Nuclepore membranes of known pore size and porosity, attached to small glass chambers were used to investigate the mechanism of humidity-induced convection found in Phragmites and other species. The convective flow of gases and the development of static pressures were studied in relation to a variety of conditions imposed on opposite sides of the membrane. Data were obtained in relation to pore size (0.015 to 3 μm diameter) and porosity, temperature and humidity gradients, membrane area and resistance to venting.

A humidity gradient across the Nuclepore membranes was far more effective than a temperature gradient per se for inducing flow; also pores of the order 0.2 μm diameter were the most effective. With a steep enough humidity gradient, however, significant flows could also be induced across pores as large as 2 μm diameter. The results accord with previous experiments and observations on Phragmites and with the mathematical treatment of the mechanism. It is concluded that humidity-induced convection should play a greater role than thermal transpiration (thermo-osmosis) in effecting convections in Phragmites and other non-floating-leaved species.

Ichthyogeography is the section of biogeography which seeks to interpret fish biodiversity in terms of present and past distributions and abundance. It can also have practical applications in fisheries management and conservation. There are thought to be more than one thousand species of fish in the 40 or so major rivers of the Guinea–Congo rain forest region, with correspondingly high levels of endemicity. In the Congo or Zaire river basin alone, the proportion of endemic fish species may exceed 80% (from a total of >690), but many more taxonomic and distributional data remain to be gathered.

Unlike terrestrial vertebrates, the diverse freshwater fishes of Guinea–Congo evidently have distributions which are closely confined by hydrography. Hence, fish distributions may be of particular help in corroborating or refuting postulated geological events, patterns and processes and in explaining associated aspects of rainforest evolution. From the 19th century until now, the ichthyogeography of Guinea–Congo has been diagnosed largely in terms of presumed post-Miocene geological sequences of fish taxa and their past and recent dispersal in relation to particular hydrological conditions: mainly riverine volume discharge, salinity and temperature. From this, the fish fauna is, by convention, divided into ‘provinces’ established on endemism, palaeogeography and supposed physical or ecological barriers to dispersal. However, in this paper it is argued that the traditional ichthyogeographical accounts which highlight endemism and dispersal are generally flawed. It is argued here that historical patterns of fish distribution can only be fully understood if phyletic (cladistic) data are taken into consideration. While Upper and Lower Guinea and the Zaïre basin may be defined in part on the basis of endemism there is a lack of taxonomic and distributional evidence to show that Guinea–Congo is itself a cohesive ichthyogeographical unit.

There is clearly a need for comparisons with fish distributions outside the rain forest zone of Guinea–Congo. African inter-provincial, trans-continental and inter-continental comparisons reveal distribution patterns which may relate more to pre-Miocene rather than post-Miocene geology or present-day rain forest ecology. Continental drift, notably between Africa and South America, probably led to the separation 85 million years ago of previously united fish populations. This may account for recent higher-level phyletic correspondences between the separate rain forest fish faunas of Africa and the neotropics.

Last, the so-called ‘marine intrusive’ fishes – which are normally excluded from zoogeographical consideration – merit a careful re-evaluation. While they may be regarded as an inconvenience in developing scientific hypotheses, such intrusives can comprise a remarkable 30% or more of the riverine fish fauna in Guinea–Congo. It seems that the widely accepted ecological divisions between marine and ‘primary freshwater’ fishes are not as clear-cut as has been supposed. In addition, zoogeographically critical marine, trans-Atlantic, phyletic relationships apparently exist. These are probably best interpreted by using area cladograms in the context of ocean basin development, rather than by referring solely to marine fish dispersal and the traditional continental and provincial ichthyogeography of Guinea–Congo.

The technical and scientific problems of ecological monitoring at Port Valdez, Alaska are discussed. Particular attention is given to the problems created by lack of understanding of the processes of the Alaskan Rocky Shore ecosystem and the paucity of data on the natural stresses controlling temporal and spatial variation in populations. In addition, taxonomic difficulties, particularly in the littoral macroalgae, further compound survey problems.

The paper suggests some possible approaches that could be applied and is illustrated by data taken on baseline surveys made in 1977. Particular attention is given to unexpected age size distributions in the limpet Collisella pelta.

The Clyde Estuary is recovering from gross pollution. In the early 1970s high densities of a small number of species of intertidal invertebrates tolerant of organic enrichment and low oxygen levels provided rich feeding for large numbers of dunlin, redshank, lapwing, oystercatcher and curlew. Winter numbers of the first three species have now declined considerably. The declines cannot be attributed to national changes in wader numbers and are not due to changes in breeding habitats or lack of reproductive success in particular regions, since each species wintering on the Clyde Estuary breeds in a different area. The most likely explanation of the decline, which is most pronounced in the species highly dependent on Corophium volutator, is either that reduced organic pollution has reduced the densities of the main prey, or that higher oxygen levels over the mudflats have allowed fish, particularly flounders, to enter the estuary and compete with the waders for the available prey. Although there is evidence of some birds having moved to other wintering areas, the fate of most birds is unknown.

The distribution of about thirty species of warm water siphonophores over the period 1947–1964 to the north-west and north of the British Isles is used to give a generalized picture of the path of the Lusitanian stream. These species, which originate much further south, are relatively intolerent to change of environment and the distances they are carried can be associated with the degree of inflow on a yearly and seasonal basis.

Grouping the findings into four series of years over the 18 year period shows an increase in their northerly distribution from 1947 reaching a maximum in 1953 and 1954. This has since been maintained, with annual variations, at least until 1963. It is hoped that the data presented here can be used when comparing future studies of climatic change with the distribution of water masses.

The mechanism by which irradiation produces gross re-arrangements of chromosomes (inversions, translocations, deletions) is now generally believed to occur in two steps: (a) breakage of one or more chromosomes, yielding two or more points of breakage; and (b) reunion of broken ends in a novel combination. Thus the frequency with which a given treatment produces re-arrangements depends not only on the number of breaks produced, but on the circumstances under which reunion takes place. In Drosophila the fertilized ovum seems to offer particularly favourable conditions for breaks produced in the mature spermatozoon to join up into new combinations. In immature germ-cells, on the other hand, re-arrangements are much less readily produced by irradiation (Muller, 1930; Shapiro and Neuhaus, 1933; Shapiro, 1937; Glass, 1939). Evidence for the occurrence of spontaneous or induced re-arrangements in somatic cells of Drosophila is very scanty.

The German professor of physiology, August Pütter, is remembered especially for his theories on the nutrition of marine animals. His major papers, ‘The nutrition of aquatic animals’ and ‘Organic matter in the sea’, appeared in 1907, followed by numerous other papers until 1925. He died about 1935. Ranson (1935,1936), Assistant at the Paris Museum of Natural History, gives the essence of the works of Pütter as follows (translated from the French):

1. Aquatic animals are not able to capture by the means which they possess enough organisms or planktonic materials to cover their nutritional requirements.

2. There is a very large amount of dissolved organic matter in sea water which, alone, is broadly sufficient to sustain the needs of the animals.

3. This soluble organic matter has as its source the activity of algae and bacteria.

4. The fundamental part of the nutritional requirements of aquatic animals is derived from dissolved organic matter; plankton plays only a secondary role.

5. Aquatic animals absorb this organic matter not only by their digestive apparatus which is often rudimentary, but by the whole exterior surface of their bodies and especially by simple epithelial tissues such as the gills.

Fouling communities typical of shallow water inshore sites were found at three locations in the Moray Firth. At each, an initial background cover of solitary tubeworms and barnacles was overgrown by secondary fouling organisms. On the piles of Nigg jetty, overgrowth consisted of mussels in the depth range 0–6 m and hydroids, sponges, soft corals and anemones from 6–26 m. Buoys in the approaches to Cromarty Firth were completely covered by a mixture of algae and mussels. Sunlit areas of the float cleaned annually bore a diverse algal cover, whereas uncleaned shaded areas and the freely hanging chain had three-year-old mussels up to 7 cm long. Mussel fouling extended down the chain to within 1 m of the seabed at 26 m depth. Concrete anchor blocks on the seabed were covered with solitary tubeworms and hydroids. Steel piled platforms in the Beatrice Field were completely fouled after four years. Mussels and seaweeds were abundant from 0–5 m. In the depth range 8–35 m the background calcareous layer was overgrown by soft corals up to 10 cm long and hydroids. From 35 m to the seabed at 46 m, soft overgrowth was provided mainly by hydroids and ascidians, with only a few small corals.

Ecological conditions for intergametophytic mating and interspecific hybridisation in the clubmosses are discussed. Several features, including the number of recorded hybrids, records of gametophyte population densities, and conditions for movement of the male gamete in the soil, indicate that intergametophytic mating in Lycopodium is not especially impeded by the subterranean habitat, as has been commonly assumed. The evidence from one site indicates highly effective spore dispersal, and a greater ecological tolerance than expected for the species involved. Two cases are discussed in which hybrids have been formed between ecologically and/or taxonomically very different parent species, in the absence of one parent sporophyte, or with one of the parent species sporophyte poorly adapted to the hybrid habitat. The protected, relatively uniform, subterranean gametophyte habitat is thought to account for successful gametophyte growth and hybridisation between species of widely different sporophyte ecology.

We have studied morphological and biochemical aspects of storage reserves and their degradation in fern spores during the germination process. The results presented here are concerned with the fate of lipid, protein and phytic acid. Depletion of lipid reserves and breakdown of lipid bodies was directly correlated with increased activity of glyoxylate cycle enzymes during early stages of germination. Degradation of protein reserves coincided with the depletion of salt soluble proteins (globulins) from the spores and was related to the time when high activity of aminopeptidase and carboxypeptidase was observed. Lipid and protein appeared to play an important role in germination. Phytic acid reserves were present in the spore and were hydrolysed by phytase after germination occurred. This storage material was implicated in growth of the prothallus.

The programme for ornithological monitoring in Shetland has concentrated on selected species of cliffnesting seabirds and inshore waterfowl. Sample study sites throughout Shetland have been selected and standard counting methods derived. These have taken account of factors such as logistics and accessibility, the effects of weather and observer error and of the seasonal and diurnal variations in the numbers of birds.

Changes in seabird and waterfowl numbers between 1975–79 have been observed. These, with the exception of the bird mortality following the Esso Bernicia oil spill, have been attributed to natural variation. From the scale and local differences between these as yet short-term observations, estimates are presented of the minimum percentage change required in either numbers of birds or their nests before such natural variation is exceeded.

The problems of interpreting changes in numbers are discussed.

The number of dead birds picked up in Sullom Voe after the Esso Bernicia spill corresponded closely to that estimated from the monitoring counts before and after the incident.

The Moray Firth forms part of the north British coastal area of the North Sea and is distinguished by its depth, hydrography and plankton from the offshore northern North Sea. The 35·0 or 35·1 × 103 isohaline can be taken as the boundary between the two areas.

Geographical and seasonal variations in temperature and salinity are described in terms of a belt of low salinity coastal water in the inner firth and along its southern shore and of “mixed” water to the north and east. During the winter the “mixed” water is warmer than the coastal water, during the summer it is colder. Tidal streams are dominantly semi-diurnal, relatively weak in the inner firth and relatively strong in the outer firth. Residual currents are largely wind driven, and some are caused by tidal effects.

Geographical variation in the seasonal changes in the phytoplankton standing stock is related to water column stratification. The early spring standing stocks are highest in the inner firth and off the southern shore. During the summer and early autumn, phytoplankton is most abundant below the pycnocline. Average zooplankton standing stocks increase from 0·2–0·6 g dry weight (100m3) 1 in winter to 1.0 g (100m3) 1 exceptionally 4·5 g (100m3) 1. in summer. Standing stocks in November–December range from 0·3 to 1·8 g (100m3) 1.

Prototypes of the more important contemporary fishing gear were in common use in Ancient Egypt. These included fish harpoons, hooks, hand and longlines, angling, trolling, cast nets, fish traps and baskets of various types, dip nets, weirs, seine nets (with and without pockets) and beam trawls.

The seine and beam trawl appeared successively in the Old Kingdom (ca 2660–2180 B.C.) and Middle Empire (ca 2180–1640 B.C.), while the iron fish hook with barb, shank and eye or flange dates back to the New Empire (ca 1640–1075 B.C.).

Archaeological material relevant to fishing consists of preserved samples, artifacts, models and papyrus scripts as well as relief illustrations in tombs and temple walls of scenes depicting fishing methods and crafts from various Dynasties.

The importance of fisheries in the economy of Old Egypt is demonstrated by the exportation of fish commodities and the imposition of taxes on fishing rights and in the engagement of a large number of the population in fish industry. Fish processing included drying, salting, pickling, fish cake and fillet; various implements used were discovered.

It is suggested that these basic fishing techniques (methods and gear) spread in time, along various routes, from Egypt to other parts of the world.

An account is given of the species Psilophyton robustius and the relevant literature is reviewed. There follows an illustrated description of a relatively well-preserved fertile, branched specimen. The morphological features of this specimen are discussed with reference to the earlier descriptions by Dawson and others. It has been found necessary to institute a new genus as Psilophyton is now apparently inappropriate for this species. The name given to this new genus is Trimerophyton, which includes the one species Trimerophyton robustius (Dawson) Hopping.

Bracken grows on sites very suitable for forest tree growth allowing a wide choice of tree species. However, the trend in afforestation is towards poorer soils and the area of bracken land being planted is declining. Bracken will damage young trees and methods of its control are reviewed. Hand weeding still has a part to play, but most weeding of heavy bracken growth is by herbicides. Experiments using dicamba, chlorthiamid, picloram and more recently asulam and glyphosate demonstrate a gradual improvement in the selectivity and cost effectiveness of herbicides. Dicamba can only be used before planting and its use is limited to sites where control over three years is assured. Picloram and chlorthiamid at the rates necessary to control bracken are damaging to conifers. Asulam is selective and can be applied after planting giving good control of the bracken. Glyphosate is more damaging to trees than asulam but its use may be justified where a wider spectrum of weed control is required.

The importance of aeolian deposition is clearly shown by the size and bulk of coastal dunes. Sand dunes occur where there is a large supply of sand, a wind to move it, and a place in which it can accumulate. A dune classification is presented which takes into account the origin, internal geometry and surface geomorphology of coastal dunes. Since the main element that distinguishes coastal dunes from desert dunes is vegetation, the relative amount of vegetation may be used as a typology. Four dune types are distinguished: vegetated dunes, parabolic dunes, medanos (i.e. large sand hills devoid of vegetation), and artificially-inseminated dunes. Vegetated and medano dunes are the end members, with parabolic dunes in between. Parabolic dunes are “anchored” by vegetation, but the centre of the dunes has migrated in the down-wind direction. The artificially-inseminated dunes are formed by vegetation plantings, fencing, or other artificial means, but with natural sand accumulation around these obstacles. These now account for a very substantial portion of the world's coastal dunes.

The role of wind and its relation to the internal geometry (i.e. cross-bed dip and direction) are discussed in some detail, with examples from Brazil, U.S. east and south coasts, Israel and China. Differences in these characteristics are detailed, and related to the different modes of formation of the four dune types.

The role of the wind in transporting and depositing sand in coastal areas is being quantified through both wind tunnel and field transport measurements. An example from a field study along the coast of Israel illustrates the differences between desert and coastal dune transport, where the role of vegetation and beach topography must be taken into account. From the Israeli study, and others, it appears that transport in coastal dunes is reduced by one-third to one-half of that in deserts, due to these factors.

Coastal dunes provide a useful, and often necessary, buffer against storm waves and the presently rising sea level. They form primarily through vertical sand accretion trapped by the sensitive dune vegetation. Provided that sufficient space exists between the high tide line and developed areas, planned dunes can be easily formed with the aid of plantings and fencing.

Changes in the status of fish populations in the Clyde Estuary between Woodhall and Glasgow since 1978 are described and data presented on species composition and distribution, temporal and spatial fluctuations in abundance and biomass and length frequency data for certain species are analysed.

The seaward part of the estuary is colonised by marine and euryhaline marine species dominated by flounder, while the ‘city reaches’ have a fresh water component dominated by three-spined stickleback and eel in addition to several euryhaline species, e.g. sand-goby and saithe.

The extent of biological recovery of the estuary from severe organic pollution can be gauged from the presence now of thirty-four species, including nineteen in the city reaches which were virtually fishless in the mid nineteenth century. The upper estuary is now able to support resident and migratory fish for much of the year, but species composition and abundance are markedly affected by seasonally variable fresh water flows to the estuary affecting primarily dissolved oxygen and salinity, leading to mortalities among resident species and providing a barrier to migrants.

The conservational vulnerability of tropical pteridophytes, which make up 80% of the known species, is outlined. Especially threatened are the areas of the world with high percentages of endemism.

From direct sampling, the deeper Rockall Trough and Faeroe-Shetland Channel are known to have a Tertiary-Quaternary sedimentary sequence up to 3000 m thick, which is in places, particularly in the north, underlain by early Tertiary basaltic volcanic rocks. The seamounts in the Rockall Trough are of basic volcanics of probable Upper Cretaceous age. The eastern shelf areas have a rifted basement of Precambrian-Devonian (-?Carboniferous) age, overlain by Permian + Mesozoic sedimentary rocks that reach 5000 m in thickness in rift basins. Tertiary sediments thicken rapidly from the shelf into deep water. The western shelf areas have extensive early Tertiary basalts from the Faeroe Islands to the southern part of Rockall Bank. A thin Tertiary—Quaternary cover exists and Precambrian basement lies beneath.

The pre-Tertiary geology of the deep water areas and the overall crustal structure have been inferred from geophysical investigations. In the Rockall Trough the crust is of oceanic thickness, about 6 km, but it is probably slightly thicker beneath the Faeroe-Shetland Channel. This fact, coupled with the size of the channel compared with other small ocean basins and the knowledge that fully developed oceanic crust exists just outside the mouth of the Rockall Trough, strongly suggests that at least parts of the deep water areas are floored by oceanic crust. However, seismic reflection and magnetic anomaly profiles do not yield observations characteristic of normal oceanic crust.

The age of any oceanic crust in the Rockall Trough and Faeroe-Shetland Channel is equivocal. Between 54° and 59° N a succession of largely sedimentary rocks up to 3000 m in thickness occurs between the Tertiary and the acoustic basement. To the north this succession is masked on seismic profiles by early Tertiary basalts but it is probably present; to the south it is interrupted by a series of acoustically opaque basement ridges. With slow sedimentation rates, this succession could extend back to the late Palaeozoic, but with rapid rates, only to the mid-Upper Cretaceous. An age of mid-Lower to mid-Upper Cretaceous for oceanic crust, equal to that of the ocean crust outside the mouth of the Rockall Trough, is accepted here. Although rapid subsidence and infill in Upper Cretaceous time is not characteristic of major shelf basins around Britain, it may be acceptable for the Rockall Trough and Faeroe-Shetland Channel if they are underlain by oceanic crust rather than continental crust.

A likely model for the formation of the Rockall Trough and Faeroe-Shetland Channel is of continental rifting and subsidence from late Palaeozoic or earliest Mesozoic to mid-Cretaceous time, then sea-floor spreading in Albian (c.105My)–Santonian (c.85 My) time, accompanied and immediately followed by rapid subsidence and deposition. The Tertiary was heralded by widespread basaltic igneous activity which briefly arrested subsidence, but was largely a period of subsidence without sedimentation keeping pace.

Only euryhaline fishes were able to recolonize Outer Hebridean fresh waters after the last glaciation so that inland waters now contain only six indigenous, truly freshwater species; salmon, trout, charr, three- and ten-spined stickleback and the freshwater eel. Parts of some lochs are invaded by the sea at stages in the tidal cycle and some 20 species of marine fish may be found at times in inland waters.

Both salmon and sea trout occur in all the larger freshwater systems and sea trout are also found in many of the minor ones.

The original sea trout gave rise to sedentary brown trout populations similar to those of the mainland.

Fluctuations in the Hebridean salmon catch suggest that the stock is affected by the same factors as those affecting Scottish west coast stocks generally: the vast-majority return to fresh water as grilse, while sea trout stocks have been declining over the last 25 years.

Brown trout and eels are almost ubiquitous. Charr occur in Lewis and parts of North Uist but have not been reported from Harris or South Uist and are now only present as sedentary forms. The three-spined stickleback is more widely distributed than the ten-spined.

Outer Hebridean lochs in general have special scientific value because, unlike many Scottish mainland lochs, they have not been affected by the introduction of alien species and some are still in an unexploited state.