Molecular characterization of four genes highly expressed during megalopa stage in Chinese mitten crab,Eriocheir sinensis

Ocean Science Journal - The molecular markers to distinguish different larval stages have various applications in ecological studies. Using the differential display RT-PCR technique, we isolated...     

Palaeoclimatic and regional implications of Older Dryas and Younger Dryas local glacier activity in the low-Arctic valley Finnkongdalen,Andøya,northern Norway

Continuous glacier margin and equilibrium-line altitude fluctuations of a former glacier on central Andøya, northern Norway, are reconstructed during the Lateglacial based on moraines and AMS ¹⁴C-dated sediments from the distal glacier-fed lake Ner-Finnkongdalsvatnet. The results indicate that a valley glacier occupied the entire valley during the Last Glacial Maximum (before 21 970±620 cal. a BP). The glacier remained large throughout the early Lateglacial until a significant glacier retreat took place about 14 300±330 cal. a BP. Major advances occurred during the Older Dryas (OD) and during the Younger Dryas (YD), while minor advances are suggested to have taken place during the Intra Allerød Cold Period and the Late Allerød Cooling. Additionally, three smaller glacier retreats/re-advances within the YD are suggested to have taken place, the latter being the largest. The glacier re-formations/advances during the Lateglacial are consistent with increases in temperature, and they are thus suggested to be the result of increased winter precipitation. Comparing the results with relevant glacier and sea-surface temperature records, a south–north migration of storm tracks may have occurred between 12 100–11 810±220 cal. a BP. The high temporal resolution of local glacier activity in Finnkongdalen improves our understanding of the climate forcing of the regional glacier fluctuations of the northwestern sector of the Scandinavian Ice Sheet during the Skarpnes- (OD) and Tromsø-Lyngen (YD) re-advances.     

Evapotranspiration models of different complexity for multiple land cover types

A comparison between half‐hourly and daily measured and computed evapotranspiration (ET) using three models of different complexity, namely, the Priestley–Taylor (P‐T), the reference Penman–Monteith (P‐M) and the Common Land Model (CLM), was conducted using three AmeriFlux sites under different land cover and climate conditions (i.e. arid grassland, temperate forest and subhumid cropland). Using the reference P‐M model with a semiempirical soil moisture function to adjust for water‐limiting conditions yielded ET estimates in reasonable agreement with the observations [root mean square error (RMSE) of 64–87 W m^?2 for half‐hourly and RMSE of 0.5–1.9 mm day^?1 for daily] and similar to the complex Common Land Model (RMSE of 60–94 W m^?2 for half‐hourly and RMSE of 0.4–2.1 mm day^?1 for daily) at the grassland and cropland sites. However, the semiempirical soil moisture function was not applicable particularly for the P‐T model at the forest site, suggesting that adjustments to key model variables may be required when applied to diverse land covers. On the other hand, under certain land cover/environmental conditions, the use of microwave‐derived soil moisture information was found to be a reliable metric of regional moisture conditions to adjust simple ET models for water‐limited cases. Further studies are needed to evaluate the utility of the simplified methods for different landscapes. Copyright © 2011 John Wiley & Sons, Ltd.     

Spatial and temporal variations in nutrient and chlorophyll-a concentrations in the northern East China Sea surrounding Cheju Island

Nutrients, chlorophyll-a (Chl-a), and environmental conditions were extensively investigated in the northern East China Sea (ECS) near Cheju Island during five research cruises from 2003 to 2007. In the eastern part of the study area, surface waters were characterized only by the Tsushima Current Water (TCW) during all five cruises. However, the western surface waters changed with season and were characterized by the Yellow Sea Cold Water (YSCW) in spring, the Changjiang Diluted Water (CDW) in summer, and the Yellow Sea Mixed Water (YSMW) in autumn. In spring and autumn, relatively high concentrations of nitrate and phosphate were observed in the surface waters in the western part of the study area, where vertical mixing brought large supplies of nutrients from deep waters. Changes in wind direction occasionally varied the inflow of the Changjiang plume in summer, clearly causing the annual variation in surface nitrate and phosphate concentrations in summer. In summer, the surface distribution of nitrate and phosphate did not coincide with that of silicate in the study area, which probably resulted from the significant drop in the Si:N ratio in the Changjiang plume since construction of the Three Gorges Dam (TGD). Despite large temporal and spatial variations in surface Chl-a concentrations, depth-integrated Chl-a concentrations exhibited little variation temporally and spatially. In the study area, surface Chl-a concentration did not well reflect the standing stocks of phytoplankton. The vertical distribution of Chl-a showed large temporal and spatial variations, and the main factor controlling the vertical distribution of Chl-a in summer was the availability of nitrate. The thermohaline front may play an important role for accumulation of phytoplankton biomass in spring and autumn.     

Evaluation of hydrologic data obtained from a local groundwater monitoring network in a metropolitan city,Korea

In the late 1980s, dramatic increases in water use caused over‐exploitation of groundwater resources and deterioration of water quality in Seoul metropolitan city. To monitor changes in quantity of groundwater resources and their quality, the metropolitan government established a local groundwater monitoring network in 1997 consisting of 119 monitoring wells. Groundwater resources in the urban area were affected by various human activities, including underground construction such as subways, pumping for public or private water use, leaky sewer systems and pavements. The variation patterns of the groundwater levels were mainly classified into four types, reflecting natural recharge due to rainfall events during the wet season, artificial recharge from leaky sewer or water supply systems, and heavy groundwater pumping for drainage or flood control purposes at underground construction sites. Significantly decreasing trends of groundwater levels in the suburbs of Seoul indicate groundwater use for various agricultural activities. Subway construction lowered the water level by an average of 25 m. Electrical conductivity values showed a wide range, from 100 to 1800 µS/cm (mean 470 µS/cm). Groundwater temperature generally showed a stable pattern, except for some sensitive increases at relatively shallow monitoring wells. Detailed analysis of the monitored groundwater data would provide some helpful implications for optimal and efficient management of groundwater resources in this metropolitan city. Copyright © 2005 John Wiley & Sons, Ltd.     

Structure and seasonal variability of the deep mean circulation of the East Sea (Sea of Japan)

The horizontal structure of deep mean circulation and its seasonal variability in the Japan/East Sea (JES) were studied using profiling float and moored current meter data. The deep circulation in the Japan Basin (JB) flows cyclonically, basically following f/H contours. The correlation between the directions of deep current and f/H contour increases as |▿(f/H)| increases, reaching remarkably high correlation coefficient (>0.8) values in steep slope regions in the JB. In contrast to the JB, the deep mean circulation in the Ulleung/Tsushima Basin (UTB) is generally weak and cyclonic accompanied by sub-basin-scale cyclonic and anticyclonic eddies. The UTB shows a poorer correlation between directions of deep current and f/H contours than other basins. The time-space averaged deep mean current is about 2.8 cm/s and the volume transport in the deep layer (800 m to bottom) in the JB reaches about 10 Sv (10 × 10⁶ m³s⁻¹), which is about four times greater than the inflow transport through the Tsushima Straits. A salient feature is that the amplitude of deep mean current in the JB reveals a remarkable seasonal variation with a maximum in March and minimum in October. The annual range of the seasonal variation is about 30% of the mean velocity, whereas that in the southern JES (UTB and Yamato Basin) is weak.     

New records of three <Emphasis Type="Italic">Paraprionospio</Emphasis> species (Polychaeta: Spionidae) from Korean waters

The spionid polychaete Paraprionospio pinnata (Ehlers 1901) has been widely reported from Korean waters. We examined some specimens belonging to the genus Paraprionospio that had been collected from Korean waters, and identified them as Paraprionospio coora Wilson, 1990, Paraprionospio cordifolia Yokoyama, 2007 and Paraprionospio patiens Yokoyama, 2007, which are new to the fauna of Korea. The present study suggests misidentification of the specimens that have been previously reported as P. pinnata from Korean waters.     

Physiological and biochemical responses of <Emphasis Type="Italic">Prorocentrum minimum</Emphasis> to high light stress

Prorocentrum minimum is a common bloomforming photosynthetic dinoflagellate found along the southern coast of Korea. To investigate the adaptive responses of P. minimum to high light stress, we measured growth rate, and generation of reactive oxidative species (ROS), superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA) in cultures exposed to normal (NL) and high light levels (HL). The results showed that HL (800 μmol m^?2 s^?1) inhibited growth of P. minimum, with maximal inhibition after 7–9 days. HL also increased the amount of ROS and MDA, suggesting that HL stress leads to oxidative damage and lipid peroxidation in this species. Under HL, we first detected superoxide on day 4 and H₂O₂ on day 5. We also detected SOD activity on day 5 and CAT activity on day 6. The level of lipid peroxidation, an indicator of cell death, was high on day 8. Addition of diphenyleneiodonium (DPI), an NAD(P)H inhibitor, decreased the levels of superoxide generation and lipid peroxidation. Our results indicate that the production of ROS which results from HL stress in P. minimum also induces antioxidative enzymes that counteract oxidative damage and allow P. minimum to survive.