The nematode/copepod ratio and its use in pollution ecology

The nematode/copepod ratio is critically examined with a view to adding some precision to its proposed use in pollution ecology. At two unpolluted intertidal sites, differing markedly in sediment grade, the metabolic requirements of copepods are shown to be equivalent to the requirements of that fraction of the nematode population which feeds in the same way. The partitioning of this total energy requirement among individuals depends on the distribution of individual metabolic body sizes and the relative rates of metabolism. The distribution of body sizes is constrained by the sediment granulometry, which affects nematodes and copepods differently. These considerations enable precise predictions of the nematode/copepod ratios expected in unpolluted situations, against which observed ratios can be compared.     

Pollution monitoring using the nematode/copepod ratio A practical application

The practical application of the nematode/copepod ratio in a pollution monitoring study in the Firth of Forth was investigated. Ratios from polluted sites were much higher than from a clean site, but there is considerable evidence which casts doubt on the credibility of the ratio as a tool to detect organic pollution. Nematodes and copepods exhibited differing degrees of contagion. Seasonal patterns of variation of the ratio were shown to vary geographically and at some sites the seasonal range was great. Along sewage pollution gradients in time and space the ratio was shown to vary in an inconsistent manner. A possible improvement to the ratio whereby only interstitial forms are included is suggested.     

Effects of Animal Size on Concentrations of Metallothionein and Metals in Periwinkles Littorina littorea Collected from the Firth of Clyde, Scotland

Different sizes of Littorina littorea were collected from four areas in the Firth of Clyde, Scotland. Their metallothionein (MT) and heavy metal concentrations were analysed using the Silver Saturation Method and Atomic Absorption Spectrophotometry, respectively. Concentrations of MT, Cd and Zn (as μg g⁻¹ dry soft-body weight) generally decreased with an increase in size of L. littorea. MT concentrations were better correlated with Cd than with Zn or Cu concentrations. Nevertheless, MT and the metals in periwinkles (as μg individual⁻¹) increased significantly with increasing size. Concentrations of MT and the metals among the sampling areas were compared at a standardised soft-body weight (10 mg). The results from Discriminant Analysis based on all metal concentrations indicate that Largs is different from the other areas and characterised by high Fe concentrations in L. littorea. The problems and differences in using either soft-body weight or shell length as independent variable for size-standardisation are discussed.     

Comparison of benthic foraminiferal and macrofaunal responses to organic pollution in the Firth of Clyde (Scotland)

By comparing benthic foraminiferal and macrofaunal responses to sewage sludge disposal in the Firth of Clyde (Scotland), we wanted to investigate the possibility of using foraminifera as bio-indicators of marine environmental degradation. Both groups present a similar distributional pattern, with poor faunas composed of species tolerant to strong oxygen depletion near to the disposal site, surrounded by high density of opportunistic species. Farther away, faunal density decreases and equilibrium taxa gradually replace opportunistic species. No more environmental impact is perceptible beyond 3 km. Nevertheless, some differences exist: foraminifera appear to be more impacted at the disposal site, probably as a consequence of the low pH, a supplementary stress factor for organisms provided with a calcareous test. At 3 km west of the disposal site, macrofauna is comparable to the reference station, whereas foraminifera still indicate environmental degradation, suggesting their higher sensitivity to this type of pollution. It appears that benthic foraminifera may add valuable information to open marine environmental monitoring.     

The distribution of 137Cs in surface intertidal sediments from the Solway Firth

The distribution of ¹³⁷Cs from the Sellafield (Windscale) nuclear fuel reprocessing plant has been examined in detail in the surface intertidal sediments of the inner Solway Firth by means of a hovercraft-borne radiometric survey. With the exception of a belt of relatively active sands to the south of Silloth, caesium distribution is generally consistent with that of fine-grained sediment such that the highest concentrations occur in mud flat and salt marsh sediments which are most extensive in sheltered coastal embayments. ¹³⁷Cs activities in July 1980 were typically 2–30 pCi g^?1 but locally exceeded 50 pCi g^?1. These levels are considerably lower than those recorded in locations, such as the outer Solway and Ravenglass estuary, which are closer to the Sellafield outfall.     

Preliminary results of experiments to determine the effects of suspended sediments on the estuarine copepod Eurytemora affinis

Suspended sediment did not significantly affect Eurytemora affinis, which is the numerically dominant, late winter, early spring mesozooplankton taxon in Chesapeake Bay. In preliminary analyses of survival, broods per female and nauplii development for suspended sediment concentrations from 0 to 350 mg l⁻¹, few significant differences were observed between populations exposed to no suspended sediment, and those in 50, 100 and 350 mg l⁻¹. However, in every case, highest suspended sediment levels reduced physiological or reproductive parameters in the copepod. These results suggest that current levels of suspended sediment in the Chesapeake Bay should not reduce population success of the copepod. However, copepod production could decline at slightly higher suspended sediment concentrations resulting from urban population growth and development in the watershed, as well as at levels which are typical of several European estuaries.     

Pollution studies in the Firth of Forth

The Firth of Forth, on the east coast of Scotland has hitherto received the untreated wastes of the city of Edinburgh. Some areas of the southern side of the Firth are heavily polluted in consequence. A new sewage treatment scheme will be introduced early in 1976 and a six-year monitoring programme is in progress to measure the efficiency of the new scheme. It is hoped that this work will eventually contribute to a better understanding of the influence of domestic and industrial sewage on the marine and estuarine environment.     

The problem of velocity inversion in refraction seismics: some observations from modelling results

The applicability of seismic refraction profiling for the detection of velocity inversion, which is also known as a low-velocity layer (LVL), is investigated with the aid of synthetic seismogram computations for a range of models. Our computational models focus on the inherent ambiguities in the interpretation of first-arrival time delays or 'skips' in terms of LVL model parameters. The present modelling results reveal that neither the measure nor even the existence of a shadow zone and/or a time shift (skip) in first arrivals is necessarily indicative of an LVL. Besides attenuation effects, the cap-layer velocity gradient is a critical parameter, determining the termination point of the cap-layer diving wave and thus the time skip.
We suggest that shallow LVLs can be delineated more reliably by traveltime and amplitude modelling of coherent phases reflected from their top and bottom boundaries, often clearly observed in the pre- and near-critical ranges in seismogram sections of refraction profiling experiments with a close receiver spacing. We demonstrate the applicability of this approach for a field data set of a refraction profile in the West Bengal Basin, India. The inferred LVL corresponds to the Gondwana sediments underlying the higher-velocity layer of the Rajmahal Traps. This interpretation is consistent with the data from a nearby well in the region.     

The stress release model and results from modelling features of some seismic regions in China

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Effects of some environmental parameters on the reproduction and development of a tropical marine harpacticoid copepod Nitocra affinis f. californica Lang

The effects of salinity, temperature, and light conditions on the reproduction and development of harpacticoid copepod, Nitocra affinis f. californica under controlled laboratory conditions were determined. Seven different salinity levels (5, 10, 15, 20, 25, 30, 35 ppt), four temperatures (20, 25, 30, 35 °C), three different light intensities (25, 56, 130 μmol m⁻² s⁻¹) and photoperiods (24 h:0 h, 1 h:23 h, 12 h:12 h LD cycle) were employed in this study. The highest (p < 0.05) overall reproduction and fastest development time were achieved by copepods reared under 30–35 ppt salinity. The optimum temperature required for the maximum reproduction was 30 °C while under 30 °C and 35 °C the copepod development time was shortest (p < 0.05) compared to other temperature levels. The overall reproduction was highest (p < 0.05) and development rate of N. affinis was shortest (p < 0.05) under lowest light intensity (25 μmol m⁻² s⁻¹). Continuous light (24 h:0 h LD) inhibited the egg production while, continuous darkness (1 h:23 h LD) and 12 h:12 h LD significantly favoured the overall reproductive activity of the female. Photoperiods 1 h:23 h and 12 h:12 h LD yielded highest total (p < 0.05) offspring female⁻¹ coupled with highest (p < 0.05) survival percentage. This study illustrated that although N. affinis can tolerate wide range of environmental conditions, prolonged exposure to subnormal environments affect its reproduction and development. This study showed that this species can be mass cultured for commercial purposes and has a potential to be used for toxicity studies due to its high reproductive performance fast development and a wide range of tolerance to environmental conditions.     

Preliminary paleomagnetic results on some Triassic rocks from East Greenland

Paleomagnetic measurements have been carried out on six samples of Early Triassic age and five samples of Middle Triassic age from East Greenland. The mean stable remanent magnetization directions obtained after alternating-field demagnetization tests give the virtual geomagnetic pole positions as: (1) 49°N, 158°E for the Middle Triassic and (2) 34° 30′N, 176°W for the Early Triassic. The Greenland Triassic paleomagnetic results have been compared with those for Europe and North America. It is inferred from this comparison that these preliminary results for Greenland do not conform with the requirements of a reconstruction based on a geometrical fit of the three landmasses.     

Effects of hydrocarbon contamination on a free living marine nematode community: results from microcosm experiments

Anthropogenic inputs of crude and refined petroleum hydrocarbons into the sea require knowledge of the effects of these contaminants on the receiving assemblages of organisms. A microcosm experiment was carried out to study the influence of diesel on a free living nematode community of a Tunisian lagoon. Sediments were contaminated by diesel that ranged in concentration from 0.5 to 20 mg diesel kg⁻¹ dry weight (dw), and effects were examined after 90 days. Gradual changes in community structure were revealed depending on the quantity of diesel administrated. In the medium (1 mg diesel kg⁻¹ and 5 mg diesel kg⁻¹ (dw)) and high (10 mg diesel kg⁻¹, 15 mg diesel kg⁻¹ and 20 mg kg⁻¹ (dw)) treated microcosms, most univariate measures, including diversity and species richness, decreased significantly with increasing level of diesel contamination whereas nematode assemblage from the low treated microcosm (0.5 mg diesel kg⁻¹ (dw)) remained unaffected. Results from multivariate analyses of the species abundance data demonstrated that responses of nematode species to the diesel treatments were varied: Chaetonema sp. was eliminated at all doses tested and seemed to be intolerant species to diesel contamination; Pomponema sp. and Oncholaimus campylocercoïdes were significantly affected at all diesel contamination levels but they were not eliminated, these species were categorized as “diesel-sensitive”; Hypodontolaimus colesi, Daptonema trabeculosum and Daptonema fallax which significantly increased respectively at 0.5, 1 and 5 mg diesel kg⁻¹ (dw) concentrations and appeared to be “opportunistic” species at these doses whereas Marylynnia stekhoveni which increased at all high doses (10, 15 and 20 mg diesel kg⁻¹ (dw)) seemed to be a “diesel-resistant” species.     

Spatiotemporal parameters of anomalous reflections from the ionosphere

Analysis of vertical sounding data obtained on the network of domestic stations equipped with Parus-A ionosondes has shown that anomalous reflections from the ionosphere previously detected in Moscow are observed throughout the whole mid-latitude region. It is shown that the longitudinal effect impacts the probability of the appearance of anomalous reflections. Their spatiotemporal scales are determined. The horizontal dimensions of the anomalies, as a rule, range from several tens to several hundred, possibly a thousand, kilometers. The region of altitudes at which anomalous reflections are observed extends from the E region to F2 layer. The frequency range in which they are most often recorded is from 2 to 14 MHz. The time of their existence ranges from a fraction of minutes to many hours.     

Effects of pollution on the benthos of the Firth of Forth

A long-term benthic study has been undertaken in the Firth of Forth to assess the environmental impact of a new sewage treatment scheme for the city of Edinburgh. The Sewage Scheme reduces the suspended solids content of the liquid effluent by approximately 60% and achieves a lowering of the concentration of materials in solution through more efficient dilution and dispersion. Marked changes in the intertidal benthic flora and fauna have been recorded along the Edinburgh coastal zone. These changes have been apparent as the decline and disappearance of populations of certain pollution indicator species and the appearance and establishment of several species previously unrecorded along the more polluted parts of the Edinburgh shoreline. Study of the sublittoral benthos has shown no deleterious effect arising from the new effluent outfall, although there does appear to be some enhancement of the fauna in the area.     

地磁钩扰的全球响应特征研究与初步统计结果

地磁钩扰是太阳耀斑效应的直观表现之一, 其研究有助于深入理解太阳爆发对地球空间环境的影响过程, 并能为空间天气建模和预报提供科学依据.本文利用山东大学威海地磁台和Intermagnet地磁链与子午工程的地磁观测数据, 联合GOES卫星及数字测高仪等的数据, 研究了一个由M5.6级太阳耀斑引发的地磁钩扰事件的全球响应特征.研究发现:地磁钩扰特征呈现出南北半球与午前/午后的差异, 且地磁响应相对于太阳耀斑存在约3 min的滞后现象, 而夜侧无明显扰动; 利用位于日侧的50余个地磁台站的数据统计分析后发现地磁钩扰幅度呈现正态分布, 且在当地时正午附近达到峰值; 利用地磁数据反演出钩扰发生时电离层的电流体系S_s和宁静日电流S_q, 并用该电流体系解释了此事件中地磁数据的变化特征.另外, 本文初步统计了1996-2015年的地磁钩扰事件数以及相关的太阳耀斑事件数, 分析后发现X级耀斑引发地磁钩扰的可能性最大, 达42%, 由M级耀斑引发的地磁钩扰事件数最多, A、B、C级等小耀斑引发地磁钩扰的可能性很小.

     

Correlation between damage distribution and ambient noise H/V spectral ratio: the SESAME project results

In the framework of the SESAME project one of the tasks was the compilation of all available ambient noise measurements within urban environments affected by historical or/and recent strong earthquakes in Europe. The aim of such a task was to give an answer to the question; “How does horizontal-to-vertical ambient noise spectral ratio compare with damage in modern cities?”. For this purpose five European urban areas, namely, Angra do Heroismo (Portugal), Fabriano and Palermo (Italy), Thessaloniki and Kalamata (Greece) were selected for which spatial damage information was available either in terms of modified Mercalli intensity or in EMS98 damage grades. The geological setting of the examined sites as well as the causative earthquakes are satisfactorily known. Ambient noise recordings compiled for all examined sites have been homogeneously processed by a technique developed and agreed upon SESAME project. Using a standard multivariate statistical analysis, namely, factor analysis and canonical correlation, the horizontal-to-vertical ambient noise spectral ratio (HVNSR) is correlated with damage pattern observed within examined urban areas. Results show that, in some cases (Thessaloniki, Palermo), the HVNSR seems to be able to differentiate between areas previously shown to be associated with higher damage. In other cases however (Angra do Heroismo, Fabriano, Kalamata), the correlation is not statistically significant indicating thus the complex character of the parameters involved, implying that currently there is no a straightforward way that a value of HVNSR can correctly predict the extent to which a given region will be associated with increased damage.     

Adaptation of the hardware/software system for seismic monitoring in the Elbrus region and some observation results

The changes in the hardware/software system for seismic monitoring as applied to the conditions of the adit of the Institute of Nuclear Research, Russian Academy of Sciences, in the Elbrus region are described. A three-component computer recording within the frequency range of 10–120 Hz was carried out with the averaging of vibration amplitudes on an interval of 5 s. The results of data processing for the first six months of monitoring carried out starting from March 2008 in the adit are considered. The seismic field in the observation site has three main components: local earthquakes related to the two main magmatic fluid sources located nearby; a slowly changing wave field, possibly related to the same sources; and technogenic noise, in particular, vibration caused by the trolleys in motion, and a weak stationary background.