Isolated oceanic islands may give rise not only to new and endemic species, but also to unique behaviours and species interactions. Multi-species fish interactions, such as cleaning, following, mob-feeding and others are understudied in these ecosystems. Here we present qualitative and quantitative observations on cleaning and mob-feeding reef fish associations at the isolated Ascension Island, South Atlantic Ocean. Cleaning interactions were dominated by juveniles of the facultative fish cleaners Bodianus insularis and Pomacanthus paru, with lesser contributions of Chaetodon sanctaehelenae, Thalassoma ascensionis and the cleaner shrimp Lysmata grabhami. Two types of feeding mobs were consistently identified: less mobile mobs led by the surgeonfish Acanthurus bahianus and A. coeruleus and the more mobile mobs led by the African sergeant Abudefduf hoefleri. This is the first record of A. hoefleri from outside of the Eastern Atlantic and also the first report of this species displaying mob-feeding behaviour. The principal follower of both mob types was the extremely abundant Melichthys niger, but the main aggressor differed: Stegastes lubbocki, a highly territorial herbivore, was the main aggressor of Acanthurus mobs; and Chromis multilineata a territorial fish while engaged in egg parental care, was the principal aggressor towards Abudefduf mobs. Our study enhances the scarce information on reef fish feeding associations at the isolated Ascension Island and at oceanic islands in the Atlantic in general.

In a previous paper (Steven, 1948), brief accounts are given of three distinct mackerel fisheries that at one time existed in the south-west of England—an inshore fishery in the English Channel carried on from Plymouth, a deep-sea fishery from Newlyn, Cornwall, and an inshore fishery from Newlyn and some other Cornish ports. One of these fisheries, the Plymouth one, no longer exists. After a few years of considerable activity following the termination of the 1914–18 war, this fishery collapsed in 1924 (Table I) and came entirely to an end a few years later. The small quantities of mackerel landed at Plymouth in subsequent years have been incidental catches by vessels fishing for herrings or pilchards.

It has long been recognized that a proper knowledge of the fauna of submerged rocks can be obtained satisfactorily only by direct study with diving apparatus (Gislen, 1930; Kitching et al., 1934). Although the latest methods of indirect underwater observation, photography and television, may be useful on a smooth sea floor, they can give little information about a rocky area owing to their inability, as yet, to look underneath a boulder or an overhanging ledge. The superiority of the ‘submarine biologist’ over the indirect methods lies in the fact that he can readily collect samples for positive identification, or mark individual organisms for further study; though at present, unless very expert, he is limited to depths of under 20 fathoms. The successful use of free-diving apparatus for biological work is well established. Five years ago Prof. Drach with Cousteau's now famous ‘aqualung’ investigated the sublittoral fauna of various rocky shores, reaching a depth of 30 m. (Drach, 1948). Much additional work has been done in the Mediterranean and other warm seas, while farther north Bainbridge (1952) used a Siebe-Gorman apparatus to study the behaviour of plankton in the Clyde.

Terebella lapidaria L. is a small terebellid common in crevices in the mid-littoral zone of rocky shores in the Plymouth area. The coelom contains abundant coelomocytes charged with haemoglobin in sufficient quantity to give the worm a brick-red colour. T. lapidaria also has a discrete vascular system with haemoglobin dissolved in the plasma. When covered by the tide the worm irrigates its burrow intermittently. When revealed by the tide it cannot do so, and is then left in a thin film of water or in moist air for 3–4 h. We thought it was of some interest therefore to determine the oxygen equilibrium characteristics of these pigments.

Very little work has as yet been done on the occurrence and distribution of marine lichens in the Plymouth district. The present investigation of the genus Lichina was undertaken at the suggestion of Dr. J. H. Orton, who, having noticed the two Lichina species at New Train Bay near Pad-stow, North Cornwall, thought it might be of interest to determine their distribution in the Plymouth area.

Sea water contains very little zinc. Values from 0–73 mg. per cubic metre have been cited in Physics of the Earth, V, 180, Washington, 1932. According to Orton it is less than 0–1 parts per million in the English Channel. Dieulafait found 2 nig. and Bodansky 7–3, erroneously quoted as 73 above. The method described here permits of the detection of as little as 8 mg. per m3 using 200 ml. of distilled water in a Hehner tube, the delicacy of the reaction being much greater than that of any other for zinc. Sea water from the English Channel gives no turbidity and so is unlikely to contain as much as 8 mg. per m3. The method is brought forward on account of its usefulness in detecting and estimating zinc in sea water contaminated by contact with metallic surfaces. Its use in fresh water has already been described (Analyst, 1935, 60, p. 400, No. 711, June), and to this paper reference may be made for some possible sources of interference and for the origin of the reagent.

The structure of the tentacle in two species of Pogonophora (of the genera Nereilinum and Oligobrachia) has been investigated by light- and electron-microscopy. The fine structure of the pinnules, epidermal cells and mucous cells is described. The surface membrane of the epidermal cells and the pinnules forms an elaborate system of microvilli which traverse the cuticle and often extend up to the surface particles.

Genetic variation was investigated in five subtidal locations from the north of San Matías Gulf (42°23′S) to the north of San Jorge Gulf (45°02′S). Fifteen loci were studied by means of vertical starch gel electrophoresis; ten loci were polymorphic. The percentages of polymorphic loci (P0·99 and P0·95 criteria) varied between 40% and 53·33% and between 33·33% and 46·67%, respectively. Expected mean heterozygosity per locus (He) ranged from 0·128 (Bajo Oliveira-El Sótano) to 0·160 (Puerto Madryn); this range is similar to those observed for other scallop species. All the loci were in Hardy–Weinberg equilibrium. The estimated genetic distances among populations were significantly lower than those reported for comparisons between populations of different pectinid species, suggesting that the five populations studied belong to the same species (Aequipecten tehuelchus). The absence of exclusive fixed alleles also supported that assumption. The results obtained suggest: (i) assignment of species or subspecies status to some morphological variants of the shells, like the ‘madrynensis’ form is not supported; (ii) the commercially exploited Tehuelche scallop from San Matías and San José Gulfs should be managed as distinct stocks.

The Cortes geoduck (Panopea globosa) has been considered a Gulf of California (GC) endemic but anecdotal and unpublished evidence has suggested its presence in Bahía Magdalena (BM), on the Pacific coast of southern Baja California. Establishing the identity of geoduck clams and their distribution limits is not only of clear biological significance to understand their structural and functional variation, but is also of consequence for their conservation and management, given the multi-million dollar fishery they support in north-west Mexico. We analysed Panopea clams from Mexican populations, including BM, using an integrative approach including genetics, morphometrics, and an ecological niche model. Our genetic results (restriction fragment length polymorphisms of nuclear ribosomal DNA and mtDNA cytochrome c oxidase subunit I sequences) clearly identify BM geoducks as P. globosa, implying a significant geographical range expansion outside of the GC and refuting its status as endemic to the Gulf. On the other hand, clams from BM were phenotypically different (shell significantly higher) from other Mexican P. globosa and Panopea generosa specimens, which may account for the confusion in their morphological identification. The ecological niche model for P. globosa, integrating ecological and distributional data from the GC, revealed a very low probability (<10%) that this species could successfully occupy BM. Our results and those of others suggest that the Cortes geoduck population in BM may be adapted to specific environmental conditions differing from those experienced by conspecifics inside the Gulf and is likely isolated. This is highly relevant for the management plans of Mexican geoducks.

The allometric growth of Uca leptodactyla from two distinct subtropical estuaries on the Brazilian coast was evaluated concerning its growth pattern and size at onset of sexual maturity. Females attained maturity at similar sizes in both sites (4·1 mm of carapace length in Indaiá and 4·2 mm in Ubatumirim), while males differed slightly. They reached the size at sexual maturity of 5·3 mm of carapace length in Indaiá and 4·6 mm in Ubatumirim. Growth pattern is usually similar among crabs from distinct sites while size at sexual maturity is frequently different. However, in the case of U. leptodactyla it did not occur, probably due to the strong habitat similarity and intrinsic features of this species.

Tigriopus californicus uses several appendages and processes in the collection and manipulation of food. Their structure and function appear to enable the species to utilize the variety of food materials found in splashpools, including: detritus and organic floes; superficial material on particles; faecal pellets; protists; diatoms; and small crustaceans. From light and scanning electron microscopy and video, the labrum and labium appear to be adapted for biting soft and hard food materials and holding food for trituration by the mandibles. From energy dispersive X-ray spectra, the gnathobase of the mandible is suggested to be sclerotized but not calcified or silicified. It has an array of bilobate and multilobate teeth, clusters of spinous processes, and a heavy, spine-bearing process to move food into the oesophagus. There is also a flange which articulates in a groove in the labrum which appears to provide a guide for the gnathobase as it moves vertically.

Two species of Portumnus occur in the Plymouth area, P. biguttatus (Risso) and P. latipes (Pennant). P. biguttatus was the only species recorded when the old fauna list of Plymouth was published (1904), but since then it is known that P. latipes is very common in certain sandy areas (see Plymouth Marine Fauna, 1931), far commoner than P. biguttatus.

P. biguttatus is rare and has not been seen since 1906. It was first found by W. Garstang and R. Todd on Drake's Island in Plymouth Sound, burrowing in fine gravel (1905), and two specimens, and are recorded from a sandy patch from the north-east corner of Drake's Island. A female in berry was recorded from the same locality by R. Todd, and L. R. Crawshay dredged one in Cawsand Bay in 1906. Apparently the eggs were not hatched out and the zoea of this species is unknown. In August 1902 R. Gurney obtained a megalopa in the plankton and from it secured the first crab stage. He describes the megalopa as being intensely blue. The cast skin of the megalopa and the crab obtained from it (Fig. 3a-c), which he kindly handed to me, are described in my paper of 1928 (Lebour, 1928c, p. 518, pl. viii, figs. 1–3). There is no reason to doubt the accuracy of the determination, especially because, as shown below, corresponding stages of P. latipes as well as the zoeae are now known and are very distinct, differing considerably from those of P. biguttatus.

In the years 1996 and 1997, the pattern of deposition of beached coral heads and pieces onto the shore of Telecom Bay within the Cape d'Aguilar Marine Reserve, Hong Kong suggested that typhoons were a significant natural perturbation. In August 1997, 808 pieces weighing 60,930 g were washed up following passage of Typhoon Victor. 1997 was also Hong Kong's wettest year on record and a survey of the living corals in the reserve in 1998 showed changes in a number of ecological parameters of species richness, composition and diversity but, most noticeably, that the formerly dominant Goniastrea aspera had been superseded by Platygyra sinensis. In 1998 and 1999, this was reflected in the changed proportions of these two beached corals. Dramatically lowered salinities in the bay during July and August 1997 may have effected this change in relative dominance. Following Typhoon Dan in October 1998, 342 pieces of corals weighing 75,600 g were collected. The 1996 and 1997 pattern seemed to be repeating itself. 1999 was a bad year for severe tropical storms and typhoons in Hong Kong, seven being reported upon. Yet, after each one only 12,490 g (Typhoon Leo), 3390 g (Typhoon Maggie), 3550 g (Severe Tropical Storm: no-name), 55 g (Typhoon Sam), 4500 g (Typhoon York and Typhoon Cam) and 3160 g (Typhoon Dan) were washed up. That is, the seven tropical depressions deposited about 27,640 g coral, approximately the same amount as only Typhoon Sally in 1996 (25,000 g) and Tropical Storm Penny and Typhoon Babs in 1998 (24,574 g) and less than half that of Typhoon Victor in 1997 (60,000 g). In July 1996, Cape d'Aguilar was declared a marine reserve, fishing banned in its 18 hectares of sea and ghost nets removed. The fishing ban seems to be halting the dislodgement of corals and they are thus not now being beached by typhoons.

Substratum heterogeneity on rocky shores can affect the distribution pattern of sessile epibenthic organisms. The rocky shore at Usujiri, southern Hokkaido, Japan, is composed of well-developed, columnar jointed dolerites. In this area, landscape is characterized by a mosaic of barnacle and mussels, where species composition in patches differs among typical topographic-classes, i.e. barnacles dominate on horizontal planes and vertical planes while mussels only inhabit in grooves. To determine the factors maintaining those distribution patterns, the recruitment of dominant sessile species in the typical topographic-classes with and without adults of barnacles and mussels were examined by field experiment. The results showed that the distribution pattern was determined by recruitment, and the recruitment pattern was strongly affected by rock-surface topography. Moreover, the presence of conspecific adults contributed to the maintenance of this topography-related mosaic by facilitating recruitment. These results show: (1) the presence of resource division for rocky topography among barnacles and mussels; and (2) that intraspecific positive interaction rather than interspecific competition may play important role in maintaining the topography-related mosaic of barnacle and mussels at Usujiri.

Salpingoeca natans Grentved and 5. spinifera Throndsen have been removed from Salpingoeca James-Clark and made the nomenclatural types of Calliacantha gen.nov., and Bicosta gen.nov., respectively.

James-Clark (1876) erected the genus Salpingoeca J.-Clk, 1867 for solitary choanoflagellates with colourless, transparent, thecae.* As for most choanoflagellates the protoplasts possessed a single anterior flagellum surrounded by a hyaline collar which, when viewed with the light microscope, appeared membranous.

Data came from the Irving, Meteor and Plato seamounts and, were obtained during the Seamount 2 Expedition on board the RV ‘Le Suroît’ in 1993. On the three seamounts, polychaetes were sampled at 44 sites from 260 to 1800 m: 8 sites on Irving, 27 on Meteor and 9 on Plato. In all five seamounts, 1753 individuals were collected: 403 on Atlantis, 346 on Hyeres, 523 on Irving, 387 on Meteor and 94 on Plato. The species richness from the five seamounts is 53: 31 on Atlantis, 24 on Hyeres, 20 on Irving, 28 on Meteor and 21 species on Plato. Only nine species are present on all five seamounts. Three families Onuphidae, Amphinomidae and Eunicidae are dominant. Two groups of seamounts were identified by cluster analysis: Atlantis and Hyeres and, Irving, Meteor and, Plato. The distribution of the polychaetes collected on these five seamounts are compared with the polychaete fauna from the North Atlantic ocean.

An investigation has been made of the species of Sagitta present in parts of the Irish Sea, their relative occurrence, and the annual number of reproductive cycles of each species. Three stages of maturity as described by Russell (1932a) have been used. To determine the maturity the Sagitta were transferred to a solution of 75% alcohol and stained with borax carmine.

S. elegans Verrill and S. setosa J. Müller were collected in Liverpool Bay and in Port Erin harbour, Isle of Man. The former species was predominant at Port Erin. The coasts of Liverpool Bay have been added to the permanent range of S. setosa.

At Port Erin there appears to be but one chief spawning period for S. elegans which extends generally from January through May. Following May the young forms appear in numbers and gradually mature through December to repeat the annual cycle.

There appear to be two main breeding seasons for S. setosa in the outer Mersey Channels. The first and most noticeable begins in April and extends into June. There is evidence for a second breeding period in August.

Both species were found in the samples taken from Morecambe Bay and Anglesey. The stage of maturity of these agreed with the Sagitta caught at the same time at Port Erin and Liverpool.

The total monthly catches of Sagitta from Port Erin and the outer Mersey Channels have been recorded.

In recent years the development stages of Copepoda have been the subject of study by various workers. Their attention, however, has been mainly directed to fresh-water species, presumably because the material is more readily available, and it seems desirable that our knowledge of the development of marine Copepoda should be extended. The material utilised for the present work was collected on the periodic and comprehensive fishery cruises carried out by the F.B.S. Explorer, and we are indebted to the Fishery Board for Scotland for permission to undertake this detailed study. Since the appearance of Grobben's standard work on Cetochilus septentrionalis Goodsir (Calanus finmarchicus Gunn.), the only important publication dealing with the life-histories of marine Copepoda, so far as we have been able to ascertain, is that of Oberg, who, in Die Metamorphose der Plankton-Copepoden der Kieler Buclit, describes the development stages of seven common marine forms. Oberg's choice of species, which are all more or less neritic, was again obviously dictated to him by the material at his disposal, and it is hoped that our collections, which cover not only the northern part of the North Sea, but also the Faroe–Shetland Channel, and part of the Atlantic itself, will furnish material for the establishment of the life-histories of some of the more oceanic forms.

The male scaled squid Lepidoteuthis grimaldii hereby reported for the first time, is equipped with a pair of grossly enlarged sabre-like hooks. These unique hooks, found only on males, are without parallel amongst cephalopods. As a sexually dimorphic character, they are more likely to be involved in reproduction than predation.

The population and reproductive characteristics of the hermit crab Pagurus proximus Komai, 2000 have been examined in the northern part of the species range (Vostok Bay, Peter the Great Bay, Sea of Japan). The average population density was 4–5 ind m−2 in winter and spring, 10 ind m−2 in summer and autumn; the biomass was 7–9 and 18–19 g m−2, respectively. Hermit crabs were found at a depth of 0 to 12 m but were most numerous at about 3 m depth with an average population density of up to 26 ± 7 ind m−2. The shield length of males varied from 1.3 to 7.8 mm and females from 1.2 to 6.7 mm. The male to female ratio was close to 1 but varied with size and season. Females attained sexual maturity at a shield length of more than 1.3 mm. Ovigerous females were found from December to August. The proportion of ovigerous females increased from 7% in December to 93% in late April; however, the embryos in clutches remained at early developmental stage until May. The mass release of larvae was observed at the beginning of June. A subsequent spawning probably took place in July. The main factors contributing to the high abundance of P. proximus in the investigated area are the presence of the embryonic diapause synchronizing the release of larvae at the most favourable time for their development, high fecundity, the presence of at least two egg clutches during the reproductive season, and total absence of parasites.