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Three procedures for the extraction of coral lipids were compared and a rapid and effective method for future use is suggested. This method was used to measure the lipid content of the branching coral Porites porites (Pallas) and the massive corals Montastrea annularis (Ellis and Solander) and Siderastrea siderea (Ellis and Solander) during July and August 1991. P. porites and M. annularis were sampled on two fringing reefs, each characterised by different water quality affecting light transmission, and at depths of down to 30 m on a barrier reef on the west coast of the island. m. annularis contained, on average, 29% of dry weight as lipid, and there were no significant differences in lipid levels between corals sampled on either fringing reef at 3 and 6 m, or between fringing reefs and the barrier reef at 13, 20 or 30 m depth. Five samples were also taken from a single massive colony of S. siderea at 3 m on a fringing reef and at 13, 20 and 30 m depth on the barrier reef. Values for lipid ranged from 26 to 35% of dry tissue weight. P. porites from 3 and 6 m depth on both fringing reefs contained the same amount of lipid (11% of dry tissue weight). However, at 13 m depth on the barrier reef this coral contained significantly less lipid (8.5% of dry tissue weight). This difference may be attributable to a higher nutritional intake by P. porites on the fringing reefs. 相似文献
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Eshleman KN Wigington PJ Davies TD Tranter M 《Environmental pollution (Barking, Essex : 1987)》1992,77(2-3):287-295
Field studies of chemical changes in surface waters associated with rainfall and snowmelt events have provided evidence of episodic acidification of lakes and streams in Europe and North America. Modelling these chemical changes is particularly challenging because of the variability associated with hydrological transport and chemical transformation processes in catchments. This paper provides a review of mathematical models that have been applied to the problem of episodic acidification. Several empirical approaches, including regression models, mixing models and time series models, support a strong hydrological interpretation of episodic acidification. Regional application of several models has suggested that acidic episodes (in which the acid neutralizing capacity becomes negative) are relatively common in surface waters in several regions of the US that receive acid deposition. Results from physically based models have suggested a lack of understanding of hydrological flowpaths, hydraulic residence times and biogeochemical reactions, particularly those involving aluminum. The ability to better predict episodic chemical responses of surface waters is thus dependent upon elucidation of these and other physical and chemical processes. 相似文献
5.
Wigington PJ Davies TD Tranter M Eshleman KN 《Environmental pollution (Barking, Essex : 1987)》1992,78(1-3):29-35
Episodic acidification is practically a ubiquitous process in streams and drainage lakes in Canada, Europe and the United States. Depressions of pH are often smaller in systems with low pre-episode pH levels. Studies on European surface waters have reported episodes most frequently with minimum pH levels below 4.5. In Canada and the United States, studies have also reported a number of systems that have had minimum pH levels below 4.5. In all areas, change in water flowpath during hydrological events is a major determinant of episode characteristics. Episodic acidification is also controlled by a combination of other natural and anthropogenic factors. Base cation decreases are an important contributor to episodes in circumneutral streams and lakes. Sulphate pulses are generally important contributors to episodic acidification in Europe and Canada. Nitrate pulses are generally more important to episodic acidification in the Northeast United States. Increases in organic acids contribute to episodes in some streams in all areas. The sea-salt effect is important in near-coastal streams and lakes. In Canada, Europe and the United States, acidic deposition has increased the severity (minimum pH reached) of episodes in some streams and lakes. 相似文献
6.
Measurements of gaseous H2O2 and peroxyacetyl nitrate (PAN) concentrations in air are given for a site in rural southern England over an approximately 4-year period. In both cases the data show both diurnal and seasonal patterns. Temperature and wind direction had clear influences on the recorded concentrations of both species. There was an indication of increasing H2O2 concentrations with time. The use of a two-dimensional global model confirmed that this would be expected to occur alongside growth in ozone formation. It is suggested that, during photochemical episodes, the sequential build-up of ozone, PAN and H2O2 could be important in influencing the ability of vegetation to resist the effects of aggressive pollutants. 相似文献
7.
P. Spencer Davies 《Marine Biology》1991,108(1):137-144
Energy budgets were determined for small pieces (nubbins) of the coralsPocillopora damicornis, Montipora verrucosa andPorites lobata living at a water depth of 3 m on the fringing reef of Coconut Island, Kaneohe, Hawaii. The budgets were determined for three different types of day: an ideal day with no cloud and an in situ daily integrated irradiance at 3 m of 14.385 E m–2 d–1; a normal day with sporadic cloud cover and daily irradiance of 11.915 E m–2 d–1; and an overcast day with daily irradiance of 6.128 E m–2 d–1. On the ideal day, the energy fixed in photosynthesis was more than that required for respiration and growth of both zooxanthellae and animal components of the association, and there was a predicted loss of between 19.3 and 32.4% of the energy fixed. On a normal day, the total photosynthetic energy fixation was lower and the excess was between 12.1 and 27.9% of the energy fixed. On the overcast day, however, in bothPocillopora damicornis andPorites lobata energy expenditure exceeded photosynthetic energy fixation and the budget was in deficit. Estimates of rate of mucus secretion on an overcast day were derived and, when incorporated into the energy budget, it was predicted that all three species would have a deficit budget, necessitating the catabolism of lipid reserves. From published values for lipid storage in these species it was calculated that the reserves would last from 28 d inPocillopora damicornis to 114 d inM. verrucosa. A model is suggested in which corals draw upon their extensive lipid stores on days of sub-optimal light, replenishing the reserves again when daily light levels are high, and finally excreting the excess energy fixed, as mucus-lipid when the lipid stores are replete. 相似文献
8.
Frances R. Sweetman Kenneth M. Gibson Lawrence Sweetman Ph.D William L. Nyhan Homer Chin William Swartz Oliver W. Jones 《黑龙江环境通报》1986,6(3):187-194
We have documented the presence of five mitochondrial enzymes in samples of chorionic villus tissue and measured the levels of activity. Three of the enzymes catalyse biotindependent reactions. These are propionyl-CoA carboxylase, 3-methylcrotonyl-CoA carboxylase and pyruvate carboxylase. the other enzymes. 4-aminobutyric acid aminotransferase and succinic semialdehyde dehydrogenase, are involved inthe degradation of the central inhibitory neurotransmitter GABA. Distinct diseases in whichthere is deficiency of each of these enzymes have been documented in man. Significant levels of activity were observed for all five enzymes in chorionic villus tissue. This methodology should permit early prenatal diagnosis of deficiencies of these enzymes by chorionic villus biopsy in the first trimester. 相似文献
9.
The phosphatic mineral, hydroxyapatite, and two ion exchange resins have been used as artificial sediment particles. The surface properties of these materials have been studied using the Langmuir adsorption isotherm to calculate the binding capacity (B(max)) and the adsorption constant (K(L)) for zinc and cadmium ions. Mussels (Mytilus edulis) were fed on the particles and their digestive glands were subsequently removed and subjected to cell fractionation. The supernatant fraction was used to determine cytosol metal levels as a measure of the materials absorbed from the ingested particles. The level of cytosol zinc and cadmium was correlated with the K(L) values of the artificial sediments. It is suggested that phagocytosis of sediment particles plays an important part in transferring pollutants into benthic organisms and that the efficiency of this process is related to the adsorption coefficient of the particle surfaces. 相似文献
10.
This paper discusses policy towards gender in the water sector. It identifies key directions in gender policy and, while recognizing the progress made by donors towards implementing this, identifies some of the obstacles and difficulties encountered. The paper is based on a review of selected donor agency documentation and on discussions with staff conducted by Katja Jobes in May 1995. 相似文献