very rapid redox changes are not resolved by bulk elemental data. Otherwise, benthic foraminifera might be much more responsive to very low concentrations of oxygen in bottom waters and temporarily disappear under strong suboxia before reaching fully anoxic conditions. • Albian-Cenomanian interval in the western Tethys (Umbria–Marche Basin, Italy). • High-resolution study of the benthic foraminiferal assemblages through the OAE 1d. • The Pialli Level displays a decrease in the abundance of benthic foraminifera. • Lower bathyal depositional setting inferred by benthic foraminifera. • Paleoceanographic changes in bottom and surface waters across the OAE 1d. [ABSTRACT FROM AUTHOR]

Drifting sediment trap experiments were conducted during various seasons to elucidate the characteristics of particles sinking through the upper 200 m of the water column in the western Pacific at subarctic station K2 and subtropical station S1. The sinking particle flux increased when primary productivity was high at each station, during June-July at K2 and during February at S1. Biogenic opal (Opal) and CaCO were the major components of the fluxes at K2 and S1, respectively. Contrary to the expectation of a high flux at the eutrophic station K2 and low flux at the oligotrophic station S1, the annual average organic carbon fluxes at 100 m were comparable at both stations: 62.7 mg C m day at K2 and 56.1 mg C m day at S1. The similarity of the fluxes was perhaps a reflection of the unexpectedly high primary production at S1. At K2, the organic carbon export ratio (organic carbon flux/primary productivity) was significantly and negatively correlated with primary production and tended to decrease with depth. The magnitude of the rate of attenuation of the organic carbon flux with depth was larger at S1 than at K2. This rate of attenuation tended to decrease and increase with primary production at K2 and S1, respectively. The explanation for these patterns may be that the flux of labile organic carbon at relatively shallow depths decreased with increasing primary production at K2, and zooplankton grazing pressure increased with increasing primary productivity at S1. [ABSTRACT FROM AUTHOR]

Coupling of a bioelectrochemical system (BES) into the upflow anaerobic sludge blanket (UASB) was developed for enhanced p -nitrophenol (PNP) removal in this study. Compared to the control UASB reactor, both PNP removal and the formation of its final reductive product p -aminophenol (PAP) were notably improved in the UASB–BES system. With the increase of current density from 0 to 4.71 A m −3 , the rates of PNP removal and PAP formation increased from 6.16 ± 0.11 and 4.21 ± 0.29 to 6.77 ± 0.00 and 6.11 ± 0.28 mol m −3 d −1 , respectively. More importantly, the required dosage of organic cosubstrate was significantly reduced in the UASB–BES system than that in the UASB reactor. Organic carbon flux analysis suggested that biogas production from organic cosubstrate was seriously suppressed while direct anaerobic reduction of PNP was not remarkably affected by current input in the UASB–BES system. This study demonstrated that the UASB–BES coupling system had a promising potential for the removal of nitrophenol-containing wastewaters especially without adequate organic cosubstrates inside. [ABSTRACT FROM AUTHOR]

The quantity and quality of organic matter reaching the deep-sea floor is believed to exert a strong control on benthic foraminiferal assemblages, including the diversity and density of populations and the distribution patterns of species. In addition, some species seem to be associated with strong seasonality in primary productivity. We test relationships between diversity and mean annual productivity based on carefully selected datasets (>63-μm sieve fraction including soft-shelled taxa) from the NE Atlantic, Weddell Sea, and Equatorial and North Pacific. We used (1) 'live' (Rose Bengal stained) foraminiferal density, (2) mean annual surface productivity and (3) estimated organic carbon flux to the seafloor as proxies for food supply to the benthos. A suite of species richness, diversity and dominance measures all decreased significantly with increasing density, whereas species density showed a significant increase. In contrast, none of the relationships between these measures and primary productivity or its seasonality were significant. Only the Margalef and Brillouin indices exhibited a significant decrease with increasing values of carbon flux to the sea floor. When sites from the NE Atlantic were treated separately, significant relationships (−ve) emerged between flux and all diversity measures, and between foraminiferal densities and most (8 of 9) diversity measures. For the equatorial Pacific, however, these relationships were mostly (16 of 18) not significant. Size fractioned (>150-μm and >63-μm fraction including phytodetritus) data from the NE Atlantic samples yielded significant correlations (−ve) between several diversity measures and foraminiferal densities, but many fewer when related to estimated carbon flux to the seafloor. We also considered published datasets from the Arctic (Wollenburg and Mackensen Mar Micropaleontol 34: 153-185, ) and North Atlantic (Corliss et al. Deep-Sea Res 56: 835-841, ) Oceans. Diversity values (Fisher α index based on 'live' counts) from seasonally and permanently ice-covered areas (depth range, 94-4,427 m) in the Arctic were significantly correlated (+ve) with estimated flux. Correlations were also significant for sites below permanent ice cover (1,051-4,427 m) and for those >4,000 m. Positive correlations between foraminiferal density and diversity were significant for the whole dataset and for sites with permanent ice cover, but not for the deep sites. Analysis of unstained calcareous foraminifera of Holocene age from the N Atlantic (2,118-4,673 m water depth) revealed significant relationships between diversity and seasonality, but not with flux. Additional analyses of 'seasonal' and 'non-seasonal' N Atlantic sites with a comparable range of estimated flux values (2-4 g C m year) revealed that diversity increased with increasing flux and density in both cases, with significantly lower diversity at the seasonal compared to the non-seasonal sites. The contradictions between our data (−ve relationship between food availability and diversity) and those of Wollenburg and Corliss (+ve relationship) are difficult to explain and underline the need for further studies employing consistent methods to analyse 'entire live' assemblages across productivity gradients. [ABSTRACT FROM AUTHOR]

Abstract: The Newport Member of the Astoria Formation, exposed on the central Oregon coast, was deposited at shallow marine depths during the Early Miocene global warming that led to the Middle Miocene Climate Optimum. This record thus provides the opportunity to examine a coastal environment over past warming and ask if the low oxygen conditions observed in recent years on the modern Oregon shelf is a recent phenomenon or a repeated symptom of global warming. Although δ18O variation can be influenced by freshwater flux, if due to temperature δ18O values suggest 2.4–4.5°C of local warming during deposition of the Newport Member. Species of Buliminacea, Fursenkoina, and Nonionella, abundant in organic-rich, low-oxygen sediments in modern seas, increased in proportional abundance after warming began. In addition, the offset in δ13C values between epifaunal to shallow infaunal taxa and a deeper infaunal species is greater in sediments with higher abundances of these taxa, further supporting increased organic carbon flux. An increase in laminated sediments coincident with these faunal and geochemical changes suggests dysoxic conditions accompanied the increase in organic carbon. Taken together, this multiproxy record suggests that high-organic, low-oxygen, environments developed in shallow waters during Early Miocene warming, perhaps driven by similar upwelling mechanisms thought to drive hypoxia on the modern Oregon coast. [Copyright &y& Elsevier]

We deployed a profiling buoy system incorporating a fast repetition rate fluorometer in the western subarctic Pacific and carried out time-series observations of phytoplankton productivity from 9 June to 15 July 2006. The chlorophyll a (Chl a) biomass integrated over the euphotic layer was as high as 45-50 mg Chl a m in the middle of June and remained in the 30-40 mg Chl a m range during the rest of observation period; day-to-day variation in Chl a biomass was relatively small. The daily net primary productivity integrated over the euphotic layer ranged from 144 to 919 mg C m day and varied greatly, depending more on insolation rather than Chl a biomass. In addition, we found that part of primary production was exported to a 150-m depth within 2 days, indicating that the variations in primary productivity quickly influenced the organic carbon flux from the upper ocean. Our results suggest that the short-term variability in primary productivity is one of the key factors controlling the carbon cycle in the surface ocean in the western subarctic Pacific. [ABSTRACT FROM AUTHOR]

Abstract: A sediment-trap monitoring program measured the fluxes of settling particles and organic carbon in Yuanyang Lake, northern Taiwan, from July 2004 to July 2006 and assessed their relations to the amounts of normal monthly and typhoon-event precipitation. The flux of settling particles varied from 0.7mgcm−2 month−1 to 14.7mgcm−2 month−1, and the monthly precipitation ranged from 56mm to 1218mm during the survey period. The contributions from typhoon-event precipitation to monthly rainfall amounts were generally larger than 70%. Higher inputs of both particulate and organic carbon into the lake were found during typhoon seasons. Of the annual settling particle loading of 14.9tonsyear−1 to the lake floor, 69% occurred during the typhoon months, and 62% of the annual organic carbon loading of 2.3tonsyear−1 happened during the typhoon months. These results show the importance of typhoon events on the fluxes of settling particles and organic carbon and their delivery to lakes. [Copyright &y& Elsevier]

The South Atlantic Bight (SAB) has been a focus for the study of continental shelf ecosystem respiration during the past two decades. However, two questions concerning respiration in this area have yet to be answered. First, why do previous estimates of respiration in the SAB exceed measured carbon fixation rates by almost an order of magnitude? Second, considering that bacteria are responsible for most of the pelagic community respiration in the SAB, why is respiration almost uniform from the coastline to the shelf break, while bacterial production estimates decrease offshore? This study addresses these critical questions by presenting new pelagic community respiration data that were collected across the entire width of the continental shelf off Georgia, USA from June 2003 to May 2006. The respiration was calculated as in vitro changes of dissolved oxygen and dissolved inorganic carbon concentrations during deck incubations. The measured respiration rates ranged from 0.3(±0.1) to 21.2(±1.4) mmol m−3 day−1. They followed a clear seasonal pattern, being lowest over the entire shelf in winter and reaching maxima in summer. Summertime respiration rates were highest on the inner shelf and decreased with distance offshore. Consistent with this trend, bacterial abundance measurements taken during the sampling month of July 2005 followed a pattern of seaward decline. The SAB organic carbon fluxes calculated from the respiration data are close to the estimates for primary production, which resolves a long-standing mystery regarding perceived carbon imbalance in the SAB. [ABSTRACT FROM AUTHOR]

Abstract: In this study, the CDOM absorption coefficient at 350nm [a CDOM(350)] and CDOM excitation emission matrix (EEM) fluorescence were used to estimate annual fluxes of dissolved organic carbon (DOC) from the Cape Fear River to Long Bay in the South Atlantic Bight. Water samples were collected during a 3.5year period, from October 2001 through March 2005, in the vicinity of the Cape Fear River (CFR) outlet and adjacent Onslow Bay (OB). Parallel factor analysis (PARAFAC) of CDOM EEM spectra identified six components: three terrestrial humic-like, one marine humic-like and two protein-like. Empirical relationships were derived from the PARAFAC model between DOC concentration and a CDOM(350), total fluorescence intensity and the intensities of respective EEM components. DOC concentration and CDOM optical parameters were very well correlated and R 2 values ranged from 0.77 to 0.90. Regression analyses revealed that the non-absorbing DOC fraction, in DOC concentration estimated from CDOM optical parameters, varied with the qualitative composition of the CDOM. DOC concentration and intensity of the humic-like CDOM components characterized by excitation maxima at longer wavelengths have significantly higher estimated non-absorbing DOC compared to the analogous relationships between DOC and intensity of the humic-like CDOM components characterized by excitation maxima at shorter wavelengths. The relationships between DOC concentration and intensity of one of the protein-like components resulted in significantly reduced non-absorbing DOC fraction in DOC concentration estimation. Results of regression analyses between fluorescence intensities of specific EEM components and CDOM-specific absorption coefficients suggest that the relative proportion of humic-like CDOM components (characterized by excitation maximum at longer wavelengths) and the main protein-like component have the most impact on the values of a⁎CDOM(350). Based on the relationships between a CDOM(350), Cape Fear River flow, and DOC concentrations, DOC fluxes were estimated for 2002, 2003 and 2004. DOC fluxes varied from 1.5 to 6.2×1010 gCyr−1, depending on river flow. [Copyright &y& Elsevier]

Abstract: The MedFlux project was devised to determine and model relationships between organic matter and mineral ballasts of sinking particulate matter in the ocean. Specifically we investigated the ballast ratio hypothesis, tested various commonly used sampling and modeling techniques, and developed new technologies that would allow better characterization of particle biogeochemistry. Here we describe the rationale for the project, the biogeochemical provenance of the DYFAMED site, the international support structure, and highlights from the papers published here. Additional MedFlux papers can be accessed at the MedFlux web site (http://msrc.sunysb.edu/MedFlux/). [Copyright &y& Elsevier]

Abstract: Prompted by recent data analyses suggesting that the flux of particulate organic carbon sinking into deep waters is determined by fluxes of mineral ballasts, we undertook a study of the relationships among organic matter (OM), calcium carbonate, opal, lithogenic material, and excess aluminum fluxes as part of the MedFlux project. We measured fluxes of particulate components during Spring and Summer of 2003, and Spring of 2005, using a swimmer-excluding sediment trap design capable of measuring fluxes both in a time-series (TS) mode and in a configuration for obtaining particle settling velocity (SV) profiles. On the basis of these studies, we suggest that distinct OM–ballast associations observed in particles sinking at a depth of ∼200m imply that the mechanistic basis of the organic matter–ballast association is set in the upper water column above the Twilight Zone, and that the importance of different ballast types follows the seasonal succession of phytoplankton. As in other studies, carbonate appears to enhance the flux of organic matter over opal. Particles must be at least half organic matter before their settling velocity is affected by ballast concentration. This lack of change in ballast composition with SV in particles with <40% OM content suggests that particle SV reaches a maximum because of the increasing importance of inertial drag. Relative amounts of OM and opal decrease with depth due to decomposition and dissolution; carbonates and lithogenic material contribute about the same amount to total mass, or increase slightly, throughout the water column. The high proportion of excess Al cannot be explained by its incorporation into diatom opal or reverse weathering, so Al is most likely adsorbed to particulate oxides. On shorter time scales, dust appears to increase particle flux through its role in aggregation rather than by nutrient inputs enhancing productivity. We suggest that the role of dust as a catalyst in particle formation may be a central mechanism in flux formation in this region, particularly when zooplankton fecal pellet production is low. [Copyright &y& Elsevier]

Abstract: The impact of the highly seasonal Antarctic primary production cycle on shelf benthic ecosystems remains poorly evaluated. Here we describe a times-series research project on the West Antarctic Peninsula (WAP) shelf designed to evaluate the seafloor deposition, and subsequent ecological and biogeochemical impacts, of the summer phytoplankton bloom along a transect crossing the Antarctic shelf near Anvers Island. During this project, entitled Food for Benthos on the Antarctic Continental Shelf (FOODBANCS), we deployed replicate sediment traps 150–170m above the seafloor (total water-column depth of 590m) on the central shelf from December 1999 to March 2001, recovering trap samples every 3–4 months. In addition, we used a seafloor time-lapse camera system, as well as video surveys conducted at 3–4 months intervals, to monitor the presence and accumulation of phytodetritus at the sediment–water interface. The fluxes of particulate organic carbon and chlorophyll-a into sediment traps (binned over 3–4 month intervals) showed patterns consistent with seasonal variability, with average summer fluxes during the first year exceeding winter fluxes by a factor of ∼2–3. However, inter-annual variability in summer fluxes was even greater than seasonal variability, with 4–10-fold differences in the flux of organic carbon and chlorophyll-a between the summer seasons of 1999–2000 and 2000–2001. Phytodetrital accumulation at the shelf floor also exhibited intense inter-annual variability, with no visible phytodetritus from essentially December 1999 to November 2000, followed by pulsed accumulation of 1–2cm of phytodetritus over a ∼30,000km2 shelf area by March 2001. Comparisons with other studies suggest that the levels of inter-annual variability we observed are typical of the Antarctic shelf over decadal time scales. We conclude that fluxes of particulate organic carbon, chlorophyll-a and phytodetritus to WAP-shelf sediments vary intensely on seasonal to inter-annual time scales, yielding dramatic temporal variability in the flux of food for detritivores to the Antarctic shelf floor. [Copyright &y& Elsevier]

Abstract: To assess the impact and fate of the summer phytoplankton bloom on Antarctic benthos, we evaluated temporal and spatial patterns in macrofaunal abundance and taxonomic composition along a transect crossing the West Antarctic Peninsula (WAP) continental shelf. As part of the FOODBANCS project, we sampled three sites at 550–625m depths during five cruises occurring in November 1999, February–March 2000, June 2000, October 2000 and March 2001. We used a combination of megacore and box-core samplers to take 81 samples, and collected over 30,000 macrofaunal individuals, one of the largest sampling efforts on the Antarctic shelf to date. Comparison of the two sampling methodologies (box core and megacore) indicates similar macrofaunal densities, but with significant differences in taxonomic composition, a reflection of the different spatial scales of sampling. Macrofaunal abundances on the WAP shelf were relatively high compared to other Antarctic shelf settings. At two of the three sampling sites, macrofaunal abundance remained constant throughout the year, which is consistent with the presence of a sediment ‘food bank’. Differences were observed in taxonomic composition at the site closest to the coast (Station A), driven by higher abundances of sub-surface-deposit feeders. A significant temporal response was observed in the ampharetid polychaetes at Station A, with an abundance peak in the late fall post-bloom period; this may have resulted from juvenile recruitment during the summer bloom. Familial composition of macrofaunal polychaetes on the WAP shelf is more closely related to deep-sea abyssal fauna than to other shelf regions, and we hypothesize that this is a result of both local ecological conditions (low temperatures) and a reflection of historical processes such as extinctions on the Antarctic shelf during previous glacial maxima followed by recolonization from the deep sea. [Copyright &y& Elsevier]

Abstract: The continental shelf of the West Antarctic Peninsula (WAP) is a highly productive region but also unusually deep as a result of isostatic depression by the polar ice cap. The close coupling of surface processes with those of the benthos would be expected in such a seasonally variable environment; however, the cold, deep conditions of the WAP shelf may allow for the persistence of organic material in the sediments as a “food bank”. Chlorophyll and carotenoid pigments were determined from the gut contents of seven species of echinoderm and from the surficial sediment on the bathyal continental shelf. Samples were collected as part of the FOODBANCS programme during successive cruises in austral spring (October 2000) and austral autumn (March 2001). Pigments were identified and quantified using reverse-phase high-performance liquid chromatography (HPLC). A lack of qualitative selectivity was observed among species, compared to that observed for deep-water assemblages at temperate latitudes, supporting the theory of a persistent “food bank”. However, significant quantitative differences were observed among species and between years and sampling location on the shelf. Species differences were marked between those we classified as “true” deposit feeders and those species whose diet also may be supplemented by scavenging and/or grazing. [Copyright &y& Elsevier]

Abstract: In this volume we present results from the FOODBANCS Project, which examined the fate and benthic community impact of summer bloom material on the West Antarctic Peninsula shelf floor. The project involved a 5-cruise, 15-month time-series program in which sediment-trap moorings, core sampling, radiochemical profiling, sediment respirometry, bottom photography, and bottom trawling were used to evaluate: (1) seafloor deposition and lability of POC, (2) patterns of labile POC consumption and sediment mixing by benthos, and (3) seasonal and inter-annual variations in biotic abundance, biomass, reproductive condition, recruitment, and sediment community respiration. We find that the seafloor flux and accumulation of particulate organic carbon on the West Antarctic Peninsula shelf exhibit intense seasonal and interannual variability. Nonetheless, many key benthic processes, including organic-matter degradation, bioturbation, deposit feeding, and faunal abundance, reproduction and recruitment, show relatively muted response to this intense seasonal and inter-annual variability in export flux. We thus hypothesize that benthic ecosystems on the Antarctic shelf act as “low-pass” filters, and may be extremely useful in resolving the impacts of climatic change over periods of years to decades in Antarctic Peninsula region. [Copyright &y& Elsevier]

Abstract: Investigations of lithogenic and biogenic particle fluxes using long-term sediment traps are still very rare in the northern high latitudes and are restricted to the arctic marginal seas and sub-arctic regions. Here data on the variability of fluxes of lithogenic matter, CaCO3, opal, and organic carbon and biomarker composition from the central Arctic Ocean are presented for a 1-year period. The study was carried out on material obtained from a long-term mooring system equipped with two multi-sampling traps, at 150 and 1550m depth, and deployed on the southern Lomonosov Ridge close to the Laptev Sea continental margin from September 1995 to August 1996. In addition, data from surface sediments were included in the study. Annual fluxes of lithogenic matter, CaCO3, opal, and particulate organic carbon were 3.9, 0.8, 2.6, and 1.5gm−2 y−1, respectively, in the shallow trap and 11.3, 0.5, 2.9, and 1.05gm−2 y−1, respectively, in the deep trap. Both the shallow and the deep trap showed significant variations in vertical flux over the year. Higher values were found from mid-July to the end of October (total mass flux of 75–130mgm−2 d−1 in the shallow trap and 40–225mgm−2 d−1 in the deep trap). During all other months, fluxes were fairly low in both traps (most total mass flux values <10mgm−2 d−1). The interval of increased fluxes can be separated into (1) a mid-July/August maximum caused by increased primary production as documented in high abundances of marine biomarkers and diatoms and (2) a September/October maximum caused by increased influence of Lena River discharge indicated by maximum lithogenic flux and large amounts of terrigenous/fluvial biomarkers in both traps. During September/October, total mass fluxes in the deep trap were significantly higher than in the shallow trap, suggesting a lateral sediment flux at greater depth. The lithogenic flux data also support the importance of sediment input from the Laptev Sea for the sediment accumulation on the Lomonosov Ridge on geological time scales, as indicated in sedimentary records from this region. [Copyright &y& Elsevier]

Abstract: The Antarctic continental shelf is large, deep (500–1000m), and characterized by extreme seasonality in sea-ice cover and primary production. Intense seasonality and short pelagic foodwebs on the Antarctic shelf may favor strong bentho-pelagic coupling, whereas unusual water depth combined with complex topography and circulation could cause such coupling to be weak. Here, we address six questions regarding the nature and strength of coupling between benthic and water-column processes on the continental shelf surrounding Antarctica. We find that water-column production is transmitted to the shelf floor in intense pulses of particulate organic matter, although these pulses are often difficult to correlate with local phytoplankton blooms or sea-ice conditions. On regional scales, benthic habitat variability resulting from substrate type, current regime, and iceberg scour often may obscure the imprint of water-column productivity on the seafloor. However, within a single habitat type, i.e. the muddy sediments that characterize much of the deep Antarctic shelf, macrobenthic biomass appears to be correlated with regional primary production and sea-ice duration. Over annual time-scales, many benthic ecological processes were initially expected to vary in phase with the extraordinary boom/bust cycle of production in the water column. However, numerous processes, including sediment respiration, deposit feeding, larval development, and recruitment, often are poorly coupled to the summer bloom season. Several integrative, time-series studies on the Antarctic shelf suggest that this lack of phasing may result in part from the accumulation of a persistent sediment food bank that buffers the benthic ecosystem from the seasonal variability of the water column. As a consequence, a variety of benthic parameters (e.g., sediment respiration, inventories of labile organic matter, macrobenthic biomass) may act as “low-pass” filters, responding to longer-term (e.g., inter-annual) trends in water-column production. Bentho-pelagic coupling clearly will be altered by Antarctic climate change as patterns of sea-ice cover and water-column recycling vary. However, the nature of such climate-driven changes will be very difficult to predict without further studies of Antarctic benthic ecosystem response to (1) inter-annual variability in export flux, and (2) latitudinal gradients in duration of sea-ice cover and benthic ecosystem function. [Copyright &y& Elsevier]

The fluctuation in primary production and mineral dust accumulation was estimated to better understand marine and terrestrial environments in the Tasman Sea, southwest Pacific, during the Late Pleistocene. Maxima in primary production were observed during late Oxygen Isotope Stage (OIS) 2, middle OIS 4 and late OIS 6 for core NGC 97 while minimum values were observed in OIS 5. On the other hand, primary production was low and relatively uniform in cores NGC 100 and 99 during the last 180 kyr. These results suggest that the Tasman Front existed between NGC 99 (∼30°S) and NGC 97 (∼35°S) during the last 180 kyr and migrated northward by a few degree (∼2–3° latitude) in OIS 2 and 4. The mass accumulation rates (MARs) of mineral aerosol (MARaerosol) estimated from the Al concentration increased southward during each OIS (excluding OIS 2 in cores NGC 100 and 99). The MARaerosol was more enhanced during glacials than interglacials in cores NGC 100 and 97 while NGC 99 showed no definite fluctuation. These results suggest small northward shifts (∼2–3° latitude) of the high pressure subtropical ridge, dividing the tropical easterly circulation from the mid-latitude westerlies, took place during glacial times. These results demonstrate that the boundary between subtropical and temperate features in both ocean and atmosphere consistently migrated by a few degrees between glacials and interglacials. In addition, profiles of MAR of organic carbon, biogenic opal and primary productivity were quite similar for cores NGC 97 and S2612 (32°19.84′N, 157°51.00′E), which shows that the boreal and austral transition zones between subtropical and subarctic waters migrated almost synchronously along the latitudinal transect around 160°E during the last 150 kyr [Kawahata et al., J. Oceanogr. 55 (1999) 521–532]. Therefore boreal and austral mid-latitudes could have probably experienced similar fluctuations in the oceanic and atmospheric environments. [Copyright &y& Elsevier]

A High Frequency Flux (HFF) experiment was conducted during spring 1997 on the continental slope of the Gulf of Lions (Northwestern Mediterranean Sea) with the aim of examining the dynamical and biological processes controlling particle transfer in this margin environment.Within this general framework, a special attention was paid to short temporal and small spatial variations of phytoplankton and bacterial production through six hydrological and biological surveys performed during a 7-week period at nine sampling stations located on a 10×20-mile grid. Downward fluxes of particulate organic carbon at each station were measured by traps deployed at 240 m depth. The f-ratio and the ratio of integrated bacterial to primary production (IBP/IPP ratio), computed as indexes of biological export for each survey and station, did not provide a clear, unambiguous understanding of the importance of biological processes in the cycling of carbon in the upper water column. However, the data collected allowed to draw up carbon budgets for the different phases of the experiment. The comparison of primary production with measured and estimated organic carbon removal terms (sinking, cycling through the microbial food web, grazing by ciliates and metazoans) showed that a balance was never reached between fluxes of production and removal of organic carbon during the course of the experiment. The system shifted from an initial situation of ‘missing’ carbon (removal>production) to one of ‘excess’ carbon (removal

Water samples were collected and analyzed in high water season (July 1997) and in middle water season (October, 1997) from two main lower reach gauge stations of the Zhujiang (Pearl) River, namely Hekou and Makou, respectively. Content of particulate organic carbon is always higher than that of dissolved organic carbon in both seasons, which is obviously different from the global average pattern, i.e. dissolved organic carbon is the dominant component of the transported riverine organic carbon. The content of dissolved and particulate organic carbon changes with the water levels in a direct ratio. The percentage of organic carbon in total suspended substance changes with the content of total suspended substance in an inverse ratio. The more intense is the soil erosion in the drainage, the more concentrated is the riverine organic carbon in the river. The contribution of autochthonous organic carbon is large in high water season than in middle water season. [ABSTRACT FROM AUTHOR]