Assessment of a Sr isotope vital effect (87Sr/86Sr) in marine taxa from Lee Stocking Island, Bahamas

 Data from Lee Stocking Island, Bahamas, confirms the hypothesis that there are no vital effects with the uptake of Sr isotopes (⁸⁷Sr/⁸⁶Sr) at the present mass spectrometer resolution [±2×10^-5 (2σ)]. Our data set contains analyses of 40 samples derived from 37 different calcareous taxa inhabiting a wide range of carbonate subenvironments (i.e., reefal, intertidal, supratidal, mangrove). The mean value of our analyses was 0.709179 with a standard deviation of 2.4×10^-5 (2σ) which was very close to the long-term uncertainty of the strontium isotope methodology [±2.0×10^-5 (2σ)] and to the widely reported ⁸⁷Sr/⁸⁶Sr value of seawater, which clusters around 0.709175. Received: 14 October 1997 / Revision received: 20 March 1998     

Induction of heat shock protein (hsp)60 in Isochrysis galbana exposed to sublethal preparations of dispersant and Prudhoe Bay crude oil

Adaptation to sublethal exposure to crude oil by phytoplankton is poorly understood. Use of chemical dispersants for oil spill remediation increases petroleum hydrocarbon concentrations in water, while exposing marine organisms to potentially toxic concentrations of dispersant. Heat shock proteins (hsps) have been found to serve as an adaptive and protective mechanism against environmental stresses. The objective of this project was to examine the induction of hsps in Isochrysis galbana, a golden-brown algae, following exposure to the water-accommodated fraction (WAF) of Prudhoe Bay crude oil (PBCO) and PBCO chemically dispersed with Corexit 9527® (dispersed oil: DO). Initial experiments using ³⁵S-labeled amino acids and 2-dimensional electrophoresis with subsequent western blotting identified and confirmed hsp60, a member of the chaperonin family of stress proteins, as being efficiently induced by heat shock in this species. One-dimensional SDS PAGE and western blotting, with hsp60 antibodies and chemiluminesence detection, were used to quantitate hsp60 following exposure to a range of environmental temperatures and concentrations of WAF and DO preparations. I. galbana cultured in 22 parts per thousand (‰) salinity showed a statistically significant increase (p<0.05) in hsp60 after exposure to 25, 30, and 35°C for 1 h compared to controls (20°C), while 34‰ cultures showed no significant increase in hsp60 with increasing temperature. Cultures (22 and 34‰) exposed to varying doses of WAF and DO exhibited statistically significant (p<0.05) increases in levels of hsp60 in all cases. A dose-related response was observed in all exposures (r²≥0.90) with the exception of 34‰ WAF. In independent exposures, a dose-related hsp60 response to naphthalene, a relatively abundant water-soluble aromatic hydrocarbon, was observed in both 22 and 34‰ cultures. Results of this study are consistent with previous studies in other species documenting increases in hsp60 levels with exposure to xenobiotics. Further studies are investigating the protective function of hsp60 against the toxic effects of exposure to WAF and DO preparations.     

The Effect of Macrofauna on Porewater Profiles and Nutrient Fluxes in the Intertidal Zone of the Humber Estuary

Macrofauna, nutrient fluxes, porewater chemistry and sediment characteristics were measured at six intertidal mudflat sites in the Humber Estuary, U.K., during the different seasons. Nereis diversicolor , Macoma balthica and Corophium volutator were found to be the dominant macrofauna. Salinity was the baseline control on macrofauna distribution but this was overprinted by periodic impoverishment due to sediment mobilization. High resolution gel probe porewater samplers provided direct evidence for the impact of burrows on porewater chemistry. The macrofauna modified nutrient fluxes during periods of mud flat stability. Nereis caused a decrease in silicate and phosphate effluxes but enhanced ammonia release and nitrate uptake. Macoma enhanced ammonia and nitrite release. The impact of Corophium was not possible to discern. The Humber is a large, highly dynamic macrotidal estuary in which sediment resuspension has a large impact on porewater profiles, nutrient fluxes and macrofaunal communities. Simple patterns and inter-relationships which are seen in small sheltered estuaries are not observed in the Humber.     

Evaluation of the Variability of the Shoreline of the Tsimlyansk Reservoir and Lake Ilmen according to Space Sounding Data

Izvestiya, Atmospheric and Oceanic Physics - This article presents the results of a study of the dynamics of the shorelines of Lake Ilmen and the Tsimlyansk Reservoir to indicate the location of...     

On Methods of Short-Term Earthquake Prediction Based on Monitoring the Hydrogeodeformation Field

Izvestiya, Atmospheric and Oceanic Physics - The permanent analysis of the hydrogeodeformation (HGD) field is one promising direction in the field of predicting strong earthquakes. As a result of...     

Eurasian Large-Scale Hazes in Summer 2016

Izvestiya, Atmospheric and Oceanic Physics - The technique for constructing the spatial distribution of maximum aerosol optical depth (MAOD) has been used to estimate the optically dense haze...     

The measurement of water losses from a forested area using a “natural” lysimeter

Water losses due to transpiration and evaporation of intercepted water were measured using a “natural” lysimeter in the Hafren forest of central Wales, and were compared with estimates of potential evaporation calculated from meteorological observations. Given certain assumptions concerning the forest canopy, the lysimeter observations were used to estimate runoff from the experimental catchment of the Upper Severn, within which the lysimeter is sited; this estimate agreed well with observation.     

Reflection of long internal waves of small amplitudes from an underwater slope

The dynamics of long waves in the vicinity of a transition point of a two-layer flow into a single-layer one is studied within the linear theory of shallow water. The analogy between this problem and the classical problem of surface wave runup on the shore is shown. Conditions for breaking internal waves on a slope are discussed.