Effects of BPA and DES on longchin goby (Chasmichthys dolichognathus) in vitro during the oocyte maturation

This study was performed in order to assess whether bisphenol (BPA) and diethylstilbestrol (DES) had agonistic or antagonistic effects on oocyte maturation using marine fish. We tested the effects of these chemicals on in vitro maturation, germinal vesicle breakdown (GVBD), assay using oocytes from the longchin goby, Chasmichthys dolichognathus. During the maturation process, low concentrations of BPA and DES triggered GVBD depending on the stage of oocyte development; BPA at 0.044 nM and DES at 0.037, 0.37, and 3.73 nM induced GVBD in 0.82-0.88 mm diameter oocytes (germinal vesicle located near the center of oocytes). In 0.76-0.80 mm diameter oocytes (fully vitellogenic oocytes), BPA induced GVBD at relatively higher concentrations (4.38, 43.8, and 438 nM). In 0.86-0.90 mm diameter oocytes, BPA and DES had no observable effect on GVBD at the concentrations tested. Oocytes with diameters between 0.82 and 0.88 mm appeared to be more sensitive to these chemicals. Moreover, our results showed that BPA and DES did not inhibit GVBD.     

Spatial and Temporal Ion Dynamics on a Complex Hydrological System: The Lower Luján River (Buenos Aires,Argentina)

The interplay of the geochemistry of the lower stretch of the Luján River is analyzed with its natural geomorphology (basin features), local hydrometeorology (tidal regime and “sudestada” events) and the impact of polluted tributaries. Major ions, dissolved heavy metals and limnological variables were analyzed using multivariate techniques. The water quality of the mainstream of the Luján River, flowing through urbanized and industrialized areas is strongly and positively influenced by the input of the Paraná River through deltaic watercourses and is negatively impacted after receiving the discharge from polluted watercourses. The longitudinal spatial variations evidenced major discontinuities in the Lower Luján Basin, showing clearly the riverine and the deltaic water influenced zones. Seasonal variations were also marked and were either temperature driven or associated with the estuarine cycle and the “sudestada”.     

Long-Term Trends in Intertidal and Subtidal Benthic Communities in Response to Water Quality Improvement Measures

Long-term monitoring studies are needed to understand changes in ecosystem status when restoration measures are implemented. A long-term data series (1996–2007) of the Tagus estuary (Portugal) intertidal and subtidal benthic communities was collected in a degraded area where mitigation measures were implemented. Multivariate analysis was used to analyze spatial and temporal patterns in benthic community composition and trends in five benthic community metrics (i.e., taxonomic richness, density, biomass, Shannon–Wiener diversity and the AMBI index) were also examined. The results revealed a clear separation between intertidal and subtidal assemblages, although they had 50% of taxa in common, including the most abundant. Significant positive trends were found for all metrics showing that both intertidal and subtidal communities responded to the restoration measures implemented. Nevertheless, biotic indices need some adaptation before being universally applied to intertidal and subtidal habitats.     

High Temporal Resolution Spectroscopic Observations of the Flare Star V1054 Oph

We present the results of a high temporal resolution spectroscopic monitoring of the flare (UV Cet type) star V1054 Oph (Wolf 630AB), classified as a dM3.5e visual binary system. Intermediate resolution spectra have been taken during four nights (2–5 April 2001) using the IDS spectrograph of the 2.5 m Isaac Newton Telescope (INT) (La Palma, Canary Islands, Spain). The V1054 Oph spectra show very strong emission lines even in its quiescent state. The analysis of the temporal evolution of the observed emission lines (from H_β to H₁₁ and the Ca II H and K lines) reveals four strong flares and several weak flares. We have studied in detail the behaviour of the chromospheric lines during the different phases (pre-flare, impulsive and gradual decay) of these flares. The observed flares last from ～25 to 95 min. The equivalent width of the H_β line changes by a factor up to ～2.3. Broad wings and asymmetric (red-shifted) lines are observed as well.     

Acetylthiocholine (ATC)--cleaving cholinesterase (ChE) activity as a potential biomarker of pesticide exposure in the Manila clam, Ruditapes philippinarum, of Korea

The acetylthiocholine (ATC) - cleaving cholinesterase (ChE) activity in Manila clam, which is widely distributed throughout the coastal environment of Korea, was assayed as a potentially useful biomarker of organophosphorous pesticides (OPs). A clear dose-response relationship was determined between inhibited ChE in adductor muscle of clams and four OPs (methidathion, chlorpyrifos, diazinon, IBP) which are heavily used OPs in Korea. The measured EC(50)-24?h values of methidathion, chlorpyrifos, diazinon, and IBP for Ruditapes philippinarum were 7.16?μg?l(-1), 0.34?mg?l(-1), 3.01?mg?l(-1), and 3.41?mg?l(-1), respectively. In field studies, ChE activity in Manila clams collected from 23 stations in the mid-western coastal region demonstrated spatial variation with statistical differences. These results suggest that ChE activity in R. philippinarum is a potential biomarker for assessing organophosphorous pesticide contamination in coastal environments.     

Foreword

Protons of energy 10⁹ GeV and 10⁴ GeV accelerating by the magnetic field of very strongly magnetized neutron stars and of extreme Kerr-Newmann black holes (respectively) may undergo instantaneous decay.     

Modern (<100 years) sedimentation in the Taiwan Strait: Rates and source-to-sink pathways elucidated from radionuclides and particle size distribution

A large number of sediment cores collected during 2005-2010 from the Taiwan Strait were analyzed for radionuclides (²¹⁰Pb, ¹³⁷Cs and ⁷Be) to elucidate sedimentation dynamics in this all-important gateway linking two largest marginal seas in the western Pacific (namely, the South China Sea and the East China Sea). Apparent sediment accumulation rates derived from ²¹⁰Pb and ¹³⁷Cs profiles vary from <0.1 to >2 cm/yr, averaging ∼0.4 cm/yr and showing a spatial pattern closely related to hydrodynamics and sediment source-to-sink pathways. Spatial-temporal variation of ⁷Be activity in surface sediments off Taiwan’s west coast indicates episodic deposition of flood layers and their mobility from river estuaries toward the north. In conjunction with particle size distribution in surface sediments and the structure of sediment strata revealed by sub-bottom echo images; the radionuclide data can be used to outline three different sediment source-to-sink dispersal systems. Based on sediment loads of surrounding rivers and the distribution of sediment accumulation rates, lateral transport is required to account for the budget and size distribution of sediments in the strait.     

Machine learning approaches to coastal water quality monitoring using GOCI satellite data

Since coastal waters are one of the most vulnerable marine systems to environmental pollution, it is very important to operationally monitor coastal water quality. This study attempts to estimate two major water quality indicators, chlorophyll-a (chl-a) and suspended particulate matter (SPM) concentrations, in coastal environments on the west coast of South Korea using Geostationary Ocean Color Imager (GOCI) satellite data. Three machine learning approaches including random forest, Cubist, and support vector regression (SVR) were evaluated for coastal water quality estimation. In situ measurements (63 samples) collected during four days in 2011 and 2012 were used as reference data. Due to the limited number of samples, leave-one-out cross validation (CV) was used to assess the performance of the water quality estimation models. Results show that SVR outperformed the other two machine learning approaches, yielding calibration R² of 0.91 and CV root-mean-squared-error (RMSE) of 1.74 mg/m³ (40.7%) for chl-a, and calibration R² of 0.98 and CV RMSE of 11.42 g/m³ (63.1%) for SPM when using GOCI-derived radiance data. Relative importance of the predictor variables was examined. When GOCI-derived radiance data were used, the ratio of band 2 to band 4 and bands 6 and 5 were the most influential input variables in predicting chl-a and SPM concentrations, respectively. Hourly available GOCI images were useful to discuss spatiotemporal distributions of the water quality parameters with tidal phases in the west coast of Korea.     

Phytoplankton response to pH rise in a N-limited floodplain lake: relevance of N2-fixing heterocystous cyanobacteria

Phosphorus has been traditionally regarded as the controlling nutrient for phytoplankton growth, however, N-limitation is likely to occur in several environments. For example, nitrogen is considered the main nutrient limiting phytoplankton in floodplain lakes of the Paraná River basin. However, N₂-fixing heterocystous cyanobacteria (N₂-cyano) are usually absent in these water bodies. The low pH values frequently found may limit the development of these algae. We hypothesise that long-term lake isolation allows conspicuous phytoplankton growth during summer, resulting in high photosynthetic rates and pH. This scenario combined with low DIN (dissolved inorganic nitrogen) would favour the development of N₂-cyano. Phytoplankton composition was studied during 16 months in a vegetated and isolated floodplain lake in the Paraná basin. Additionally, pH was artificially increased in in situ mesocosms to test effects on phytoplankton structure. Lake phytoplankton was dominated by flagellates (cryptophytes and euglenophytes) and small coccoid algae (chlorophytes and colonial cyanobacteria). Algal biomass was highest during warm periods. Although pH increased up to 8.8 during the second summer period, N₂-cyano remained rare, most likely because of the high DIN concentration recorded. The alkalophilic diatom Cyclotella meneghiniana dominated and was positively correlated with pH. Conversely, PO₄⁼ concentrations in the mesocosm experiment were high and DIN remained relatively low. pH enhancement in the treated mesocosms (avg. pH = 8.2) promoted the development of N₂-cyano (Anabaena spp.) and C. meneghiniana, which after 1 month of incubation accounted together for 50% of the biomass in contrast to less than 1.6% in control containers. Our results support the hypothesis that during the warm season and under low DIN concentration, high pH favours N₂-cyano growth in these lakes. We provide new evidence supporting the idea that even under optimal nutrient conditions, N₂-cyano do not thrive unless other requirements are satisfied.     

Patterns of spatial variation of nutrient content,epiphyte load and shoot size of Posidonia oceanica seagrass meadows (Mediterranean Sea)

Knowledge of patterns of spatial variability of vegetative development, epiphyte load and nutrient availability in seagrass meadows is essential for the adequate design of research and environmental monitoring programmes. Differences in shoot size, epiphyte load and nutrient content of leaves and epiphytes of the Mediterranean endemic seagrass Posidonia oceanica at spatial scales ranging from metres to hundreds of metres are evaluated using a hierarchical nested sampling design. The size and epiphyte load of P. oceanica shoots and the nitrogen and phosphorus content of leaves and epiphytes were different in most of the spatial scales considered. Sampling efforts concentrated at the metre scale incorporated most of the variability in size, epiphyte load and nutrient content of the leaves and epiphytes of P. oceanica shoots. Epiphyte load showed no correlation with nutrient content in the epiphytes or in the leaves. However, epiphyte load and shoot size were negatively correlated, which suggests that light penetration in the canopy may be a main determinant of epiphyte load.