Effects of external osmolality,calcium and prolactin on growth and differentiation of the epidermal cells of the cichlid teleost Sarotherodon mossambicus

Summary Osmolality and concentrations of divalent cations calcium, and to a lesser extent magnesium of the water are the main environmental factors that determine development and degree of mucification of the skin epithelium of Sarotherodon mossambicus. Epithelial thickness and number of mucocytes in fish exposed to low (freshwater level) concentrations of calcium and magnesium are directly related to the height of the osmotic gradient between water and blood plasma. No such relationship is found in fish exposed to a high (seawater level) concentration of calcium in the water, irrespective of the height of the osmotic gradient.The results strongly indicate that the effects of osmolality and divalent cations are indirect, and mediated by prolactin, since administration of ovine or fish prolactin stimulates growth and multiplication of the cells of the basal layer of the epidermis, and promotes the differentiation of the mucocytes.     

Semi-strong Hybrid Scaling,a new ordination algorithm

There is a small group of association measures that appear optimal for comparing sites on the basis of their species composition. These measures can accurately estimate affinity between sites when they are ecologically similar. Once sites share few or no species, these measures always under-estimate the ‘ecological distance’ between them. A new ordination algorithm called Semi-strong Hybrid Scaling, SHS, uses these features in an attempt to provide a better configuration of the sites. The new method is evaluated by a direct comparison of the structure in simulated data with the Hybrid method of Faith, Minchin & Belbin (1987). To evaluate SHS and compare it with Hybrid Scaling, 3240 datasets were generated using the COMPAS simulator (Minchin 1987). The data were designed to simulate as closely as possible, what is known of the distribution of species on environmental gradients. The factors included the dimensionality of the data, the number of sites and species, the shape of the species response surfaces, positioning of the sites in the simulation space, carrying capacity and level of noise. Recovery of the simulated site positions by SHS and Hybrid Scaling was evaluated using Procrustes rotation. SHS produced a better recovery in 88% of the datasets.     

Appropriate experimental design for transplanting mussels (Mytilus sp.) in analyses of environmental stress: an example in Sydney Harbour (Australia)

Some locations in Sydney Harbour (Sydney, Australia) contain large amounts of contaminants (heavy metals and hydrocarbons), sometimes in concentrations thought to affect biological systems. In order to estimate effects of sediment-bound contaminants on the physiology of organisms living above the sediment, the rates of clearance and respiration and the efficiency of absorption of mussels, Mytilus sp., living in a contaminated location were measured, the scope for growth (SfG) was calculated and compared to that of mussels living in uncontaminated locations. Two different models were proposed to explain expected differences. The first was that the contaminants at the impacted location reduced the SfG of local mussels; the second was that at the contaminated location only those mussels survived that had a small SfG (genetic differences between populations might be a reason for differential survival). To test which model applied, mussels were transplanted between the contaminated and uncontaminated locations. Moving and disturbing mussels (handling, tagging and caging) required the inclusion of two control treatments. These treatments were essential for a proper evaluation of the results but have generally not been included in similar studies. Effects of moving were estimated by translocating mussels from the uncontaminated and from the contaminated location to similar locations. To estimate effects of disturbance, mussels in the experimental locations were given the same treatment as the experimental mussels, but were returned to the place of origin. It was predicted that translocating and disturbing mussels would have no effect on the SfG, which would be similar to that of mussels at the place of origin. As expected, SfG was smaller (because rate of clearance was reduced) in undisturbed mussels at the contaminated location compared with those of mussels at the uncontaminated location. Because there were significant effects of disturbance on the SfG of mussels at the contaminated location, it was concluded that this difference was not caused by differences between the amounts of contaminants in the two locations, but was caused by other confounding factors (physical disturbance by crabs and fouling organisms). That the interpretation of the results would have been different if proper controls were not included is discussed in this paper and the importance of proper experimental controls is stressed.     

Does non-exercise activity thermogenesis contribute to non-shivering thermogenesis?

We wanted to examine if spontaneous physical activity contributes to non-shivering thermogenesis. Ten lean, healthy male subjects wore a physical activity, micro-measurement system while the room temperature was randomly altered at two hourly intervals between thermoneutral (72 °F), cool (62 °F) and warm (82 °F) temperatures. Physical activity measured during the thermoneutral, cooling and warming periods was not significantly different. Cooling increased energy expenditure above basal and thermoneutral values 2061±344 kcal/day (p<0.01). Thus, the increase in energy expenditure associated with short-term environmental cooling in lean, healthy males does not appear to be due to increased spontaneous physical activity or fidgeting.     

Variability in patterns of growth and morphology of Posidonia oceanica exposed to urban and industrial wastes: contrasts with two reference locations

Urban and industrial wastes have been claimed to negatively affect Posidonia oceanica meadows, but few studies have addressed this issue by comparing disturbed locations with replicated reference locations. Here, we examined the general proposition that patterns of growth and morphology of P. oceanica exposed to urban and industrial effluents were different from those observed in reference meadows. Hypotheses were both on differences in mean values of response variables and on variation of these measures at a hierarchy of spatial scales (from centimetres to hundreds of metres). Results indicated a significant reduction in mean number of intermediate leaves at the outfall compared to reference locations, whereas the opposite pattern occurred for juvenile leaves. There were significant, though temporally variable differences in growth of rhizomes between disturbed and reference locations, with reduced growth at the outfall in 2 out of 3 years analysed. Measures of spatial variance in number of juvenile leaves and length of adult leaves at the scale of shoots were significantly larger at the outfall compared to reference locations. At the same scale, measures of spatial variance in length of juvenile and intermediate leaves were significantly lower at the putatively impacted location. Spatial variance in number of intermediate leaves was reduced at the outfall compared to reference locations at the scale of quadrats. Past values of spatial variance in number of leaves per shoot were lower at the outfall than at the two reference locations at the scale of shoots, whereas the opposite occurred at the scale of areas. None of the structural variables examined showed any difference between the putatively impacted location and the two reference locations, either in terms of mean response or as changes in spatial variance. These results indicated that integrating methods to examine present and past events of disturbance, including analyses to detect changes in spatial variance of response variables, may provide a powerful approach to the analysis of environmental impacts on P. oceanica.     

The role of sinking particles in the overwintering process of Vibrio parahaemolyticus in a marine environment

Abstract The behavioral pattern of Vibrio parahaemolytics during the winter season (December 1988 to March 1989) in the water column, sediment, plankton and sinking particles was determined in a eutrophic marine environment. A total of 15 environmental parameters and seven microbial characteristics were examined. This halophile was isolated sporadically from bottom water and plankton materials, whereas it was undetectable in the surface water and sediment samples. However, V. parahaemolyticus was isolated from the sinking particles continuously throughout the sampling period with highest counts during February 1989. Out of 195 strains identified, 10 Vibrio spp. and 3 Listonella spp. were observed of which V. alginolyticus was predominantly isolated irrespective of the samples tested. Simple correlation and multiple regression analyses show that the occurrence of V. parahaemolyticus is not governed by any single biotic or abiotic factor of the environment. Possibly, the cumulative effect of all these environmental parameters on the distribution of V. parahaemolyticus is conceivable.     

Inupiat Health and Proposed Alaskan Oil Development: Results of the First Integrated Health Impact Assessment/Environmental Impact Statement for Proposed Oil Development on Alaska’s North Slope

We report on the first Health Impact Assessment (HIA) for proposed oil and gas development in Alaska’s North Slope region. Public health is not generally analyzed in the Environmental Impact Statement (EIS) process in the U.S. We conducted an HIA for proposed oil development within the National Petroleum Reserve - Alaska in response to growing concerns among North Slope Inupiat communities regarding the potential impacts of regional industrial expansion on their health and culture. We employed a qualitative HIA methodology, involving a combination of stakeholder input, literature review, and qualitative analysis, through which we identified potential health effects. The possible health outcomes identified include increases in diabetes and related metabolic conditions as a result of dietary change; rising rates of substance abuse, domestic violence, and suicide; increased injury rates; more frequent asthma exacerbations; and increased exposure to organic pollutant, including carcinogens and endocrine disruptors. There are also potential benefits, including funding for infrastructure and health care; increased employment and income; and continued funding of existing infrastructure. Based on these findings, we recommend a series of public health mitigation measures. This project represents the first formal effort to include a systematic assessment of public health within the U.S. EIS process. The inclusion of public health concerns within an EIS may offer an important and underutilized avenue through which to argue for environmental management strategies that focus on public health, and may offer communities a stronger voice in the EIS process. An erratum to this article can be found at     

Stable patterns in size structure of a phytoplankton species of Lake Kinneret

The aim of the study was a search for typical structure patterns of phytoplankton assemblages, based on the long-term dynamics analysis. As a test case we used the interannual phytoplankton variability of Lake Kinneret (Israel). The dominant phytoplankton species (Peridinium gatunense) structure was presented as the frequency-weighted taxonomic size spectrum (TSS) which describes the size distribution of the operational taxonomic unit (OTUj) occurrence frequencies. Using 24 years monitoring data, the TSS annual patterns of P. gatunense were compared. Typical persistent TSS patterns were evident even during years of pronounced deviations from the typical patterns of phytoplankton biomass dynamics and species composition. By correlation analysis, hierarchical cluster analysis and ANOVA the TSS variability was quantified and compared. While the TSS general shape was almost constant, its amplitude variations allowed us to distinguish between three levels of annual bloom intensity. Electronic Supplementary Material Supplementary material is available for this article at and accessible for authorised users