ALBERT

Description: Males of Eledone cirrhosa grow to a size little over 600 g and normally have well-developed, and presumably active, reproductive organs from about 200 g upwards. Total weight of the genital bag is well correlated with total body weight (r= 0·906). Growth of the testis precedes that of the spermatophoric sac, and the size of neither of these reproductive components is predictable from body weight. The sizes of these organs and the estimated number and length of stored spermatophores are given for 100 g intervals of total body weight. No evidence was obtained for a seasonal trend in male maturity.

Description: Serological methods for prey identification have been applied to detection of residues ofsandeel (Ammodytidae) protein in faeces of common seals (Phoca vitulina) and grey seals(Halichoerus grypus) from the Moray Firth, north-east Scotland. Antisera raised to muscleprotein from Ammodytes marinus were evaluated by testing their reactions with proteinextracts made from a range of North Sea fish species and protein residues in in vitro digestates,seal digestive tracts and seal faeces. It was concluded that, using fused rocketimmuno-electrophoresis, linkage of precipitin peaks from unknown samples with peaksfrom standard sandeel extract was a reliable indicator of the presence of sandeel in theunknown sample. Seasonal variation in the incidence of sandeels in common seal diet in theMoray Firth was examined by identifying otoliths, bones, and proteins, and all threemethods indicated that sandeels occurred in the majority of samples tested in the summer,but were less important during the winter. Proteins were detected in fewer samples thanotoliths, particularly in February and March. Possible reasons for this difference arediscussed. Serological identification of sandeel proteins is potentially applicable to dietarystudies on all marine predators.

Description: Age and growth were estimated in the European squid, Loligo vulgaris, by examining growth increments in the statoliths of 203 specimens collected from off the French Mediterranean coast. Length and increment data were analyzed assuming that the increments were formed daily. The relationships between age and length showed that: growth rate varied considerably among individuals; growth was double exponential; the squids grew on average to 240 mm ML at 240 d from hatching, with a maximum of 350 mm at 240 d; the life span is probably about one year.

Description: Some of the limits to the use of serology to identify prey species in the digestive tracts of cephalopods have been evaluated. Cuttlefish, Sepia officinalis, were given meals of krill slurry (Euphausia superba). Protein extracts of contents from four regions of the digestive tract, stomach, caecum, digestive gland and intestine, were tested for prey antigenicity. Digestion times (loss of antigenicity) ranged from 1 to 8 h depending on sampling site. Stomach and caecum emptied rapidly, but meal antigenicity persisted longer in the digestive gland. The Sepia experiments provide a basis for interpretation of results from natural predation by cephalopods).

Description: An investigation was carried out on larvae of the oceanic tropical squid Sthenoteuthis pteropus in the equatorial Atlantic (2°30′N–7°S;12°W –8°30′E) The age of the larvae was calculated from the statolith microstructure of 20 larvae; mortality was estimated from the size structure of 1128 larvae. The larval stage lasts 32–38 days. At ages ranging from 14 to 38 days. the daily relative growth rates of mantle length decrease from 7.5 to 2.8% day −1 and from 14–16 to 5.8% of body weight day −1 At age 12–24 days, mortality rates were estimated using both raw catch data and corrected data accounting for net avoidance. The mean value of raw mortality rates was 0.189, the corrected value was 0.158. During the proboscis division (transformation of the larva into juvenile) at age 25–35 days, a sharp decrease in larval growth rates and a simultaneous increase in mortality rates (raw 0.443, corrected 0.379) were observed.

Description: The stomachsof 23 striped dolphins (Stenella coeruleoalba Meyen, 1833, Cetacea), stranded along the Ligurian coast (western Mediterranean Sea), contained 32 species of cephalopods, crustaceans and fishes, totalling an estimated 2,723 prey specimens representing about 36 kg in weight. Cephalopods and bony fishes were equally important in the diet (50%). Todarodes sagittatus (34.5%) and Micromesistius poutassou (25.9%) were found to be the most important food species. Other species belonging to six cephalopod families, three crustacean families and nine bony fish families, contributed to the diet with variable numbers, weights, and occurrences, demonstrating the opportunistic character of striped dolphin feeding.

Description: In 1988 and 1989 the occurrence of external diseases in fish from the German part of the Wadden Sea was quantified. Thirty-two stations, located along seven transects including four estuaries, were sampled monthly or at 3-month intervals with shrimp trawlers: more than 124 000 fish were studied. Six percent of the seven dominant fish species of 〉 12 cm length were diseased. In fish species which complete their life cycle in the Wadden Sea (gobies, hooknose, eelpout, sea scorpion) the total disease incidence was below 0.4%. In whiting, plaice and sole it was between 0.5 and 2.5%, while 6–8% of smelt, cod, eel, dab and flounder suffered from external lesions. The incidence of most diseases increased with increasing fish length. Similar geographical patterns in prevalence were observed for: (1) two types of skeletal deformities, (2) lymphocystis in dab and flounder, (3) papillomatosis in smelt and dab and (4) several infectious ulcerative diseases. Most of these ulcerative diseases of cod and flounder occurred on central estuarine stations, suggesting an impact of the relatively low, but greatly variable salinity on disease development. Buccal granulomatosis of smelt and papillomatosis of eels showed the highest incidence in the Elbe estuary as the most heavily polluted region of the Wadden Sea. A causal relationship between disease development and pollution, however, is not yet clear and requires experimental evidence. The disease types found are ranked into three priority groups regarding their indicator value for a pollution monitoring on the basis of fish diseases. There is evidence that the total disease load of fish in the Wadden Sea is higher than in other shallow coastal regions outside the North Sea. Little is known of the effects of these diseases on single fish and fish populations. “Yellow pest” of cod, which was recorded for the first time during this survey, and which occurred with an incidence of up to 14% in single estuarine samples, causes the most serious lesions and is supposed to be lethal. In total, however, the effects of a number of pathogenic parasites on fish survival is considered to be more serious than that of deformities and infectious diseases.

Description: Thirty-four adult individuals of Loligo forbesi (males and females with dorsal mantle lengths from 27–77 cm) were observed in captivity in a 3 m diameter closed sea-water system on Faial Island, Azores. Squids were caught by jigging and were fed with horse mackerel (Trachurus picturatus) and chub mackerel (Scomber japonicus), either alive or dead. The maximum survival was 73 days. Feeding behaviour was dependent upon both the size of prey and its state of preservation;e.g. the squid would eat the head of small fish (〈 about 15 cm), reject the head of medium-sized fish (about 15–35 cm) and would eat only the dorsal part of a big fish (〉 about 35 cm) or a fish poorly preserved. Seventeen chromatic, 9 postural and 6 movement components of body patterns were observed and described. Conspecific interactions considered to be aggression and dominance were observed among males; no such interactions occurred when one male and two females were kept together. Body patterns in relation to relaxation, stress, shock, feeding, locomotion and aggression are also described.

Description: The presence of Stoloteuthis leucoptera in the Mediterranean is recorded on the basis of three specimens, including an adult male, caught by IKMT and by commercial otter-trawl in the Ligurian Sea. The hypothesis of a recent immigration is discussed. The list of Mediterranean cephalopods (Mangold Wirz, 1963; Torchio, 1968; Bello, 1986; Mangold & Boletzsky, 1987) includes the Sepiolidae of the subfamily Heteroteuthinae, whose members are supposed to be pelagic throughout their life cycle. Mangold Wirz (1963) recognizes in the Mediterranean fauna the unique species Heteroteuthis dispar, the other authors include H. atlantis Voss, which Voss himself (1955) reported at Messina. To this group may now be added Stoloteuthis leucoptera (Verrill, 1878) a species until now recorded in limited Atlantic areas. Verrill (1881) wrote “This species is an exceedingly beautiful one, when living, owing to the elegance and brilliancy of its colours and the gracefulness of its movements. In swimming it moves its fins in a manner analogous to the motion of the wings of a butterfly.”

Description: We present chemical data on magmatically heterogeneous pyroclastic deposits of late Quaternary age erupted from zoned magma systems underlying Tenerife (Canary Islands), Sao Miguel and Faial (Azores), and Vesuvius. The most fractionated magmas present at each centre are respectively Na-rich phonolite, trachyte, and K-rich phonolite. Within any one deposit, chemical variation is either accompanied by changes in the phenocryst assemblage (petrographic zonation) or is largely manifested in trace element abundances, unaccompanied by any petrographic change (occult zonation). Zoning is analogous to that in calc-alkaline systems where the most fractionated products are high-silica rhyolites. When a range of magma types are considered, a correlation emerges between roofward depletion of trace elements (especially REE) in the zoned system and compatability of those same trace elements in the accessory phenocryst phases present. Thus, allanite- or chevkinite-bearing rhyolitic systems are light-REE depleted roofwards, the sphene-bearing Tenerife system is middle-REE depleted roofwards, the melanite-bearing Vesuvius system is heavy-REE depleted roofwards, while the Azores systems, which lack these phases, display roofward REE enrichment. Therefore, the behaviour of trace elements may in each case be explained by fractionation of observed phenocryst assemblages. The resemblance between features of zoned magma systems and published work on the dynamic consequences of cooling saturated aqueous solutions prompts us to suggest that sidewall crystallization and consequent boundary-layer uprise to form a capping layer at top of the system may be a plausible mechanism for the generation of both petrographic and occult zonation. Reverse zoning occurs among the first-erupted tephra of some deposits, demonstrating that the most highly differentiated magma available is not always the first to be tapped during an eruption from a zoned system.

Description: Changes in the relative size of the ovary, oviducal glands and eggs are described for Eledone cirrhosa captured from the North Sea off Aberdeen over a 3 year period (N = 488). The analysis is based only on freshly caught animals, excluding those held in aquarium conditions (〉 5 days). Ovary enlargement and egg size estimates are used as indices of sexual maturity. Between 0–15% and 18–95% of total body weight is contributed by the ovary. Maximum egg length in the ovary ranges up to 7 mm. On these criteria, sexual maturation typically occurs at body sizes between 400–1000 g although some animals of 1000–1200 g are found showing no evidence of ovary enlargement. The majority of the monthly sample is always immature but maturation can apparently occur at almost any time of the year. Increase in mean ovary index and mean values for egg size are strongly seasonal and indicate a peak incidence of sexual maturity over 2–3 months in the July-September period. Spawning is presumed to follow within 1 month. Estimates of the fecundity of the females, based on the egg sample from the ovary, range from 2·2 × 103 to 55 × 10 3 eggs with a mean of 11 × 10 3 and a mode of 7·5 × 10 3 eggs.

Description: Female Eledone cirrhosa held in aquarium conditions for periods of time of five daysand over show relatively enlarged ovary sizes. Values for ovary index considerably exceed thoseof freshly caught animals and the incidence of the final stage of maturity, in which eggs pack the oviducts, is greater. A comparison of maturity indices for fresh and aquarium males was inconclusive. The range of factors associated with aquarium conditions is briefly reviewed and it is concluded that studies of cephalopod reproductive maturation must distinguish fresh and aquarium animals. Introduction External factors effective in inducing sexual maturation in cephalopods have been suggested several times. The influence of the absence of light has been implicated since the experiments of Wells & Wells (1959) showed that blinded Octopus vulgar is matured precociously. An effect of short day length in stimulating the optic glands of Sepia has been found by Defretin & Richard (1967) and Richard (1967) but this is not clearly the case for Octopus (Buckley, 1977). Octopuses kept in aquarium conditions for lengthy periods are said to have larger relative gonad sizes than those fresh from the sea (Wells & Wells, 1975). One of the factors associated with aquarium conditions is often a degree of starvation, and this circumstance alone is held to be a factor in inducing precocious sexual maturation in Eledone (Mangold & Boucher-Rodoni, 1973). In the course of recent studies on the growth and reproduction of Eledone cirrhosa from the North Sea (Boyle & Knobloch, 1982,1983,1984) animals which had remained in aquarium conditions for 5 days or over were separated from the analysis.

Description: Earlier work by the second author on the growth of oceanic squids, based on sizefrequency distributions of beaks sampled from sperm whale stomachs and on structural marks on those beaks, showed that these squids apparently had growth rates far in excess of those reported for the fastest-growing fishes, e.g. bluefin tuna. The application of recently developed methods for analysis of length-frequency distributions to some of these earlier data, and new approaches for assessing and comparing the growth performance offish and aquatic invertebrates, suggest the need for a downward revision of these high growth estimates. This is illustrated here with data on Kondakovia longimana (Cephalopoda, Onychoteuthidae) sampled off Durban and Donkergat, South Africa, in the early to mid-1960s.

Description: Samples of two loliginid squids Alloteuthis africana and A. subulata were collected from the continental shelf off the west Sahara in August-September 1987. Statoliths were taken from 124 specimens and processed using statolith ageing techniques. Statoliths of both species were very similar in shape. In the ground statolith, growth increments were examined and grouped into four growth zones distinguished mainly by the width of the increments. Age of adult mature males of both species did not exceed eight months, that of females six months. Alloteuthis africana grew faster than A. subulata in weight and, particularly, in length. At age 180 d the mantle of A. africana was twice as long and the body weight 1·2–1·5 times as large. Both species matured over a wide range of sizes and ages (from 120 to 180 d). The life span of A. africana and A. subulata hatching between January and May on the west Saharan shelf is about six months, much shorter than that of A. subulata in its northern temperate range.

Description: Artificial selection processes associated with harvesting may operate over relatively short time scales in short-lived semelparous species. The ommastrephid squid Illex argentinus on the Patagonian Shelf is the target of a major fishery. Recent work has provided new information on the biological characteristics of squid in this fishery. That information has been utilized in the development of a model of the cohort dynamics and some of the within-seasons selective effects considered. The model results are consistent with earlier data from the shelf fisheries, supporting suggestions that the males nature and migrate earlier towards the spawning grounds than the females. Earlier maturation results in a smaller mean size in the spawning stock, while later maturation results in greater exposure to the fishery and a reduced numbers of individuals surviving to spawn. Under the current fishing regime greater egg production and a larger spermatophoric complex mass for the whole cohort is achieved by relatively late maturation. In general, however, the earlier maturation occurs, the earlier is the peak in total egg production. The within-season pattern of effort expenditure in the fishery can affect not only yield from the fishery but also the reproductive potential of the spawning stock. The management policy adopted for this fishery is likely to be conservative in terms of maintenance of a spawning stock, however, the potential for selective effects is larger and this may affect both yield and reproductive potential. The results are discussed in relation to short- and long-term effects in the fishery and the implications for future research requirements.

Description: A new species of a monogenean Isancistrum subulatae (Gyrodactylidae) has been discovered on the arms and tentacles of the cephalopod mollusc Alloteuthis subulata at Plymouth and I. loliginis, on the gills of the same host, has been re-discovered for the first time since its original description in 1912. I. subulatae, like other gyrodactylids, is viviparous, and has been shown by experiments to transfer to new hosts by contagion. In nature such transfers probably take place during copulation of the hosts and since the parasite may occur in numbers of several thousands per host, it may thereby constitute a venereal disease.

Description: Samples of female lllex argentinus were taken from the catch of a Japanese squid jigging vessel on the Patagonian Shelf during March 1986. Morphometrics of the somatic and reproductive organ systems and the histological structure of the mantle in relation to maturation were examined. The data suggest that growth and maturation occur simultaneously during most of the time that lllex argentinus females are on the feeding grounds. In a squid of a ‘standard’ mantle length the whole body mass increases relative to mantle length during maturation and growth of the reproductive organs. This is accompanied by a small but significant decrease in the relative mass of the mantle, head and viscera whilst the mass of the digestive gland remains constant. Although mantle mass of a ‘standard’ female squid decreases relative to mantle length with maturity this is not associated with degeneration of the mantle muscles. Energy and nutrient resources for maturation are apparently derived from the squid's food, not from reserves, and during the course of maturation there is an increasing shift of emphasis from somatic growth to production of gonad and accessory reproductive organs.

Description: The timing of spawning and recruitment in the squid Loligo forbesi in Scottish waters is described on the basis of data from three sources: monthly samples of squid caught by commercial trawls (1986–1988), egg masses found by fishermen (1987–1991), and statistical data on animals caught by research trawls (1978–1987). Spawning females were present in samples from December to June, with peak spawning occurring in March. Most records of egg masses were from these months, but eggs were also found in August and September. These results suggest that there is an extended spawning season. Small squid (≤100 mm dorsal mantle length) were rarely present in commercial samples, but were recorded in research samples almost all year round. Thus there appears to be more or less continuous recruitment into the catchable population. The results of the present study are consistent with published data from other parts of the geographic range in that there is a regular seasonal peak in spawning, and spawning adults disappear from the population in summer. Further interpretation of the life-cycle of this species is not justified on the basis of current knowledge, and more information is needed on migrations, geographical variation, and lifespan in Loligo forbesi.

Description: Gray whales (Eschrichtius robustus) feeding in the northern Bering Sea produce prey-rich mud plumes that provide ephemeral foraging opportunities for seabirds. Approximately 67% of all gray whales were attended by birds. In four whale-associating bird species (Northern Fulmar, Fulmarus glacialis; Red Phalarope, Phalaropus fulicaria; Black-legged Kitti-wake, Rissa tridactyla; and Thick-billed Murre, Uria lomvia), from 17 to 87% of all individuals that we observed on the water or foraging were in the whales' mud plumes. The combined density of these same four species was strongly correlated with whale density over a broad range of spatial scales. The whale-associating seabirds exhibited species-specific patterns of foraging behavior at plumes, including differences in mean group size, mean residence time, and patterns of movement between plumes. Birds tended to form larger groups and to form more mixed-species flocks in association with whales. The association of marine birds with gray whales in the Bering Sea provides a model system for examining seabird interactions at fine-scale oceanographic patches and demonstrates the importance of these patches in shaping patterns of seabird distribution and behavior.

Description: Cephalopod remains from the stomachs of a Risso's dolphin (Grampus griseus Cuvier, 1812, Cetacea) entangled in a fishing net off the Ligurian coast (central Mediterranean Sea) include squids Ancistroteuthis lichtensteini, Histioteuthis bonnellii, H. reversa and Todarodes sagittatus and the sepiolid Heteroteuthis dispar. All these cephalopods live in oceanic water including water over the steep continental slope where Risso's dolphin is frequently sighted. Histioteuthis reversa contributed 78% of the cephalopods by number, 81% of the wet weight and 73% of the dry weight and calorific value. The total calorific value of the cephalopods represented by lower beaks was 17,300 kj.

Description: The stomach contents of 235 specimens of the squid Sthenoteuthis oualaniensis (4·3–36·5 cm mantle length, ML) were examined. A detailed list of 60 species of prey, comprising young and adult squid, is given together with their frequency of occurrence and proportional contribution. The size and number of each food item was investigated. Three ontogenetic size-groups of S. oualaniensis were distinguished: I, fry and young (4–10 cm ML), micronektonic epipelagic plankton-eaters; II, transient critical size group (10–15 cm ML), converting from feeding on planktonic crustaceans and fish larvae to myctophid fishes; III, medium-sized (adult) nyctoepipelagic nektonic predators (15–36·5 cm ML), feeding primarily on myctophids and secondarily on squid. Myctophids (genera Symbolophorus, Myctophum and Hygophum) were the most abundant prey in the diet of adult S. oualaniensis from different parts of its distribution.

Description: The data presented provides new information on the distribution of Antarctic squids and on the summer diet of the emperor penguins. The diet of 58 adult emperor penguins (Aptenodytes forsteri) on the fast ice of the Drescher Inlet, Vestkapp Ice Shelf (72°52′S, 19°25′W) in the eastern Weddell Sea was investigated. Prey consisted principally of squid, fish, krill, amphipods and isopods. Squids were identified by the lower beaks and allometric equations were used to estimate the squid biomass represented. Beaks occurred in 93% of the stomach samples. Each sample contained a mean of 27 beaks (range 1–206). Ninety-two percent of the squids could be identified by the lower beaks and belonged to four families (Onychoteuthidae, Psychroteuthidae, Neoteuthidae and Gonatidae). The most abundant squid was Psychroteuthis glacialis which occurred in 52 samples with lower rostral lengths (LRL) ranging from 1.4–7.2 mm. Forty-five samples contained Alluroteuthis antarcticus (LRL range 1.8–5.8 mm), 17 Kondakovia longimana (LRL range 4–12.1 mm), and four Gonatus antarcticus (LRL range 4.1–6.1 mm). In terms of biomass K. longimana was the most important species taken by the penguins comprising 50% of total estimated squid wet mass (245348 g) in 1990 and 48% in 1992 (154873 g). However, if only fresh beaks were considered for estimations of squid consumption, i.e. beaks that have been accumulated for not longer than 5–6 days in the stomachs, squid diet was of minor importance. Then total squid wet mass accounted for only 4809 g in 1990 and 5445 g in 1992 which implies that one penguin took c.30 g squid d−1 with P. glacialis and A. antarcticus being the most important by mass. The prey composition suggests that emperor penguins take squid at the steep slope regions of the eastern Weddell Sea.

Description: Mortality of two dogs, after exposure to water of a brackish lake on the German North Sea coast in 1990, is considered to be caused by a toxic Nodularia spumigena Mertens bloom.

Description: The Rhynchoteuthion larvae of Illex argentinus resulting from summer spawning in North Patagonic shelf waters, its distribution and abundance, are described in this paper. The material was collected in the Argentine Sea (35–55°S) by means of plankton nets. The research cruises were made by the R/V Shinkai Maru and the R/V Walther Herwig during the period April 1978 to April 1979. The most important spawning ground of the summer spawning subpopulation is found in continental-shelf waters (between 43 and 46°S) during the period December-February. This area was established on the basis of both ripe (December) and spent females (February). The larvae which were caught during the same period, especially in March, confirmed the spawning area of this demographic unit. The larvae showed the length of the mantle (ML) to be from 1.2 to 6.5 mm. Tentacles were splitting in specimens from 5.0 to 6.5 mm ML (transition stage). When 7.0 mm ML or more, all specimens were juveniles and had their tentacles completely separated. Larvae were characterized as type C, following the proposal of Sato (1973) and Sato and Sawada (1974) in the Bulletin of the Shizuoka Prefectural Fisheries Experimental Station.

Description: The growth of the octopus Eledone cirrhosa has been studied in a population from the North Sea off Aberdeen. Data are presented for the growth of individuals isolated in aquarium conditions; the growth of size classes in thefieldpopulation; and preliminary information on the growth relationships of gonad, somatic, cardiac and brain components of the body. At 15 °C Eledone cirrhosa is capable of growing from 10 to 1000 g in 270 days. From octopuses which feed readily in captivity, weight specific growth rates of up to about 3–5 % day-1 for animals of 100 g body weight are recorded, falling to a maximum of about 1–5 % day-1 at body sizes above 500 g. Females stop growing when sexually mature, but in the sample captured they were consistently larger than males, a feature which may account for the 7:1 bias towards the incidence of females. On a wet-weight basis, the mean food incorporation into growth is 37 % of the food ingested, which is 49% of the gross weight of crabs killed. Field data for 1978/79 suggest that animals recruited to the population at the beginning of the year grew steadily until December, overwintered without growing, then grew rapidly for several months in the subsequent year before disappearing from the samples. The estimated average age of those animals and by implication, the life span, is 20 months.

Description: Samples of male Illex argentinus were taken from the catch of a Japanese squid jigging vessel on the Patagonian Shelf during March 1986 and an analysis was carried out on the morphometrics of the somatic and reproductive organ systems in relation to maturation. The data show that growth and maturation occurred simultaneously during most of the time that Illex argentinus males were on the feeding grounds over the southern Patagonian Shelf. In a squid of a ‘standard’ mantle length the whole body mass increased relative to mantle length during maturation and this could be attributed to the increase in mass of the reproductive and accessory reproductive organs. During maturation the mantle and digestive gland mass showed no significant change relative to mantle length. The mass of the head increased and the mass of the viscera decreased relative to mantle length. In male Illex argentinus, as in the female, the energy and nutrient resources for maturation are derived from the squid's food and during the course of maturation there is an increasing shift of emphasis from somatic growth to production of gonad and accessory reproductive organs. The proportional investment of body mass in reproductive and accessory reproductive organs predicted for a fully mature male Illex argentinus was less than half that of the female.

Description: A joint research cruise (Japan-Argentina-Uruguay) was carried out in the South-western Atlantic during August-September 1989 in order to study the winter-spawning and hatchery areas of Illex argentinus, and also the migration pattern of the juveniles towards the continental shelf. A few Rhynchoteuthion larvae were found in subtropical waters of the Brazil Current, next to the Brazil-Malvinas confluence, and in the frontal zone with shelf water, but never at temperatures below 14°C. Large numbers of juveniles found in subantarctic waters (6–10°C) on the shelf were probably migrating southward from their hatchery grounds following the zooplankton concentrations on which they were feeding.

Description: During a study based on catches taken in the northern North Sea by selected Scottish fishing boats during 1985–1992, large numbers of the normally rare short-fin squid, Todaropsis eblanae (Cephalopoda: Ommastrephidae), were recorded in 1987 and 1990. Our findings, supported by data obtained from plankton/young fish surveys in 1988 and 1989, suggest that in northern waters Todaropsis eblanae generally mates and spawns during late summer and early autumn (June-November). Successful hatching events appear to occur during October-March, producing juvenile (stage I) squid in the early part of the year (January-June). Estimations of maximum male reproductive output and female fecundity were up to 130 spermatophores and ~28,000 eggs per individual, respectively.

Description: Statoliths of Loligo gahi were sampled in the fishery region 45–47°S on the Patagonian shelf during September 1989. Peculiarities of the growth zones in the ground statoliths of adults are described. Maximum age of large maturing and mature females (130–160 mm of mantle length, ML) was estimated to be 325–345 d, that of large mature males (250–290 mm ML) ranged from 360 to 396 d. The squid Loligo gahi d'Orbigny, 1835, occurs in temperate shelf and upper slope waters of the Atlantic and Pacific coasts of South America and is caught commercially by the international fleet in the southern part of the Patagonian shelf within the Falkland Islands Interim Conservation Zone (FICZ) (Roper et al., 1984; Csirke, 1987). Occasionally, dense shoals of L. gahi appear in the fishery region 45–47°S off the Exclusive Economic Zone of Argentina (EEZA) and have been caught in significant numbers by trawlers at depths of 120–150 m in September-October (Chesheva, 1990). Loligo gahi is a medium sized loliginid; in Falkland waters males attain 350 mm ML, females 210 mm ML (Hatfield, 1991), while in the fishery region 45–47°S maximum size is 260 mm and 160 mm, respectively (Chesheva, 1990). Patterson (1988) revealed two Falkland spawning stocks of L. gahi of unclear status, spring-spawners and autumn-spawners (austral seasons) and pointed out that the life span of squid of each stock lasted ~1 y. Recently Hatfield (1991) used statoliths to elucidate Patterson's (1988) estimations of age and growth of Falkland stocks of L. gahi and confirmed the 1-y duration of L. gahi's life span.

Description: Ripe egg dimensions in the squid genus Illex are close to the minimum for cephalopods. The average diameter varies significantly depending on species (0.77–0.82 mm in I. coindeti , 0.75–0.88 mm in I. illecebrosus , and 0.96–1.04 mm in I. argentinus ), on geographical distribution intraspecifically, e.g. I. argentinus (0.96–0.97 mm in the shelf groups and 1.04 mm in the slope oceanic group), and between pre-spawning and spawning females of the summer-spawning shelf group of I. argentinus (0.97 and 0.92 mm, respectively). The potential fecundity (PF), defined as total oocyte stock both in the ovary and oviducts, depends on mantle length (ML in each species. It varies from 90 000 (ML = 150–160 mm) to 800 000 (ML = 230–250 mm) in I. coindeti , from 200 000 to 630 000 (ML = 220–280 mm) in I. illecebrosus , and from 75 000 (ML = 150–170 mm) to 1 200 000 (ML = 360–380 mm) in I. argentinus . It is possible to estimate the actual value of PF shortly before vitellogenesis begins and up to a start of spawning, when the diameter of the smallest oocytes exceeds 0.05 mm. The summer-spawning shelf females of I. argentinus release about of 70% of PF. Their spawning is intermittent and ripe egg production decreases over time with only a 50% replacement of the initial stock of vitelline oocytes and a decreasing volume of eggs at each release. Feeding activity decreases and the mantle wall and internal organs shrink once spawning commences. In spent animals, a degeneration of both vitelline and protoplasmic oocytes occurs. The squids genus Illex is one of typical r-strategists among the cephalopods.

Description: Total biomass and biomass of large taxonomic groups (polychaetes, molluscs, crustaceans, echinoderms) and species diversity of the macrofauna were determined for almost 200 North Sea stations sampled synoptically by seven vessels during Spring 1986 and for 120 additional stations sampled in earlier years by the Marine Laboratory in Aberdeen. There exists a clear and significant decreasing trend in biomass with latitude, both in total biomass and for the different taxonomic groups. Apart from latitude, sediment composition and chlorophyll a content of the sediment also infuence total biomass and biomass of most groups significantly. Biomass increases consistently in finer sediments and sediments with a higher chlorophyll a content. The same trends are found for the results within laboratories. Some interaction exists, indicating weak laboratory and zonal effects. Diversity, as measured by Hill's diversity index N1 = (exp H′) shows a clear and significant trend with latitude. Towards the north of the North Sea diversity increases considerably. The trend is also found for laboratories separately and is everywhere equally strong. Also longitude and depth show an effect on diversity. Sediment variables have no clear influence on diversity. Other diversity measures show the same trend but are more variable than N1,. Total density tends to increase towards the north, but sediment related variables have a larger influence. Mean individual weight becomes considerably smaller towards the northern part of the North Sea.

Description: In 1986 participants of the Benthos Ecology Working Group of ICES conducted a synoptic mapping of the infauna of the southern and central North Sea. Together with a mapping of the infauna of the northern North Sea by Eleftheriou and Basford (1989) this provides the database for the description of the benthic infauna of the whole North Sea in this paper. Division of the infauna into assemblages by TWINSPAN analysis separated northern assemblages from southern assemblages along the 70 m depth contour. Assemblages were further separated by the 30, 50 m and 100 m depth contour as well as by the sediment type. In addition to widely distributed species, cold water species do not occur further south than the northern edge of the Dogger Bank, which corresponds to the 50 m depth contour. Warm water species were not found north of the 100 m depth contour. Some species occur on all types of sediment but most are restricted to a special sedimentand therefore these species are limited in their distribution. The factors structuring species distributions and assemblages seem to be temperature, the influence of different water masses, e.g. Atlantic water, the type of sediment and the food supply to the benthos. Eleftheriou, A. and Basford, D. J. Journal of the Marine Biological Association of the UK, 69: 123–143.

Description: The upper bathyal sea-pen Kophobelemnon stelliferum extends to depths of about 1600 m in the Porcupine Seabight, to the south-west of Ireland, but is rare below about 1150 m. Photographic data suggest that the species attains numerical abundances of more than 2 m−2and a wet weight biomass of at least 4 g m−2. The highest densities, however, do not necessarily correspond to the highest biomass values since there is a clear depth-related change in population structure. The largest sea-pens are restricted to the deeper parts of the bathymetric range of the species. There is also a marked change in the growth form at a total colony length of about 250 mm, with larger colonies having relatively more polyps than smaller ones. The sexes are separate in Kophobelemnon stelliferum and the sex ratio of colonies is about 1:1. The maximum oocyte diameter is about 800 μm, but there is no evidence of seasonal reproduction by this pennatulid in the Porcupine Seabight.

Description: A correlation of the Campanian–Maastrichtian boundary is attempted using foraminiferal and nannoplankton data from two areas: the eastern North Atlantic and northwestern Germany. The Boreal benthic and Tethyan planktonic foraminiferal zonation schemes are applied to Site 548A, where both foraminiferal groups occur frequently. A direct comparison of both biozonations reveals that the base of the Maastrichtian, according to planktonic foraminifers, has to be placed in the Upper Campanian of the Boreal benthic foraminiferal biozonation, which concurs with the nannoplankton results. The Tethyan Middle and Upper Maastrichtian are probably equivalent to the Upper Maastrichtian in the Boreal sense. The bases of the Maastrichtian substages are thus diachronous between the Boreal and Tethyan realms. Palaeotemperatures (which were estimated using the oxygen isotopic composition of the Goban Spur chalks) indicate, in combination with palaeowind directions, that the faunal and floral distribution pattern recorded is the result of a stable, warm water outflow from the northwest European epicontinental seas through the Channel area to the Celtic Shelf sea and Goban Spur. This mechanism appears to have been a dominant separating factor of the Boreal and Tethyan bioprovinces on the western European Shelf.

Description: The planktonic foraminifer Globigerinoides sacculifer (Brady) was cultured under two different light intensities and in continuous darkness. High light intensity (HLI = 4oo-soo einsteins/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 einsteins/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 m. 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 6oo ,urn 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.

Description: Vesteris Seamount is a solitary alkaline volcano in the Greenland Basin some 280 km NW of Jan Mayen. Topographic and geophysical studies have shown no sign of an associated plume trace. Evidence from ash layers in sediment cores around the volcano and dating of dredged samples show that it has been active in Quaternary times. The lavas from Vesteris studied here consist of basanites, tephrites, mugearite, and alkali basalts. Crystal fractionation models are consistent with the generation of the tephrites and mugearite from a basanitic parent. Extensive kaersutite fractionation is required late in the fractionation sequence to produce the extreme mugearite composition. Na-Al-Fe-rich green cores to many clinopyroxene phenocrysts at Vesteris suggest a fractionation history beginning at high pressure in the mantle. Differences between Vesteris and Jan Mayen in the ratios of highly incompatible trace elements such as Ce/Pb and Rb/Cs, which will not normally be fractionated from one another during mantle melting, suggest that the two are not derived from the same source. Relatively unradiogenic Sr isotope ratios (compared with Bulk Earth), and highly incompatible trace element patterns similar to those for St. Helena, suggest that Vesteris magmas are derived from a depleted, asthenospheric source. We propose that the Vesteris basanites are very low degree partial melts (˜1%) of this source, most probably those which give rise to the seismic low-velocity zone (LVZ). Such small-degree melts may preferentially tap small-scale heterogeneities in the asthenosphere. Vesteris lies at the intersection of two major structural trends in the Greenland Basin—(1) a zone of major reorientation of spreading direction on the Mohns Ridge north of Jan Mayen and (2) the extension of the Kolbeinsey Ridge axis. We propose that a combination of the extensional stress fields related to these two lineaments produces sufficient dilation of the lithosphere at Vesteris to allow magmas from the LVZ to reach the surface.

Description: Outer membrane (OM), cytoplasmic membrane (CM) and intracytoplasmic membranes (ICM) from the halophilic phototrophic purple sulphur bacterium Ectothiorhodospira mobilis 9903 were purified and characterized. The three membrane fractions were significantly different in regard to protein profiles on SDS-PAGE, and to the composition of amino acids, fatty acids and lipids. The presence of lipoproteins, the occurrence of lyso-phosphatidyl-ethanolamine and an increased content of saturated and short-chain fatty acids are characteristic properties of the OM. CM and ICM fractions are different on the basis of buoyant density, of protein profiles and amino acid composition, and due to the presence of succinate dehydrogenase activity in CM. In addition, CM and ICM showed significant differences in pigment content and absorption spectra.

Description: The abundance and sedimentation of acantharia and their cysts was recorded in the water column and sediment traps in the East Greenland Sea in August-September 1990. Although acantharia constituted 〈1% of total suspended particulate organic carbon (POC) in the water column, up to 90% (average 55%) of the POC sedimenting in 100 m was present in the form of acantharian cysts during a 9 day drift experiment. Rapid dissolution of strontium sulphate, of which their shells and spines are constructed, was evidenced by their disappearance with depth in the water column, maximum dissolution occurring between 500 and 1000 m water depth. Mass encystment and sedimentation of this single group of sarcodine protozoa can have dramatic effects on, the measurement of particulate fluxes in the open ocean, and may be a recurrent phenomenon in the eastern North Atlantic.

Description: The basalt stratigraphy of the Deccan Trap between Mahabaleshwar Ghat and Belgaum over-steps the basement from north to south. Sr-isotope and Zr/Nb ratios, and Sr, Rb, and Ba concentrations correlate portions of the post-Poladpur stratigraphy over 250 km along the Western Ghats, thereby confirming a southerly component of dip of 0·06°. At the southwestern margin, the stratigraphy extends upwards from the compositionally uniform Ambenali Formation (Cox & Hawkesworth, 1984) into a sequence of grossly heterogeneous flow units which have been allocated to the Mahabaleshwar and Panhala Formations (Lightfoot & Hawkesworth, 1988). The Mahabaleshwar Formation is represented only by a sequence of highly fractionated flows (termed the Kolhapur unit) with similar 87Sr/86Sr0 to the Mahabaleshwar (0·7045), but with Sr〈240 ppm and TiO2〉2·25%. Succeeding the Kolhapur unit are a series of flows with high 87Sr/86Sr0 (0·7045-0·705), Zr/Nb 〉 13, and low Sr (〈 200 ppm), which have been allocated to the Panhala Formation, and a group of flows with high 87Sr/86Sr0 (0·707–0·708) and Sr (〉230), but trace element concentrations similar to the Mahabaleshwar Formation; these have been allocated to the Desur unit of the Panhala. Geochemical variations in flows overlying the Ambenali define two distinct trends: one is attributed to gabbro fractionation, and the other to variations in the compositions of the parental magmas, and arguably their source regions. There is little evidence for significant crustal contamination in these flows, and the degree of fractionation and the composition of the phase extract are shown to vary along strike within the Mahabaleshwar Formation. The high TiO2 content of Kolhapur unit flows is shown to be the result of shallow-level gabbro fractionation, rather than the presence of a primitive high-Ti magma. Mahabaleshwar Formation basalts exhibit a broad negative correlation between the degree of fractionation and Sr-isotopic composition. The endmember with lower 87Sr/86Sr0 has different Zr/Y from the Ambenali basalts, and would appear to have been generated by lower degrees of melting of a similar source. The other endmember has more radiogenic Sr, lower Zr/Nb, similar Zr/Y, but higher mg-number. The simplest interpretation is that these magmas were more primitive and hence hotter and more able to interact with the lithosphere en route to the surface, and that they then mixed to produce the Mahabaleshwar array. The Panhala Formation basalts plot on the Sr-Nd array defined by the Mahabaleshwar Formation, and the Desur unit basalts plot on an extension of this array; this suggests that the source characteristics are also lithospheric. The absolute elemental abundances may then be a function of melting and fractionation. We are impressed by the apparent switch from crustal lithospheric contributions to mantle lithospheric contributions through the stratigraphy, and suggest that this, together with the more protracted fractionation of the magma, reflects a change in the availability of the lithospheric components accompanying the southerly migration of the volcanic edifice.

Description: The plankton multiplier is a positive feedback mechanism linking the greenhouse effect and biological pump (Woods.J.D., Royal Commission on Environmental Pollution, 1990). As pollution increases the atmospheric concentration of carbon dioxide, the enhanced greenhouse effect induces radiative forcing of the ocean, which diminishes the depth of winter convection, reducing the annual resupply of nutrients to the euphotic zone and therefore the annual primary production. That weakens the biological pump, which contributes to oceanic uptake of CO2,. As the ocean takes up less CO2, more remains in the atmosphere, accelerating the rise in radiative forcing. We have used a mathematical model of the upper ocean ecosystem, based on the Lagrangian Ensemble method, to estimate the sensitivity of the biological pump to radiative forcing, which lies at the heart of the plankton multiplier. We conclude that increasing radiative forcing by 5 W m− (equivalent to doubling atmospheric CO2) reduces the deep flux of paniculate carbon by 10%. That sensitivity is sufficient to produce significant positive feedback in the greenhouse. It means that the plankton multiplier will increase the rate of climate change in the 21st century. It also suggests that the plankton multiplier is the mechanism linking the Milankovich effect to the enhanced greenhouse effect that produces global warming at the end of ice ages.

Description: Rhodomonas minuta v. nannoplanctica Skuja and Rhodomonas lens Pascher et Ruttner were found to perform vertical migrations. From sunrise until afternoon they adjust their vertical position to an optimum light-intensity, which is for R. minuta 2.5 times higher than for R. lens. The spatial separation of both species is increasing throughout the whole light phase. The species distinction between them has been questioned recently, but can be maintained not only because of morphological differences but also because they are occupying different niches within the plankton community.

Description: Five hundred and twenty-eight specimens of Loligo forbesi Steenstrup, from landings in Horta, Faial, Azores, during the year 1 March 1980 to 28 February 1981, were tudied; 59·3 % were males, 40·7 % females. Of the males 80·2 % were sexually mature, of the females 91·6 %, both sexes showing the highest degree of maturity in spring and he lowest in autumn. The mean dorsal mantle length of the mature males was 56·5 cm, or females 33·5 cm. A weight-length relationship was calculated. he stomachs of 622 specimens were sampled, of which 306 contained food. The prey omponents were studied qualitatively. The main prey was fish (82·0%), of which 0·5 % were horse mackerel, Trachurus picturatus, this being the most important food rganism. Preliminary results of statolith readings are given.

Description: The free-running locomotor activity rhythms of freshly-captured swimming crabs Liocarcinus holsatus and L. depurator have been studied in constant conditions in the laboratory. L. holsatus captured in the intertidal zone of sandy beaches showed strong circatidal activity rhythms with maximum activity at high tide. L. holsatus captured in the sublittoral zone had a clear tendency to show circadian activity rhythms with highest activity during day-time hours. L. depurator occurred only sublittorally and showed circadian activity patterns with highest activity during the night. Exposure to hydrostatic pressure cycles of tidal amplitude and periodicity, entrained strong circatidal activity rhythms in previously arhythmic L. holsatus. This activity pattern also showed a marked circadian component. Exposure to the same regime entrained a circadian rhythm, but not a circatidal rhythm in L. depurator. In the sublittoral zone L. depurator is active mainly during the night, whereas L. holsatus, is active mainly during the day. This may constitute a behavioural mechanism for minimizing competitive interactions between these two sympatric crabs

Description: Symbiotic luminous bacteria have been described in, and cultured from, a number of species offish and cephalopod. Indeed only in these two groups are extracellular luminous bacteria believed to be utilized as a source of light (see Buchner (1965) and Herring (1978) for references). Despite several earlier investigations of such symbioses in cephalopods the bacteria in these animals have not been adequately identified, nor has the extent of their role been clarified. The ultrastructural relationships between bacteria and the tissues of the squid accessory nidamental gland have been investigated in the non-luminous species Loligo pealei (Lesueur) (Bloodgood, 1977) and Sepia officinalis L. (Van den Branden et al. 1979) but no comparative work on luminous species has been undertaken apart from that on Heteroteuthis dispar (Rüppell), whose photophore does not contain typical luminous bacteria (Dilly & Herring, 1978; cf. Leisman, Cohn & Nealson, 1980). The order Sepioidea contains five families, among which are the two families Sepiolidae and Spirulidae. Though the presence of luminous bacteria is known in some sepiolids (as well as in certain loliginids (order Teuthoidea)) some doubt remains about the source of light in the photophore of Spirula spirula Hoyle. The steady luminescence of this species has prompted speculation that bacteria may be involved (Harvey, 1952). In this paper we compare the anatomy and ultrastructure of the photophores of both Sepiola and Spirula in order to clarify some of these problems.

Description: This is the first detailed analysis of cephalopod beaks from the stomach of a northern bottlenosed whale, Hyperoodon ampullatus (Forster, 1770). The digestive action of many predators barely affects the chitinous beaks of cephalopods and some cetaceans accumulate the beaks in considerable numbers in their stomachs. The present beaks are clean and unbroken. Identification of cephalopod beaks from stomachs of predators such as sperm whales (see Clarke, 1977), seals (Clarke & Trillmich, 1980) and albatrosses (Clarke, Croxall & Prince, 1980) throws considerable light on the biology and relative ecological importance of the species of cephalopods concerned as well as providing useful information on the diet of the predators.

Description: Changes of algal biomass, as carbon, cell numbers and volume were determined for phytoplankton of Lake Constance suspended in situ in 2 1 glass bottles. Phytoplankton placed at the 6% surface penetrating light level (photosynthetically available radiation) were close to the compensation depth for growth estimated as total paniculate carbon and total cell volumes. Cell counts of individual algal species however, showed appreciable growth of diatoms offset by the decline of flagellates. Bottles suspended at two shallower depths in a separate experiment showed some growth of all species and indicated a vertical niche separation of growth of Rhodomonas minuta Skuja and R. lens Dascher and Ruttner in accordance with their vertical distribution.

Description: Sedimentation of nine phytoplankton species was studied in Lake Constance with the aid of sedimentation traps exposed at six different depths from 20 to 120 m. The study examines sedimentary fluxes at all depths, temporal variation of sinking velocities into the uppermost trap, annual averages of the sinking velocities at all depths and survival of algae during the sedimentation process. In spite of high intraspecific temporal variability of the sinking velocity there is a clear hierarchy from the pennate and the filamentous centric diatoms sinking the fastest to the Cryptomonads, nearly not at all affected by sedimentary losses. Temporal variability of the sinking velocity within species seems to be related to the ‘physiological state’, the highest velocities always occurring during stationary or decline phases of the population development. An analysis of the role of sedimentary losses in the population dynamics of Asterionella formosa, Fragilaria crotonensis, Stephanodiscus binderaniss, Melosira granulata reveals positive correlations between the sedimentation rate and cell mortality.

Description: We report major and trace element X-ray fluorescence (XRF) data for mafic volcanics covering the 15-Ma evolution of Gran Canaria, Canary Islands. The Miocene (12-lS^Ma) and Pliocene-Quaternary (0-6 Ma) mafic volcanics on Gran Canaria include picrites, tholeiites, alkali basalts, basanites, nephelinites, and melilite nephelinites. Olivine±clinopyroxene are the major fractionating or accumulating phases in the basalts. Plagioclase, Fe-Ti oxide, and apatite fractionation or accumulation may play a minor role in the derivation of the most evolved mafic volcanics. The crystallization of clinopyroxene after olivine and the absence of phenocrystic plagioclase in the Miocene tholeiites and in the Pliocene and Quaternary alkali basalts and basanites with MgO〉6 suggests that fractionation occurred at moderate pressure, probably within the upper mantle. The presence of plagioclase phenocrysts and chemical evidence for plagioclase fractionation in the Miocene basalts with MgO〈6 and in the Pliocene tholeiites is consistent with cooling and fractionation at shallow depth, probably during storage in lower-crustal reservoirs. Magma generation at pressures in excess of 3-0-3-5 GPa is suggested by (a) the inferred presence of residual garnet and phlogopite and (b) comparison of FeO1 cation mole percentages and the CIPW normative compositions of the mafic volcanics with results from high-pressure melting experiments. The Gran Canaria mafic magmas were probably formed by decompression melting in an upwelling column of asthenospheric material, which encountered a mechanical boundary layer at ~ 100-km depth.

Description: The subaerial portion of Gran Canada, Canary Islands, was built by three cycles of volcanism: a Miocene Cycle (8-5—15 Ma), a Pliocene Cycle (1-8-60 Ma), and a Quaternary Cycle (1-8-0 Ma). Only the Pliocene Cycle is completely exposed on Gran Canaria; the early stages of the Miocene Cycle are submarine and the Quaternary Cycle is still in its initial stages. During the Miocene, SiO2 saturation of the mafic volcanics decreased systematically from tholeiite to nephelinite. For the Pliocene Cycle, SiO2 saturation increased and then decreased with decreasing age from nephelinite to tholeiite to nephelinite. SiO2 saturation increased from nephelinite to basanite and alkali basalt during the Quaternary. In each of these cycles, increasing melt production rates, SiO2 saturation, and concentrations of compatible elements, and decreasing concentrations of some incompatible elements are consistent with increasing degrees of partial melting in the sequence melilite nephelinite to tholeiite. The mafic volcanics from all three cycles were derived from CO2-rich garnet lherzolite sources. Phlogopite, ilmenite, sulfide, and a phase with high partition coefficients for the light rare earth elements (LREE), U, Th, Pb, Nb, and Zr, possibly zircon, were residual during melting to form the Miocene nephelinites through tholeiites; phlogopite, ilmenite, and sulfide were residual in the source of the Pliocene-Quaternary nephelinites through alkali basalts. Highly incompatible element ratios (e.g., Nb/U, Pb/Ce, K/U, Nb/Pb, Ba/Rb, Zr/Hf, La/Nb, Ba/Th, Rb/Nb, K/Nb, Zr/Nb, Th/Nb, Th/La, and Ba/La) exhibit extreme variations (in many cases larger than those reported for all other ocean island basalts), but these ratios correlate well with degree of melting. Survival of residual phases at higher degrees of melting during the Miocene Cycle and differences between major and trace element concentrations and melt production rates between the Miocene and Pliocene tholeiites suggest that the Miocene source was more fertile than the Pliocene-Quaternary source(s). We propose a blob model to explain the multi-cycle evolution of Canary volcanoes and the temporal variations in chemistry and melt production within cycles. Each cycle of volcanism represents decompression melting of a discrete blob of plume material. Small-degree nephelinitic and basanitic melts are derived from the cooler margins of the blobs, whereas the larger-degree tholeiitic and alkali basaltic melts are derived from the hotter centers of the blobs. The symmetrical sequence of mafic volcanism for a cycle, from highly undersaturated to saturated to highly undersaturated compositions, reflects melting of the blob during its ascent beneath an island in the sequence upper margin-corelower margin. Volcanic hiatuses between cycles and within cycles represent periods when residual blob or cooler entrained shallow mantle material fill the melting zone beneath an island.

Description: Cephalopod statoliths are paired calcareous stones which lie in cavities, the statocysts, within the skull. They have a form which, though variable, shows promise as a source of criteria for taxonomic and evolutionary studies. As a preliminary to more detailed studies, Clarke (1978) published a description of the form of a generalized teuthoid statolith, coined nomenclature for the various parts and gave a very brief survey of variation of statoliths within the living Cephalopoda. This nomenclature was used in a detailed description of fossilized teuthoid statoliths by Clarke & Fitch (1979). Here, descriptions of the statoliths of the living species Berryteuthis magister (Berry, 1913), Gonatopsis borealis Sasaki, 1923, Gonatopsis (Boreoteuthis) makko Okutani & Nemoto, 1964 and Gonatus fabricii (Lichtenstein, 1818) are given and the fossil Berryteuthis species described in outline by Clarke & Fitch (1979) is compared with B. magister. A statistical analysis of measurements of the statoliths of these five species has been made and the results are presented. This forms the first part of a general description of teuthoid statoliths and similar studies on the Ommastrephidae and the Loliginidae are in preparation.

Description: The functional morphology of the buccal mass of 23 species of cephalopod (Octopoda, 4 species; Teuthoidea, 17; Sepioidea, 2) was investigated by gross dissection, histology and observations on fresh preparations. Cephalopod beaks lack a joint or articulation point. The jaws slide and rotate around an area rather than a fixed point. During closing the superior mandibular muscle (SMM) provides the force of a bite and the largest movement vector, whilst the inferior mandibular muscle (IMM) acts to retract the upper beak, causing shearing action. Dorsal portions of the lateral mandibular muscles (LMM) flex the upper beak walls outwards, probably to accomodate the backwards sweep of the radula and buccal palps during closing. To open the beaks, the ventral portions to the lateral mandibular muscles pull the rear lateral walls of the two beaks towards each other, moving the lower beak back relative to the upper. The buccal mass weighs more in decapods (0.65-4.34% of body weight) than octopods (0.49-0.77%). The weight difference is mainly accounted for by the size of the superior mandibular muscle. Beak shape and muscle volume are related. Increasing the size of the upper beak hood and lateral wall area results in larger SMM and LMM respectively Increasing hood size in the lower beak increases IMM size, and altering the angle by which the wings meet the lateral wall changes the volume of the SMM and LMM. To accomodate the decapod pointed upper rostrum, the lateral walls of the lower beak have shortened in length, whilst increasing in breadth and surface relief to maintain the area available for muscle insertion. In species with a lateral wall ridge or fold (e.g. Onychoteuthis) this may mark the insertion point of the LMM.

Description: Arm autotomy was induced in a living specimen of Metacrinus rotundus (Echinodermata: Crinoidea). An arm was autotomized at a ligamentary articulation known as a cryptosyzygy, following incision by scissors distal to the break point. Although sessile stalked crinoids cannot entirely escape from a predatory attack by arm autotomy and they do not have an active defense, arm autotomy at cryptosyzygies reduces damage and arm loss by effective distribution, and by minimizing trauma and facilitating subsequent regeneration. The paradigmatic distribution of cryptosyzygies in which arm loss is set at a minimum, compared with the actual distribution, shows that these two patterns are similar and that actual specimens successfully reduce arm loss by the effective distribution of cryptosyzygies. The crinoid branching pattern also affects arm loss, and two different paradigms are discussed: anti-predatory and harvesting. Arm branching patterns of various isocrinids have tended toward the anti-predatory configuration from the Jurassic to the Recent, suggesting that the isocrinids have coped with increased predation. Shallow-water comatulids generally adopt the anti-predatory paradigm in their branching pattern, whereas many deep-water, stalked crinoids adopt a harvesting paradigm, reflecting that shallow-water comatulids receive more predatory attacks than do deep-water crinoids.

Description: Organic-rich shales sampled from the aples Beach section of the Monterey Formation. Califomia. contain authigenic phosphorite phases which apparently formed within bacterial mat laminations. Light and scanning electron microscope observations show that the fossilized remains ofthese mats are similar to communities of filamentous sulfur-oxidizing bacteria found today at slope-depth, sediment, oxic anoxic interfaces. The crystal size and habits ofthe phosphatic minerals resemble contemporaf) prec1pitates in contact with pore water solutions. Mineralogical and chemical analyses ofthe most phosphatic layers show that some are a nearly pure carbonate fluorapatite (or francolite). These la)ers are lightly colored and are sandwiched between black siliceous muds with 〈0.2% CaCOJ . and organic carbon contents that excecd 25%. In othcr phosphatic intcrvals of thc Naplcs Beach section. ca leite is a major diluent oflight and dark layers. The C:P ratio of a single modern bacterial mat sample shows that these benthic communities are more enriched in phosphorus than planktonic organic matter. Thus, the generally believed premise that authigenic phosphorite formation results from organic matter diagenesis in near-surface anoxic sediments is hcre modified by the contention that such transformations are more highly favored in sediments supporting massive microbial communities.

Description: The influence of photoperiodicity on hatching of Loligo forbesi and Loligo vulgaris embryos was investigated under different experimental light-dark (LD) conditions. The transition from light to dark stimulated hatching and functions as a "Zeitgeber" or synchronizer. Independent of the timing and duration of the dark period most embryos hatched soon after termination of the light period. Embyros which had developed in constant light, showed no hatching rhythm at all. If these embryos were exposed to a dark shock most embryos hatched soon after the onset of darkness. A twilight shock, in which the light was reduced by 50% (i.e. 50 µE s -1m-²), could not simulate hatching. Embryos which were kept from stage X on in an artifically controlled LD cycle, preferentially hatch in a period which coincides with the period at which darkness usually occured when placed in constant illumination from stage XX onwards.

Description: Light absorbed by the photoreceptor membranes of the retina is transformed by a series of biochemical steps into changes in receptor potential. The visual pigment, rhodopsin, and associated enzymes which relay the visual signal belong to a widespread family of receptorenzyme complexes which transmit sensory, hormonal and neurotransmitter signals into cells. In the invertebrate visual system, rhodopsin activates enzymes which increase cytoplasmic calcium. The highly specialised and structurally ordered photoreceptors of the squid retina provide a favourable system for studying the mechanisms of these enzyme pathways.

Description: Within the Western Ross Sea, there are six emperor penguin colonies of widely different size that occur exclusively on sea ice. In 1990 a survey of all six sites, two by close overflights and four from the ground, showed that the breeding habitats were highly variable. The most important physical characteristics of these habitats appear to be stable fast ice, nearby open water, access to fresh snow, and shelter from the wind.

Description: This article describes the natural history of a large colony of emperor penguins Aptenodytes for steri , its size, dispersal pattern of chicks, and associations with other bird and mammal species. A mid-season count of 19,364 chicks indicated that about 20–25,000 breeding pairs had been present in June and July. The colony was fragmented into several sub-groups which showed different mean sizes of chicks and survival to fledging. Other species observed included leopard seals Hydrurga leptonyx , the only major predators, which preyed heavily on both adults and fledging chicks. Fledgelings left the colony over a period of about 10 days; departure was an active process in which the chicks walked to the ice edge and dispersed in groups, swimming consistently southward. At this time they were still in about 60% down and weighed about 10 kg, having lost some 30% of the heaviest mass achieved during parental feeding.

Description: The population dynamics and the trophic role of Aurelia aurita medusae in the Kiel Bight/western Baltic are described from nine years of investigation between 1978 and 1993. There is considerable yearly variation in standing stock with summer median abundance ranging from 0.2 to 16 ind. 100 m−3 and biomass from 0.2 to 4.4 g C 100 m−3. The lower variation is due to marked differences in size of adult medusae between years. In years of low abundance medusae exhibit an average dise diameter of about 30 cm and weight about 1 kg. In bloom years, however, adult size is only about 20 cm and weight ranges between 200 and 400 g. Estimates of feeding are somewhat contradictory, but feeding rates of 40–80 mg C ind.−1 day−1 seem probable. It can be concluded that Aurelia medusae consume about 2/3 of daily secondary production in years of high abundance, and are thus responsible for a decline of mesozooplankton in these years.

Description: Two biochemical methods for measuring larval fish condition – tryptic enzyme activity and RNA/DNA ratio measurement - were applied to laboratory-reared and wild-caught herring larvae. The comparison of both methods when applied to laboratory-reared herring larvae showed that tryptic enzyme activity and RNA/DNA ratio are linear and positively correlated under constant nutritional conditions. Wild-caught larvae were transferred to the laboratory and used to compare both indicators in relation to shortterm changes in food availability and long-term starvation periods (13 days). In the starvation experiments with the wild-caught larvae the lowest trypsin values were obtained after 3–4 days and a significant decrease in RNA/DNA ratios was obtained after 5–6 days. Prolongation of the starvation time did not result in a further significant change in either parameter. The results of the study demonstrate the usefulness of both methods in monitoring nutritional condition offish larvae in field samples.

Description: The nutrient status of two common Antarctic diatoms (Corethron criophilum and Thalassiosira cf. antarctica) was analysed by studying the growth response in enrichment bioassays and by estimates of the cell quotas of Si, N and P after size-fractionation of net plankton samples Corethron had higher biomass-specific N-quotas; Si- and P-quotas were quite similar between both species. Corethron was Si-limited in five enrichment experiments and not nutrient limited in five experiments. Thalassiosira was not nutrient limited in six experiments, N-hmited in four experiments and Si-limited in one experiment Droop-kinetics of Si-limited growth of Corethron and of N-hmited growth of Thalassiosira were obtained by combining the growth rates in the bioassays and the cell quotas from the natural populations. The minimal Si-quota of Corethron was 0 041 mol Si/mol C, the saturating cell quota was 0.158 mol Si/mol C respectively The minimal N-quota of Thalassiosira was 0 0223 mol N/mol C, the saturating cell quota was 0.208 mol N/mol C Corethron was N-saturated at cell quotas of 〉0 106 mol N/mol C; Thalassiosira was Si-saturated at cell quotas of 〈0 132 mol Si/mol C. As the better competitor for N and the poorer one for Si, Corethron became more important with increasing Si N ratios, while Thalassiosira became more important with decreasing Si:N ratios in the water

Description: The groundmass of andesitic dykes at Sezaki, southwest Japan, has trachytic texture and contains microscopic shear zones. The shear zones comprise a conjugate pair formed by flattening of the solidifying dyke rock, probably caused by the magma pressure of the still molten part of the dyke. This pressure shortened the solidifying rock perpendicular to the dyke margins and caused it to extrude parallel to the magma flow direction. The groundmass shears indicate that locally the magma flowed 60° upward in the dykes. It is concluded that while groundmass shears are a useful indicator of flow direction in dykes, phenocryst alignment in dykes is strongly influenced by magma-pressure flattening and thus may be a poor indicator of flow direction.

Description: The deep eastern Arctic basin between the Lomonosov Ridge and the Eurasian continental margin differs from other ocean basins in the very slow spreading of its floor and unusual depositional environment under perennial sea-ice cover. The recent expedition ARK IV/3 of RV Polar stern for the first time made geoscientific investigations from the northern margin of the Barents Sea north to the Nansen-Gakkel Ridge. Much deeper than most other mid-ocean ridges, this ridge is poorly-surveyed, but has a central valley which in places is deeper than 5.5 km, 1–1.5 km below the basin floors on either side. Heat flow in the central part of the valley is very rapid; both basement rocks and overlying sediments showed unexpectedly the influence of intense and long-term hydrothermal activity. The sediments on the northern and southern flanks of the ridge are slightly calcareous pelagic mud layers alternating with carbonate-free horizons, where up to 40% of the sedimentary section is soft mud clasts. Similar mud aggregates were observed on the surface of the multi-year sea ice, appearing to represent a special type of sediment transport by sea ice in the Transpolar Drift. In contrast to the western Arctic, Fram Strait and the Norwegian-Greenland Sea, gravel is rarely found in sediment cores. Recovered cores indicate that icebergs and sea ice carrying coarse sediment seldom rafted detritus to the study area during the last approximately 300,000 years.

Description: Dissolution rates of small forsterite spheres in superheated melts of basalt, andesite and rhyolite composition have been measured at 1300°C, atmospheric pressure. The rate is constant (83 µm hr−1) in the basalt, regardless of run duration. In the andesite the initial dissolution rate is 200µm hr−1, followed by a decrease to a constant value of 16µmhr−1 in 2–3 hours. Dissolution rate in the rhyolite decreases from an initial value of 1.7 to 〈0.1 µmhr−1 over 280 hours and never reaches a constant rate. Once the rate of dissolution has become constant, the film of contaminated melt that forms in melt about a crystal does not thicken with time, indicating attainment of a steady-state condition. Steady state is attributed to natural convection arising from the difference in density between the film of contaminated melt surrounding a crystal and that beyond. The density difference is approximately 2% of the density of the rock melt.