The fifth paper of this series (1930) was the author's last, after which the work was handed over to L. H. N. Cooper. It was resumed by the author in 1948 to compare the early years with the post-war, since the determinations had lapsed. Measurements of the extinction coefficient of the water were also resumed, and it was desirable to obtain the chemical data at precisely the same time.

The phosphate results are, as before, expressed as P2O5 in mg./m.3, since for crop calculations this old unit is convenient; to convert to mg. P, which is more rational, multiply by 0437; to bring to milligram atoms multiply by 0–0141. The analyses have not been corrected for salt error, since the early results were not^ and the factor for this correction has not as yet been agreed upon.

The silicate results are given as mg./m.3, of SiO2, but though the standard used in Plymouth was checked for me by Dr E. J. King in Canada and agreed with his (King & Lucas, 1928), yet a different value had to be assigned to the silica factor of the picric acid solution. All values have accordingly been multiplied by I.44.

The phosphate results for E1, surface, from 11 February 1948 to 1 February 1949 are shown in Fig. plotted against the dates.

A net sample of phytoplankton taken in the outer Moray Firth in which there were many cells of R. hebetata forma semispina and several cells of R. hebetata forma hiemalis (Fig. 1 a, b) was also found to contain cells either with one forma semispina calyptra or one forma hiemalis calyptra, in which the cell wall changed abruptly at the opposite end to a thin weakly silicified, sometimes almost membranous structure, ending in a central, broadly conical apex with a delicate hollow spine (Fig. 2j, k). The perizonium like appearance of one end of these cells suggested that they might be a stage in the development of the auxospore in R. hebetata Bailey (sensu Gran).

The diet of Synaphobranchus kaupi from the Porcupine Seabight is described. A sample of 110 eel stomachs containing food, were analysed and the general size–depth trend among eels with food in their stomachs. Larger individuals are found in deeper waters. Fish are the main prey for larger eels and crustaceans are preferred by smaller individuals.

Synaphobranchus kaupi Johnson, 1862 is a slope dwelling eel, abundant in the north-east Atlantic Ocean from 230 to 2420 m deep on the continental slope (Haedrich & Merrett, 1988). It is the most abundant species on the slopes of the Porcupine Seabight, off south-west Ireland (Merrett et al, 1991; Priede et al., 1994) and was classified as a benthopelagic predator of the fourth level, predator of predators (Saldanha, 1991).

The diet of S. kaupi has been described from the slope off the middle Atlantic coast of the USA (Sedberry & Musick, 1978), from the Portuguese slope and in the Bay of Biscay (Saldanha, 1991), from the west African slope (Merrett & Marshall, 1981; Merrett & Domanski, 1985) and from the Rockall Trough (Gordon & Mauchline, 1996).

Our specimens were captured during a joint IOS/SAMS survey (Merret et al., 1991). From a total catch of 8792 S. kaupi, captured between 1979 and 1983 in the Porcupine Seabight, ranging from 470 to 2230 m deep, fish stomachs were removed aboard ship and 110 with food were kept in 5% formalin for further analysis.

Little is known about colonization of remote island coasts by marine invertebrates, other than corals. The structure of hard substrata assemblages was investigated across Ascension Island's littoral zone in comparison with other sites. Arrays of acrylic panels were deployed at two sites for 2 years at Ascension Island to measure subtidal recruitment. Colonization of panels at Ascension I. was low, though space occupation, abundance and richness varied considerably. After ~1 and 2 years Ascension panels were <17 and <37% covered by fauna and each had <22 recruits and 54 recruits (per 100 cm2) respectively, amongst the lowest density of recruits reported. Recruitment rates of corals (25 m2 year−1) at Ascension I. were also similar to the lowest levels reported elsewhere (e.g. at Bermuda or Midway islands). Less dispersive animal types, e.g. cheilostome bryozoans, were poorly represented. Panels immersed in Tanzania and Scotland were >30% covered, with >76 recruits per 100 cm2 and with bryozoans well represented after 1 year. Across-littoral surveys of established macrofauna at five remote islands (Ascension I., Easter I., Azores, South Georgia and Signy I., Antarctica) revealed similar trends of a rich sublittoral and lower littoral reducing drastically up-shore; molluscs dominating abundance and species numbers, whilst polychaetes, crustaceans and echinoderms were well represented. Established sessile animals occurred patchily at a mean density of 8.26 m−2 but recruits had mortality levels >99%. Polar or remote temperate/tropical sites are typically less colonized than at non-remote, low latitudes but the lowest levels reported are at remote polar sites. Reduced colonization at Ascension island reflects remoteness.

The larval shell morphology of 14 species of neogastropod from the Rockall Trough, N.E. Atlantic has been examined using scanning electron microscopy. Mode of development has been interpreted from protoconch size and morphological features, from the ratio of protoconch diameter to number of larval whorls and by comparisons with confamilial or congeneric shallow-water neogastropods in which development is known. Eight species have non-planktotrophic and 6 have planktotrophic development. Food availability and feeding strategy are important factors in the development of the two different reproductive strategies in the deep sea.

A large-volume pump system (2.8 m3 min-1) for sampling fish larvae under open-sea conditions is described. Comparative efficiency trials by day and night showed that the pump was generally as efficient, or in some cases more efficient, in capturing larvae than vertically hauled 200 μm WP2 nets, though there was some evidence of visual avoidance by particular larval size classes during daylight. The pump system is particularly appropriate for investigating fine-scale vertical aggregations (1–10 m3) of larval fish in relation to the distribution of their food organisms.

INTRODUCTION

Studies of the distribution of larval fish and their food organisms in relation to physical structure in the water column require sampling techniques capable of resolving fine-scale temporal and spatial distributions. As an alternative to conventional nets, large-volume pumps, sampling at rates in excess of 1 m3 min-1; provide such a capability. Major benefits of using large pumps in addition to temporal and spatial resolution are that a wide range of sizes of plankton including larval fish can be sampled simultaneously in relation to physical and chemical properties of the water column; there is reliable control of the volume of sample filtered and problems of clogging of towed nets are avoided; long series of sequential samples can be taken in studies of small-scale distribution; and instrumentation with in situ CTD and fluorometers at the intake enables real-time control of sampling in relation to physical structure.

General engineering considerations for using such pumps have been reviewed in detail by Miller & Judkins (1981), and a particular area of application has been in power-plant entrainment studies in shallow fresh water (Portner & Rhode, 1977; Bowles & Merriner, 1978; Gale & Mohr, 1978; Ney & Schumacher, 1978; Elder et al. 1979; Leithiser, Ehrlich & Thum, 1979; Cada & Loar, 1982).

The larva of the fly Canace nasica Haliday feeds on Enteromorpha in the intertidal zone. Its pupae, like those of a number of other intertidal flies, have plastron-bearing spiracular gills. The gills are unlike those of any other known Diptera in that they are modified spiracles: those of other flies are modifications of the body wall adjoining the spiracle, or of both the body wall and the spiracle. Although the spiracular gills are pupal structures, they are the respiratory organs of the adult before it emerges from the puparium.

During the progress of the work on Gammarus chevreuzi it became increasingly evident that heterozygosity must exist in the wild population.

Lake Vouliagmeni (Attica, Greece) is a lagoon of great scientific interest due to its endemic fauna, widely used for recreational activities. Understanding the dynamics of this peculiar ecosystem is essential for its conservation. An ecological survey of the benthic communities was carried out, in both spatial and temporal scales. Material was collected with SCUBA diving, by taking off samples from the principal habitats of the lagoon, i.e. meadows, soft and hard substrata. The identification of the collected 61,975 living specimens revealed the presence of 12 floral and 20 faunal species. Multivariate analyses separated the sampling sites according to the four different habitats of the lagoon, whereas no temporal patterns came up. Micrograzers were the dominant trophic group, followed by deposit feeders regardless of the habitat studied. Lake Vouliagmeni is among the less diverse Mediterranean lagoons, mostly due to its isolation from the sea that hinders the entrance of marine species.

Previous studies on the significance of dissolved organic compounds in the nutrition of the smaller species of the phylum Pogonophora (Little & Gupta, 1968, 1969; Southward & Southward, 1968, 1970) were handicapped by lack of information about the levels of free amino acids in the tissues. In this brief note we give preliminary results for four species, using a modification of the technique described by Clark (1964, 1968, 1973) to estimate the amino acids in extracts of the whole body.

During the winter of 1927–28 the progress of the herring fishing at Plymouth was followed for the fourth consecutive season. A diary of market events was again kept by Mr. A. J. Smith of the Laboratory staff, while statistics of commercial landings and of the number of visiting drifters were kindly supplied by Mr. T. Edser of the Statistical Department, Ministry of Agriculture and Fisheries, and by Mr. E. C. Nelder of the Sutton Harbour Improvement Company, respectively. In the examination of age and growth of random samples of herrings, Mr. F. J. Warren, Laboratory Assistant, again acted as recorder. Details of the methods of treatment of the data collected will be found in Part I of this series of Reports (Ford, 1).

A description is given of a filamentous red alga which was found growing within a sponge collected from the sublittoral off Santander, Spain. The plant appears to be closely related to Acrochaetium spiculiphilum Dawson. A survey is given of the specific characters available for the typification of the known partially and completely endozoic Acrochaetium species, and some suggestions made on the more important lines of study.

Introduction

During the summer of 1957 some specimens of the keratinous sponge Haliclona were collected from the sublittoral off Santander, Spain, by Mr G. R. Forster. Certain of the specimens bore extensive areas of red, and on preliminary examination this colour was found to be due to the filaments of a red alga showing an extensive ramifying growth within the skeleton of the sponge. The drawings and cell measurements to be reported were made from the plant material by A. D. B. soon after its collection. This information has been retained pending a more comprehensive study of endophytic and endozoic red algae. Work is now in progress on these lines (mainly by E. B. W.), and a re-examination of the Santander material has enabled us to make a critical study of the data available for a precise typification of plants of this habit. Further, since the association of endozoic filamentous red algae with sponges appears to be of rare occurrence, any examples need to be fully described.

Description of Plant

The cells were of variable shape and size, and contained much-dissected parietal chromatophores (Fig. 1 a). Individual filaments tended to be closely packed together within the host (Fig. 1 b), and there was no extensive growth of erect filaments outside of the host material.

A survey was carried out from April 1998 to June 2000 to study the structure and the secondary production of the population of Heteromastus filiformis in the Loire estuary. Each month, samples were collected in the intertidal zone of Mindin harbour. The length of the thorax (L12) was correlated with the fresh weight (FW) with the relation FW=1·49848 L12–3·62804 (r=0·92). In 1999, the mean density was 2184 ind m−2 with a minimum of 1104 ind m−2 in December and a maximum of 3328 ind m−2 in March. The mean annual biomass was 15·4 g m−2 with a minimum of 2·6 g m−2 in December and a maximum of 28·2 g m−2 in March. Most of the histograms of size–frequency are unimodal and could be considered a single cohort except in May and November/December 1999. The abundance and biomass of the population of H. filiformis decreased during summer and winter which are mortality periods and increase during spring and autumn which are recruitment periods for the population. The life time for a cohort was from six to nine months depending on the recruitment period and on the inter-annual variations. The secondary production was estimated by the method of Crisp (1971). The annual secondary production in 1999 was P=104·3 g m−2 with B¯=15·4 g m−2 and P:B¯=6·8. The quantity of sediment reworked by H. filiformis is about 116 l m−2 y−1 or 65 kg m−2 y−1 which is approximately a deep-sediment layer of 12 cm transported to the surface annually.

Diel feeding pattern of red mullet in the Hisarönü Bay was studied from samples collected by bottom trawl during a 24-h period in the summer of 1997. Feeding activity of red mullet commenced at dawn and reached its maximum value at noon. During the period between noon to early evening, feeding intensity slowed down and then showed a small increase towards sunset. After sunset, the feeding activity nearly stopped and fish with empty stomachs increased. At night almost all stomachs were empty. Polychaetes, decapods, bivalves and amphipods were the major prey groups in the diet of red mullet and no significant diel variations were observed in the relative importance of these groups.

INTRODUCTION

Lincoln (1979) stated that ‘four species (of Gammaropsis Liljeborg) are reported from the British Isles, Gammaropsis maculata (Johnston), G. palmata (Stebbing & Robertson), G. nitida (Stimpson) and G. sophiae (Boeck)’. In fact, six species of Gammaropsis have been reported from the British Isles in the literature, the records of G. lobatus (Chevreux) (Spooner, i960) and G. melanops (Sars) (Jones, 1948) having apparently been overlooked by Lincoln (1979). Spooner's (1960) material is apparently no longer extant, but the material attributed to G. melanops by Jones (1948) has been re-examined by us and found to be referable to G. lobata. Recent collections of G. lobata from the west coast of Ireland confirm a rather wide distribution of this species in the southwest of these islands.

Five species of Gammaropsis are therefore now known from these islands, and G. melanops can, at least for the present, be deleted from the British and Irish list of species.

Lincoln (1979) was unable to examine any British material of G. sophiae, everything labelled as such, in the material examined by him (including the Norman collection at the B.M.N.H.)* being referable to G. nitida. He therefore figured the species from West African material. G. sophiae is quite widespread along the southwest coast of Ireland and since it differs somewhat from the material described by Lincoln (1979) it is figured herein from the Celtic Sea.

Krapp-Schickel & Myers (1979) reviewed the Mediterranean species of Gammaropsis and segregated the species into two groups, group ‘A’ species characterized by the possession of a toothed urosome, toothed coxa 1 and long acute epistome, and group ‘B ‘ species characterized by having a smooth urosome, smooth coxa 1 and short epistome.

This small species was described by Verrill in 1898, and first observed by Miss Verrill in 1892 near New Haven, U.S.A.

In 1902 Parker noted a number of new localities, and remarked upon its rapidly extending range on the American coast.

The oilfish, Ruvettus pretiosus, is an incidental by-catch of the drifting surface longlines targeting swordfish and Thunnidae in the Mediterranean and elsewhere. Despite its global distribution and frequent occurrence in the catch of many fishing gears, little is known about its biology. In this study we examined the dietary preferences and reproductive biology of this species from specimens caught in the eastern Mediterranean. The most numerous and frequently occurring prey items were benthopelagic fish, followed by cephalopods. The sex-ratio was highly skewed in favour of females (1:8.4), while histological examination of the collected ovaries displayed six developmental stages (perinucleolar, early and late lipid stage; early, middle and late vitellogenesis). Oocyte diameter ranged from 23–69 μm at the perinucleolar stage to 224–366 μm at the late vitellogenesis stage. Spawning is expected to occur during mid and late summer; however there were no individuals available from this period. The findings are discussed in relation to the ecology of the species.

Homogenates of pyloric caeca, gonads, spermatozoa and eggs from the starfish Asterias rubens were fractionated by gel filtration chromatography.

It appeared that a glycolipoprotein fraction, present in oocytes and gonads of female animals, is absent in spermatozoa and gonads of male animals.

The possible role in vitellogenesis of this fraction and of a more omnipresent one is discussed.

The prevalence and infestation intensities of Octolasmis lowei in the branchial chambers of Libinia spinosa were evaluated according to the host's sex, size, and moult condition. Epibionts were classified as cyprid larvae, non-ovigerous or ovigerous according to their developmental stage. A median intensity of infestation of 21 epibionts/host was found (range = 1–644; Q3 = 81). Epibiont prevalence values (88%) were higher on ovigerous female hosts than on males (55%) or on non-ovigerous females (31%). Intensity of infestation was positively correlated with host size in both sexes for non-ovigerous and ovigerous epibionts. No preference between host sex by cyprid larvae was observed, nor any correlation between cyprid abundance and host size. Cyprid larvae abundance was positively correlated with settled epibionts on both host sexes. The duration of the intermoult phase was the main factor linked to the establishment of sessile epibionts. These observations are important in relation to crabs that have a terminal moult, because these animals cannot eliminate their epibionts in future moults, thus increasing the importance of density-dependent mechanisms on epibiont establishment; in that way, prevalence of infestation alone can underestimate the real impact of infestation on the host's life cycle.

1. The yellow colours of the hydroids include at least two groups, the carotinoids found in the Antennulariidæ and Haliciidæ and the flavone-like pigments that occur in the Sertulariidæ. From the literature a third group, the uradines, may be added.

2. The flavone pigments and their relatives are all water soluble and are thus distinguished from the carotinoids which are not water soluble, but may be dissolved in the usual fat solvents.

3. In the Sertulariidæ studied, a graded series of chromatophore groups and pigments was found which ranged from the colourless species Sertularia argentea Ellis and Solander, through the yellow of Sertularella gayi Lamaroux and S. polyzonias Linnæus, to the orange-brown of Thuiaria articulata Pallas. The brown of Sertularia pumila is probably also a flavone derivative.

4. The flavones and related pigments occur extensively in the plant kingdom. It is probable that the flavone-like pigments found in the Sertulariidæ are of plant origin.