Sublethal effects of oiled sediment on the sand worm, Nereis (neanthes) virens: Induced changes in burrowing and emergence

The burrowing and emergence behavior of sand worms, Nereis (Neanthes) virens Sars, in sediment contaminated with sublethal concentrations of Prudhoe Bay crude oil ranging from 74 to 5222 ppm, was studied in the laboratory. Initial burrowing in oiled sediment did not differ from that observed in unoiled sediment. Emergence of exposed worms was related to the oil concentration and the extent of weathering of oiled sediment. Sand worms buried in unoiled sediment did not emerge. Worms dug from oiled sediment after 12 hours' exposure and placed on unoiled sediment were impaired, resulting in a significant increase in time to burrow. However, after 12h, they recovered and burrowed at normal rates. Worms held in oiled sediment for 96 h also recovered. Possible causes for recovery are discussed. Results suggest that oil-induced aberrations may increase vulnerability to predation.     

Preservation of enzymic activity in marine plankton by low-temperature freezing

The measurement of enzymic activity in plankton communities is useful in the study of marine ecosystems. Such measurements can lead to a clearer understanding of the biological transformations in plankton communities at a particular time. However, the assays are somewhat time-consuming. To facilitate analysis of large numbers of samples, we have developed a method of quick-freezing of whole cells and of cell-free extracts of the diatom, Skeletonema costatum, followed by storage at ?60°C for up to one week. No loss in either the electron transport system (ETS) or the glutamate dehydrogenase (GDH) activity occurs. Similar conditions of storage can be used for the preservation of ETS activity in the marine copepod Calanus pacificus. Also, no measurable loss in either the GDH or the ETS activity is detectable after the quick-frozen whole cells of S. costatum have been kept frozen for over a year.     

Numerical modelling of the seasonal variability of the North and Tropical Atlantic currents using an adaptation approach

The paper reports computed data on the seasonal variability of the Atlantic Ocean currents which were obtained through numerical integration (using conservative difference schemes) of non-linear equations of hydrothermodynamics taking into account an upper quasi-homogeneous layer and the bottom topography. The seasonal variability of the meridional heat transfer is discussed. The results were obtained using an adaptation approach.Translated by Vladimir A. Puchkin.     

Oxygen Uptake During Repeated Exposure to Temperature Change: Physiological Divergence in Panamanian Cognate Pairs and Latitudinally Distant Populations of Decapod Crustacea

Abstract. The emergence of the Isthmus of Panama subdivided the amphi-American biota. In the present study, Pacific and Atlantic populations of four cognate pairs of crabs were used to discern whether exposure to different thermal regimes in habitats, in the putative absence of gene flow, has resulted in physiological divergence. Populations that potentially form a common genetic pool were also used; these were populations of the Atlantic Panama cognate that occur in Belize and Florida. Decreases in water temperature occur periodically in Pacific Panama and Florida, but not in Atlantic Panama or Belize. In this study, physiological divergence in oxygen uptake was assessed in response to repeated exposure to either control and decreased temperature or control and increased temperature. Results indicate that, in only some of the genera tested, exposure to decreases in habitat temperature has resulted in divergence. Partial support is found for the corollary that adaptation to an environment with periods of decreased temperature results in reduced compensation during exposure to elevated temperature.     

Errors in recent ocean tide models: possible origin and cause

Recently, the TOPEX/POSEIDON Science Working Team has recommended the FES95.2.1 and CSR3.0 ocean tide models for reprocessing the TOPEX/POSEIDON Geophysical Data Records. Without doubt, the performance of these models, especially in the deep oceans, is excellent. However, from a comparison of these hydrodynamically consistent models with the purely empirical DW3.2 and DEOS96.1 models, it appears that FES95.2.1 and CSR3.0 are affected by basin boundary related errors which are caused by the basin-wise solution procedure of the FES ocean tide model series. In their turn, the empirical DW3.2 and DEOS96.1 models seem to suffer from significant errors in the Antarctic seas due to the seasonal growth and decay of Antarctic sea ice. Also, bathymetry-induced differences were found between the hydrodynamically consistent models and the empirical models. Concerning these differences, TOPEX/POSEIDON and ERS-1 crossover statistics unfortunately do not provide conclusive results on which models are in error.     

A study of heavy metals in limpets Patella sp. collected along a section of the southeastern turkish mediterranean coast

Limpets collected at three locations along the Turkish Mediterranean coast were analyzed for zinc, copper, cadmium, lead, chromium, nickel, iron, arsenic and strontium. Average metal concentrations in samples taken from busy harbor areas and near sewage outfalls differed little from those collected in primarily agricultural areas. Generally, an inverse relationship of metal concentration with size is seen. The average levels found in these samples are of the same order of magnitude as those in limpets from other regions of the world and thus should serve as a good indication of current background levels in this region.     

The application of isotopic and biogeochemical markers to the study of the biochemistry of organic matter in a macrotidal estuary, the Loire, France

The biogeochemistry of organic matter in a macrotidal estuary, the Loire, France, has been studied for two years during different seasons. Both particulate matter and sediment have been sampled in the riverine zone, in the maximum turbidity zone and in the ocean near the river mouth. Two techniques have been used: carbon isotopic ratio determination and analysis of lipid-marker signatures in the n-alkane, n-alkene and fatty acid series. For the period corresponding to the output of the maximum turbidity zone in the ocean, the complete change of organic matter, continental in nature in the inner estuary, pure marine in the outer estuary is well illustrated by the decrease of δ¹³C values and of carbon preference index of n-alkanes. Input sources of organic matter by continental plants, plankton and micro-organisms are discussed from biogeochemical-marker analyses data along with the processes of accumulation of particles and their evolution with the season. Some criteria for evidencing the nature of various organic-matter pools are assessed and compared in different chemical-marker series as follows: high molecular weight n-alkanes and fatty acids, perylene for continental imprints, polyunsaturated 18-, 20- and 22-carbon fatty acids, n-C₁₇, n-alkenes and squalene for algae imprints, branched iso and anteiso fatty acids, Δ11-C_18:1 for microbial imprints.