IN the waters off Plymouth there exists a definite inshore fishing-ground, approximately 13 square miles in area, locally known as the “corner.” In order to obtain some idea of the Bionomic conditions prevailing on this ground an intensive study of the bottom fauna was undertaken. Quantitative seasonal observations extending over a period of one year (August, 1928–July, 1929 inclusive) have been made, using the 0.1 square metre Bottom Sampler and the “Agassiz” Trawl, a method having been devised for obtaining quantitative hauls with the latter instrument. Investigations into the food actually eaten by the fishes within the area have been carried on simultaneously, and the stomach contents of over 2000 fishes comprising 29 different species have been examined. On account of the length of time required for stomach examination, it was found impossible to make seasonal observations on them also, but comparable winter and summer examinations were made.

INTRODUCTION

The occurrence of dense beds of the brittle-star Ophiothrix fragilis (Abildgaard) in certain localized areas around the British Isles has been reported by several authors (Allen, 1899; Vevers, 1952; Cabioch, 1961; Holme, 1961; Brun, 1969), with population densities varying from 340/m2 (Vevers, 1952) to 2196/m2 (Brun, 1969). These populations seem to be permanent features of the sea bed since the aggregation sampled by Allen was in the same position as that photographed by Vevers fifty years later.

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.

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.

A range of 62 species of marine fishes representing 34 families was examined for the presence of parasitic copepods. Forty-one species were found to harbour 39 species of copepod belonging to 9 families. The remaining 21 species of fishes were not infected. The incidence and intensity of infection were recorded and these provided material data on the host-parasite relationships. The site of infection and the developmental stage of the parasite were also recorded. The frequency distributions of number of copepods per host were calculated for Clavella adunca and Bomolochus confusus. The age of the host was shown to influence the frequency distribution of Bomolochus confusus. The host specificity of the copepod species was analysed and 70 % of the species were found to be specific for one host species or for different species of the same genus.

Scallops of the bivalve family Pectinidae are very valuable shellfish and the subject of various important commercial fisheries around the world. Most of these fisheries are at present dependent upon natural populations, which can fluctuate widely in abundance from year to year due to irregular recruitment and overfishing. In recent years there has been considerable interest in the possibilities of cultivating various scallop species and some success has been obtained in rearing larvae of Pecten maximus (L.) in the laboratory (Comely, 1972; Gruffydd & Beaumont, 1972). However, by far the most successful cultivation system developed for pectinids has been carried out for several years in Japan for Patinopecten yessoensis (Jay). Naturally produced spat settling on Collectors made from artificial materials are grown on to market size in cages in the sea or used to restock natural beds (Ito, Kanno & Takashashi, 1975; Querellou, 1975; Motoda, 1977).

Continental shelf and upper slope fish communities were studied along the Catalan coast based on 66 experimental bottom otter trawls. A total of 79 demersal fish species were studied by means of cluster analysis and multi-dimensional scaling (MDS) ordination for community structure. Analysis revealed the existence of five major location clusters. Similarity percentage analysis (SIMPER) was determined by comparing the dissimilarity between two groups of samples using the discriminating species. Geomorphological characteristics, bottom substratum and depth showed direct influences on species assemblages. High correlation between the biotic data samples and depth was observed. The fish species assemblages identified five main demersal fish associations which corresponded with the five location clusters and with five benthic sediments (mud of the upper slope, sand and gravel, mud of the shelf, muddy-sand and sand with rocky outcrops).

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.

An important fishery for the scallop, Pecten maximus (L.), is carried on during the winter months round the Isle of Man. A knowledge of the breeding of this lamellibranch would be useful should legislation become necessary with regard to the fishery.

Regular samples of scallops were dredged, whenever possible, at roughly weekly or fortnightly intervals throughout the period October 1950-October 1952, from a depth of 13–16 fm. off Bradda Head and Bay Fine, near Port Erin. Approximately 8000 scallops of all ages up to 13 years were examined, though very few young ones were caught. Scallops were aged by means of the growth-rings on the shell, of which one is laid down each spring (Mason, 1957).

The growth rates of Aplysia punctata Cuvier feeding on eight species of marine algae were found to decrease in the order: Plocamium > Enteromorpha > Ulva > Heterosiphonia > Cryptopleura > Delesseria > Laminaria. The brown alga, Desmarestia aculeata, was not eaten. Except for Enteromorpha and Desmarestia, this was also the order found for the feeding preference of sublittoral Aplysia. Enteromorpha was eaten by Aplysia in preference to all the other algae studied.

No clearly defined trends in the concentrations of ash, protein, fat and carbohydrate in the seaweeds were found to account for these differences in growth rates. Absorption of total dry food matter was lowest from the algae giving the poorest growth (45 and 53%, respectively, of the total dry weight consumed for Delesseria and Laminaria diets) and highest from the seaweeds giving moderate growth (71–75% for Ulva, Heterosiphonia and Cryptopleura diets). For Plocamium and Enteromorpha diets the values were 59 and 65%, respectively. Carbohydrate materials were found to constitute 42–75% of the total dry weight of food material absorbed by Aplysia on all the algal diets, and represented the major portion of each. The efficiency of conversion of absorbed food matter into tissues was highest on the algae giving the poorest over-all growth (73% for Delesseria and 40% for Laminaria). For the other seaweed diets the efficiencies decreased in direct relation to the decrease in the value of each for growth of Aplysia (from 35% for Plocamium to 15 % for Cryptopleura).

The same amino acids were found in each food.

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 features of the vertical distribution of meso- and bathypelagic fishes are poorly known. Much of our present knowledge is based upon data collected on the early, major expeditions (i.e. Brauer, 1906; Murray & Hjort, 1912; Jespersen, 1915; Jespersen & Tåning, 1926; Norman, 1929, 1930; Regan & Trewavas, 1929, 1930; Benin, 1934, 1937; Ege 1934 1948, 1953, 1957; Bertelsen, 1951; Parr, 1960; Ebeling, 1962; Ebeling & Weed, 1963; Nafpaktitis, 1968). Fishing depths were not accurately determined, the depth of net generally being calculated from the length of wire out and the wire angle to the water surface. Closing nets were infrequently used. From these reports a general appreciation of vertical distributions has been possible. More recently, distribution studies mostly made in restricted areas using open nets with depths more accurately determined indicate a limited vertical distribution for each species (Aron, 1962; Pearcy, 1964; Pearcy & Laurs, 1966; Lavenberg & Ebeling, 1967; Paxton, 1967).

An apparatus and experimental method for the investigation of the effects of changes of pressure on the behaviour of marine animals is described.

In 43 of a total of 53 species examined in this apparatus definite responses to abrupt pressure changes of 1000 millibars or less have been observed, increased pressure generally causing increased activity and movement upwards or towards the light, and decreased pressure causing decreased activity and movement downwards or away from the light. The relative importance of light and gravity in the orientation of these movements is generally correlated with the degree of development of the light and gravity receptors in the species concerned.

The possible significance of these pressure responses in nature is discussed and it is suggested that pressure may be an important factor affecting the distribution of marine plankton, particularly during the hours of darkness.

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.

During the last 30 years the fecundity of the plaice, Pleuronectes platessa L., has been widely studied over its complete geographical range. In this paper all this previous work is brought together and a distinct pattern (with two exceptions) emerges. The fecundity is lowest in the Southern Bight of the North Sea, and radiating from there in all directions the fecundity increases, while in Faxa Bay (Iceland) and in the Barents Sea it is lower again. The possible factors producing this pattern are examined in detail and it is concluded that the amount of food available, which in turn is related to population density, is the most important. Only in Trondheim Fjord and in the Baltic is the fecundity so different that it is necessary to postulate racially distinct populations. Finally the importance of fecundity variations in natural population regulation is stressed.

Much information concerning the vertical migration of plankton animals has been gained by using nets at different levels in the sea and at different times of the day and night, and also by experimenting with animals in apparatus of various kinds both in the laboratory and in the sea itself. Such observations and experiments have been summarized in the extensive reviews by Russell (1927) and Cushing (1951) who give full lists of references.

Marinogammarus obtusatus Dahl, an intertidal amphipod, was first described by Dahl (1938). Prior to this date it appears that this species was often confused with and identified as M. marinus. In later years, M. obtusatus has been shown to be common around the coast of Britain (Sexton & Spooner, 1940), and in a preliminary survey of Cullercoats Bay, Northumberland, we have found that this species is by far the commonest amphipod present.

Evidence is provided that warming of the North Atlantic is responsible for the northward extensions of the ranges of warm water fish species, causing increasing numbers of southern immigrant species to appear off the Cornish coast of the UK. The increasing number of immigrant species is significantly correlated with temperature increases in the North Atlantic over the last 40 years.

Two of the new species of Chrysochromulina to be described here are somewhat more like the type species (C. parva Lackey) than were any of those included in our last communication (Part II of this series—Parke, Manton & Clarke, 1955). The diagnostic generic character of the presence of three filiform appendages arising close together is shared by all, and as before two of the appendages are flagella of equal or almost equal length and the third is a special organ to which the name haptonema has been given (Gr. åπτω to attach, υ⋯ματα pl. υ⋯ματα, a thread) (1955, p. 581). In our previous species the haptonemata when fully extended were relatively short, being not very different in length from the flagella. When not extended it was coiled in a flat spiral. Our three new species all have much longer haptonemata, of the order of twice the length of the flagella in C. ericina and three to five times the length of the flagella in C. ephippium and C. alifera.

Long-term variations in shell growth of the mollusc Arctica islandica (Mollusca, Bivalvia) from the northern North Sea have been assessed retrospectively using the annually deposited internal growth lines. Relatively young specimens yielded a detailed year-to-year chronology while the growth record of specimens older than 30 y yielded a time series with a length exceeding 100 years. The long-term growth trends demonstrated a marked alternating sequence of periods in which growth was below and above expectation. A 33-y long cycle could be discerned. Since the 1960s the growth patterns in Arctica from two nearby locations were opposite, while they resembled each other in the period before 1960.