Experiments were carried out to assess the importance of desiccation during tidal exposure upon the vertical distribution of the intertidal limpets Patella aspera and P. vulgat vulgata. The rate at which water is lost during desiccation varies inversely with body size.

The Council of the Marine Biological Association appointed me, in 1889, to make observations on the perceptions of fishes, and especially on those which constitute the modes by which they hunt for and recognise their food. It was suggested that this subject should be treated in as wide a manner as possible, and in accordance with this suggestion I have endeavoured to utilize any opportunities which presented themselves of getting an insight into the natural history of marine animals. In addition to this I have also made some experiments towards the practical solution of the bait question, both by making artificial baits, and by endeavouring to preserve materials which are already in use for bait.

Foraging activity of roving herbivorous reef fish (RHs) from families Acanthuridae (surgeonfish; three species) and Scaridae (parrotfish; five species), and its relationship to resource availability and interference competition, was studied in the largest South Atlantic Reef complex (Abrolhos Bank, eastern Brazil). Observations were undertaken at four sites differing in resource availability and competitors' abundance (i.e. RHs and territorial herbivores from genus Stegastes). Turf algae (TA) were selected by most species in most sites, while other food items were generally avoided. Surgeonfish had higher feeding rates than parrotfish, the former grazing more frequently on fleshy algae (FA) and the latter on crustose calcareous algae (CCA). Both surgeonfish and parrotfish interacted agonistically most frequently with damselfish, followed by confamilial interactions. Despite these consistent patterns, feeding rates, food selection and frequency of agonistic interactions differed significantly between sites for most species. Bite rates on CCA and FA were disproportionally higher in sites where such items were more available, leading to significant spatial variation in grazing selectivity (i.e. positive rather than negative selection of CCA and ‘lower avoidance’ of FA). Although agonistic interactions were more frequent at sites where herbivorous fish (both roving and territorial) were most abundant, there was no clear relationship between interference competition and foraging patterns. These results indicate that the scarcity of other food may induce RHs to consume the dominant resources. They also support the hypotheses that RHs are unable to clear large tracts of reef surface of FA once these have proliferated, and that territorial herbivores do not limit the access of RHs to particular resources.

The rations removed by adult and stage V Calanus helgolandicus (Claus) feeding on large cells of the diatom Biddulphia sinensis Grev. were measured using an apparatus especially designed to keep the plant cells in suspension and estimated to reach a maximum of 1800 cells/animal/day at a food concentrationof 11,300 cells/1. A continual flow method was used to study feeding at very low algal concentrations and it was found that the animals still captured Biddulphia at a food level of only 270 cells/1.

The animals in the feeding experiments were used at a very low population density (6 copepods/1350 ml.) and the maximum value found for the volume of sea water swept clear – 700 ml./animal/day - was unusually high.

The maximum daily rations consumed by each animal were also high, being equivalent to 47–5 % of the body nitrogen and 46–4 % of the body phosphorus. The number of faecal pellets released by the animals increased with the size of ration captured, but the percentage of the ration lost as faecal pellets was fairly constant. In terms of dietary nitrogen the average value was 65–9% and that for dietary phosphorus 59·6%.

The percentage of the daily ration of nitrogen excreted in soluble form was 266% and that of phosphorus 41–2%, these values being significantly higher than those found using unfed animals. Nearly 90 % of the nitrogen excreted by the animals, whether feeding or unfed, was in the form of ammonia. The amounts of excreted ammonia and total soluble phosphorus increased significantly when the animals fed; but the small quantities of nitrogen released in forms other than ammonia did not change.

Although nematodes form the dominant meiofaunal group in almost all marine sediments, ecological investigations have been confined mainly to littoral or shallow water habitats. Among these studies may be included those of Wieser (1959), Gerlach (1953, 1954), Capstick (1959), King (1962), Rie-mann (1966) and Hopper & Meyers (1967). The qualitative distribution of the nematode fauna of various types of substrates in Kiel Bay and from the Chilean Coast have been discussed by Gerlach (1958) and Wieser (1959a). The only work which contains both qualitative and quantitative data from offshore substrates is that of Wieser (1960), which concerns the shallow sediments (12–30 m) in Buzzards Bay, Massachusetts, and contains a review of the purely quantitative results of previous authors.

An historical data set, collected in 1958 by Southward and Crisp, was used as a baseline for detecting change in the abundances of species in the rocky intertidal of Ireland. In 2003, the abundances of each of 27 species was assessed using the same methodologies (ACFOR [which stands for the categories: abundant, common, frequent, occasional and rare] abundance scales) at 63 shores examined in the historical study. Comparison of the ACFOR data over a 45-year period, between the historical survey and re-survey, showed statistically significant changes in the abundances of 12 of the 27 species examined. Two species (one classed as northern and one introduced) increased significantly in abundance while ten species (five classed as northern, one classed as southern and four broadly distributed) decreased in abundance. The possible reasons for the changes in species abundances were assessed not only in the context of anthropogenic effects, such as climate change and commercial exploitation, but also of operator error. The error or differences recorded among operators (i.e. research scientists) when assessing species abundance using ACFOR categories was quantified on four shores. Significant change detected in three of the 12 species fell within the margin of operator error. This effect of operator may have also contributed to the results of no change in the other 15 species between the two census periods. It was not possible to determine the effect of operator on our results, which can increase the occurrence of a false positive (Type 1) or of a false negative (Type 2) outcome.

The symbiotic condition of Convoluta roscoffensis has been resynthesized in vitro by feeding new-born colourless larvae with various clones of Platymonas convolutae Parke & Manton available in culture. Greening has also been brought about by feeding larvae with other species distinguishable from the natural symbiont by pyrenoid characters, but subsequent growth of the greened larvae was less and the length of time required for greening greater. The minimum presentation time effective in initiating greening with alien symbionts in 100% of tested larvae was also greater. Cell multiplication of successful symbionts is mitotic, division stages being demonstrated in sections of worms with different types of symbiont. When cultures of potential symbionts were made available competitively in pairs, greening normally involved only one member of a pair, success being apparently determined by the order of relative efficiency demonstrated in the single-culture infections. A chimaeral condition, with two different symbionts present together, was produced and is demonstrated—but only as a temporary phase in an experiment designed to give an alien symbiont a very long start before admitting the real one. In this experiment effective greening with Prasinocladus marinas did not impede prompt entry of Platymonas convolutae when it was supplied, and this was followed by rapid and complete elimination of the alien symbiont. An interpretation of these various findings is discussed in a preliminary way.

Recent studies suggest that sand can serve as a vehicle for exposure of humans to pathogens at beach sites, resulting in increased health risks. Sampling for microorganisms in sand should therefore be considered for inclusion in regulatory programmes aimed at protecting recreational beach users from infectious disease. Here, we review the literature on pathogen levels in beach sand, and their potential for affecting human health. In an effort to provide specific recommendations for sand sampling programmes, we outline published guidelines for beach monitoring programmes, which are currently focused exclusively on measuring microbial levels in water. We also provide background on spatial distribution and temporal characteristics of microbes in sand, as these factors influence sampling programmes. First steps toward establishing a sand sampling programme include identifying appropriate beach sites and use of initial sanitary assessments to refine site selection. A tiered approach is recommended for monitoring. This approach would include the analysis of samples from many sites for faecal indicator organisms and other conventional analytes, while testing for specific pathogens and unconventional indicators is reserved for high-risk sites. Given the diversity of microbes found in sand, studies are urgently needed to identify the most significant aetiological agent of disease and to relate microbial measurements in sand to human health risk.

The planktonic foraminifer Globigerinoides sacculifer (Brady) was cultured under two different light intensities and in continuous darkness. High light intensity (HLI = 400–500 μeinsteins/m2/s) resulted in a longer lifespan, a greater number of chambers formed, and a larger final shell size compared with individuals cultured under low light intensity (LLI = 20–50 μeinsteins/m2/s) or in continuous darkness. Shell growth rates were unaffected by increasing light intensity, but gametogenesis was delayed. Continuous darkness induced a rapid onset of gametogenesis in organisms with shell lengths larger than 250 μm. Feeding frequency had a greater effect on growth and reproduction than light intensity under conditions of LLI and HLI, but continuous darkness had an overriding effect on growth and reproduction owing to the rapid onset of gametogenesis which terminated the life of the mother cell. Our previous data indicated that the longevity of G. sacculifer was dependent on feeding frequency, and that G. sacculifer cultured under LLI had a lifespan of approximately 2–4 weeks. Present results suggest that the lifespan can vary from a minimum of 8 days for organisms fed daily in continuous darkness to a maximum of 54 days for organisms fed once every 7 days and maintained in HLI. It is concluded that individual G. sacculifer attain a shell size greater than 600 μm only if they maintain their position in the euphotic zone. Prolonged existence below the euphotic zone would result in premature death or gametogenesis following stunted shell growth.

Methods are described for rearing turbot (Scophthalmus maximus L.) and brill (Scophthalmus rhombus L.) to late larval stages; the major part of the work was done on the former species. Turbot were reared to 16–0 mm and brill to 17–0 mm in length. Rearing tanks ranged in capacity from 8 to 60 1. Turbotlarvae hatched at 2–7–3–0 mm and successful first feeding was established on rotifers (Brachionus plicatilis) at a length of 3–6–3–8 mm; larvae were transferred to a diet of Artemia nauplii at 5–6—6–0 mm. Experiments on the effect of temperature on growth and yolkabsorption rates in yolksac turbot larvae showed optimal growth efficiency at 15–0 °C. Delayed initial feeding reduced subsequent survival. Drawings of larval development of turbot and brill were made as an aid to their identification in plankton samples.

The common mussel inhabits an environment of fluctuating temperatures, salinities and water turbulence. To help cope with these stresses, mussels have evolved some extraordinary structural and biochemical adaptations. The production of the byssus is one such adaptation. The byssus is a complex array of threads and adhesive plaques that serves alternatively to attach the mussel to solid objects, to absorb shock, or to scale a vertical face (Waite, 1983 a; Price, 1983). Because of its location outside the animal's living tissues, the byssus cannot count on the same kind of repair and remodelling offered to structures within the animal. The byssus is thus confronted with two conflicting demands. One is to be a mechanically dynamic structure shielding the animal against the buffeting impact of waves; the other is to be chemically inert towards the hydrolytic action of sea water and microbial enzymes.

The name Codium tomentosum (or its nomenclatural synonym C. dichotomum) has been applied to dichotomous representatives of the genus in the British Isles ever since the genus was established by Stackhouse in 1797. The purpose of this paper is twofold: to show that three distinct species are involved; and to clarify the nomenclature.

I am grateful to the directors and curators of the following herbaria for the loan of specimens: British Museum (BM); Royal Botanic Garden, Edinburgh (E); Farlow Herbarium, Harvard University (FH); University of Glasgow (GL); Royal Botanic Gardens, Kew (K); Rijksherbarium, Leiden (L); Linnean Society of London (LINN); University of Michigan (MICH); New York Botanical Garden (NY); University of Oxford (OXF); Museum National d'Histoire Naturelle, Laboratoire de Cryptogamie, Paris (PC); Marine Bio-logical Association, Plymouth (PL); Naturhistoriska Riksmuseet, Stockholm (S); Trinity College, Dublin (TCD); University of California, Berkeley (UC); United States National Museum (US). Liquid-preserved and dried material, which has been placed in the Herbarium of the University of California, was kindly provided by Dr Sheila Lodge, Dr Betty Moss, Dr Mary Parke, Dr Mairfn de Valera, and Dr M. A. Wilson. Special thanks are due to Dr Mary Parke for her sustained interest, encouragement, and help in this study

Hydroidolina is a group of hydrozoans that includes Anthoathecata, Leptothecata and Siphonophorae. Previous phylogenetic analyses show strong support for Hydroidolina monophyly, but the relationships between and within its subgroups remain uncertain. In an effort to further clarify hydroidolinan relationships, we performed phylogenetic analyses on 97 hydroidolinan taxa, using DNA sequences from partial mitochondrial 16S rDNA, nearly complete nuclear 18S rDNA and nearly complete nuclear 28S rDNA. Our findings are consistent with previous analyses that support monophyly of Siphonophorae and Leptothecata and do not support monophyly of Anthoathecata nor its component subgroups, Filifera and Capitata. Instead, within Anthoathecata, we find support for four separate filiferan clades and two separate capitate clades (Aplanulata and Capitata sensu stricto). Our data however, lack any substantive support for discerning relationships between these eight distinct hydroidolinan clades.

The family Pyramidellidae contains a number of species of gastropod molluscs of similar structure and mode of life.

The shell is calcareous and spirally wound and may be closed by an operculum. The foot bears a transverse fold anteriorly, the mentum (Fig. 1, MT), separating the opening of the penial sheath (PO) below from the mouth (M) above. It has a lateral glandular streak on each side (Fig. 2), presumably sensory.

The head has ear-shaped tentacles (Fig. 1, T), richly innervated and with cilia setting up a strong water current, so that they constitute a powerful sensory mechanism. The eyes (E) lie between the tentacles.

A survey has been made of reflecting layers in the integument of selected fishes, including silvery sea lamprey and various silvery and partially translucent teleosts. Lamprey and juvenile rockling have only a stratum argenteum. Other silvery teleosts have a layer of oriented reflecting platelets lying outside the stratum argenteum; these lie more or less parallel to the vertical to the surface of the water.In dace, herring, and salmon parr the platelets on the upper flanks are tipped slightly upwards; but in some pelagic fishes, e.g. the mackerel and gar-fish, the platelets here are tipped downwards. Smelt, sand smelt, half-beaks, found in shallow or coastal waters, are partially translucent, partially silvery. The implications of these arrangements of reflecting layers are discussed. Both in clear oceanic waters, away from the surface, and in shallow or turbid rivers or ponds, light is distributed almost symmetrically about the vertical to the surface, and the greatest intensity is directed downwards. Under these conditions the reflecting layers diminish thevisibility of the fish from most fields of view because they reflect light approximately equal to the background light against which the fish is seen. On the lower flanks, when the surface is sloping, the reflected light tends to be spread and to beless intense than the incident light. Thin fishes, dark above with vertically reflecting sides, are effectively camouflaged except for the ventral extremity. The lower flanks of tapering or rounded fishes are well camouflaged by reflexion from below and behind because the platelets slope inwards towards the tail, and the projected area of incidence relative to reflexion is thereby increased.

The evolution of symbiotic relationships involving reef corals has had much impact on tropical marine biodiversity. Because of their endosymbiotic algae (zooxanthellae) corals can grow fast in tropical shallow seas where they form reefs that supply food, substrate and shelter for other organisms. Many coral symbionts are host-specific, depending on particular coral species for their existence. Some of these animals have become popular objects for underwater photographers and aquarists, whereas others are hardly noticed or considered pests. Loss of a single coral host species also leads to the disappearance of some of its associated fauna. In the present study we show which mushroom corals (Scleractinia: Fungiidae) are known to act as hosts for other organisms, such as acoel flatworms, copepods, barnacles, gall crabs, pontoniine shrimps, mytilid bivalves, epitoniid snails, coralliophilid snails, fish and certain types of zooxanthellae. Several of these associated organisms appear to be host-specific whereas other species are generalists and not even necessarily restricted to fungiid hosts. Heliofungia actiniformis is one of the most hospitable coral species known with a recorded associated fauna consisting of at least 23 species. The availability of a phylogeny reconstruction of the Fungiidae enables comparisons of closely related species of mushroom corals regarding their associated fauna. Application of a phylogenetic ecological analysis indicates that the presence or absence of associated organisms is evolutionarily derived or habitat-induced. Some associations appear to be restricted to certain evolutionary lineages within the Fungiidae, whereas the absence of associated species may be determined by ecomorphological traits of the host corals, such as coral dimensions (coral diameter and thickness) and polyp shape (tentacle size).

Few studies have been reported on the predatory habits of planktonic foraminifera or on their position in marine food webs. Planktonic foraminifera are large marine Sarcodina possessing a calcium carbonate shell (usually < 1 mm diam.) surrounded by a dense halo of rhizopodia that in some species may increase the cell diameter to 20 mm. Food organisms are snared by the sticky rhizopodia which entangle the prey and draw it into a dense layer of cytoplasm near the shell where digestion occurs (Anderson & Bé, 1976). Clearly species survival, their abundance, and their distribution in a region are deter-mined by the availability of food organisms, so that species that prey on a wide variety of organisms have greater survival advantage than those with a more restricted range of prey. Hence, many of the traditionally studied topics in foraminiferal research such as species abundance, survival time, geographical distribution and contribution to calcium carbonate sediments may be significantly determined by foraminiferal trophic activity. A clearer understanding of foraminiferal predation may help to explain ancient and modern assemblages of species and thus contribute to a more systematic interpretation of foraminiferal ecology.

Experiments with isolated hearts of various Crustacea (Cancer pagurus, Maia squinado, Homarus vulgaris, Squilla mantis) were performed in order to test the postulated secretory function of the pericardial organs (nerve trunks of unusual structure lying in the pericardial cavity). Tests were made with extracts of these elements added to the fluid perfusing isolated hearts.

In Cancer, Homarus and Squilla the extracts caused a distinct increase in amplitude and frequency of the heart beat, and their effect proved to be very similar to that produced by adrenaline and noradrenaline tested on the same hearts. In Maia the extracts produced an increase in amplitude and decrease in frequency of the heart beat.

Extracts of the pericardial organs of Cancer pagurus gave the fluorescence reaction characteristic of adrenaline and related compounds. Blood taken from the pericardial cavity gave the same reaction, but that taken from the leg arteries did not.

It is assumed that the function of the pericardial organs in the Crustacea consists in liberating, through fine neuropile-like terminations of the nerve fibres, some hormone passing with the blood into the heart and producing on it a stimulating effect. There is certain evidence that the pericardial organs might release a second hormone having an inhibitory and perhaps also a stabilizing effect on the heart rhythm.

The possibility of dissolved organic compounds acting as complexing or chelating agents in natural waters has received considerable attention in the last two to three decades. Stumm & Morgan (1970) have expressed doubts about the existence of humicmetal ion complexes in natural waters. Strickland (1972) has also stated that although the addition of chelating agents to sea water often improved the growth of phytoplankton, there was little evidence that the function of dissolved organic matter in oceans and lakes was to complex metals so as to increase or decrease their availability to phytoplankton. Strickland argued that even if all dissolved organic carbon were present as a compound of strong complexing ability it would not be able to compete for most metals with inorganic ligands such as chloride, sulphate and hydroxide. However, there is an increasing amount of data indicating that metals in natural waters may exist in chelated forms with dissolved organic matter (see, for example, Davey, Morgan & Erickson, 1973; Chau & Lum-Shue-Chan, 1974).

INTRODUCTION

The copepod Temora longicornis Miiller is one of the common zooplankton species in the North Sea and adjacent waters. All developmental stages have been recorded throughout the year off the west coast of Sweden, Temora being considered more common in offshore than inshore waters (Eriksson, 1973). In Loch Striven on the west coast of Scotland it was abundant only in summer, living mainly near the surface (Marshall, 1949). Similarly in the English Channel off Plymouth Temora is present mainly during the summer months (Digby, 1950). T. longicornis was found throughout the year in the Northfrisian Waddensea with temperatures ranging from ca. 1–20 °C (K¨nne, 1952).