This study investigates the possibility of developing the RFLP/PCR assay as a new mutagenicity screening test for the detection and monitoring of the genetic effects of chemical pollution in the freshwater environment using <I>Xenopus laevis</I>. The two mutagens used were N-methyl-N-nitro-N-nitrosoguanidine (MNNG) and benzo[a]pyrene (B[a]P). MNNG- and B[a]P-induced mutations were detected at a frequency of 10<SUP>-4</SUP> in a sequence specific manner at selective recognition sites of the α<SUP>A</SUP><SUB>1</SUB>-globin, β<SUP>L</SUP><SUB>1</SUB>-globin and <I>c-myc</I> I genes during larval development. In maturing toadlets, B[a]P-induced G:C to T:A transversions at a frequency of 10<SUP>-1</SUP> at the BsiLI-site 913-917. Stage-specific differences in the incidence, frequency and time dependence of the B[a]P-induced mutations were observed during development. The nature of the effects of N-methyl-N-nitrosourea (NMU) upon <I>in vitro</I> DNA synthesis were also investigated, by determining if the mutagen induced intracellular environment could enhance the mutagenic and carcinogenic capacity of NMU through an increase in the mispairing probability of the methylated bases and simultaneous damage to the specific activity and fidelity of a DNA polymerase. The sensitivity of the PCR based assay depended on the target sequence length. The NMU damaged DNA template and polymerase acted in concert to potentiate DNA synthesis inhibition and produced dose-dependent differences in the mechanism of this inhibition. Using an error-prone activity the <I>Taq</I> polymerase was able to read through a small fraction of DNA lesions. Although no significant differences were observed in the types and frequencies of the base substitution mutations, the spectrum of susceptible nucleotide positions and miscoding potential of NMU depended on which component of the replication complex was targeted.

Oogenesis is examined in two rockling species. Seven developmental stages are described in <i>Ciliata mustela</i> L. and six stages in <i>Gairdropsarus mediterraneus</i> L., since both species were collected at the same time, suggesting the possibility of an earlier spawning in the first species. Ultrastructural differences in the zona radiata occur, monopartite in <i>G. mediterraneus</i> and bipartite and double thickness in <i>C. mustela</i>. Cortical alveoli are first formed in the cortex originating from Golgi vesicles. Ultrastructural evidence suggests that protein yolk formation has a contribution from both exogenous and endogenous sources while lipid yolk is solely endogenous. The endogenous protein is synthesised by Golgi complexes. Lipid yolk is formed in close association with rough endoplasmic reticulum in <i>G. mediterraneus</i> and annulate lamellae in <i>C. mustela</i> suggesting that both organelles play a role in lipid formation. Fertilised eggs of <i>Clupea harengus</i> L. were exposed to different acid pHs. Egg, perivitelline space, and yolk volumes were measured in relation to osmoregulation. The effect of acid on the morphology of the hatched larvae was also demonstrated. Jaw, branchial and skeletal abnormalities were observed. Exophthalmus condition was recorded in these larvae. Acid water causes epidermal necrosis, degeneration of the chloride cells, and swelling of the membrane-bound structures of the trunk muscle tissue at the ultrastructural level. The study demonstrates that aluminium is extremely toxic at pH 5.0 causing 99.52% cumulative mortality to <i>C. harengus</i> eggs. Ultrastructural and morphometric evidence show that aluminium causes disruption and swelling in the cell membranes of the brain and muscle tissues of <i>C. harengus</i> larvae accompanied by degeneration of mitochondrial cristae. Such effects would reduce the metabolic activity and survival potential of these larvae with subsequent consequences on recruitment success of the stock.

A study was undertaken of the occurrence and seasonal variation in the levels of zinc, cadmium and copper in the limpet Patella vulgata and green algae Enteromorpha spp., collected from Mumbles Head and Oxwich Point along the south Gower coast, S. Wales, U.K. Metal concentrations in limpets showed significant regional variation. Levels of zinc and copper in organisms collected from Mumbles, from different levels on the intertidal zone during the study period, are higher than those from Oxwich. This is not significant for cadmium. Apparent zonal variations occur regarding size and the concentration of zinc and cadmium, but not copper. Both animal weight and metal concentration showed significant seasonal variation. Minimum weight is associated with the breeding period. A drop in zinc concentration correlated with breeding activity. The highest zinc concentrations were found in the smallest limpets but cadmium and copper were found to be cumulative. Limpets were found to accumulate different metals unevenly in different organs. Zinc was found to increase before and during gonadal development and decrease after spawning. Cadmium in the gonad, digestive gland and food of limpets collected from Oxwich is higher than in those from Mumbles. An attempt was made to attribute this to cadmium concentration in green algae and/or sediments. Analysis of Enteromorpha collected from the same sites showed that levels of zinc and copper in algae from Mumbles are higher than those from Oxwich, with no significant variation in cadmium. Fluctuation in metal concentrations of algae were parallel to those in some organs of limpets. Intertidal and sublittoral sediment samples from Oxwich and Port Eynon Bays, plus sublittoral samples from the area off the south Gower coast, underwent analysis for zinc, cadmium, copper, nickel and lead. Beach sediments were found to contain low concentrations of zinc, nickel and lead and are free from cadmium and copper. Sublittoral sediments can be considered unpolluted in comparison with sediments from other areas.

No description available.

The aquatic environment contains a variety of natural and anthropogenic compounds capable of interacting with the genetic material of exposed organisms. The <SUP>32</SUP>P-postlabelling assay for the detection of DNA adducts and the micronucleus assay offer considerable potential for the qualitative and quantitative assessment of genotoxin exposure. This work describes several studies in which the two techniques were adapted for evaluation of genotoxin exposure in the benthic teleosts dab, <I>Limanda limanda</I>, turbot, <I>Scophthalmus maximus</I>, the intertidal teleost shanny, <I>Lipophrys pholis </I>and the bivalve mollusc, <I>Mytilus edulis</I>. Studies detailing the detection of DNA adducts in feral fish samples showed the suitability of the <SUP>32</SUP>P-postlabelling assay for monitoring exposure to genotoxins. Sampling of <I>L. limanda</I> from sites of contrasting contamination demonstrated the detection of DNA adducts may be related to the levels of sediment-bound contaminants. These findings were further supported by the detection of elevated levels of adducts in <I>L. pholis</I> and <I>M. edulis</I> collected from oil exposed shores following the Sea Empress incident. A series of mesocosm experiments were conducted with <I>L. limanda</I> and <I>S. maximus</I> which confirmed adduct induction by exposure to mixtures of polycyclic aromatic hydrocarbons. The suitability of the micronucleus assay for aquatic monitoring remains to be determined. No statistically significant elevations of micronuclei were detected in the peripheral erythrocytes of <I>S. maximus</I> following treatment with contaminated sediment extracts. In contrast, elevated frequencies of micronuclei were detected in the haemocytes of <I>M. edulis</I> collected from oil exposed shores following the Sea Empress incident. These studies suggest that the determination of micronuclei may not be universally applicable as a biomarker of genotoxin contamination in the aquatic environment. Finally, as a step in the development of methods for detecting point mutations in aquatic species, a number of gene sequences were characterised.

No description available.

This thesis was initiated to study the ecological effects of refinery effluent discharges by field study and comparison with their toxicity in the laboratory. The study comprises two parts which were complementary to each other: (a) field studies on ecological effects of effluent discharges in various estuarine environments including saltmarshes and rocky shores; and (b) the development of a rapid laboratory toxicity test using behavioural responses of a periwinkle as a criterion to determine whole effluent toxicity and to compare the toxicities of some important effluent components (ammonia, sulphide and phenol). An additional study was also carried out on the rhythmic behaviour of the periwinkle both in the field and in the laboratory in order to determine whether natural rhythms (i.e. tidal and circadian) could affect toxicity test results. Studies of three contrasting refinery effluents (a large water-cooled refinery effluent discharged to a Spartina marsh in Southampton Water, and two modern air-cooled refineries discharging small effluents to rocky shore areas in Milford Haven) show that effluent effects depend on the biological and physical nature of the receiving environment, effluent volume and quality, and the location of the discharge point. Information from the studies reported here and elsewhere can be used in predicting effects of future developments and in locating discharges to ensure minimum damage. To study effluent effects of individual effluent components and whole effluents, a behavioural test was developed using the periwinkle, Littorina nigrolinesta. Activity was used as the test criterion. The test proved simple, reliable, repeatable and could be carried out very rapidly. Natural activity rhythms (tidal and circadian) were investigated in the field and laboratory, and were shown not to interfere with test results. Observed rhythms appeared to be largely controlled by physical factors (tidal cycles and day/night cycles) but further experimental work would be required to determine their persistence, control and adaptive significance. Using the test to compare toxicity of whole effluents, ammonia, sulphide and phenol showed that toxicity of effluents varied from sample to sample, and that toxicities increased in the order of magnitude from ammonia -4 phenol-2), sulphide. Concentrations which depress periwinkle activity to 50% of the controls over a two-hour test period were 95, 39 and 9.6 ppm respectively. Various combinations of ammonia, sulphide and phenol resulted in an additive effect, but neither synergistic nor antagonistic reactions. Effects of effluents on whole communities could not be predicted from toxicity tests. Actual field studies of whole communities at present provide the only means of assessing whether standards of effluent quality are effective in producing acceptable levels of environmental impact. Toxicity testing and field studies may be used in a complementary manner - the former as a means of identifying toxicities of industrial components and that effluent quality is maintained, and the latter in ensuring that environmental quality is acceptable. Where unacceptable effects are observed, toxicity test data can be valuable for identifying the most toxic constituents for remedial action. Treatment of effluent streams to high standards is very costly. Ultimately a balance has to be achieved between economic considerations and acceptable environmental standards in the discharge area. Sensible decisions can only be made with suitable biological data being available.

Studies of trace metal (Cd, Cu, Fe, Mn, Ni, Pb and Zn ) distributions in Spartina anglica, Halimione portulacoides, Puccinellia maritime, Salicornia spp., Fucus vesiculosus, Enteromorpha spp., faeces of horses and sheep, Littorina littorea, saltmarsh detritus and sediments were carried out in the Burry Inlet saltmarshes (South Wales) at various sites and during four different seasons in 1976. Samples of H. portulacoides, P. maritime, F. vesiculosus, Fhteromorpha spp., detritus and sediments were also collected from one non-saltmarsh site near the mouth of the River Tawe in central Swansea. The results show that the levels of trace metals in the saltmarsh angiosperms of the Burry Inlet are comparatively low compared with the levels found in F. vesiculosus, Enteromorpha spp., faeces of horses and sheep, detritus and sediments. The levels of most metals in biota and sediments vary from site to site and show smaller variations from season to season at any one site. The results show that, with respect to the metals that were investigated, the Burry Inlet is only a slightly contaminated estuary (mostly in its middle and inner regions) whilst contamination in the River Tawe is much more severe. General features of the ecology of the saltmarshes of the Burry Inlet are also described, including some ecological factors affecting the marshes. The combined effects of Cu, Zn and Na on the growth of Spartina anglica seedlings in a solution culture factorial experiment were also included in this study. The results show that plants are considerably more vulnerable to metal toxicity at high salinities. Growth was affected by copper levels of 3.2 ppm and above in full basic nutrient solution with 5 g NaCl/litre, but by copper levels of 0.32 ppm and above with 15 g NaCl/litre. Symptoms of leaf injury and inhibition of growth resulting from high levels of NaCl and copper were clearly exhibited in test plants. There were no visible effects from zinc treatments from 0.131 to 131 ppm with 5, 15 and 25 g NaCl/litre.

No description available.

Investigation of the recycling of elements in plantations of Pinus contorta and Betula pubescens and in unforested sites in the Lower Swansea Valley showed accumulations of some heavy metal elements in the partially decomposed needle and leaf litter and in specific horizons of the mineral soil profile. The horizons of accumulation differed between elements and the extent of accumulation varied with the vegetative cover. It was shown that copper, zinc and lead are leached by rainwater in tips of copper smelter waste. The depths to which these metals move as a consequence of leaching was shown to be pH dependent. It was concluded that natural weathering of this copper waste would not reduce its toxicity to plant growth in a reasonable time period. Growth of Festuca rubra and Agrostis tenuis was shown to be inhibited on copper and lead/zinc smelter wastes from the Lower Swansea Valley in the absence of nutrient stress. In some instances this was partially alleviated by liming. In the presence of adequate nutrients a lead/zinc-tolerant variety of Festuca rubra ('Merlin') and a copper-tolerant variety of Agrostis tenuis were shown to be better suited for growth on a particular copper smelter waste than were 'normal' varieties (not specifically selected for metal tolerance) of these species. It was shown that the applied nutrient regime affected the growth and the concentrations of copper and zinc in the aerial parts of both lead/zinc-tolerant and 'normal' Festuca rubra when grown on this copper smelter waste. Use of topsoil; subsoil; sewage sludge; and metal-tolerant grass seed were coated as alternative revegetation techniques for use on copper smelter waste in the Lower Swansea Valley. The use of metal-tolerant seed was shown to be an economically viable alternative.