The estuary and coastal zone are the key areas for socio-economic development,and they are also the important channels for pollutants transported to the sea.The construction of the Jiaozhou Bay Bridge changed the hydr...The estuary and coastal zone are the key areas for socio-economic development,and they are also the important channels for pollutants transported to the sea.The construction of the Jiaozhou Bay Bridge changed the hydrodynamic condition of the bay,which made the self-purification capacity of the bay weakened and the pollution in the estuary and adjacent coastal zone become more serious.In this study,55 surface sediment samples were collected from the three seriously polluted estuaries and the adjacent coastal zone of Jiaozhou Bay to comprehensively study how the benthic foraminifera response to heavy metal pollution and human engineering,and to assess the ecological risks of the bay.A total of 80 species,belonging to 42 genera,were identified in this study.The results showed that Cu,Pb,Cr,Hg,Zn,and As had low to median ecological risks in the study area which would definitely affect the ecological system.The construction of the Jiaozhou Bay Bridge has resulted in pollutants accumulated at the river mouth of Loushan River,which has adverse effects on the survival and growth of benthic foraminifera.The lowest population density and diversity as well as the highest FAI(Foraminiferal Abnormality Index)and FMI(Foraminiferal Monitoring Index)occurred at Loushan River Estuary which indicated that the ecological environment of the northeastern part of Jiaozhou Bay(Loushan River Estuary)had been seriously damaged.Licun River and Haipo River estuaries and the adjacent coastal zone were slightly polluted and had low ecological risk.As a consequence,it suggested that the supervision of industrial and domestic waste discharge and the protection of the ecological environment in northeast Jiaozhou Bay should be paid more attention.展开更多
Assemblages of benthic foraminifera in a sediment core(C02)near the western margin of the southern Yellow Sea Mud were studied to decipher the phase evolution of Holocene paleoenvironmental changes associated with the...Assemblages of benthic foraminifera in a sediment core(C02)near the western margin of the southern Yellow Sea Mud were studied to decipher the phase evolution of Holocene paleoenvironmental changes associated with the Holocene marine transgression.It appears that during the early Holocene(11.2 10.1 kyr BP),the faunal was dominated by low salinity and shallow water species Cribrononion subincertum,Buccella frigida and Ammonia beccarii,reflecting a near coast depositional environment.A rapid increase of the relative abundance of Ammonia compressiuscula between 10.1 9.3 kyr BP indicates that the sea level rose rapidly during that time period.From 9.3 7.7 kyr BP,the benthic foraminiferal assemblage was dominated by high percentage of A.compressiscula,suggesting that the sea level was relatively stable.An obvious transition of benthic foraminifera,from the A.compressiuscula-dominated assemblage to an Ammonia ketienziensis-dominated assemblage,occurred between 7.7 6.2 kyr BP,possibly corresponding to a second sea level rapid rise period in the Yellow Sea during the Holocene.This transition may correspond to the gradually strengthened Yellow Sea warm current(YSWC)and finally is established the modern-type circulation in the Yellow Sea.It may also mark the formation of the Yellow Sea cold bottom water(YSCBW)during that period.Since then,the benthic foraminiferal assemblage based on core C02 was dominated by typical YSCBW species,A.ketienziensis,Astrononion italicum and Hanzawaia nipponica,at 6.2 4 kyr BP.A non-deposition period occurred since 4 kyr BP,which possibly related to the hydrology changes caused by the East Asia monsoon.The two obvious benthic foraminiferal transitions recorded in core C02 during the early and middle Holocene provide evidence that the Yellow Sea has undergone a two-phase rapid sea level rise during the Holocene marine transgression.展开更多
Controlled experiments, including mesocosms and laboratory cultures, are used to identify a potential speci?c cause- effect relationship that has been previously inferred in field studies. In this study, a series of m...Controlled experiments, including mesocosms and laboratory cultures, are used to identify a potential speci?c cause- effect relationship that has been previously inferred in field studies. In this study, a series of mesocosm experiments are carried out to assess the impact of different concentrations of copper on benthic foraminiferal assemblages over time. This pilot investigation documents that Cu contamination has a detrimental effect on foraminifera when compared to original and control samples. In particular, increased concentrations of Cu (normally higher than 120 μg/l) lead to a lowering of foraminiferal density and diversity and an increased occurrence of abnormalities. This study thus supports that the use of an experimental approach is suitable for investigating the response of benthic foraminifera to stress including pollution. Moreover, the application of mesocosms represents an innovative tool to be placed alongside field studies and culture experiments.展开更多
Beginning in the 1980s,dramatic ecological changes happened to the bay and the adjacent Everglades.Several U.S.government organizations such as the U.S.Geological Survey and National Park Service united to try to rest...Beginning in the 1980s,dramatic ecological changes happened to the bay and the adjacent Everglades.Several U.S.government organizations such as the U.S.Geological Survey and National Park Service united to try to restore these ecosystems.As part of the whole project,this study establishes a baseline of variability for the last 100 to 4000 years in seagrass abundance(an indicator of water quality),展开更多
Benthic foraminifera, preserved in the Late Cretaceous organic carbon-rich sediments of Gamba, southern Tibet, provide high-resolution proxies for sea-level changes and dissolved oxygen fluctuations of southeastern Te...Benthic foraminifera, preserved in the Late Cretaceous organic carbon-rich sediments of Gamba, southern Tibet, provide high-resolution proxies for sea-level changes and dissolved oxygen fluctuations of southeastern Tethys. The fossils were statistically analyzed and divided into three faunas of "Cenomanian fauna", "Turonian fauna", and "Coniacian fauna". A middle neritic-upper bathal environment (50-250m) was estimated considering the ratios of planktonic and epifaunal benthic foraminifera (P/(P+E)), the morphological analysis according to the studies of recent foraminifera and the abundant distributions of depth-related species such as Alabamina creta, Laevidentalina sp., Praebulimina spp., Pleurostomella cf. naranjoensis, Pyrulina sp., Quinqueloculina spp., Haplophragmoides spp., etc. The result shows an almost parallel trend with the global transgressive and regressive cycles, but the former fluctuates more frequently at upper Cenomanian, which probably indicates tectonic instability of the continental margin. According to the benthic foraminiferal richness (BFN), Shannon-Weiner diversity (H(s)), as well as benthic foraminiferal oxygen index (BFOI), five periods of oxygen depleted conditions (dysoxic-anoxic) have been recognized. They correspond to the OAE2, the lower Turonian, the upper Turonian, the Turonian-Caniacian boundary event and the probably OAE3. In addition, the oxygen fluctuations in Gamba might be controlled directly by sea-level changes, while the paleoproductivity and oxygen conditions interacted with each other under oxygen deficiency environments.展开更多
Previous studies on deep modern benthic foraminifera in the Mediterranean Sea are not abundant and generally are focused at the fossilizing polythalamous component of the foraminiferal assemblages.We present prelimina...Previous studies on deep modern benthic foraminifera in the Mediterranean Sea are not abundant and generally are focused at the fossilizing polythalamous component of the foraminiferal assemblages.We present preliminary results of living(Rose Bengal stained)benthic foraminiferal faunas in bathyal and abyssal sediments.Benthic foraminiferal density, species composition and biomass are determined at 10 sites across a transect from the展开更多
The first study of early cretaceous succession in Northeast of Torbat-e-Heydarieh, led to recognition of 30 genera and 25 species of benthic foraminifera such as Rectodictyorbitolina sp., Dictyoconus arabicus, Orbitol...The first study of early cretaceous succession in Northeast of Torbat-e-Heydarieh, led to recognition of 30 genera and 25 species of benthic foraminifera such as Rectodictyorbitolina sp., Dictyoconus arabicus, Orbitolina discoidea,Palorbitolina lenticularis, Mesorbitolina parva, Orbitolina kurdica,Praeorbitolina sp., Valvullammina picardi, Pseudocyclamina lituus, Charentia cuvillieri, Lenticulina sp., Nezzazata picardi, Quinqueloculina robusta,Nautiloculina oolitica, Subaudia minuta, Praechrysalidina infracteracea, Rumanoloculina sp., Choffahella decipiens, Vercorsella arenata. Regard to Stratigraphy range of above mentioned, the Barremian–Aptian age suggested for this succession.展开更多
The effects of temperature and salinity on intertidal foraminiferal community under laboratory conditions are poorly understood. We designed a two-factor crossed experiment in which foraminiferal communities were cult...The effects of temperature and salinity on intertidal foraminiferal community under laboratory conditions are poorly understood. We designed a two-factor crossed experiment in which foraminiferal communities were cultured at different temperatures (6, 12, and 18℃) and salinities (15, 20, 25, and 30 psu) for 10 weeks. In total, 2616 living (stained) specimens were obtained and analyzed. Foraminiferal abundance ranged from 9 to 202 individuals/10 g wet weight of sediment. The highest abundance was obtained at 12℃, 25 psu and the lowest at 6℃, 15 psu. Statistical results demonstrated that temperature affected foraminiferal community more significantly than salinity. Most foraminiferal community parameters (abundance, species richness, Margalef index, and Shannon-Wiener diversity) were significantly positively correlated to temperature, but not to salinity, whereas Pielou's evenness was significantly negatively correlated to both temperature and salinity. The interactive effect of temperature and salinity on foraminiferal abundance was significant. In addition, with increasing temperature, the species composition shifted from hyaline Rotaliida to porcellaneous Miliolida. The abundance of dominant species (e.g., Ammonia aomoriensis, A. beccarii, and Quinqueloculina seminula) showed significant positive correlations to temperature. Our study indicated that the intertidal foraminiferal community responds sensitively and rapidly to the changes of salinity and, especially,temperature by shifting foraminiferal species composition and altering the community parameters.展开更多
Examples of evolution,extinction and homoplasy of the larger benthic foraminifera(LBF)occur throughout their history.Since the Carboniferous,LBF have thrived in carbonate-rich tropical and subtropical shallow-marine s...Examples of evolution,extinction and homoplasy of the larger benthic foraminifera(LBF)occur throughout their history.Since the Carboniferous,LBF have thrived in carbonate-rich tropical and subtropical shallow-marine shelf environments.Their high abundance and diversity are due primarily to their extraordinary ability to inhabit a range of ecological niches and by hosting a variety of symbionts.Attaining relatively large,centimetre-scale sizes,made some forms very specialized and vulnerable to rapid ecological changes.For this reason,some LBF have shown a tendency to suffer periodically during major extinctions,especially when environmental conditions have changed rapidly and/or substantially.This,however,makes them valuable biostratigraphic microfossils and,in addition,gives invaluable insight into the spatial and temporal process of biological evolution,such as convergent/homoplasy and homology/iterative evolution.Here the evolutionary behavior of two important morphological types that occurred throughout the history of the LBF are discussed,namely the planispiral-fusiform test as typified by the fusulinids in the Late Paleozoic and the alveolinids in the Mid-Cretaceous and Neogene,and the three-layered discoid lenticular test as characterized by the orbitoids in the Mid-to Late Cretaceous,the orthophragminids in the Paleogene,and lepidocyclinids in the Oligocene to Quaternary.Understanding the propensity of these forms to convergent and iterative evolution,with the repeated re-occurrence of certain morphological features,is essential in understanding and constructing their phylogenetic relationships more generally within the main groups of the LBF.The insights gained from the history of these LBF have wider implications,and provide a more general understanding of the impacts of climate and ecological changes as driving forces for biological evolution.展开更多
Stable isotopes of carbon and oxygen variations in foraminiferal shells have been widely used in paleo-environment studies.However,studies about the shells of benthic foraminifera in methanehydrate-bearing sediments a...Stable isotopes of carbon and oxygen variations in foraminiferal shells have been widely used in paleo-environment studies.However,studies about the shells of benthic foraminifera in methanehydrate-bearing sediments as reliable geochemical proxies to reconstruct the potential methane release events in the geologic past are rare.In this study,we present the stable carbon and oxygen isotopes of fossil benthic foraminifera including one epifaunal species(Cibicidoides wuellerstorfi)and two infaunal species(Bulimina mexicana and Uvigerina peregrina)from the Site U1447 of IODP 353 Expedition to trace methane events in the Andaman Sea,where one of the thickest and deepest gas hydrate stability zones was discovered.Theδ^(13)C values of benthic foraminifera show that there are eight distinct intervals with negative values in the last~10 Myr,interpreted as a record of long-term fluctuations in methane emission.Six of these methane events occurred during the glacial sea-level lowstands in the last~1.1 Myr.We,therefore,infer that the trigger mechanism for these events might be the hydrate destabilization caused by sea level fall.The methane events that occurred at~2.11 and~5.93 Ma are more likely related to the sudden changes in sedimentation,either slide events or marked variations in sedimentation rate.展开更多
The ocean absorbs large amounts of CO_2 emitted from human activities, which results in a decrease in seawater p H.Marine calcifying organisms such as foraminifera, are most likely to be affected by this declining pH....The ocean absorbs large amounts of CO_2 emitted from human activities, which results in a decrease in seawater p H.Marine calcifying organisms such as foraminifera, are most likely to be affected by this declining pH. In this study, we collected sediments from five stations of different depths(34–73 m) in a continental shelf of the Yellow Sea. The entire benthic foraminiferal communities together with sea sediments were cultured under three constant pHs(8.3, 7.8, and 7.3) for 6 and 12 weeks in the laboratory to study their responses to pH or incubation time. The microcosm's experimental results obtained showed that most of the foraminiferal community parameters(abundance, species richness, Margalef index, and Shannon-Wiener diversity) decreased significantly(p<0.05) with the decline in pH in all the tested stations. The responses of foraminifera to the decline in p H were species-specific, for instance, Protelphidium tuberculatum and Cribroelphidiumfrigidum were highly sensitive to declining pH and were finally eliminated at low pH, while some species(e.g., Lagenammina atlantica, Verneuilinulla advena, V. propinqua, Haplophragmoides applanata, and H. canariensis) could tolerate low pH and acted as pH-tolerant species. In addition, the proportion of hyaline taxa showed a significant(p<0.05) positive correlation with pH, while agglutinated type showed a negative response. Furthermore, different incubation times(6 and 12 weeks) showed significant effects on the nearshore communities other than the offshore treatments, which were, however, entirely declined after 6 weeks' incubation under low p H manipulation. Our results indicated that nearshore foraminiferal communities showed rather a resilience to the declining p H and the offshore foraminifera, especially those in the central area of the Yellow Sea Cold Water Mass were found to be more sensitive to the decline in pH in the continental shelf sediments of the Yellow Sea.展开更多
Twenty-one outcrop samples collected from a 28-m-thick section from the Safranbolu Formation of the southwestern part of the Safranbolu Basin,Anatolia,Turkey yielded well-preserved benthic foraminifera belonging mainl...Twenty-one outcrop samples collected from a 28-m-thick section from the Safranbolu Formation of the southwestern part of the Safranbolu Basin,Anatolia,Turkey yielded well-preserved benthic foraminifera belonging mainly to the genera Alveolina,Nummulites,Assilina,Rotalia,Disclocyclina and Orbitolites.Alveolina is the most diversified genus that is represented by sixteen species:Alveolina archiaci,A.axiampla,A.barattoloi,A.carantana,A.colatiensis,A.cuspidata,A.distefanoi,A.histrica,A.lehneri,A.oblonga,A.polatliensis,A.rakoveci gueroli,A.ruetimeyeri,A.rugosa,A.safranboluensis and A.sirelii.Alveolina safranboluensis and A.sirelii are described new.Comparison of the fossil assemblage with those assemblages previously reported from both Turkey and other Tethyan sub-basins revealed that the deposition occurred during the Cuisian(Eocene)and corresponded to Shallow Benthic Foraminiferal Zones(SBFZ)10–12.The abundance and diversity of the larger benthic foraminifera indicated that the Safranbolu Formation was deposited under transgressive conditions.展开更多
A piston sediment core E017 from the middle-southern Okinawa Trough was investigated. A preliminary study of the deep-water evolution since 18 cal. ka BP was performed basedon the quantitative census data of benthic f...A piston sediment core E017 from the middle-southern Okinawa Trough was investigated. A preliminary study of the deep-water evolution since 18 cal. ka BP was performed basedon the quantitative census data of benthic foraminiferal fauna, together with planktonic foraminiferal oxygen and carbon isotope, AMS14C dating, and the previous results achieved in thesouthern Okinawa Trough. The result shows that the benthic fauna was dominated by Buliminaaculeata (d′Orbigny), Uvigerina peregrina (Cushman), Hispid Uvigerina and Uvigerina dirupta(Todd) during the glaciation-deglaciation before 9.2 cal. ka BP, while Epistominella exigua(Brady), Pullenia bulloides (d′Orbigny), Cibicidoides hyalina (Hofker), Sphaeroidina bulloides(d’Orbigny) and Globocassidulina subglobosa (Brady) predominated the fauna in the post-glaciaperiod after 9.2 cal. ka BP. The benthic foraminifera accumulation rate (BFAR), paleoproductivityestimates and benthic foraminiferal assemblage conformably indicate that surface water paleoproductivity and organic matter flux during the glaciation-deglaciation were higher than those othe post-glacial period in the middle-southern Okinawa Trough, and gradually enhanced from thesouthern to the central Okinawa Trough during the glaciation-deglaciation, which could becaused by the discrepancy of the terrigenous nutrients supply. High abundances of E. exigua, anindicator of pulsed organic matter input, after 9.2 cal. ka BP may indicate that the intensity oseasonally riverine pulsed flux during the post-glacial period was stronger than that of the glaciation-deglaciation period, and the seasonal influx in the central trough might be stronger than inthe south. The temporal distributions of the typical species indicating bottom water oxygen content and ventilation condition show that the ventilation of the bottom water during the post-glaciaperiod is more active than the glaciation-deglaciation, which reflects that the evolution of the intermediate and deep waters of the northwestern Pacific during the last glaciation has no evideninfluence on the deep-water of the middle-southern Okinawa Trough. Additionally, the variationsin agglutinated benthic foraminiferal abundance and other carbonate dissolution proxies indicatethat carbonate dissolution gradually increased since the last 18 ka in the Okinawa Trough andrapidly enhanced at 9.2 cal. ka BP. The modern shallow carbonate lysocline could form at 3 calka BP.展开更多
Quantitative analyses have been carried out on benthic foraminifera from 66 samples of Core 255 in the southern Okinawa Trough, in combination with the stable isotopic analyses of planktonic and benthic foraminifera a...Quantitative analyses have been carried out on benthic foraminifera from 66 samples of Core 255 in the southern Okinawa Trough, in combination with the stable isotopic analyses of planktonic and benthic foraminifera and AMS 14C dating, in order to reconstruct the history of change under deep water conditions and surface paleoproduclivity over the last 20 000 years. The variations in the ratio of agglutinants in benthic foraminiferal fauna and the ratio of fragments in planktonic foraminifera] fauna indicate higher carbonate dissolution during the postglacial stage than during the glacial stage. The distribution of species and the results of Q-mode factor analysis show that there are three distinctly different benthic foraminiferal assemblages during the glacial, deglacial and postglacial stages in the Okinawa Trough over the last 20000 years: the glacial Bulimina aculeata assemblage (especially the dominant species Uvigerina pereyrina) is associated with high surface primary productivity and organic展开更多
Thirty three benthic foraminiferal species belong to 23 genera and 16 families have been recorded from the coral reefs of the Callovian Tuwaiq Formation, Khashm Al-Qaddiyah area, Central Saudi Arabia. Three species: A...Thirty three benthic foraminiferal species belong to 23 genera and 16 families have been recorded from the coral reefs of the Callovian Tuwaiq Formation, Khashm Al-Qaddiyah area, Central Saudi Arabia. Three species: Astacolus qaddiyahensis, Nodosaria riyadhensis, Siderolites jurassica are believed to be new. Nearly all identified foraminifera are of Atlantic-Miditeranean affinity. The foraminiferal assemblage recorded in the present work is mixed of open marine, moderately deep marine conditions associations and shallow to deep lagoon. The reefal part of upper Twiaq Formation may have been deposited in shallow water of lower to middle shelf depth(20–50 m) as indicated by abundant corals and benthic foraminifera. The coral fauna and bearing benthic foraminifera indicated moderate water energy.展开更多
Transfer functions between the benthic foraminiferal fauna of seventy-one sediment surface-samples retrieved from the South Yellow Sea inner shelf and the environmental factors, including the summer bottom-water salin...Transfer functions between the benthic foraminiferal fauna of seventy-one sediment surface-samples retrieved from the South Yellow Sea inner shelf and the environmental factors, including the summer bottom-water salinity(Ss), the summer bottom-water temperature(Ts) and the winter bottom-water temperature(Tw) have been developed utilizing weighted averaging partial least square regression(WA-PLS). Subsequently, the transfer functions have been applied to a late Holocene piston core SY01 from the South Yellow Sea inner shelf, established the variation curves of the Ss, Ts, and Tw during the last 3.9 cal. ka. The Ss and Ts showed a nearly synchronous trend to the published stalagmite δ18O curve from the Jiuxian Cave, meaning they could be used as reliable indicators for the summer monsoon. Similarly, the Tw could be used as an indicator for the winter monsoon for its synchronous change to the insensitive grain size variation of the core ZY-2 retrieved from the Central Yellow Sea mud area. These results suggest that transfer functions based on benthic foraminiferal fauna can be a potentially useful tool in palaeoceanographic and palaeoenvironmental research along the Chinese seaboard.展开更多
A total of six d13C minimum events,i.e.,VI,V,IV,III,II,and I,were observed via a stable carbon and oxygen isotope analysis of infaunal benthic foraminifera Uvigerina spp.in gravity core OS03-1 in the southeastern Okho...A total of six d13C minimum events,i.e.,VI,V,IV,III,II,and I,were observed via a stable carbon and oxygen isotope analysis of infaunal benthic foraminifera Uvigerina spp.in gravity core OS03-1 in the southeastern Okhotsk Sea over the last 180 ka.These events occurred at112–109,102–90,85–76,57–54,44–40,and 17–10 ka BP.The largest negative excursions reached 2.5%in event V and were greater than 1%in the other events.We proposed that all d13C minimum events were caused by the increase in sea surface water productivity,the weakened formation of Okhotsk Sea intermediate water,and the enhancement of the oxygen minimum zone.The negative excursions were unaffected by methane hydrate destabilization and subsequent methane release based on the results obtained by using archaeal lipid markers.展开更多
The Southern Yellow Sea Cold Water Mass(YSCWM) is closely related to the modern circulation system of the east China shelf seas, which has significantly influenced regional marine environmental changes. The study of t...The Southern Yellow Sea Cold Water Mass(YSCWM) is closely related to the modern circulation system of the east China shelf seas, which has significantly influenced regional marine environmental changes. The study of the Holocene evolution of the YSCWM will greatly improve our understanding of the mechanisms of regional environmental change. Benthic foraminifera are sensitive to bottom water environmental changes and can serve as useful indicators in bottom water environmental reconstruction. In this study, benthic foraminifera were analyzed in core N02 from the northwestern margin of the southern Yellow Sea Mud to decipher the phase evolution of the YSCWM during the last 7 kyr. Benthic foraminifera census counts and Q-mode factor analysis indicate that the Holocene sedimentary environment can be divided into three stages: From6.9–5.0 ka, the fauna was dominated by Ammonia ketienziensis, indicating that the YSCWM was at its strongest during the last 7 kyr, while the Yellow Sea Coastal Current(YSCC) had a weak influence on the bottom water of the study area. From 5.0–2.9 ka,the relative abundance of Hanzawaia nipponica remarkably increased while the abundance of A. ketienziensis decreased significantly, reflecting that the strength of the YSCWM was relatively weak and the range of the YSCWM might have contracted. The influence of the YSCC on the bottom water might have slightly increased, although its influence was still weak during this time. A notable increase in low-temperature and low-salinity species, such as Protelphidium tuberculatum and Buccella spp. has occurred since 2.9 ka, indicating that the YSCC has had a strong influence on bottom water during this period,while the strength of the YSCWM has been at its weakest during the last 7 kyr. Generally, the influence of the YSCWM and the YSCC on the bottom water properties of the study area show an obvious seesaw pattern, with one's influence increasing while the other's influence decreases and vice versa. The fluctuations in the strength of YSCWM during the Holocene may be caused by the different effect allocations of regional climatic factors(i.e. El Ni?o Southern Oscillation, East Asian Winter Monsoon,summer insolation in the northern hemisphere, etc.) acting on the circulation system during different periods.展开更多
The contribution of benthic foraminifera to sediment bioturbation has widely been overlooked despite their huge abundance in intertidal soft sediments. In this preliminary study, we specifically chose to focus on two ...The contribution of benthic foraminifera to sediment bioturbation has widely been overlooked despite their huge abundance in intertidal soft sediments. In this preliminary study, we specifically chose to focus on two key species of benthic foraminifera in temperate intertidal mudflats, <i><span style="font-size:12px;font-family:Verdana;">Quinqueloculina seminula</span></i><span style="font-size:12px;font-family:Verdana;"> and </span><i><span style="font-size:12px;font-family:Verdana;">Ammonia</span></i> <i><span style="font-size:12px;font-family:Verdana;">tepida</span></i><span style="font-size:12px;font-family:Verdana;">, and first experimentally investigated their individual movements at the sediment surface. We subsequently derived from these observations the individual-level surface sediment reworking rates, and used the actual abundance of these species to extrapolate these rates at the population level. Individual surface sediment reworking rates </span><i><span style="font-size:12px;font-family:Verdana;">SSRR</span><sub><span style="font-size:12px;font-family:Verdana;">i</span></sub></i><span style="font-size:12px;font-family:Verdana;"> ranged between 0.13 and 0.32 cm<sup>2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;"><sup><span style="font-family:Verdana;"></span></sup></span><span style="font-size:12px;font-family:Verdana;">ind</span><span style="font-family:Verdana;font-size:8.33333px;"><sup>-1</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">day<sup>-1</sup></span> <span style="font-size:12px;font-family:Verdana;">for</span><span style="font-size:10pt;font-family:;" "=""> <i><span style="font-size:12px;font-family:Verdana;">Q. seminula</span></i><span style="font-size:12px;font-family:Verdana;">, and between 0.12 and 0.28 cm<sup>2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">ind<sup>-1</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">day<sup>-1</sup></span><span style="font-size:12px;font-family:Verdana;"> for </span><i><span style="font-size:12px;font-family:Verdana;">A. tepida</span></i><span style="font-size:12px;font-family:Verdana;">. Population-level surface sediment reworking rates were subsequently estimated as ranging between 11,484 and 28,710 cm<sup>2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">m<sup>-2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">day<sup>-1</sup></span><span style="font-size:12px;font-family:Verdana;"> for </span><i><span style="font-size:12px;font-family:Verdana;">Q. seminula</span></i><span style="font-size:12px;font-family:Verdana;"> and 27,876 and 65,044 cm<sup>2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">m<sup>-2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">day<sup>-1</sup></span><span style="font-size:12px;font-family:Verdana;"> for </span><i><span style="font-size:12px;font-family:Verdana;">A. tepida</span></i><span style="font-size:12px;font-family:Verdana;">. Noticeably, these reworking rates are comparable to, and eventually even higher than, the rates reported in the literature for populations of intertidal macro-invertebrates, such as the annelid polychaete </span><i><span style="font-size:12px;font-family:Verdana;">Melinna palmata</span></i><span style="font-size:12px;font-family:Verdana;"> and the bivalve </span><i><span style="font-size:12px;font-family:Verdana;">Abra</span></i> <i><span style="font-size:12px;font-family:Verdana;">ovata</span></i><span style="font-size:12px;font-family:Verdana;">. Taken together these results suggest that despite their minute size intertidal benthic foraminifera are, thanks to their abundance, non-negligible contributors to the reworking of surface sediment, and may then play an unanticipated role in the benthic ecosystem functioning, through e.g. the enhancement of fluxes at the sediment-water interface.</span></span>展开更多
基金funded by the National Natural Science Foundation of China(41376079,41276060)the projects of the China Geological Survey and the Marine Geology Survey(DD20160137,DD20190205 and GZH200900501)+1 种基金the Foundation of the Shandong Provincial Key Laboratory of Marine Ecology and Environment&Disaster Prevention(201304)the Student Research Developing Program(SRDP)of Ocean University of China。
文摘The estuary and coastal zone are the key areas for socio-economic development,and they are also the important channels for pollutants transported to the sea.The construction of the Jiaozhou Bay Bridge changed the hydrodynamic condition of the bay,which made the self-purification capacity of the bay weakened and the pollution in the estuary and adjacent coastal zone become more serious.In this study,55 surface sediment samples were collected from the three seriously polluted estuaries and the adjacent coastal zone of Jiaozhou Bay to comprehensively study how the benthic foraminifera response to heavy metal pollution and human engineering,and to assess the ecological risks of the bay.A total of 80 species,belonging to 42 genera,were identified in this study.The results showed that Cu,Pb,Cr,Hg,Zn,and As had low to median ecological risks in the study area which would definitely affect the ecological system.The construction of the Jiaozhou Bay Bridge has resulted in pollutants accumulated at the river mouth of Loushan River,which has adverse effects on the survival and growth of benthic foraminifera.The lowest population density and diversity as well as the highest FAI(Foraminiferal Abnormality Index)and FMI(Foraminiferal Monitoring Index)occurred at Loushan River Estuary which indicated that the ecological environment of the northeastern part of Jiaozhou Bay(Loushan River Estuary)had been seriously damaged.Licun River and Haipo River estuaries and the adjacent coastal zone were slightly polluted and had low ecological risk.As a consequence,it suggested that the supervision of industrial and domestic waste discharge and the protection of the ecological environment in northeast Jiaozhou Bay should be paid more attention.
基金supported by the National Basic Research Program of China (973 Program 2010CB428901)the National Natural Science Foundation of China (40976031,91228207)
文摘Assemblages of benthic foraminifera in a sediment core(C02)near the western margin of the southern Yellow Sea Mud were studied to decipher the phase evolution of Holocene paleoenvironmental changes associated with the Holocene marine transgression.It appears that during the early Holocene(11.2 10.1 kyr BP),the faunal was dominated by low salinity and shallow water species Cribrononion subincertum,Buccella frigida and Ammonia beccarii,reflecting a near coast depositional environment.A rapid increase of the relative abundance of Ammonia compressiuscula between 10.1 9.3 kyr BP indicates that the sea level rose rapidly during that time period.From 9.3 7.7 kyr BP,the benthic foraminiferal assemblage was dominated by high percentage of A.compressiscula,suggesting that the sea level was relatively stable.An obvious transition of benthic foraminifera,from the A.compressiuscula-dominated assemblage to an Ammonia ketienziensis-dominated assemblage,occurred between 7.7 6.2 kyr BP,possibly corresponding to a second sea level rapid rise period in the Yellow Sea during the Holocene.This transition may correspond to the gradually strengthened Yellow Sea warm current(YSWC)and finally is established the modern-type circulation in the Yellow Sea.It may also mark the formation of the Yellow Sea cold bottom water(YSCBW)during that period.Since then,the benthic foraminiferal assemblage based on core C02 was dominated by typical YSCBW species,A.ketienziensis,Astrononion italicum and Hanzawaia nipponica,at 6.2 4 kyr BP.A non-deposition period occurred since 4 kyr BP,which possibly related to the hydrology changes caused by the East Asia monsoon.The two obvious benthic foraminiferal transitions recorded in core C02 during the early and middle Holocene provide evidence that the Yellow Sea has undergone a two-phase rapid sea level rise during the Holocene marine transgression.
文摘Controlled experiments, including mesocosms and laboratory cultures, are used to identify a potential speci?c cause- effect relationship that has been previously inferred in field studies. In this study, a series of mesocosm experiments are carried out to assess the impact of different concentrations of copper on benthic foraminiferal assemblages over time. This pilot investigation documents that Cu contamination has a detrimental effect on foraminifera when compared to original and control samples. In particular, increased concentrations of Cu (normally higher than 120 μg/l) lead to a lowering of foraminiferal density and diversity and an increased occurrence of abnormalities. This study thus supports that the use of an experimental approach is suitable for investigating the response of benthic foraminifera to stress including pollution. Moreover, the application of mesocosms represents an innovative tool to be placed alongside field studies and culture experiments.
文摘Beginning in the 1980s,dramatic ecological changes happened to the bay and the adjacent Everglades.Several U.S.government organizations such as the U.S.Geological Survey and National Park Service united to try to restore these ecosystems.As part of the whole project,this study establishes a baseline of variability for the last 100 to 4000 years in seagrass abundance(an indicator of water quality),
基金financially supported by the project of National key basic research and development of China("973" project) "Late Mesozoic Greenhouse Climatic-environmental evolution of East Tethys (No.2012CB822000-G)"
文摘Benthic foraminifera, preserved in the Late Cretaceous organic carbon-rich sediments of Gamba, southern Tibet, provide high-resolution proxies for sea-level changes and dissolved oxygen fluctuations of southeastern Tethys. The fossils were statistically analyzed and divided into three faunas of "Cenomanian fauna", "Turonian fauna", and "Coniacian fauna". A middle neritic-upper bathal environment (50-250m) was estimated considering the ratios of planktonic and epifaunal benthic foraminifera (P/(P+E)), the morphological analysis according to the studies of recent foraminifera and the abundant distributions of depth-related species such as Alabamina creta, Laevidentalina sp., Praebulimina spp., Pleurostomella cf. naranjoensis, Pyrulina sp., Quinqueloculina spp., Haplophragmoides spp., etc. The result shows an almost parallel trend with the global transgressive and regressive cycles, but the former fluctuates more frequently at upper Cenomanian, which probably indicates tectonic instability of the continental margin. According to the benthic foraminiferal richness (BFN), Shannon-Weiner diversity (H(s)), as well as benthic foraminiferal oxygen index (BFOI), five periods of oxygen depleted conditions (dysoxic-anoxic) have been recognized. They correspond to the OAE2, the lower Turonian, the upper Turonian, the Turonian-Caniacian boundary event and the probably OAE3. In addition, the oxygen fluctuations in Gamba might be controlled directly by sea-level changes, while the paleoproductivity and oxygen conditions interacted with each other under oxygen deficiency environments.
文摘Previous studies on deep modern benthic foraminifera in the Mediterranean Sea are not abundant and generally are focused at the fossilizing polythalamous component of the foraminiferal assemblages.We present preliminary results of living(Rose Bengal stained)benthic foraminiferal faunas in bathyal and abyssal sediments.Benthic foraminiferal density, species composition and biomass are determined at 10 sites across a transect from the
文摘The first study of early cretaceous succession in Northeast of Torbat-e-Heydarieh, led to recognition of 30 genera and 25 species of benthic foraminifera such as Rectodictyorbitolina sp., Dictyoconus arabicus, Orbitolina discoidea,Palorbitolina lenticularis, Mesorbitolina parva, Orbitolina kurdica,Praeorbitolina sp., Valvullammina picardi, Pseudocyclamina lituus, Charentia cuvillieri, Lenticulina sp., Nezzazata picardi, Quinqueloculina robusta,Nautiloculina oolitica, Subaudia minuta, Praechrysalidina infracteracea, Rumanoloculina sp., Choffahella decipiens, Vercorsella arenata. Regard to Stratigraphy range of above mentioned, the Barremian–Aptian age suggested for this succession.
基金supported by the National Natural Science Foundation of China(Grant Nos.41476043,41630965&41830539)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA11030104)+1 种基金the National Program on‘Global Change and Air-Sea Interaction’(Grant No.GASI-03-01-03-01)the Continental Shelf Drilling Program of China(Grant No.GZH201100202),the Paul Bronnimann Foundation 2014
文摘The effects of temperature and salinity on intertidal foraminiferal community under laboratory conditions are poorly understood. We designed a two-factor crossed experiment in which foraminiferal communities were cultured at different temperatures (6, 12, and 18℃) and salinities (15, 20, 25, and 30 psu) for 10 weeks. In total, 2616 living (stained) specimens were obtained and analyzed. Foraminiferal abundance ranged from 9 to 202 individuals/10 g wet weight of sediment. The highest abundance was obtained at 12℃, 25 psu and the lowest at 6℃, 15 psu. Statistical results demonstrated that temperature affected foraminiferal community more significantly than salinity. Most foraminiferal community parameters (abundance, species richness, Margalef index, and Shannon-Wiener diversity) were significantly positively correlated to temperature, but not to salinity, whereas Pielou's evenness was significantly negatively correlated to both temperature and salinity. The interactive effect of temperature and salinity on foraminiferal abundance was significant. In addition, with increasing temperature, the species composition shifted from hyaline Rotaliida to porcellaneous Miliolida. The abundance of dominant species (e.g., Ammonia aomoriensis, A. beccarii, and Quinqueloculina seminula) showed significant positive correlations to temperature. Our study indicated that the intertidal foraminiferal community responds sensitively and rapidly to the changes of salinity and, especially,temperature by shifting foraminiferal species composition and altering the community parameters.
文摘Examples of evolution,extinction and homoplasy of the larger benthic foraminifera(LBF)occur throughout their history.Since the Carboniferous,LBF have thrived in carbonate-rich tropical and subtropical shallow-marine shelf environments.Their high abundance and diversity are due primarily to their extraordinary ability to inhabit a range of ecological niches and by hosting a variety of symbionts.Attaining relatively large,centimetre-scale sizes,made some forms very specialized and vulnerable to rapid ecological changes.For this reason,some LBF have shown a tendency to suffer periodically during major extinctions,especially when environmental conditions have changed rapidly and/or substantially.This,however,makes them valuable biostratigraphic microfossils and,in addition,gives invaluable insight into the spatial and temporal process of biological evolution,such as convergent/homoplasy and homology/iterative evolution.Here the evolutionary behavior of two important morphological types that occurred throughout the history of the LBF are discussed,namely the planispiral-fusiform test as typified by the fusulinids in the Late Paleozoic and the alveolinids in the Mid-Cretaceous and Neogene,and the three-layered discoid lenticular test as characterized by the orbitoids in the Mid-to Late Cretaceous,the orthophragminids in the Paleogene,and lepidocyclinids in the Oligocene to Quaternary.Understanding the propensity of these forms to convergent and iterative evolution,with the repeated re-occurrence of certain morphological features,is essential in understanding and constructing their phylogenetic relationships more generally within the main groups of the LBF.The insights gained from the history of these LBF have wider implications,and provide a more general understanding of the impacts of climate and ecological changes as driving forces for biological evolution.
基金supported by the National Key R&D Program of China(No.2018YFC031000404)the National Natural Science Foundation of China(No.42276068)State Key Laboratory of Marine Geology,Tongji University(No.MGK202206)。
文摘Stable isotopes of carbon and oxygen variations in foraminiferal shells have been widely used in paleo-environment studies.However,studies about the shells of benthic foraminifera in methanehydrate-bearing sediments as reliable geochemical proxies to reconstruct the potential methane release events in the geologic past are rare.In this study,we present the stable carbon and oxygen isotopes of fossil benthic foraminifera including one epifaunal species(Cibicidoides wuellerstorfi)and two infaunal species(Bulimina mexicana and Uvigerina peregrina)from the Site U1447 of IODP 353 Expedition to trace methane events in the Andaman Sea,where one of the thickest and deepest gas hydrate stability zones was discovered.Theδ^(13)C values of benthic foraminifera show that there are eight distinct intervals with negative values in the last~10 Myr,interpreted as a record of long-term fluctuations in methane emission.Six of these methane events occurred during the glacial sea-level lowstands in the last~1.1 Myr.We,therefore,infer that the trigger mechanism for these events might be the hydrate destabilization caused by sea level fall.The methane events that occurred at~2.11 and~5.93 Ma are more likely related to the sudden changes in sedimentation,either slide events or marked variations in sedimentation rate.
基金supported by the National Natural Science Foundation of China(Grant Nos.41630965&41830539)Monitoring and Protection of Ecology and Environment in the East Pacific Ocean(Granted No.DY135-E2-5)+1 种基金the Senior User Project of RV KEXUE(Grant No.KEXUE2018G27)the Paul Bronnimann Foundation 2014。
文摘The ocean absorbs large amounts of CO_2 emitted from human activities, which results in a decrease in seawater p H.Marine calcifying organisms such as foraminifera, are most likely to be affected by this declining pH. In this study, we collected sediments from five stations of different depths(34–73 m) in a continental shelf of the Yellow Sea. The entire benthic foraminiferal communities together with sea sediments were cultured under three constant pHs(8.3, 7.8, and 7.3) for 6 and 12 weeks in the laboratory to study their responses to pH or incubation time. The microcosm's experimental results obtained showed that most of the foraminiferal community parameters(abundance, species richness, Margalef index, and Shannon-Wiener diversity) decreased significantly(p<0.05) with the decline in pH in all the tested stations. The responses of foraminifera to the decline in p H were species-specific, for instance, Protelphidium tuberculatum and Cribroelphidiumfrigidum were highly sensitive to declining pH and were finally eliminated at low pH, while some species(e.g., Lagenammina atlantica, Verneuilinulla advena, V. propinqua, Haplophragmoides applanata, and H. canariensis) could tolerate low pH and acted as pH-tolerant species. In addition, the proportion of hyaline taxa showed a significant(p<0.05) positive correlation with pH, while agglutinated type showed a negative response. Furthermore, different incubation times(6 and 12 weeks) showed significant effects on the nearshore communities other than the offshore treatments, which were, however, entirely declined after 6 weeks' incubation under low p H manipulation. Our results indicated that nearshore foraminiferal communities showed rather a resilience to the declining p H and the offshore foraminifera, especially those in the central area of the Yellow Sea Cold Water Mass were found to be more sensitive to the decline in pH in the continental shelf sediments of the Yellow Sea.
基金supported by and carried out under the Graduate Studies of Eskisehir Osmangazi University,Council of Higher Education of Turkey.
文摘Twenty-one outcrop samples collected from a 28-m-thick section from the Safranbolu Formation of the southwestern part of the Safranbolu Basin,Anatolia,Turkey yielded well-preserved benthic foraminifera belonging mainly to the genera Alveolina,Nummulites,Assilina,Rotalia,Disclocyclina and Orbitolites.Alveolina is the most diversified genus that is represented by sixteen species:Alveolina archiaci,A.axiampla,A.barattoloi,A.carantana,A.colatiensis,A.cuspidata,A.distefanoi,A.histrica,A.lehneri,A.oblonga,A.polatliensis,A.rakoveci gueroli,A.ruetimeyeri,A.rugosa,A.safranboluensis and A.sirelii.Alveolina safranboluensis and A.sirelii are described new.Comparison of the fossil assemblage with those assemblages previously reported from both Turkey and other Tethyan sub-basins revealed that the deposition occurred during the Cuisian(Eocene)and corresponded to Shallow Benthic Foraminiferal Zones(SBFZ)10–12.The abundance and diversity of the larger benthic foraminifera indicated that the Safranbolu Formation was deposited under transgressive conditions.
基金the CAS Pilot Project of the National Knowledge Innovation Program(Project No.KZCFX3-SW-220) the National Natural Science Foundation of China(Grant Nos.40176019 , 90411014) the National Major Fundamental Research and Development Project(Grant No.G20000467).
文摘A piston sediment core E017 from the middle-southern Okinawa Trough was investigated. A preliminary study of the deep-water evolution since 18 cal. ka BP was performed basedon the quantitative census data of benthic foraminiferal fauna, together with planktonic foraminiferal oxygen and carbon isotope, AMS14C dating, and the previous results achieved in thesouthern Okinawa Trough. The result shows that the benthic fauna was dominated by Buliminaaculeata (d′Orbigny), Uvigerina peregrina (Cushman), Hispid Uvigerina and Uvigerina dirupta(Todd) during the glaciation-deglaciation before 9.2 cal. ka BP, while Epistominella exigua(Brady), Pullenia bulloides (d′Orbigny), Cibicidoides hyalina (Hofker), Sphaeroidina bulloides(d’Orbigny) and Globocassidulina subglobosa (Brady) predominated the fauna in the post-glaciaperiod after 9.2 cal. ka BP. The benthic foraminifera accumulation rate (BFAR), paleoproductivityestimates and benthic foraminiferal assemblage conformably indicate that surface water paleoproductivity and organic matter flux during the glaciation-deglaciation were higher than those othe post-glacial period in the middle-southern Okinawa Trough, and gradually enhanced from thesouthern to the central Okinawa Trough during the glaciation-deglaciation, which could becaused by the discrepancy of the terrigenous nutrients supply. High abundances of E. exigua, anindicator of pulsed organic matter input, after 9.2 cal. ka BP may indicate that the intensity oseasonally riverine pulsed flux during the post-glacial period was stronger than that of the glaciation-deglaciation period, and the seasonal influx in the central trough might be stronger than inthe south. The temporal distributions of the typical species indicating bottom water oxygen content and ventilation condition show that the ventilation of the bottom water during the post-glaciaperiod is more active than the glaciation-deglaciation, which reflects that the evolution of the intermediate and deep waters of the northwestern Pacific during the last glaciation has no evideninfluence on the deep-water of the middle-southern Okinawa Trough. Additionally, the variationsin agglutinated benthic foraminiferal abundance and other carbonate dissolution proxies indicatethat carbonate dissolution gradually increased since the last 18 ka in the Okinawa Trough andrapidly enhanced at 9.2 cal. ka BP. The modern shallow carbonate lysocline could form at 3 calka BP.
基金Project supported by the National Natural Science Foundation of China.
文摘Quantitative analyses have been carried out on benthic foraminifera from 66 samples of Core 255 in the southern Okinawa Trough, in combination with the stable isotopic analyses of planktonic and benthic foraminifera and AMS 14C dating, in order to reconstruct the history of change under deep water conditions and surface paleoproduclivity over the last 20 000 years. The variations in the ratio of agglutinants in benthic foraminiferal fauna and the ratio of fragments in planktonic foraminifera] fauna indicate higher carbonate dissolution during the postglacial stage than during the glacial stage. The distribution of species and the results of Q-mode factor analysis show that there are three distinctly different benthic foraminiferal assemblages during the glacial, deglacial and postglacial stages in the Okinawa Trough over the last 20000 years: the glacial Bulimina aculeata assemblage (especially the dominant species Uvigerina pereyrina) is associated with high surface primary productivity and organic
基金funded by King Saud University, Deanship of Scientific Research, College of Science Research Center
文摘Thirty three benthic foraminiferal species belong to 23 genera and 16 families have been recorded from the coral reefs of the Callovian Tuwaiq Formation, Khashm Al-Qaddiyah area, Central Saudi Arabia. Three species: Astacolus qaddiyahensis, Nodosaria riyadhensis, Siderolites jurassica are believed to be new. Nearly all identified foraminifera are of Atlantic-Miditeranean affinity. The foraminiferal assemblage recorded in the present work is mixed of open marine, moderately deep marine conditions associations and shallow to deep lagoon. The reefal part of upper Twiaq Formation may have been deposited in shallow water of lower to middle shelf depth(20–50 m) as indicated by abundant corals and benthic foraminifera. The coral fauna and bearing benthic foraminifera indicated moderate water energy.
基金supported by the National Natural Science Foundation of China(Grant Nos.41006021,41176132)the Western Pacific Ocean System Project(Grant No.XDA11030104)
文摘Transfer functions between the benthic foraminiferal fauna of seventy-one sediment surface-samples retrieved from the South Yellow Sea inner shelf and the environmental factors, including the summer bottom-water salinity(Ss), the summer bottom-water temperature(Ts) and the winter bottom-water temperature(Tw) have been developed utilizing weighted averaging partial least square regression(WA-PLS). Subsequently, the transfer functions have been applied to a late Holocene piston core SY01 from the South Yellow Sea inner shelf, established the variation curves of the Ss, Ts, and Tw during the last 3.9 cal. ka. The Ss and Ts showed a nearly synchronous trend to the published stalagmite δ18O curve from the Jiuxian Cave, meaning they could be used as reliable indicators for the summer monsoon. Similarly, the Tw could be used as an indicator for the winter monsoon for its synchronous change to the insensitive grain size variation of the core ZY-2 retrieved from the Central Yellow Sea mud area. These results suggest that transfer functions based on benthic foraminiferal fauna can be a potentially useful tool in palaeoceanographic and palaeoenvironmental research along the Chinese seaboard.
基金supported by the National Basic Research Program of China (2013CB429700)the Basic Scientific Fund for the National Public Research Institutes of China (2012G07, 2013G38)+1 种基金the National Natural Science Foundation of China (40431002, 4071006900 and 40906035)the Youth Marine Science Foundation of the State Oceanic Administration (2013313)
文摘A total of six d13C minimum events,i.e.,VI,V,IV,III,II,and I,were observed via a stable carbon and oxygen isotope analysis of infaunal benthic foraminifera Uvigerina spp.in gravity core OS03-1 in the southeastern Okhotsk Sea over the last 180 ka.These events occurred at112–109,102–90,85–76,57–54,44–40,and 17–10 ka BP.The largest negative excursions reached 2.5%in event V and were greater than 1%in the other events.We proposed that all d13C minimum events were caused by the increase in sea surface water productivity,the weakened formation of Okhotsk Sea intermediate water,and the enhancement of the oxygen minimum zone.The negative excursions were unaffected by methane hydrate destabilization and subsequent methane release based on the results obtained by using archaeal lipid markers.
基金supported by the National Basic Research Program of China (Grant No. 2010CB428901)the National Natural Science Foundation of China (Grant Nos. 41476040 & 91228207)the Strategic Special Project of Chinese Academy of Sciences (Grant No. XDA11030104)
文摘The Southern Yellow Sea Cold Water Mass(YSCWM) is closely related to the modern circulation system of the east China shelf seas, which has significantly influenced regional marine environmental changes. The study of the Holocene evolution of the YSCWM will greatly improve our understanding of the mechanisms of regional environmental change. Benthic foraminifera are sensitive to bottom water environmental changes and can serve as useful indicators in bottom water environmental reconstruction. In this study, benthic foraminifera were analyzed in core N02 from the northwestern margin of the southern Yellow Sea Mud to decipher the phase evolution of the YSCWM during the last 7 kyr. Benthic foraminifera census counts and Q-mode factor analysis indicate that the Holocene sedimentary environment can be divided into three stages: From6.9–5.0 ka, the fauna was dominated by Ammonia ketienziensis, indicating that the YSCWM was at its strongest during the last 7 kyr, while the Yellow Sea Coastal Current(YSCC) had a weak influence on the bottom water of the study area. From 5.0–2.9 ka,the relative abundance of Hanzawaia nipponica remarkably increased while the abundance of A. ketienziensis decreased significantly, reflecting that the strength of the YSCWM was relatively weak and the range of the YSCWM might have contracted. The influence of the YSCC on the bottom water might have slightly increased, although its influence was still weak during this time. A notable increase in low-temperature and low-salinity species, such as Protelphidium tuberculatum and Buccella spp. has occurred since 2.9 ka, indicating that the YSCC has had a strong influence on bottom water during this period,while the strength of the YSCWM has been at its weakest during the last 7 kyr. Generally, the influence of the YSCWM and the YSCC on the bottom water properties of the study area show an obvious seesaw pattern, with one's influence increasing while the other's influence decreases and vice versa. The fluctuations in the strength of YSCWM during the Holocene may be caused by the different effect allocations of regional climatic factors(i.e. El Ni?o Southern Oscillation, East Asian Winter Monsoon,summer insolation in the northern hemisphere, etc.) acting on the circulation system during different periods.
文摘The contribution of benthic foraminifera to sediment bioturbation has widely been overlooked despite their huge abundance in intertidal soft sediments. In this preliminary study, we specifically chose to focus on two key species of benthic foraminifera in temperate intertidal mudflats, <i><span style="font-size:12px;font-family:Verdana;">Quinqueloculina seminula</span></i><span style="font-size:12px;font-family:Verdana;"> and </span><i><span style="font-size:12px;font-family:Verdana;">Ammonia</span></i> <i><span style="font-size:12px;font-family:Verdana;">tepida</span></i><span style="font-size:12px;font-family:Verdana;">, and first experimentally investigated their individual movements at the sediment surface. We subsequently derived from these observations the individual-level surface sediment reworking rates, and used the actual abundance of these species to extrapolate these rates at the population level. Individual surface sediment reworking rates </span><i><span style="font-size:12px;font-family:Verdana;">SSRR</span><sub><span style="font-size:12px;font-family:Verdana;">i</span></sub></i><span style="font-size:12px;font-family:Verdana;"> ranged between 0.13 and 0.32 cm<sup>2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;"><sup><span style="font-family:Verdana;"></span></sup></span><span style="font-size:12px;font-family:Verdana;">ind</span><span style="font-family:Verdana;font-size:8.33333px;"><sup>-1</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">day<sup>-1</sup></span> <span style="font-size:12px;font-family:Verdana;">for</span><span style="font-size:10pt;font-family:;" "=""> <i><span style="font-size:12px;font-family:Verdana;">Q. seminula</span></i><span style="font-size:12px;font-family:Verdana;">, and between 0.12 and 0.28 cm<sup>2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">ind<sup>-1</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">day<sup>-1</sup></span><span style="font-size:12px;font-family:Verdana;"> for </span><i><span style="font-size:12px;font-family:Verdana;">A. tepida</span></i><span style="font-size:12px;font-family:Verdana;">. Population-level surface sediment reworking rates were subsequently estimated as ranging between 11,484 and 28,710 cm<sup>2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">m<sup>-2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">day<sup>-1</sup></span><span style="font-size:12px;font-family:Verdana;"> for </span><i><span style="font-size:12px;font-family:Verdana;">Q. seminula</span></i><span style="font-size:12px;font-family:Verdana;"> and 27,876 and 65,044 cm<sup>2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">m<sup>-2</sup><span style="white-space:nowrap;">·</span></span><span style="font-size:12px;font-family:Verdana;">day<sup>-1</sup></span><span style="font-size:12px;font-family:Verdana;"> for </span><i><span style="font-size:12px;font-family:Verdana;">A. tepida</span></i><span style="font-size:12px;font-family:Verdana;">. Noticeably, these reworking rates are comparable to, and eventually even higher than, the rates reported in the literature for populations of intertidal macro-invertebrates, such as the annelid polychaete </span><i><span style="font-size:12px;font-family:Verdana;">Melinna palmata</span></i><span style="font-size:12px;font-family:Verdana;"> and the bivalve </span><i><span style="font-size:12px;font-family:Verdana;">Abra</span></i> <i><span style="font-size:12px;font-family:Verdana;">ovata</span></i><span style="font-size:12px;font-family:Verdana;">. Taken together these results suggest that despite their minute size intertidal benthic foraminifera are, thanks to their abundance, non-negligible contributors to the reworking of surface sediment, and may then play an unanticipated role in the benthic ecosystem functioning, through e.g. the enhancement of fluxes at the sediment-water interface.</span></span>
