The shore environment - problems for organisms and their investigators Vertical distributions - zonation and its causes Communities on the shore - the effects of wave exposure Algae, the primary energy sources Grazers and their influences Suspension feeders - how to live on floating food Predators and their influences The functioning of rocky shore communities Biodiversity, pollution, and conservation.

This chapter reviews the ecological studies at Lough Hyne, County Cork, a very sheltered sea lough that receives very little fresh water from streams, and has a considerable tidal turnover. The flora and fauna of tide pools at Carrigathorna are described in relation to conditions at a range of depths in these pools. The distribution of plants and animals in the Bullock Island Cave is interpreted in relation to illumination and to protection from the unfavorable effects of exposure to air. The Rapids control the tide in the lough, reducing and rendering asymmetrical the rise and fall. Lough Hyne is closely surrounded by low hills, so that its catchment area is small; its tidal exchange is considerable. This unique feature exercises a special influence on the pattern of the hydrography, with regular summer stratification, followed by anoxia of the deep water of the Western Trough, and all its consequences for the fauna, and with regular winter recirculation and reoxygenation. The special features of the flora and fauna of the lough are related in part to its somewhat Mediterranean features, and in part to the intensive study which it has received. Finally, the geological history of the lough will be outlined as far as is possible.

An ecological account is given of the rocky shallow sublittoral of Lough Ine, County Cork, Republic of Ireland, from low water level to about 1 m below this level. With increasing distance from the Rapids mouth a forest of laminarian algae gives way to low algal bush, and still further into the lough the sea urchin Paracentrotus lividus destroys all soft upstanding algae. Much of the grazed area becomes overgrown by crustose coralline algae. Patches of the green algae Codium fragile ssp. tomentosoides and Enteromorpha clathrata fringe the Paracentrotus graze patches. An account is given of the effects of Paracentrotus on the shallow sublittoral community. Algae in the ungrazed areas accommodate large numbers of individuals and many species of invertebrates, especially amphipods, small gastropods and small polychaetes. In grazing, Paracentrotus destroys this population and its habitat. However, the removal of these algae, and of the sediment that they trap, provides a new habitat, suitable for plant and animal species that can resist Paracentrotus . Crustose coralline algae cover much of the rock, and are burrowed into or enclose the tubes of a characteristic and entirely different polychaete fauna. On the surface of the rocks are found saddle oysters ( Anomia ephippium ), limpets ( Patella aspera ) and other hard- shelled animal species. The relations between Codium and Paracentrotus have been investigated by transfer experiments in the ‘field’ and by observations with an aquarium tank. Paracentrotus readily eats Codium , especially when the urchins are at a high population density; but Codium benefits from the clearance of other algae, and is a quick recolonist, so that on balance it benefits from the presence of the urchin. Paracentrotus feeds mainly by day, and on a steep shore some wander up into the littoral region as the tide rises and destroy Fucus serratus . This accounts for the almost complete absence of F. serratus from the North Basin. Paracentrotus does not move upwards by night. The hard-shelled animal species Anomia, Patella, Chlamys varia , adult Gibbula cineraria and Pomatoceros , found plentifully on graze patches in the North Basin, diminish in abundance southwards even within grazed areas, while the numbers of the starfish Marthasterias glacialis under the rocks increase. Experiments show that Marthasterias readily eats Anomia . These Marthasterias are quite small. As they grow bigger they move away onto muddy areas and extend their diet to include large buried lamellibranchs. Small Paracentrotus are usually found in larger numbers underneath boulders than above, while larger ones tend to come up by day onto the tops, where they form graze patches. From a study of growth lines in the interambulacral plates and from growth in cages we conclude that a horizontal diameter of 30-40 mm (with considerable variation) is reached in 3-4 years from settlement. The peak in numbers of Paracentrotus visible in the South Basin in 1979 might perhaps be ascribed to a good settlement in the warm summers of 1975 and 1976. Temperature of the shallow marginal water of the lough is subject to diurnal fluctuation, as in a tide pool, and can reach high levels in summer. This might favour Paracentrotus . However, numbers of Paracentrotus are probably severely reduced by predators in the South Basin. Crabs have already been implicated. It is possible that the small or half grown Marthasterias under shallow sublittoral rocks might destroy newly settled Paracentrotus , although this still has to be demonstrated.

Collections of Nucella lapillus (L.) from various eastern Atlantic areas have been measured, and shell shape has been analysed by D'Arcy Thompson's method in terms of whorl ratio, apical angle, and spiral angle. In southwestern Ireland N. lapillus varies greatly from tall and narrow in sheltered situations to short and wide at very wave-exposed sites. A local population is described for a bay near Crookhaven, County Cork. In northwestern Spain the open-sea form is developed only weakly. In southwestern Ireland N. lapillus effectively populates mussel beds in the lower littoral on open coasts, whereas in Spain it is sparse or absent from such situations but plentiful high up on the shore on barnacles in places where there is some local shelter from rocks or crevices. It is suggested that failure to develop the open-sea type in Spain is responsible for this difference in niche. Both in Spain and at a site in Scotland N. lapillus feeding on mussels in sheltered situations is of the tall narrow type, so that a diet of mussels cannot alone be responsible for the development of the open sea type, although it still might be a necessary condition. It is to be expected that the genetic composition of populations will vary regionally and will contribute to variation in shell form, but the part which it plays on a purely local scale remains uncertain.

The size and age structure of rural populations of Rattus norvegicus containing individuals resistant

ABSTRACT A study has been made of the effects of helium, nitrogen and argon at partial pressures of 10–120 atm on the swimming speed, behaviour and survival of the heterotrich ciliate Spirostomum ambiguum. Experiments have also been carried out with hydrostatic pressure alone. Hydrostatic, helium and nitrogen pressures reduced the swimming speed approximately equally but pressure of argon reduced it to an even greater extent. Hydrostatic, helium, nitrogen and argon pressures caused a reduction in the number of reversals in a given time but the number of reversals/distance travelled did not change significantly. All the treatments increased the durations of individual forward movements. Pressures of helium, nitrogen and argon also increased the durations of reversals but at high hydrostatic pressures the durations of reversals were reduced. Argon caused cytolysis at 30–40 atm and nitrogen at 80 atm; helium did not cause any visible cell damage over periods of 1 h at 120 atm. Addition of substantial partial pressures of helium protected Spirostomum against partial pressures of argon which would otherwise have caused cytolysis. The increase of hydrostatic pressure may have been responsible.

The distribution and shell form of the three species of Thais present have been investigated along the southeast shore of Barkley Sound (Vancouver Island) along a gradient of decreasing exposure to waves, from Pachena Point (open Pacific) to Grappler Inlet (extreme shelter). The 20 stations comprised rocky promontories and adjacent boulder beaches, the latter giving some local shelter.

The effects of helium, nitrogen, argon and krypton on Echinosphaerium nucleofilum (Heliozoa) have been studied at partial pressures of 10-130 atm. Additional experiments have been carried out with hydrostatic pressure alone. Helium causes shortening of the axopods over the whole range of pressures, and damage to the cell body at pressures of 60-90 atm, both with a maximum at 80 atm. These effects cannot be explained in terms of hydrostatic pressure alone; a 'pressure reversal' effect may be operating, causing the peak at 80 atm. Nitrogen also causes both cell damage and axopod shortening, the severity increasing with increasing pressure. Argon and krypton cause cell damage but no shortening. The order of potency for cell damage is krypton greater than argon greater than nitrogen greater than helium. It is suggested that there may be tuo sites of action, possibly the microtubules (for axopod shortening) and the cell membrane (for cell damage). In appropriate mixtures of helium and argon, both the cell damage usually caused by argon, and the axopod shortening usually caused by helium, are prevented. Possible mechanisms include the effects of hydrostatic pressure on gas solubility coefficients, reversal of the effects of the gases by the increase in total pressure, and competition for sites of action.

Log-phase cultures of Acanthamoeba castellanii, Neff strain, have been maintained at elevated hydrostatic pressures over periods of several days and the population has been recounted at the end of the experimental period. A pressure of 2,000 psi (136 atm) depressed growth of the population, but was quickly reversed on release. A pressure of 4,000 psi (272 atm) severly depressed population growth, and any increase was slight and short-lasting at 5,000 psi (340 atm). Growth of the population was resumed only after an interval of 1 or more days after release.

This paper is concerned with the ecological significance of variation in shell form within the thaisid gastropod genus Lepsiella in New Zealand. Shell form has been investigated by measurement of shell height and breadth, aperture length and width, the diameters of consecutive whorls, apical angle, shell weight, and shell capacity, although in many cases shell height and shell breadth could not be measured because of erosion. L.albomarginata has been studied intensively at 4 stations in the South Island, and L. scobina less intensively at 6 stations in the North and South Islands. Comparisons of pairs of characters between stations have been tested by regression analysis and analysis of covariance where appropriate. Shells of L. albomarginata are relatively taller and narrower, and have a thicker wall, at a very sheltered station (Hakahaka Bay) that at more wave-exposed stations. L. scobina (sensu stricto), characterised by the presence of spiral ribs on the shell, exhibits less striking but comparable differences in shell shape. In laboratory tests in a tidal tank the thicker-shelled L. albomarginata from a sheltered station (Hakahaka Bay in Port Underwood) was much better able to resist attack by the shore crab Hemigrapsus edwardsi than was L. albomarginata from a nearby wave-exposed station (Whites Bay, near Cape Campbell, South Island). L. scobina from both stations was resistant to attack. H. edwardsi abounds at sheltered stations, but is missing from wave-exposed rock reefs such as those at Whites Bay, so that the ability to survive encounters with shore crabs is ecologically important to L. albomarginata inhabiting sheltered stations. L. scobina occupies a lower zone on the shore, where it is probably liable to encounter other more powerful predators. Its spiral ribs probably strengthen the shell. We do not know to what extent differences in shell form and thickness depend on environmental factors, and to what extent they originate genetically. Thin shells are associated with an abundance of mussels (Mytilus edulis ssp. aoteanus or Modiolus neozelanicus). There is an interesting possibility that a scarcity of mussels or other food caused by superior nonspecific predators might result in the production of better-protected Lepsiella.

SYNOPSIS. The ameboid phase of Naegleria gruberi can be activated to transform to the flagellate phase, and cysts to excyst and transform to the flagellate phase, by a limited treatment with high hydrostatic pressure followed by release. The most effective treatment at 21 G is 45 min at 3500 psi (238 atm), which leads to almost 100% transformation. Following this dose of high pressure, 50% of amebae transform within 55–70 min after release of pressure, and nearly all within 75–120 min. Nearly all cysts hatch and transform within 200–240 min after release. Pressures of 4000 psi (272 atm) and above, and of 1000 psi (68 atm) and below, were ineffective at any duration of treatment.

ABSTRACT Six different anaesthetic agents were found to cause reversible collapse of the axopods of Actinosphaerium nucleofilum. The effect occurred at concentrations proportional to those required to anaesthetize man. Electron microscopy showed dispersal of the microtubular system and disaggregation of the microtubules of the axonemes, and expanded microtubules without interlinkage were seen in the related heliozoon Actinophrys sol under treatment with halothane. In both genera there was a rapid reassembly during the recovery period. Diethyl ether, an inhalational anaesthetic with a particularly large molecule, was ineffective except at relatively very high concentrations, and with this agent cytolysis often occurred with little or no shortening of axopods.

ABSTRACT Spirostomum ambiguum fails to make the avoiding reaction at pressures of 4000 p.s.i. and over. The critical pressure is between 2000 and 4000 p.s.i. Light or moderate mechanical stimulation with a hair no longer produced reversal or body contraction at pressures over 4000 p.s.i. Blows severe enough to kink the body surface, or sudden exposure to NaCl in solution, elicited prolonged reversal at 6000 and 7000 p.s.i. In a direct current the cilia on the cathodal side reversed with a threshold voltage either the same or not more than twice as great as that required without application of pressure. It is suggested that at pressures of 4000 p.s.i. and over the cilia at the anterior end of the organism fail to receive and translate the stimulus. This failure could be due either to the reduced activity of the cilia or perhaps to an impairment of mechanical properties of the ectoplasm.

PROTOZOA of the order Heliozoa are provided with numerous straight radiating processes known as axopods, which in certain genera (Actinophrys, Actinosphaerium) are known to be supported by axial filaments consisting of microtubules in elaborate array. In transverse section across an axopod these microtubules are seen to form two sheets spirally interwound (Fig. 1)1–3.