Comments are presented on the continuing need for a better taxonomy of ferns as a basis for experimental studies of all kinds; some aspects of the ecology of Malesian ferns are also considered.

Twelve species of trematode are described from 70 gulls of 5 species examined at Loch Leven. Observations on these trematodes are given with additional morphological details. The environmental origins of the parasites are discussed and related to the habits of the hosts.

Common dogwhelks (Nucella lapillus) show a characteristic response to exposure to tributyltin compounds. Females develop male sexual characteristics, a phenomenon termed imposex. Dogwhelks have been collected for assesment of imposex from sites throughout Sullom Voe and Yell Sound in 1987, 1990 and 1991.

Results of the 1991 survey have indicated that dogwhelks were completely absent from the terminal area, on the promontory of Calback Ness. The degree of imposex was highest in the population from Kames, the site closest to the terminal. Juveniles were completely absent from this site. Incidence of imposex was high in populations throughout the Voe and 91% of the females examined from within the Voe were reproductively unviable due to blockage of their reproductive tracts with vas deferens tissue. Outside the Voe, in the well flushed waters of Yell Sound, imposex was much lower, but only fell to levels associated with populations from areas distant from tributyltin (TBT) contamination in the two most northerly sites surveyed.

Results of the survey have indicated that activities associated with the oil terminal are the source of TBT contamination to the area, and that contamination arising from the terminal operations has not only affected dogwhelks in Sullom Voe, but populations throughout Yell Sound.

Comparison of the imposex levels from 1987 and 1990 data indicates that the reproductive capacity of females has progressively declined and that populations within the Voe are gradually being eliminated. Forty-six percent of females sampled from populations within the Voe were sterile in 1987, compared to 65% in 1990, and 91% in 1991. In 1987, both adult and juvenile dogwhelks were present in the jetty area, although 94.5% of the females were sterile. In 1990, juveniles were absent from this area, and all females were sterile. No dogwhelks were found in the terminal area during the 1991 survey and, at Kames, the next closest site, juveniles were absent.

The major impact of artificial radioactive material on the oceans has been as a potential pollutant, and, in particular, concern has centred on the public health problems that might arise through human exploitation of marine environments. This public health problem has been an important stimulus to marine pollution methodology. The development and deployment of critical path analysis techniques to the control of this material and to the assessment of its significance for human radiation exposure (Preston 1969; Foster, Ophel and Preston 1971; Slansky 1971) not only exemplifies the control of a chemical pollutant but has served as a stimulus to produce much of the basic physical, chemical and biological data required for its proper implementation. In more recent years the advantages which labelled environments confer for studies of a much wider physical, chemical or biological nature are being increasingly recognised (Natn. Sci. Fdn 1971; Volchok et al. 1971; Lowman, Rice and Richards 1971; Duursma, 1972; Preston, Jefferies and Pentreath 1972,) and many of the tools of nuclear technology, radio-isotopes, reactor propulsion systems, isotope power sources, neutron activation analysis techniques, etc., will enjoy an increasingly important role in oceanography, not only in basic investigations but also in the rational exploitation of marine resources.

This paper is a first report on the Echiurids and Sipunculids of Zanzibar, and deals with the material collected by Dr J. D. Robertson during the years 1948–1950 on the shores of Zanzibar, supplemented with a few dredgings. These collections contained two species of Echiurids and eighteen species and varieties of Sipunculids. Of these, one Echiurid (Ochetostoma zanzibarense) and two Sipunculids (Dendrostoma robertsoni and Phascolion robertsoni) are described as new species. Six others are recorded from the area for the first time. The list of species now described from the Zanzibar area contains eight species of Echiurids and twenty-four species and varieties of Sipunculids. Rich as the area is in species, it is even more remarkable for the numbers of individuals, some species being dominant forms in the population.

Senecio vernalis and Calendula arvensis (Asteraceae) are two annuals which grow together in mixed populations and flower in Israel soon after the first winter rains. They were found to be potential selfers, without a self-incompatibility system. The average pollen production per floret and per flowering head was compared with the percentage of pollen with a known function or allocation: pollen grains deposited on stigmas, grains remaining in wilted florets, and non-viable pollen—overall totals of 24% in S. vernalis, 36% in C. arvensis. The remaining pollen (76% & 64%) is distributed according to fluctuating ecological factors, biotic (insects, etc.) and abiotic (rain, wind etc.). The outbreeding potential was assessed by study of the flowering phenology of florets and heads and the behaviour of pollinating insects, mainly flies. Considerable differences were found between the two species in most parameters. In both, especially C. arvensis, the probability of foreign pollen (i.e. pollen not from the same head) reaching the stigmas is very small. Pollenovule ratios for heads were found to be comparatively higher than those recorded for flowers with a similar rate of outbreeding. The efficiency of pollen transfer in the capitulum of the Asteraceae and the large investment in pollen are discussed.

Caryedon gonagra (F.) is a beetle pest in ground nut kernels and occurs in this country in stored nuts. The karyotype has been investigated in both sexes. The chromosome complement of 2n = i8 includes a heteromorphic sex-determining pair—a large metacentric X and a small spherical Y. Particular attention has been paid to the sex bivalent in the male since study of this character alone may prove sufficiently diagnostic in species separation in closely related members of the Bruchidae.

Known amounts of the Rous No. 1 sarcoma virus were injected into the legs of chicks. The birds were killed, the legs extracted, and the virus content determined at intervals. Controls showed complete recovery of the virus by the methods used. After 16 hours the amount of virus was 1 per cent, or less of the injected amount, and this low level remained until about 70 hours, when an increased amount of virus suddenly appeared. This is taken to imply that, like the necrotising viruses, those of the fowl sarcoma multiply in the cell in a non-infective and probably disaggregated form. These times agree well with previous histological findings. The implications of such a method of reproduction are discussed.

The introduction indicates the legal position relative to the control of discharges to the Forth estuary. Details are given of the volumes of the known sources of pollution, in 1958; chemical, bacteriological and biological data then follow relative to a survey carried out in August and September of that year. The conclusions, drawn from the 1958 Survey, emphasised the gross pollution existing at that time, and suggested methods whereby the pollution might be reduced. Section 4 of the paper discusses the results of chemical, biological, bacteriological and hydrographical surveys carried out since 1962. The results stress the deterioration in conditions in the estuary compared with the earlier survey, and in particular, the lower dissolved oxygen concentration in inshore waters and the increase in the Coliform and Escherichia coli counts in certain areas. Isolation of Salmonella species implies the possible health hazards existing at the present time. Work so far carried out in respect of the determination of heavy metal concentrations in core samples taken in the intertidal zone along the shore has indicated relatively high concentrations of certain metals and their effect on the ecology of the estuary has yet to be fully assessed. Float tests made over a period emphasise the tendency for the sewage discharges to be confined to inshore waters, resulting in the gross pollution of certain beaches. Present information stresses the need for the continuance of the monitoring programme.

The results of our first experiment in applying fertilizers to a small sealoch, Loch Craiglin (Gross, 1947; Marshall, 1947; Orr, 1947; Raymont, 1947; for references see No. V), were sufficiently encouraging to justify an extension of the work to a larger area. Loch Craiglin provided a good site for preliminary investigations because it could be easily enclosed and, for all practical purposes, isolated from the main loch. The conditions in Loch Craiglin were, however, atypical in many respects, and it seemed desirable that the results obtained there should be tested by investigations in a body of water (1) sufficiently large to reduce the extreme fluctuations in salinity, pH and other factors, encountered in Loch Craiglin; (2) sufficiently deep to reduce the proportion of seaweed to phytoplankton in the productivity of the cultivated area; and (3) with its connection with the main loch or the sea left undammed, to test the possibilities of fertilizer application in open, i.e. not artificially enclosed, sea-lochs.

This paper describes the isolation and characterization of the polysaccharides synthesized by the unicellular organism, Monodus subterraneus. Complete extraction of polysaccharide material proved difficult and the method finally adopted, after removal of colouring matter by immersion in dimethyl sulphoxide, was successive extractions with (i) cold water, (ii) hot water, (iii) aqueous ethanol, (iv) chlorite solution, and (v) dilute alkali. The major polysaccharide, isolated from (v), is a glucan. It was shown by periodate oxidation, methylation and enzymic studies to consist mainly of β-l, 4-linked glucose units. The presence of a small proportion of β-1, 3-linked glucose units, either incorporated with the β-1, 4-linked units in a single polymer of the lichenin-type or in a separate polymer of the laminarin-type, was also established. Further small quantities of this mixed glucan were also deposited from (ii) and from (iii) on keeping these extracts in the cold. Heterogeneous crude polysaccharide material was isolated from (i), (ii), (iii) and (iv) by alcohol precipitation. The sugars present in these various precipitates and their respective oxopolysaccharides were identified chromatographically, and, in the case of the major constituents, separated and characterized as crystalline derivatives. The polysaccharide extracted by cold water was found to contain glucose, mannose, galactose, xylose and 12 per cent of sulphate; that extracted by hot water comprised glucose (major), galactose (major), and possibly fucose; and that extracted by chlorite solution consisted of glucose (major), xylose (major), ribose and a trace of galactose.

A checklist of 576 species of lepidoptera has been produced for the islands of Rhum, Canna, Coll and Colonsay. Within these islands the status and habitat requirements of selected species, including some Scottish rarities, are discussed. Brief mention is made of some species which occur in other islands but which have not been recorded in the four sample islands. The status of Zygaenidae is discussed. This family is of outstanding interest in that five of the seven species recorded in Scotland occur in the Inner Hebrides. One is restricted to Skye, whilst another now appears to be confined in Britain to the Isles of Mull and Ulva.

The distribution of Bathyporeia pilosa is discussed in relation to variations in a number of physical and chemical characters of the sediment on eight transects. Relationships were found between density and median particle diameter, silt content, and water content of the sediment, but stability of the beach appeared to be the main parameter influencing B. pilosa distribution. Sediment preference experiments showed that sediments varied in attractiveness, medium and fine grade sands being preferred: coarse sands and muds were avoided as were sediments with a high silt and clay content. Attractiveness in laboratory conditions was not correlated with observed field densities in some cases, indicating that other parameters were important in determining the distribution. Studies of swimming behaviour demonstrated the importance of current speed during the pelagic phase and it is concluded that hydrological conditions may be as important as sedimentary characteristics in the determination of the distribution of this species.

The first part of the fifth and final day of Acidic Deposition: Its Nature and Impacts was devoted to a discussion of three questions:

(1) What is now known of the nature and impacts of acidic deposition (recognising that effects on materials and buildings were being discussed for the first time in the series of international conferences of which Acidic Deposition was the latest)?

(2) Where are the gaps in knowledge perceived to be?

(3) Is it necessary to fill some or all of the gaps/are the gaps worth filling?

To a significant extent the answers to these questions influence the reactions of the lay public and their political representatives, but it has to be recognised that the politics of acidic deposition have, on occasion, outpaced scientific comprehension largely because of the inability/unwillingness of scientists to communicate. This is a serious weakness, particularly in relation to pollution and other environmental issues where the problems are complex and cannot be conceived in terms of black and white.

The birthcoats of both coarse and fine-fleeced sheep can be separated into different types of fibres. Each type of fibre is formed by a particular type of follicle. The ratios of the different types of follicles are the same in all the breeds of British sheep studied, and therefore variation of the follicle population can be excluded as a factor in the evolution of the British types of fleeces. Some birthcoats are coarse, others are fine, and some birthcoats are short, others long. The two differences are independent both developmentally and genetically. In the few lambs studied, the coarse type is dominant over the fine type, and the short type is dominant over the long type. It is suggested that the Down shortwool fleece evolved along a different route from that which gave rise to the Merino shortwool fleece.

Some time ago, in a short article on maturation in the liver fluke Fasciola hepatica (L.), Sanderson (1953) suggested that development might be gynogenetic on the grounds that she was unable to find any second maturation division nor any polar bodies. Nevertheless, the presence of two large “pronuclei” seemed to point to normal zygogenesis. Unable to come to any definite conclusion the author decided to investigate maturation in another digenetic trematode, Haplometra cylindracea (Zeder 1800) when ample supplies came to hand from class dissections of frogs.

A general survey of the biomass of the benthic infauna of the Clyde Sea Area and the distribution and abundance of the dominant species throughout the area, based on data from surveys undertaken in 1972 and 1974, is described. Recent surveys of the distribution of species along a well-defined gradient of organic enrichment on the Garroch Head sewage sludge disposal grounds in the central Firth of Clyde are used comparatively to suggest that benthic populations in the inner sea lochs, Kilbrannan Sound and in areas along the Ayrshire coast are markedly enriched. It is suggested that this enrichment may be caused by a general eutrophication of the Clyde Sea Area enhancing the effects of localised carbon inputs from urban areas.

During 1970 a pilot-scale water treatment plant was operated at Loch Leven to investigate the feasibility of producing a potable water from such a source.

The study showed that while no particular problems were encountered in producing a water of satisfactory chemical quality it was rarely possible to produce a water of satisfactory biological quality. This was due to the fact that the water treatment processes investigated were unable to retain sufficiently large numbers of the small algae so characteristic of Loch Leven and as a consequence the finished water nearly always contained unacceptably high numbers of algae.

1. A general survey of the sub-tidal populations of Modiolus modiolus (L.) to a depth of 18 or 21 m was carried out in five Shetland voes, with particular emphasis in Sullom Voe. Estimations of density distribution and growth rate were made.

2. Commencing in June 1976 samples were collected at three-monthly intervals from two sites in Sullom Voe, and from one site in Cat Firth in 1977, to investigate seasonal variations in flesh and biochemical content. The data indicate that Shetland Modiolus are generally similar in their biology to those from Scottish lochs, and are liable to considerable variation between and within populations, with groups responding to environmental variations of very local extent.

3. A list of animals found associated with Modiolus and their byssus complexes is given. As no effort was made to collect the fauna systematically or quantitatively, the list is not comprehensive.

The distinctive ecological elements of the machair environment, calcareous sand and an oceanic climate, which combine to give a lime-rich but unstable habitat, in which machair vegetation develops, are discussed initially. A number of different studies employing both phytosociological and ecological approaches, and drawing data from machairs in the Uists, Monach Islands and South Harris, are summarized. Based upon these, the main characteristics of machair vegetation and its key ecological relationships are described. Finally a model of machair vegetation is advanced in which two distinct types of vegetation, ‘dune’ and ‘pasture’ are recognized, and patterns of vegetation development are explained by means of ‘phases’ and ‘sequences’, terms applied to describe relative location of types of vegetation in both time and space.