Clyde Estuary Research Articles

Conservation of natural resources

SynopsisAn indication is given of the importance of the Clyde Estuary for economic, scientific and aesthetic purposes. The main thrust of the World Conservation Strategy and the Conservation and Development Programme for the U.K. is explained. In the light of this the attitudes and actions of a range of agencies operating in the estuary are examined.

Bioturbation, microbial activity and sediment properties in an estuarine ecosystem

SynopsisMacrobenthic bioturbation and microbial activity can have major ecological effects on present day marine sediments some of which are also seen in the fossil record. The coastal and estuarine sediments in the Clyde Estuary area are described. They contain very high densities of benthic macroorganisms and microorganisms. These organisms have dramatic effects on the physical and chemical properties of sediments, and field and laboratory studies have shown that many geotechnical and geochemical properties of sediments are dictated by them. The effects can be on a microscale of a few millimetres horizontally or vertically (micro-spatial variation), or can have large scale consequences over hundreds of metres (macro-spatial variation).Sediment stability (shear strength and critical erosion velocity), permeability and particle sedimentation are all altered by macro-invertebrate bioturbation or microbial activity, and many chemical properties such as Eh and pH may be influenced in a similar manner.Biological activity may therefore play a major role in modifying sediment geotechnics and early sediment diagenesis. It also has direct relevance to the siting of man-made structures on the sea-bed and to sediment stability and transport in estuaries.In situseeding experiments may lead to biological control and manipulation of these most important field phenomena.

Seasonal variations in prey selection by estuarine black-headed gulls ( Larus ridibundus)

The number of black-headed gulls ( Larus ridibundus) in the Clyde Estuary is large. In summer the average density has reached 1350 gulls km −2 and in winter 180 gulls km −2. This paper compares prey selection and feeding efficiency in gulls during summer and winter on tidal flats, and considers how seasonal differences may be adaptations to cope with seasonal changes in prey availability. Gross and net rates of energy intake were highest in summer because gulls captured more of the polychaete N. diversicolor than the amphipod C. volutator. In winter, gulls selected for C. volutator and therefore an energetically less profitable diet. Throughout the year gulls selected more C. volutator relative to N. diversicolor than expected on energetic grounds and so apparently did not maximize potential net rate of energy intake. Gulls used three techniques to capture prey and made most intensive use of the ‘crouch’ technique. Crouching gulls attained a much higher net rate of energy intake than ‘upright’ or ‘paddling’ gulls. A log-linear model showed that (a) season, water depth and gull density determined feeding technique and (b) feeding technique and season independently determined foraging success and prey selection. Thus gull density and water depth acted on prey selection through imposed variations in feeding technique. Reasons for gulls selecting energetically unprofitable C. volutator and for the use of several distinct feeding techniques are discussed.

J B Stevenson, Exploring Scotland's Heritage: The Clyde Estuary and Central Region, RCAHMS, 158pp., Edinburgh, 1985,£6.95.

J B Stevenson, <i>Exploring Scotland's Heritage: The Clyde Estuary and Central Region</i>, RCAHMS, 158pp., Edinburgh, 1985,£6.95.

Depositional characteristics of estuarine alluvium: some engineering implications

Summary A review of sea level change during the Flandrian period concludes that a steady rather than oscillatory rise has occurred. In Britain the eustatic rise has been modified by isostatic effects; these are reflected in slightly different sea level curves for the Severn, Thames and Clyde estuaries. Higher undrained shear strengths recorded in the outer Thames estuary and taken to imply a transgressive/regressive sequence are inconclusive of an oscillatory curve; such desiccated horizons are not present in the Severn Levels. The pattern of sea level rise is reflected in the nature of the sediment. The characteristics of a silty sand deposited during a period of rapid sea level rise and overlain by a laminated mud/silty sand sequence with occasional peat horizons are discussed. A proposed description for laminae thickness is presented. Bioturbation may modify the sediment character of tidal river environments. Tidal pills, common in salt marsh areas, are difficult to detect when infilled. The geotechnical affects of the features are related to their different consolidation properties and skin friction compared with the normally deposited (layered) sediments. The importance of laminations in soils to lateral pore water dissipation and the implications for road embankment construction are considered.

Long Term Monitoring of the Macrobenthos of the Upper Clyde Estuary

The sublittoral macrobenthic invertebrate populations of the Upper Clyde Estuary are described. The estuary has a long history of organic pollution. The long term changes in species composition, faunal density and dominance patterns between 1974 and 1980 are presented. The fauna is dominated by brackish, pollution tolerant oligochaetes and polychaetes. Fluctuations in populations can be related to both seasonal variation in environmental conditions and long term improvements in water quality through a reduction in pollution loading to the estuary.

Metal pollution in marine sediment cores from the West Coast of Scotland

Levels of the trace metals lead, zinc, copper and chromium were measured in sediment cores from sea lochs Gareloch and Loch Goil in the Clyde Sea Area and from the comparatively remote Minch off the north-west coast of Scotland. Concentrations (CH 3CO 2H/NH 2OH·HCl extractable fraction) of up to 520 μg/g (Pb), 640 μg/g (Zn), 260 μg/g (Cr) and 730 μg/g (Pb), 630 μg/g (Zn), 760 μg/g (Cr) were found in the top 15 cm of sediment from Loch Goil and Gareloch, respectively, but maximum concentrations in the Minch reached only 10·6 μg/g (Pb) and 8·5 μg/g (Zn). Enrichment factors of 17–30 for 6·3–7·8 for Zn, 7·5–8·9 for Cr and 1·2–3 for Cu, reflecting anthropogenic metal pollution, were found for upper layers of Loch Goil sediment relative to background concentrations as removed by CH 3CO 2H/NH 2OH . HCl leaching. Radionuclide studies suggest that bioturbational effects have obscured the sedimentary chronological record of pollutant metal input in the Clyde sea lochs and the Minch. However, consideration of the metal inventories and concentrations in the Clyde sea loch sediments in the light of various potential contributory sources shows that the major input of pollutant metals has been via the Clyde Estuary and the River Clyde. Inventories of ‘excess’ Pb and Zn in Minch sediment are < 1% of those of the Clyde sea lochs and only 5–7% of the integrated atmospheric deposition alone for the Glasgow area as deduced from a Loch Lomond core.

Variations in Densities of Invertebrate Benthos of the Clyde Estuary Tidal Flats

Abstract The Clyde Estuary is recognised as an important area for overwintering flocks of ducks and waders (Smyth et al., 1974. Here we draw attention to some of the spatial and temporal variations in the invertebrate populations on which these birds feed. Smyth et al. (1977) discuss possible relationships between the bird populations and their invertebrate prey. A 12-month survey, 1976–77, provides the main information on numbers of feeding birds (Halliday, 1978), complemented by sampling over the estuarine flats for invertebrate prey species and for chemical environmental factors: salinity, organic carbon, organic nitrogen, dissolved oxygen, as well as sediment grades. Although there is no constant monitoring shceme for the estuarine flats, a series of surveys provide data over the period 1973–1981.

The composition and biosynthesis of lipids in Thysanoessa raschi from the Clyde Estuary, Scotland

The lipid composition and biosynthesising activity of Thysanoessa raschi collected from the Clyde Estuary, Scotland, in May 1981 were examined. Triacylglycerols were the major lipid class present, although 16.7% of the total lipid were wax esters in which phytol was the dominant fatty alcohol. The thoracic contents (“hepatopancreas”) of the krill were capable of biosynthesising lipids in vitro from various labelled substrates. Radioactivity from [1-14C] palmitic acid was incorporated into lipids in the order phospholipids>triacylglycerols>wax esters; the bulk of the radioactivity was present in all cases in the fatty acyl moieties of the lipids. [U-14C] glucose labelled lipids in the order phospholipids>triacylglycerols>free fatty acids> was esters; in the first two lipids the radioactivity was mainly in the glycerol moieties, whereas in was esters it was solely in the fatty acyl moieties. The extent of labelling of these lipids from [U-14C] alanine was less than that from [U-14C] glucose, but the pattern of labelling was generally similar. More than 90% of the radioactivity incorporated into total lipid from 3H2O was present in free fatty acids from which it was calculated that the “hepatopancreas” of T. raschi can synthesise 2.5 μg of fatty acid per hour at 15°C. This value is approximately three times lower than that previously determined for T. inermis from Balsfjorden, northern Norway. The results are discussed in terms of the sources of the dietary lipids of krill and the role of endogenous biosynthesis in contributing to its lipid reserves.

A finite-element model of pollution in the Clyde estuary: formulation, validation and utilisation

A one-dimensional, finite-element computer model of the pollution mechanisms in the Clyde Estuary is described and tested. Two examples are presented of its routine use in pollution management.

Heterotrophic nutrition inMelosira nummuloides, a possible role in affecting distribution in the Clyde Estuary

The benthic centric diatom Melosira nummuloides dominated sites of heavy pollution on the Clyde Estuary, occurring in conditions conducive to heterotrophic growth—positive correlation with BOD and suspended solids and negative correlation against light penetration of the water. A clone (Renf-1) of the organism, isolated from a polluted site and rendered axenic grew in culture through a range of light intensities, with compensating light below 150 lx. Some initial growth occurred in the dark on medium enriched with site water. Growth was best at a salinity of 10‰. for samples adapted to 4, 10 and 12‰.. Addition of certain amino acids to the medium caused significant enhancement of growth, due to leucine, arginine and serine at 0 klx, leucine, arginine and glutamic acid at 0·1 klx and glutamic acid at 3·3 klx. Eight amino acids were accumulated by carrier mediated methods in the dark. Kinetics for arginine uptake were best (low K m) in the dark and at a salinity of 10‰, with a corresponding greater growth e...

Dietary mercury in the Glasgow area

A survey of the mercury content of the diet in the Glasgow area is described. A higher intake of mercury (60 μg/day/person) than that expected is found. However, there does not appear to be any concentration of mercury by man. None of the foodstuffs show any exceptional mercury content. Fish levels are similar to other foods and a preliminary sample of shellfish from the Clyde estuary, a contaminated area, shown no sign of their having concentrated mercury to any significant degree.

THE RESTORATION OF THE SCOTTISH CATHOLIC HIERARCHY IN 1878

During the half-century from the Emancipation Act of 1829 to the Restoration of the Hierarchy in 1878, the Catholic Church in Scotland experienced changes more profound and more enduring than anything it had known since the unexpected triumph of the Calvinist faction in the sixteenth-century religious revolution. The emancipation legislation of 13 April 18291 had given to Scots Catholics, as well as to the Catholics of England, the security of a recognised place in the national life for their corporate existence, something which had been denied them for two and a half centuries and, in consequence, a new mood of optimism and expansion became apparent, which found expression in new churches, schools, religious orders, societies and institutions, a renewal of devotional and liturgical life and other manifestations of vitality. The large-scale development of the industrial belt which stretched across Scotland from the Clyde estuary to Angus, Fife and the Lothians, attracted men and women from the traditionally Catholic districts in the north-east, the north-west and the south-west of Scotland and, in vast numbers they came from across the Irish Sea. The geographical distribution and balance of Scottish Catholicism, which had remained largely unaltered for more than two centuries was now radically changed. The main centres of Catholic life in Scotland would

The recovery of the polluted Clyde Estuary

SynopsisThe Clyde Estuary is recovering from gross pollution inherited from the age of the Industrial Revolution.It is necessary now to establish the degree of recovery and determine any subsequent effects of future planning consents. Documentation on water quality was subjective until the 1960's when quantitative studies on pollution levels commenced.Much attention has been paid to dissolved oxygen (DO) levels in the estuary. The changes in the DO regime over the last ten years have been quantified with the help of multiple regression techniques. The use of these techniques in establishing the changes resulting from improvements to Dalmarnock and Paisley sewage treatment works is described. Deterministic models, based on the diffusion-convection equation, have been used to predict future DO conditions. The theoretical base of these models is outlined and examples are given of the use of the models in predicting the effects of possible developments on the estuary.Biological monitoring has also been utilised to assess estuarine recovery. Benthic data has been accumulated since 1967. Regular surveys highlight improvements in species richness, diversity and stability. Spatial and temporal population variation was investigated and the salinity tolerances of the species considered. Fish life is increasing and is now present for much of the year, although salmon are still excluded from the upper Clyde system. The lower estuary remains an important overwintering feeding ground for wader populations.

A faecal sterol survey in the Clyde Estuary

5β-Stanols, and in particular coprostanol, which is one of the principal sterols of human sewage, show promise as chemical tracers of faecal pollution in estuaries. In the present survey, coprostanol has been measured gas chromatographically in the waters and sediments of the Clyde Estuary. Thus, the bottom sediments contained 0.1–14 ppm of coprostanol (5β-cholestan-3β-ol) together with the corresponding 24-methyl- and 24-ethyl-5β-stanols, while in the seawater samples, the coprostanol concentrations closely paralled the faecal coliform counts. Overall, the amounts of coprostanol correlate well with the location and amounts of the known inputs of sewage from outfalls and dumping.

Chlorine-containing pesticides and polychlorinated biphenyls in British coastal waters

Gas chromatographic procedures have been developed for the determination of PCBs, DDT residues (∑DDT) and dieldrin in seawater, marine sediments and marine air. In order to minimize contamination, chlorinated hydrocarbons were concentrated from seawater in situ using a towed ‘fish’. Sampling was carried out in 1974 in the eastern Irish Sea, the Firth of Clyde, northern Scottish coastal waters, the English Channel and North Sea. Concentrations of PCBs in areas subject to least pollution averaged ~0·2 ng l −1, a value considerably lower than that found by most previous workers, which may reflect a continuation of the decline in their surface concentration reported by Harvey et al., (1974). The chromatograms of the PCB concentrates from all these areas closely matched that of Aroclor 1254. Higher concentrations (up to 1·5 ng l −1) were found in the Clyde Estuary, Liverpool Bay and the North Sea, particularly in the vicinity of sludge dumping areas, and the chromatograms of samples from such areas often matched that of Aroclor 1260. The levels of ∑DDT in the English Channel and northern Scottish waters ranged from below detection level (< 0·01 ng l −1) to 0·03 ng l −1. Samples from the Liverpool Bay area and the mouth of the River Wyre were considerably higher (~0·2 ng l −1); such samples were also the richest in dieldrin (0·04 – 0·3 ng l −1) which was usually at, or below, the detection limit (0·01 ng l −1) in samples from offshore areas. Determinations of chlorinated hydrocarbons were carried out on sediments and suspended particulates from the Irish Sea; in general, the levels in the latter were considerably higher than those in the former. A limited number of estimations were carried out on marine air, these showed the presence of 0·2 – 0·8 ng PCBs m −3, usually matching a mixture of Aroclor 1254 and 1242.

Sample disturbance in soft alluvial Clyde Estuary clay : Technical note. 12F, 6R. CAN. GEOTECH. J. V11, N4, NOV. 1974, P651–660

Sample disturbance in soft alluvial Clyde Estuary clay : Technical note. 12F, 6R. CAN. GEOTECH. J. V11, N4, NOV. 1974, P651–660

Intertidal organisms of an industrialized estuary

A study of the intertidal organisms of the Clyde Estuary is being undertaken to assess the effects of changing levels of pollution and to relate to these and other changes the distribution of important winter flocks of waders and ducks.

Sample Disturbance in Soft Alluvial Clyde Estuary Clay

The alluvium of the Clyde Estuary provides the foundation material for a number of medium rise developments in the Glasgow area. Standard site investigation and testing techniques often result in an expensive foundation design involving piling. A more sophisticated investigation conducted at Laurieston, has afforded a chance to compare the disturbance due to different qualities of sampling. The degree of disturbance to macro- and microstructure has been assessed using standard photographic techniques and a scanning electron microscope. The effect of disturbance on shear strength has been measured using hand vane and triaxial tests; and on consolidation and compression parameters using Rowe cells of different sizes. On the basis of the standard and the improved site investigations two foundation designs have been prepared and their cost compared.

Sediment Balance of Clyde Estuary

Active research in sediment transport should lead to the solution of practical engineering problems. With this in mind, the development of the Clyde Estuary in Scotland in relation to its sedimentation is considered. The historical facts relating to the changes in regime of the Estuary are listed and lead up to the present (1969) conditions. The results of 3 years of detailed research into the sediment transport conditions of the major rivers draining into the Estuary are presented. These include comparison of annual sediment loads computed by two different methods and the particle size of the transported sediment, together with typical graphs of the weekly suspended sediment loads transported by the rivers Clyde, White Cart, and Kelvin. The results of this research are then compared to the historical data and conclusions drawn.