Paleoceanographic changes during the past 1.9 Myr at DSDP Site 238, Central Indian Ocean Basin: Benthic foraminiferal proxies

Deep-sea benthic foraminifera have been quantitatively analyzed in samples (> 125 μm size fraction) from Ocean Drilling Program (ODP) Site 238, to understand paleoceanographic changes in the Central Indian Basin over the past 1.9 Myr. Factor and cluster analyses of the 25 highest-ranked species made it possible to identify five biofacies, characterizing distinct deep-sea environmental settings. The environmental interpretation of each biofacies is based on the ecology of recent deep-sea benthic foraminifera. The benthic faunal record indicates fluctuating deep-sea conditions in environmental parameters including oxygenation, surface productivity and organic food supply. These changes appear to be linked to Indian summer monsoon variability, the main climatic feature of the Indian Ocean region. The benthic assemblages show a major shift at ∼ 0.7 to 0.6 Ma, marked by major turnovers in the relative abundances of species, coinciding with an increased amplitude of glacial cycles. These cycles appear to have influenced low latitude monsoonal climate as well as deep-sea conditions in the Central Indian Ocean Basin.     

Deep-sea palaeoceanography of the Maldives Islands (ODP Hole 716A), equatorial Indian Ocean during MIS 12-6

Deep-sea benthic foraminifera, planktic foraminifer Globigerina bulloides and pteropods have been quantitatively analysed in 451 samples from Ocean Drilling Program (ODP) Hole 716A, to understand both surface and deep-sea palaeoceanographic changes in the equatorial Indian Ocean basin during the late Quaternary (∼444–151 Kyrs). Benthic foraminifera were analysed from >125 μm size fraction whereas Globigerina bulloides and pteropods were analysed from >150 μm size fraction. Factor analysis of most dominant benthic foraminiferal species over the studied time span made it possible to identify three biofacies characterizing distinct deep-sea environmental settings at Hole 716A. The environmental interpretation of each species is based on the ecology of recent deep-sea benthic foraminifera. The faunal record indicates fluctuating deep-sea conditions including changes in surface productivity, organic food supply and deep-sea oxygenation linked to changing wind intensities. These changes are pronounced on glacial-interglacial time scales driven by summer monsoon winds.     

Timing and magnitude of early Aptian extreme warming: Unraveling primary δO variation in indurated pelagic carbonates at Deep Sea Drilling Project Site 463, central Pacific Ocean

In order to elucidate early Aptian marine paleotemperature evolution across the period of enhanced organic carbon (C_org)-burial [Oceanic Anoxic Event (OAE) 1a], stable isotope analyses were performed on pelagic limestones at Deep Sea Drilling Project Site 463, central Pacific Ocean. The δ¹⁸O data exhibit a distinct anomaly by ~ − 2‰ spanning the OAE 1a interval (i.e., a ~ 6 m-thick, phytoplanktonic C_org-rich unit constrained by magneto-, bio- and δ¹³C stratigraphy). Elucidation of paleotemperature significance of the δ¹⁸O shift is made by taking account of recent Sr/Ca evidence at the same section, which revealed that geochemical signals in carbonate-poor lithologies are relatively unaltered against burial diagenesis. By discriminating δ¹⁸O values from carbonate-poor samples (CaCO₃ contents = 5–30 wt.%), it appears that an abrupt rise in sea-surface temperatures (SSTs) by 8 °C (= − 1.7‰ shift in δ¹⁸O) occurred immediately before OAE 1a, whereas a cooling mode likely prevailed during the peak C_org-burial. In terms of its stratigraphic relationship as to the C_org-rich interval and to a pronounced negative δ¹³C excursion, as well as its timescale, the observed SST rise resembles those associated with the Paleocene–Eocene thermal maximum and, more strikingly, Jurassic Toarcian OAE. This observation is consistent with the hypothesis that these paleoenvironmental events were driven by a common causal mechanism, which was likely initiated by the greenhouse effect via massive release of CH₄ or CO₂ from the isotopically-light carbon reservoir and terminated by a negative productivity feedback.     

Miocene to recent eolian dust record from the Southwest Pacific Ocean at 40° S latitude

A 14-meter long pelagic clay core recovered at Marlin Rise (40°00.531′S, 154°2.601′W; 4775 m water depth) in the Southwest Pacific Basin contains a record of eolian dust deposited since the early Miocene. Downcore analysis of detrital minerals reveals a dominantly eolian signature with relatively constant proportions of quartz, feldspar and illite and trace amounts of chlorite, kaolinite and smectite, consistent with a continental (loess-like) source region. Fish tooth Sr isotope stratigraphy reveals the base of the core to be 17.5 Ma, with low sedimentation rates (< 0.5 mm/kyr LSR) indicated for the interval 17.5 to 10 Ma; several hiatuses in deposition appear to be present upcore, but are beyond the age resolution of the fish teeth stratigraphy. These intervals are revealed as apparent discontinuities in the Sr isotope record, accompanied by pulses of anomalously rapid sedimentation at ~ 10 Ma, 6.7 Ma and 4.1 Ma. Bulk mass accumulation rates (MAR) are calculated at ~ 10 mg/cm²/kyr over the last 4 Myr, consistent with previously estimated Quaternary eolian flux rates to this part of the Pacific. Nd, Pb and Sr radiogenic isotopic compositions of the detrital mineral extract (< 38 µm) show no trends with age, while ⁴⁰Ar/³⁹Ar ages show an upcore younging trend (~180 Ma to ~150 Ma), in concert with a slight coarsening of eolian grain-size distributions. These ages likely reflect mixing of Mesozoic illite-dominated clay from at least two continental source areas: southeastern Australia (Murray–Darling Basin/Lake Eyre Basin) and New Zealand (South Island). The data indicate remarkable constancy of continental eolian sources exposed to weathering and dispersal at this latitude during the Neogene.     

High-resolution sea surface temperature records derived from foraminiferal Mg/Ca ratios during the last 260 ka in the northern South China Sea

High-resolution sea surface temperatures (SST) derived from Mg/Ca ratios of Globeriginoides sacculifer at ODP Site 1144 were reported to reveal the SST changes during the last 260 ka in the northern South China Sea (SCS). The results indicate an average Holocene SST of about 26.7 °C, about 3.6 °C increase from LGM to the Holocene, and higher temperature during MIS 5.5 than the Holocene. These agree well with other foraminifer Mg/Ca and U^k₃₇ SST records in this region. The Mg/Ca records suggest warmer SSTs during MIS 3 in the northern SCS, compared with those in the eastern Pacific. Strong East Asian summer monsoon during MIS 3 indicated by paleoclimate records from nearby continents may account for it. Step-wise increases during terminations are shown in our SST record, and the beginning of deglacial warming occurs at about 19 ka, which precedes the change of oxygen isotopes, suggesting a tropical driven forcing for the SST change in the northern SCS. This is further supported by a robust semi-precessional cycle centering at  9.1 ka in the spectra of the SST record, which is absent in that of the oxygen isotopes. However, tropical driven forcing seems not to be indicated in another Mg/Ca SST record in the northern SCS [Oppo, D.W. and Sun, Y.B., 2005. Amplitude and timing of sea-surface temperature change in the northern South China Sea: Dynamic link to the East Asian monsoon. Geology, 33 (10): 785–788.]. The discrepancy may be caused by different post-deposition dissolutions of foraminifer tests at these two sites. Details about the modification of foraminifer Mg/Ca ratios after burial, however, are not well known in this region, and further studies are needed.     

Lake Baikal climatic record between 310 and 50 ky BP: Interplay between diatoms, watershed weathering and orbital forcing

The environmental record from Lake Baikal, Russia, from 310 to 50 ky BP (MIS 9a to MIS 3) was interpreted using rock magnetic, UV–Vis spectral, mineralogical, and diatom analyses. The age model was based on a correlation of the diatom and chemical weathering records and the summer insolation curve at 55°N and checked against an age model based on the proxy of relative palaeointensity of the Earth's magnetic field. Peaks in chemical weathering within the watershed, inferred from maximum concentration of magnetic and coloured minerals and mica, the lowest mean Fe oxidation state in silicates and highs in expandable clay minerals correlated with the Northern Hemisphere summer insolation minima at 55°N. Reconstructed changes in weathering intensity are better correlated to insolation patterns than to global ice volume records. We propose a scheme of yet missing palaeoenvironmental interpretation of the diatom assemblage, including also some extinct species. Aulacoseira baicalensis and Aulacoseira skvortzowii were abundant in the early stages of lake flora recovery immediately after deglaciation and during MIS 7e and MIS 5e; periods of more pronounced continental climate and peak chemical weathering. Stephanodiscus formosus var. minor, Cyclotella minuta and Cyclotella ornata dominated in intervals of decreased seasonality and decreased humidity at the end of most interglacial/interstadial diatom zones. Stephanodiscus grandis, Stephanodiscus carconeiformis and Stephanodiscus formosus were ubiquitous between MIS 8 and MIS 5, an interval marked by high seasonality, i.e., large differences between winter and summer insolation, and low humidity revealed by a low hydrolysis of expandable clay minerals in the watershed. Diatom concentrations peaked in the climatic optima of MIS 7e and MIS 5e and in the short periods marked by shifts to warmer conditions in the upper sections of MIS 5: MIS 5c (103–99 ky BP), MIS 5b (90–88 ky BP), and MIS 5a (84–79 ky BP) in which increased humidity resulted in enhanced hydrolysis of clay minerals. No such short similar climatic optimums were found from MIS 9a to MIS 6. Sharp climate deteriorations recorded in the diatom and clay mineral records at 107, 94, and 87 ky BP, however, occurred within 1–2 ky of cold extremes in North Atlantic sea surface temperature emphasizing the strong teleconnections between the two localities.     

Deep-sea benthonic foraminiferal faunal turnover near the Eocene/Oligocene boundary

Eocene-Oligocene deep-sea benthonic foraminifera in D.S.D.P. Site 277 in the southwest Pacific have been analyzed to determine the benthonic foraminiferal response to the development of the psychrosphere near the Eocene/Oligocene boundary. Biostratigraphic ranges of 41 taxa show that 23 taxa are found throughout the Late Eocene to Early Oligocene sequence, while 18 taxa exhibit first or last occurrences. Comparison of the faunal changes in Site 277 with a benthonic foraminiferal oxygen isotope record shows that the development of the psychrosphere did not have a profound effect upon the benthonic foraminifera, and the overall faunal change preceding and subsequent to the bottom-water circulation event occurred gradually. The inferred water-mass event affected the relative abundance of one species, Epistominella umbonifera. The lack of major faunal changes at the Eocene/Oligocene boundary in Site 277 probably reflects either wide environmental tolerances of the benthonic foraminifera, or a bottom-water temperature change less than 3°C.Examination of previously published benthonic foraminiferal biostratigraphic data from D.S.D.P. Sites 167, 171, 357, 360, 363, and 400A, and deep-sea ostracode data from D.S.D.P. Leg 3 show faunal changes occurred during discrete intervals in the Middle Eocene-Early Oligocene. The faunal patterns from these data and from Site 277 show that the Eocene/Oligocene cooling event did not cause rapid, catastrophic changes of the benthonic faunas of the open ocean, although significant faunal changes are associated with the water mass event in Sites 167, 171 and 400A.The benthonic faunal changes in Middle Eocene-Early Oligocene time are consistent with the gradual decrease of inferred bottom-water temperatures, based on previously published oxygen isotopic data. The δ ¹⁸O Eocene/Oligocene enrichment of 0.76‰ is a major event in the Southern Ocean oxygen isotopic record, but is considerably less in magnitude than the 1.75-2.00‰ change that occurred gradually from mid-Early Eocene to the Eocene/Oligocene boundary. The benthonic foraminiferal and isotopic data indicate that bottom-water circulation may have developed during the Middle Eocene to Early Oligocene interval, with the 3°C bottom-water cooling near the Eocene/Oligocene boundary representing part of this development.     

A fast and gentle method for the isolation of myrosinase complexes from Brassicaceous seeds

Myrosinase is a β-thioglucosidase glucohydrolase that catalyses the hydrolysis of the thioglucoside bond in glucosinolates, allelochemicals present in Brassicaceous plants. These isoenzymes have been found to form complexes with other proteins; however, traditional isolation procedures involving ammonium sulphate precipitation and/or ion exchange chromatography do not allow for the isolation of these complexes. The present paper reports a fast and gentle procedure for the isolation of myrosinases in the complex form. Partial purification by Con A affinity chromatography followed by Sephadex G-200 gel filtration allowed for the isolation of myrosinase complexes from seeds of Brassica carinata, B. oleracea var. capitata, B. napus and Sinapis alba. Myrosinases in the Brassicas formed complexes of different molecular weight (500–600 kDa, 270–350 kDa and 140–200 kDa) whereas in seeds of S. alba it was only possible to isolate and detect 140–200 kDa complexes. In all species the complexes were formed by isoenzymes with isoelectric points between 4.8 and 5.6 and in some cases up to 6.8. SDS-PAGE confirmed that the myrosinase isoenzymes were composed by several protein subunits of molecular weights ranging between 10 and 110 kDa. The relative amount and enzymatic activity of the myrosinase complexes varied amongst the species studied. The isolation of myrosinase complexes in their native form is of great importance for the study of the hydrolysis of glucosinolates under autolysis conditions.     

Cyclic changes in Turonian to Coniacian planktic foraminiferal assemblages from the tropical Atlantic Ocean

Abundance patterns of planktic and benthic foraminifera from a tropical Atlantic drill site (Ocean Drilling Program Site 1259, Demerara Rise, Suriname margin) display a pronounced 400 kyr cyclicity, uninterrupted throughout our  87.8–92 Ma record, between two clearly distinguishable assemblages: (1) a pelagic foraminifer fauna, which represents a deep oxygen minimum zone, and (2) another assemblage representing a shallow oxygen minimum zone where the foraminifer fauna is dominated by a higher diversity population of mostly small clavate and biserial species common in epicontinental seas. The cyclic changes in the long eccentricity band (400 kyr) between these two assemblages are proposed to reflect changes in the mean latitudinal position of the Intertropical Convergence Zone (ITCZ). Associated fluctuations in precipitation and trade wind strength may have influenced the upwelling regime at Demerara Rise leading to the observed cyclicity of planktic foraminiferal assemblages. The severe Turonian to Coniacian paleoclimatic and paleoceanographic changes in the Atlantic Ocean (e.g., gateway opening, cooling, and glaciation), however, seem to have no influence on the composition of tropical planktic foraminiferal faunas. There is no apparent relationship between foraminifer abundances and a major deflection in the stable isotope record interpreted elsewhere as a sign of the growth and decay of a large polar ice sheet.     

Conceptual model of seagrass die-off in Florida Bay: Links to biogeochemical processes

Seagrasses are recognized as important plant communities in coastal estuaries and lagoons across both tropical and temperate climes; thus, large-scale seagrass die-off events worldwide are of general concern. In Florida Bay, at the southern terminus of the Florida peninsula, seagrass die-off events up to 4000 ha have been reported and smaller scale mortality events are noted annually. In the present study, we examined several hypothesized causative factors (high temperature, hypersalinity, sulfide toxicity) of seagrass (Thalassia testudinum) mortality in Florida Bay. To test sulfide effects, in situ sulfide production was stimulated by applying a labile carbon source (glucose) to sulfate reducers in the sediment at five sites across the bay (northeastern, northcentral, and southwestern basins). During the one year study, high temperature (32–36 °C) and salinity (> 50 psu) were recorded in the bay associated with a regional drought. We also experienced major seagrass die-off events at two of our southwestern bay sites. These field conditions provided an excellent opportunity to closely examine cause–effect relationships among stressors and die-off events in the field, and verify results of our previous mesocosm experiments. Even though glucose amendments stimulated porewater sulfides in bay sediments (4–8 mmol L^− 1), no significant differences in biomass, short shoot density or final growth rates were found between control and glucose plots. In addition, the highest growth rates and shoot densities were concomitant with maximum water column salinity (> 50 psu) and temperature (32–36 °C), when porewater sulfides were also in the millimolar range. Large-scale seagrass mortality events, encompassing  50% of the entire meadow at one site, occurred at southwestern bay sites when plants were down regulating (slower growth and shoot density), probably in response to shorter day length and lower temperature (30–34 to 23–26 °C) from October, 2004 to January, 2005. Sulfate reduction rates (SRR) were also 2-fold higher in the southwestern (214–488 nmol cm^− 3 d^− 1) versus northcentral and northeastern (97–240 nmol cm^− 3 d^− 1) bay sites, possibly limited by labile carbon, which we found to stimulate SRR 3-fold in northeastern and northcentral bay sites (461–708 nmol cm^− 3 d^− 1) and 4-fold at southwestern bay sites (1211–2036 nmol cm^− 3 d^− 1). Based on a synthesis of the field data reported herein, our mesocosm experiments to date, and contributions by others, we present a conceptual model of seagrass die-off in Florida Bay outlining a cascade of stressors, stimulated by P enrichment, which leads to high O₂ consumption in the system triggering a seagrass die-off event.     

Experimentally induced effects of water temperature and immersion time on reproductive output of bivalves in the Wadden Sea

Results of experiments are reported on the effects of water temperature and immersion time in winter on egg size and egg numbers in three intertidally living bivalves in the Dutch Wadden Sea, the Baltic tellin Macoma balthica, the common cockle Cerastoderma edule and the common mussel Mytilus edulis. Macoma (14–17 mm shell length) produced large eggs (diameter of 107 μm) in relatively small numbers (20 000–70 000) in early spring. Later in spring, Cerastoderma (28–33 mm shell length) produced smaller eggs (77 μm, excluding the surrounding jelly layer) in tenfold larger numbers (200 000–700 000). Mytilus (45–55 mm shell length) spawned even smaller eggs (72 μm) in high (but not easily assessed) numbers over a more extended period. In Macoma egg size was not affected by winter temperatures or immersion time. Effects of winter–spring temperatures and immersion time on egg size could be demonstrated in Cerastoderma. Smaller eggs were produced at the higher temperatures. Effects of immersion time were non-consistent: at lower water temperatures larger, but at higher temperatures smaller eggs were produced by animals kept at longer immersion times. In Mytilus, no temperature effects were observed. However, a longer immersion time resulted in larger eggs. In Macoma as well as in Cerastoderma significantly more eggs were produced at the lower temperature. Immersion time effects were most pronounced at the lower temperature, where more eggs were produced at the subtidal level than at the tidal level. At the higher water temperature differences between egg numbers produced at the two tidal levels were small. Just prior to spawning, egg numbers were strongly positively related to body mass at a certain shell length.     

Reproductive phase dependent circadian variations of plasma melatonin, testosterone, thyroxine and corticosterone in Indian palm squirrel, Funambulus pennanti

To explain the complex mechanism of environmental influence along with internal hormonal (factors) milieu on daily variations in the circulating levels of melatonin, testosterone, thyroxine and corticosterone were analyzed with the help of inferential statistics (Cosinor rhythmometry) in a seasonally breeding tropical rodent, F. pennanti during the reproductively active (RAP) and inactive phases (RIP). Plasma melatonin, thyroxine and corticosterone levels exhibited a significant circadian oscillation during both the active and inactive phases of the annual reproductive cycle. Melatonin showed higher amplitude during RIP in the circulating plasma. Testosterone presented a peak level during evening hours (16:00 - 18:00 h) during RAP only. The phase of thyroxine was noted ∼09:76 h and ∼10.35 h during active and inactive phases, respectively. Corticosterone showed a peak level at ∼12.00 h during both phases of the reproductive cycle. Further, in this tropical rodent, the minimum difference in photoperiod (∼3 - 4 hours) and maximum variation in temperature (max. 18°C - min. 10°C during RIP and max. 45°C - min. 32°C during RAP) and humidity (85% during RIP and 35% during RAP) regulated the diurnal rhythm of circulating melatonin circadian rhythm by ∼1 hour phase advance during RIP. In conclusion, the studied hormonal rhythms may be part of an integrative system to coordinate reproduction and physiological processes successfully with environmental factors.     

Thermoregulatory behavior and critical thermal limits of the angelfish Pterophyllum scalare (Lichtenstein) (Pisces: Cichlidae)

(1)Final temperature preferendum of juvenile (0.9–1.9 g) and adult (5.2–12.5 g) angelfish Pterophyllum scalare were determined with acute and gravitation methods. The final preferenda were similar, independent of the method and development stage (29.0–31.1°C).

(2)The critical thermal maxima (CTMax) for juveniles were 36.9°C, 37.6°C, 40.6°C, 40.8°C and for adults 38.4°C, 38.6°C, 41.0°C, 42.1°C. Adult angelfish CTMax was slightly higher than in juveniles (1°C; P<0.05); the endpoint of CTMax was the onset of spasms.

(3)The acclimation response ratio for both stages had an interval of 0.33–0.44; these values are in agreement with results for subtropical and tropical fishes.

(4)Therefore it is recommended that angelfish cultivation should be consistent with temperatures that do not change abruptly throughout the year and temperature maximum does not exceed 30°C.

     

Rapid isolation of host-independent Bdellovibrio bacteriovorus

A new method of isolating host-independent Bdellovibrio bacteriovorus has been developed. Filtered suspensions of host-dependent cells are dropped in small volumes onto 0.2 μm membranes laid on rich media agar. Significant growth is observed within 1–2 days; these cells were confirmed to be B. bacteriovorus using microscopic observations and PCR.     

A 36,000-yr vegetation history from the Peloncillo Mountains, southeastern Arizona, USA

A 36,200 cal yr B.P. vegetation history was developed from macrofossils and pollen from 55 packrat middens from 1287 to 1442 m elevation in the Peloncillo Mountains of southeasternmost Arizona, USA. Today, these elevations are dominated by semidesert grassland with a mixture of Chihuahuan and Sonoran Desert shrubs, including an eastern disjunct population of jojoba (Simmondsia chinensis). From 36,200 to 15,410 cal yr B.P., rocky areas just above large, pluvial lakes that occupied what are now dry playas supported Pinus edulis, Juniperus osteosperma, Juniperus cf. coahuilensis, Quercus cf. turbinella and a rich understory of summer-flowering C₄ annuals and grasses, indicating abundant summer rains and mild winters. After  15,410 cal yr B.P., P. edulis declined in abundance and disappeared briefly at 13,925 cal yr B.P., coincident with expansion of more xeric species and paleohydrological evidence for regional aridity during the Bølling–Allerød warm interval. P. edulis rebounded briefly during the Younger Dryas at 12,405 cal yr B.P. before disappearing along with other mesic woodland species sometime after 12,100 cal yr B.P. The few middens dating from the early to middle Holocene (10,000–4000 yr B.P.) indicate wetter conditions than today at 7790 cal yr B.P. followed by a general drying trend. The 35 middens from the late Holocene detail the sequential arrival of desertscrub species as vegetation became more modern in character.     

WST-1-based cell cytotoxicity assay as a substitute for MTT-based assay for rapid detection of toxigenic Bacillus species using CHO cell line

Bacillus cereus continues to be one of the important foodborne pathogens due to its ability to produce various heat-labile and -stable toxins. Several methods have been developed to assess the pathogenicity of the B. cereus strains; however, most of these take more than 2–3 days to provide confirmatory results. In this study we standardized a one-step cytotoxicity assay using WST-1 (4-[3-(4-iodophenyl)-2-(4-nitrophenyl)-2H-5-tetrazolio]-1,3-benzene disulfonate) and compared with the traditional MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide)-based assay for rapid detection of cytotoxic Bacillus spp. using Chinese hamster ovary (CHO) cell line. Crude toxin preparations from 50 isolates of Bacillus spp. were exposed to CHO cell line for 1 h or 24 h and the cytotoxicity was determined by using WST-1 and MTT-based methods. Most B. cereus strains and some strains of other Bacillus species from our collection or from food sources showed comparably high cytotoxicity using either of the methods (P = 0.81); however, WST-1 assay provided results in only 3 h while MTT assay in 44–52 h. A positive correlation (R² = 0.93) between WST-1 and MTT assays strongly suggests that the WST-1-based cytotoxicity assay could be used as an alternative method to MTT assay for rapid (3 h) confirmation of toxigenic Bacillus species in foods prior to their retail distribution or consumption.     

Late marine isotope stage 3 palaeoclimate for East Asia: A data–model comparison

Climate prediction under impact of anthropological greenhouse-gas emission is impossible to validate, but it can be inferred from past climate and modeling. In East Asia, a general warm–wet period at late Marine Isotope Stage 3, ca. 30–40 ky BP has been identified based upon extensive geological records; this provides an arid/humid reference for possible future warming caused by human activities. Based upon syntheses of geological evidence and the AGCM + SSiB modeling, this paper presents climate simulations focused on 35 ky BP, using forcing of insolation, glaciation and land surface conditions for East Asia. Results of the simulation can be compared with geological records and show that (1) the climate patterns of 35 ky BP were warm–wet conditions in northern China, but with warm–dry conditions in southern China compared to today; (2) mean annual temperatures were higher in most mid-low latitude areas, mainly contributed to by increased winter temperatures, suggesting that insolation has generated significant climate effects through the coupling in atmospheric circulation with land surface patterns; (3) Quaternary ice sheets in the Northern Hemisphere played an important role in temperature decrease at the mid-high-latitudes, and also enhanced the south–north temperature gradients, which in turn, increased moisture transport from low to high latitudes and increased monsoonal precipitation over the Tibetan Plateau; and (4) Vegetation changes in East Asia resulted from an increased temperature in the low latitudes, extended rain-belt northwards into China, and an enlarged area of increased precipitation inland.     

The effects of short-term exposures to ultraviolet radiation in the Hawaiian Coral Montipora verrucosa

Exposure to ultraviolet radiation (UVR, 290–400 nm) is an important abiotic factor that tropical marine organisms have been exposed to over evolutionary time. Additionally, UVR is known to cause coral bleaching independently and is an important synergistic factor in bleaching caused by thermal stress. Corals can avoid some of the damage associated with exposure to UVR by producing UVR-absorbing compounds such as mycosporine-like amino acids (MAAs). To examine the role of MAAs in the UVR photobiology of corals we conducted experiments on the Hawaiian coral Montipora verrucosa. M. verrucosa colonies were collected from 1, 5 and 10 m and exposed to three different UVR treatments for 3 days under constant visible irradiances equivalent to a depth of 0.15 m depth in Kane'ohe Bay. In addition to quantifying the MAA concentration of these corals several types of UVR-induced damage were measured to assess whether MAAs were providing protection. Quantum yields of photosystem II (PSII) fluorescence and excitation pressure on PSII were measured for each coral, and the formation of direct UVR damage to DNA was measured as cyclobutane pyrimidine dimers (CPDs) and (6-4) pyrimidine–pyrimidone photoproducts for the holobiont. All corals exhibited midday depressions in quantum yields, developed DNA photoproducts, and increased their MAA concentrations significantly as a result of UVR exposures. CPD accumulation in M. verrucosa was highest in corals from 1 m, which had the lowest MAA concentrations at the end of the experiment. Corals originally from 10 m showed the highest MAA concentration and lowest DNA damage in response to exposure to UVR. While corals from all collection depths displayed some sensitivity to increased irradiances of UVR, their respective levels of tolerance were clearly dependant on their previous light history.     

Late Pleistocene freshwater fish (Cottidae) trackways from New England (USA) glacial lakes and a reinterpretation of the ichnogenus Broomichnium Kuhn

New trace fossil material from Late Pleistocene glaciolacustrine varves of the Connecticut River Valley, New England, USA represent the first evidence of freshwater sculpin in glacial Lake Hitchcock. Paleobiogeographic data constrain the timing of the last reinhabitation of freshwater cottids from a Wisconsinan glacial refugium. Freshwater sculpin were present in the area of study by ~ 13.7 ky BP, moving approximately 400 km in 5000 yr, and following the ice margin at distances as close as 35 km. The trace fossils warrant erection of a new ichnospecies, Broomichnium flirii isp. nov. Comparison of this new ichnospecies to Broomichnium permianum reveals distinct similarities, and it is possible that the Permian examples of B. permianum also were made by fish, which would reconcile a long-running controversy. Many groups of fish are demersal and make ventral body contact with the substrate and could potentially leave similar traces. Identifying new forms of trace fossils made by fish that use alternative modes of locomotion will prove useful in paleoenvironmental interpretations.     

The alternating current polarographic behavior and determination of lansoprazole and omeprazole in dosage forms and biological fluids

The alternating current (AC_t) polarographic behavior of lansoprazole (LNS) and omeprazole (OMP) was studied in Britton Robinson buffers (BRb) over the pH range 4.1–11.5. In BRb of pH 9.6 and 10.5, well-defined AC_t peaks were obtained for both LNS and OMP, respectively. The current–concentration plots were rectilinear over the ranges of 0.4–20 µg mL^− 1 and 0.2–10 µg mL^− 1 for LNS and OMP respectively. The minimum detection limits (S/N = 2) were 0.02 µg mL^− 1 (5.4 × 10^− 8 M) and 0.01 µg mL^− 1 (2.9 × 10^− 8 M) for LNS and OMP, respectively. The proposed method was successfully applied to the analysis of the two drugs in their commercial capsules. The average percent recoveries were favorably compared to those obtained by reference methods. Co-administered drugs such as naproxen and methotrexate did not interfere with the proposed method. The proposed method was further extended to the in-vitro determination of the lansoprazole in spiked plasma, the percentage recoveries was 98.47 ± 1.29 (n = 4). The pathway for the electrode reaction for both drugs involved reduction of the sulphonyl group into the corresponding thiol group at the Dropping Mercury Electrode. The advantages of the method were time saving and more sensitive than the other published voltammetric method. Yet The present study is the first report on the use of alterating current polarography (AC_t) in this respect.