Characterization and Transcriptional Response of Ecdysone Receptor Gene in the Mud Crab Macrophthalmus japonicus: Effects of Osmotic Stress and Endocrine Disrupting Chemicals

Ocean Science Journal - The ecdysone receptor (EcR) induces hormonal pathways by binding ecdysteroids to other nuclear receptors for development, reproduction, and molting processes. To further...     

Assessment of Tidal Stream Energy Resources Using a Numerical Model in Southwestern Sea of Korea

Ocean Science Journal - In this study, tidal stream energy resources of the Southwestern Sea of Korea were assessed using a numerical model, Modelo Hidrodinâmico (MOHID). This numerical model...     

Acidification at the Surface in the East Sea: A Coupled Climate-carbon Cycle Model Study

This modeling study investigates the impacts of increasing atmospheric CO₂ concentration on acidification in the East Sea. A historical simulation for the past three decades (1980 to 2010) was performed using the Hadley Centre Global Environmental Model (version 2), a coupled climate model with atmospheric, terrestrial and ocean cycles. As the atmospheric CO₂ concentration increased, acidification progressed in the surface waters of the marginal sea. The acidification was similar in magnitude to observations and models of acidification in the global ocean. However, in the global ocean, the acidification appears to be due to increased in-situ oceanic CO₂ uptake, whereas local processes had stronger effects in the East Sea. pH was lowered by surface warming and by the influx of water with higher dissolved inorganic carbon (DIC) from the northwestern Pacific. Due to the enhanced advection of DIC, the partial pressure of CO₂ increased faster than in the overlying air; consequently, the in-situ oceanic uptake of CO₂ decreased.     

Stipe Length as an Indicator of Reproductive Maturity in the Kelp <Emphasis Type="Italic">Ecklonia cava</Emphasis>

We conducted testing to determine whether stipe length is a useful indicator of reproductive maturity in the kelp Ecklonia cava, a species that plays a pivotal role in ecosystem functioning and services in subtidal areas. Approximately 100 sporophytes with stipes of various lengths were collected during the fertile period (July–November, 2013). We investigated the relationships between stipe length and other morphological characteristics to determine whether stipe length could indicate the age of reproductive maturity. Primary blade length, longest blade length, thallus height, and total length showed significant relationships with stipe length. The length of the primary and longest blades gradually declined as stipe length increased above 125 mm. Zoosporangial sori were found on the blades of more than 70% of individuals with stipes longer than 125 mm, but on only 8% of individuals with stipes less than 125 mm long. Stipe length therefore seems to be an acceptable proxy for reproductive maturity. Another factor to consider, however, is that all specimens with zoosporangial sori, regardless of stipe length, had a dry weight of 80 g or more; thus, individual biomass may also be an important parameter influencing the initiation of reproduction.     

Grappling with Growth: Perceptions of Development and Preservation in Faster- and Slower-Growing Amenity Communities*

Amenity-rich rural communities attract tourists, retirees, second-home owners, and others whose values are often assumed to conflict with those of longtime residents. While prior research has examined attitudinal differences across types of residents, questions about the effects of community growth on residents’ attitudes remain unanswered. This study examines whether and how seasonal and permanent residents differ within and across towns experiencing different rates of growth, and the implications of differences for attitudes toward community development and preservation. Results showed that permanent residents (both short- and long-term) perceived community development initiatives as more important to maintaining future quality of life than did seasonal homeowners. Further, community growth rates had statistically significant effects: residents of slower-growth towns attributed higher importance to both development and preservation initiatives than did residents of faster-growing towns. Growth rate was thus a stronger predictor of attitudes toward both development and preservation than resident type.     

Modeling water quality and hypoxia dynamics in Upper Charlotte Harbor,Florida, U.S.A. during 2000

Hypoxia has occurred in Upper Charlotte Harbor, a shallow (∼3 m) estuary in Southwest Florida, during moderate to high freshwater flows from the Peace and Myakka Rivers and after hurricanes, due to nutrient loading and vertical stratification. This paper studies the annual hypoxia and water quality dynamics in Upper Charlotte Harbor in 2000, using CH3D-IMS, an integrated modeling system which includes coupled models of circulation, wave, sediment transport, and water quality. The CH3D-IMS simulations showed that bottom-water hypoxic conditions occur during periods with relatively steady moderate to high (5–40 m³/s) freshwater inflows and sediment oxygen demand (SOD). During periods of relatively steady moderate to high river discharge, strong vertical salinity stratification results in reduced vertical mixing which prevents surface water from supplying dissolved oxygen (DO) to bottom water where SOD continuously consumes DO. There was significant temporal fluctuation of the hypoxic water volume, as a result of significant temporal variation in vertical turbulent mixing associated with combinations of spring-neap tides and river discharge. The validated modeling system could be used to forecast hypoxia.     

Clockwise rotations recorded in Early Cretaceous rocks of South Korea: implications for tectonic affinity between the Korean Peninsula and North China

Recent interest has focused on whether South Korea may have undergone variable tectonic rotations since the Cretaceous. In an effort to contribute to the answer to this question, we have completed a palaeomagnetic reconnaissance study of Early Cretaceous sedimentary and igneous rocks from the Kyongsang basin in southeast Korea. Stepwise thermal demagnetization isolated well-defined characteristic magnetization in all samples. The palaeomagnetic directions reveal patterns of increasing amounts of clockwise (CW) rotation with increasing age for Aptian rock units. Palaeomagnetic declinations indicate clockwise vertical-axis rotations of R = 34.3° ± 6.9° for the early Aptian rock unit, R = 24.9° ± 10.6° for the middle Aptian, and R = −0.9° ± 11.8° for the late Aptian relative to eastern Asia. The new Cretaceous palaeomagnetic data from this study are consistent with the hypothesis that Korea and other major parts of eastern Asia occupied the same relative positions in terms of palaeolatitudes in the Cretaceous. An analysis of and comparison with previously reported palaeomagnetic data corroborates this hypothesis and suggests that much of Korea may have been connected to the North China Block since the early Palaeozoic. A plausible cause of the rotation is the westward subduction of the Kula plate underneath the Asian continent, which is inferred to have occurred during the Cretaceous according to several geological and tectonic analyses.     

Distribution of caustic-crossing intervals for Galactic binary-lens microlensing events

Detection of caustic crossings of binary-lens gravitational microlensing events is important because by detecting them one can obtain useful information about both the lens and the source star. In this paper, we compute the distribution of the intervals between two successive caustic crossings, f ( t _cc), for Galactic bulge binary-lens events to investigate the observational strategy for the optimal detection and resolution of caustic crossings. From this computation, we find that the distribution is highly skewed towards short t _cc and peaks at t _cc∼1.5 d. For the maximal detection of caustic crossings, therefore, prompt initiation of follow-up observations for intensive monitoring of events will be important. We estimate that, under the strategy of the current follow-up observations with a second caustic-crossing preparation time of ∼2 d, the fraction of events with resolvable caustic crossing is ∼80 per cent. We find that if the follow-up observations can be initiated within 1 d after the first caustic crossing by adopting more aggressive observational strategies, the detection rate can be improved to ∼90 per cent.     

26Al–26Mg chronology of high-temperature condensate hibonite in a fine-grained,Ca-Al-rich inclusion from reduced CV chondrite

Al–Mg mineral isochron studies using secondary ion mass spectrometry (SIMS) have revealed the initial ²⁶Al/²⁷Al ratios, (²⁶Al/²⁷Al)₀, for individual Ca-Al-rich inclusions (CAIs) in meteorites. We find that the relative sensitivity factors of ²⁷Al/²⁴Mg ratio for SIMS analysis of hibonite, one of the major constituent minerals of CAIs, exhibit variations based on their chemical compositions. This underscores the critical need for using appropriate hibonite standards to obtain accurate Al−Mg data. We measured the Al−Mg mineral isochron for hibonite in a fine-grained CAI (FGI) from the Northwest Africa 8613 reduced CV chondrite by SIMS using synthesized hibonite standards with ²⁷Al/²⁴Mg of ~30, ~100, and ~400. The obtained mineral isochron of hibonite in the FGI yields (²⁶Al/²⁷Al)₀ of (4.73 ± 0.09) × 10⁻⁵, which is identical to that previously obtained from the mineral isochron of spinel and melilite in the same FGI (Kawasaki et al., 2020). The uncertainties of (²⁶Al/²⁷Al)₀ indicate that the constituent minerals in the FGI formed within ~0.02 Myr in the earliest solar system. The disequilibrium O-isotope distributions of the minerals in the FGI suggest that the O-isotope compositions of the nebular gas from which they condensed underwent a transitional change from ¹⁶O-rich to ¹⁶O-poor within ~0.02 Myr in the earliest solar system. Once formed, the FGI may have been removed from the forming region within ~0.02 Myr and transported to the accretion region of the parent body.     

Photometric Survey of Galactic Open Clusters

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