ALBERT

Description: A new image of the French continental crust between Brabant (Belgium) and the Basque province of Spain is presented on the basis of considerable recent geological and geophysical information as well as the compilation and reInterprétation of previously available data. The resulting section, which shows the main basement structures to a depth of 45 km, also is the first nonspeculative image of the westernmost part of the Variscan orogen. The French Global Geoscience Transect reveals a complete picture of this orogen between its remnant root and the surface. The divergent thrusts are bounded on the north and in the south by the old Brabant and Ebro-Aquitaine cratons, respectively; these thrusts also involve two previous plate boundaries. The lower part of the orogen is limited by a layered lower crust, probably of Permian age. Near the surface the Hercynian orogen is buried—near the northern end of the transect by the Paris Basin, which can be considered an eastward extension of the English Channel, and in the south by the South Armorican continental margin, which makes a transition between the oceanic crust of the Bay of Biscay and the axis of the Variscan orogen. In this area, the deep Parentis graben is located at the site of pronounced crustal thinning, since only 7 km of Hercynian crust are now preserved.

Description: The assessment of direct effects of anthropogenic CO2 increase on the marine biota has received relatively little attention compared to the intense research on CO2-related responses of the terrestrial biosphere. Yet, due to the rapid air–sea gas exchange, the observed past and predicted future rise in atmospheric CO2 causes a corresponding increase in seawater CO2 concentrations, [CO2], in upper ocean waters. Increasing [CO2] leads to considerable changes in the surface ocean carbonate system, resulting in decreases in pH and the carbonate concentration, [CO2−3]. These changes can be shown to have strong impacts on the marine biota. Here we will distinguish between CO2-related responses of the marine biota which (a) potentially affect the ocean's biological carbon pumps and (b) are relevant to the interpretation of diagnostic tools (proxies) used to assess climate change on geological times scales. With regard to the former, three direct effects of increasing [CO2] on marine plankton have been recognized: enhanced phytoplankton growth rate, changing elemental composition of primary produced organic matter, and reduced biogenic calcification. Although quantitative estimates of their impacts on the oceanic carbon cycle are not yet feasible, all three effects increase the ocean's capacity to take up and store atmospheric CO2 and hence, can serve as negative feedbacks to anthropogenic CO2 increase. With respect to proxies used in palaeo-reconstructions, CO2-sensitivity is found in carbon isotope fractionation by phytoplankton and foraminifera. While CO2- dependent isotope fractionation by phytoplankton may be of potential use in reconstructing surface ocean pCO2 at ancient times, CO2-related effects on the isotopic composition of foraminiferal shells confounds the use of the difference in isotopic signals between planktonic and benthic shells as a measure for the strength of marine primary production. The latter effect also offers an alternative explanation for the large negative swings in δ13C of foraminiferal calcite between glacial and interglacial periods. Changes in [CO2−3] affect the δ18O in foraminiferal shells. Taking this into account brings sea surface temperature estimates for the glacial tropics closer to those obtained from other geochemical proxies.

Description: Exposure of Fucus spiralis germlings to precise copper concentrations (0 to 844 nM Cu2+) in chemically defined medium demonstrated a relationship between urltrastructural changes and growth retardation with increasing copper concentration. Electron-translucent vesicles, present in ova, which normally disappear after fertilization, accumulated in germlings exposed to Cu2+ above 10.6 nM, suggesting that copper may inhibit a metabolic pathway involved in cell wall formation which is initiated by fertilization No membrane damage was observed during the exposure period. During a post-exposure period in copper-free medium, recovery occurred (rhizoid extension, apical hair formation) in germlings previously exposed to concentrations below 106 nM Cu2+ and electron-translucent vesicles became granular and disappeared. It is proposed that the electron-translucent vesicles contain a cell wall precursor and that copper inhibits its incorporation into the cell wall, preventing growth and development of the zygote.

Description: The “rugophilic”; behaviour (e.g. the preference for settling in concavities) of barnacles is well documented. In contrast, little is known about settlement preferences of other species with regard to surface microtopography. In a randomized block design, five different rugosities (smooth, 0.1 mm, 0.5 mm, 1 mm, 5 mm) were exposed to natural fouling in the Baltic Sea. In four experiments, test panels were colonized by Mytilus edulis, Polydora dliata, Balanus improvisus, diatoms, hydrozoa, bryozoa, and several ciliates. Settlement densities and microtopographical preferences for pits or elevations as a function of grain size were evaluated. Rugosities influenced settlement densities and the microtopographical preferences of almost all investigated species. Settlement densities were generally lowest on smooth panels, with most species showing distinct preferences for different rugosities. While a preference for pits was frequent, in some species the proportion of individuals settling on elevations significantly increased with roughness. These data on microtopographical preferences of different species give new insights into interactions between settlement behaviour, surface roughness, boundary layer hydrodynamics and community structure.

Description: A quantitative relationship between observed sea-ice roughness and simulated large-scale deformation work is established in order to provide new means for model validation and a better representation of the sea-ice component in climate modelling. Sea-ice roughness is introduced as an additional prognostic variable in a dynamic–thermodynamic sea-ice model with a viscous-plastic rheology. It is defined as the accumulated work of internal forces acting upon an ice volume, given in energy per area. A fraction of this total deformation work is transferred to the potential energy stored in pressure ridges. Using ridge geometries and distribution functions from observations, observable quantities like mean pressure ridge height, ridge frequency as well as volumetric and areal fractions of deformed ice are derived from the simulated ice roughness. Comparisons of these simulated quantities with measurements (submarine-borne sonars, laser altimeters on helicopters) show good agreement. Satellite-borne observations of sea-ice roughness now under development will provide an even larger data set which will be used for model verification. Additionally roughness-dependent drag coefficients are introduced to account for the effect on the momentum exchange between ocean and atmosphere due to the form drag of roughness elements. The simulations indicate that the inclusion of sea-ice roughness provides for a more realistic representation of the boundary layer processes in climate models.

Description: To study the variability of the thermohaline circulation in the North Atlantic on decadal time scales, the atmospheric regional model REMO is currently investigated as a component of a fully-coupled atmosphere–ice–ocean model for the Arctic/North Atlantic. A comparison of a 5-year uncoupled simulation of the regional model with a 5-year NCEP/NCAR reanalysis period is carried out in order to assess the performance of the regional model in polar and subpolar regions. The model simulates basic structures realistically. It performs well in middle latitudes but shows some problems in the region of the marginal ice zone and in continental regions with extreme temperature amplitudes. The high elevations of Greenland in the central part of the model domain give rise to problems in the model dynamics, resulting in moderate deviations from NCEP/NCAR reanalysis.

Description: Stomach contents of Todarodes sagittatus caught by trawlers working from 100 to 800 m depth in the Balearic Sea (western Mediterranean) were studied. From the 348 stomachs examined (153 males and 195 females) 33.62% were empty (39.21% in males and 29.74% in females). The diet of the squid was composed of 58 different prey items belonging to four major groups: Osteichthya, Crustacea, Cephalopoda and Chondrichthya. Osteichthyes, crustaceans and cephalopods were the most common prey, with a frequency of occurrence value of 84.85, 48.92 and 29.87% respectively. A change in the diet as the squid grows was observed, since juveniles feed basically on fishes while adults prey more actively on crustaceans. Analysis of the diet by size-classes reflected an ontogenetic migration to deeper waters since, parallel to the increase of size, a raise in the percentage of prey species inhabiting deeper waters was detected. Cannibalism was quite frequent, since T. sagittatus was the second most common cephalopod prey. Females had higher fullness-weight index and lower emptiness index than males, which reflects their major energetic demand for egg production.

Description: The population structure of the European flying squid Todarodes sagittatus was studied using data of about 5000 squid caught in waters off the western Sahara between 1969 and 1997. The bulk of the population consisted of winter-spawned squid, which occurred as juveniles of 80–120 mm mantle length (ML) over the slope in spring, and as immature squid of 160–180 mm ML both on the shelf and slope in summer. In autumn, the squid attained 220–280 mm ML, matured, and shifted to the slope, where the spawning was supposed to occur in winter. Age and growth of T. sagittatus was studied using statolith ageing techniques. Assuming daily production of putative growth increments within statoliths, as well as sizes and proportions of immature and maturing females, the lifespan of the west Saharan populations of T. sagittatus lasts ∼1 y. Todarodes sagittatus is a fast growing squid at juvenile and immature ontogenetic phases. Early maturation (at ages 220–230 d in males and 250–260 d in females, respectively) and subsequent decrease of somatic growth rates caused rather small modal sizes of mature squid (250–300 mm ML) compared with those of their northern counterparts (350–420 mm ML). Both hatching dates and seasonality in occurrence of mature females shows that in waters off the western Sahara T. sagittatus spawns throughout the year with a well-pronounced winter peak.

Description: Size of ripe eggs and potential fecundity are described in the squid of the subfamilies Todaropsinae and Todarodinae (Oegopsida: Ommastrephidae)— Todaropsis eblanae from West Africa, Todarodes angolensis from Namibia, Todarodes sagittatus from north-west Africa and the Mediterranean Sea, Todarodes sp. from the south-east Pacific, Nototodarus hawaiiensis from the south-east Pacific and West Indian Ocean and Martialia hyadesi from the south-west Atlantic. Females of both subfamilies are characterized by a wide range of ripe egg size (0.7–2.4 mm) and low and medium values of potential fecundity (20,000–2,500,000).

Description: Application of a neural network to ERS-SAR images to retrieve pressure ridge spatial frequencies is presented. For an independent dataset, the rmserror between the retrieved and the true ridge frequency as determined by means of laser profiling was about 5 ridges per kilometre, or 30%. The network is trained with results from in situ laser profiling of ridge distributions and coincident SAR backscatter properties. The study focuses on summer data from the Bellingshausen, Amundsen and Weddell Seas in Antarctica, which were gathered in February 1994 and 1997. Pressure ridge frequencies varied from 3 to 30 ridges per kilometre between different regions, thus providing a wide range of training and test data for the algorithm development. From ERS-SAR images covering the area of the laser flights with a time difference of a few days at maximum, histograms of the backscatter coefficient sigma0 were extracted. Statistical parameters (e.g. mean, standard deviation, tail-to-mean ratio) were calculated from these distributions and compared with the results of the laser flights. Generally, the mean backscatter increases with a growing ridge frequency, and the signal range becomes narrower. However, these correlations are only poor, and improved results are obtained when the statistical parameters are combined to train the neural network.

Description: It is well documented that animals take risk of predation into account when making decisions about how to behave in particular situations, often trading-off risk against opportunities for mating or acquiring energy. Such an ability implies that animals have reliable information about the risk of predation at a given place and time. Chemosensory cues are an important source of such information. They reliably reveal the presence of predators (or their presence in the immediate past) and may also provide information on predator activity level and diet. In certain circumstances (e.g., in the dark, for animals in hiding) they may be the only cues available. Although a vast literature exists on the responses of prey to predator chemosensory cues (or odours), these studies are widely scattered, from marine biology to biological control, and not well known or appreciated by behavioural ecologists. In this paper, we provide an exhaustive review of this literature, primarily in tabular form. We highlight some of the more representative examples in the text, and discuss some ecological and evolutionary aspects of the use of chemosensory information for prey decision making. Curiously, only one example illustrates the ability of birds to detect predator odours and we have found no examples for terrestrial insects, suggesting a fruitful area for future study.

Description: The capture of 52 specimens of the cirrate octopod Grimpoteuthis glacialis (Robson, 1930), of dorsal mantle length 20-165 mm during a 1996 trawling survey near the Antarctic Peninsula allowed the basic biology of the species to be examined. Their presence in bottom trawls at depths of 333-879 m, but their absence from benthopelagic and pelagic trawls, is consistent with a primarily benthic habitat. The largest single sample, 40 animals, came from a soft mud bottom and highlights the patchy nature of the distribution. Males tended to be bigger in total length and mass than females of similar mantle length. The males, however, were mature at a smaller size. Mature males have tiny sperm packets, rather than typical cephalopod spermatophores, in their distal reproductive tract. Mature females have large, smooth eggs in the proximal oviduct, in the huge oviducal gland and in the distal oviduct. Eggs in the distal oviduct have a thick, sticky coating that hardens in seawater into a secondary egg case. Ovarian eggs vary greatly in size, possibly indicating protracted egg laying. Observations on live animals indicate that the species swims primarily by fin action, rather than by jetting or medusoid pulses with the arm/web complex. It may be capable of limited changes in colour pattern, especially on the oral surface of the web. Three pairs of surface structures that appear superficially to be white spots anterior to the eyes and near the bases of the fins are actually transparent patches in the skin. When considered in association with the transparent subdermal layer and the anatomy of the eyes, optic nerves and optic lobes, these clear patches seem to function in detecting unfocused light on the horizontal plane of the benthic animal.

Description: A total of 57 comparative hauls using a rectangular midwater trawl with a fishing mouth area of 50 m2 (RMT 50) were carried out along the sides of an imaginary triangle south of Madeira in 1986. A total of 1258 cephalopods were caught, giving a mean of 22 per haul with a range from 0 to 67. The nets were used with a diver's light on the top bar which was either switched off or was operated with a 20, 70 or 150 W bulb, powered by a car battery. A significantly greater number of individuals per haul was caught with lights on than without lights, increasing from a mean of 13·5–25·1, a factor of 1·8. Similarly, the number of species caught was increased from a mean of 7 to 10·4, a factor of 1·5 and the volume of cephalopods was increased from a mean of 41·1–162·3ml, a factor of 3·9. Similar comparisons made for catches during day or night separately and on the three courses separately also showed marked increases with the lights. Samples show that increase in power of the lights increased the total number of cephalopod individuals caught. In the 12 species with more than ten individuals, in 33 of the 36 comparisons (of number of individuals, species and volumes) there is an increase with the light. The most influenced species was Taonius pavo which increased in numbers by a mean factor of 3·9 times with 20W, 4·0 times with 70W and 6·1 times with 150W when compared with the numbers caught with no light.

Description: Beaks of 133 specimens of Todarodes sagittatus caught in the central East Atlantic were studied. Relationships between several measurements of the upper and lower beaks and dorsal mantle length (DML) and total mass were calculated. The darkening process or pigmentation of both beaks was investigated and a qualitative scale of eight degrees of pigmentation developed. Except for the hood of the lower beak, the growth of both beaks was allometrically negative in relation to DML in males, whereas the growth of several parts of both beaks of females was allometrically positive. The hood grew faster than all other parts of the male beak and faster than all parts of the lower beak of females. Regression coefficients calculated for the growth of the beaks revealed differences between the growth patterns of females and males (p 〈 0.05). The results relating to darkening and the maturing process suggest that they are related and that they take place over a very short period in the life of the squid.

Description: A total of 206 specimens of the ommastrephid squid Todarodes sagittatus, obtained from three areas of the central eastern Atlantic (Canary Islands/African coast, Madeira, and the Gettysburg Bank area south of Portugal) were examined. New information on size, mass, length-mass relationships, reproductive biology, and diet of the squid from a hitherto not very well studied area is supplied. Females dominated the samples (78%) and attained larger size and mass than males. Dorsal mantle lengths of T. sagittatus in the Canary Islands/African coast samples and in the Madeira region were similar, 167 – 348 mm for females and 175 – 269 mm for males. From the Gettysburg Bank all specimens were immature, females ranging between 71 and 276 mm and males from 98 to 233 mm. Mature females were found mainly during winter and mature males nearly year-round, indicating that they mature earlier than females and at a smaller size. Prey consisted mainly offish (54.9%), decapods (18.8%) and cephalopods (12.1%). Otoliths and fish bones identified from stomach contents suggest that myctophids were the most common and diverse prey.

Description: Deep waters of the Sea of Japan and surface waters of the Pacific Coast of Honshu and the northeast Sea of Japan were analysed for polychlorinated biphenyls (PCBs) pollution. the ΣPCB concentrations in solution in the Sea of Japan (50–3000 m) were between 140 and 1230 fg dm−3. the space-integrated surface water concentration near the Pacific coast of northern Honshu was 140 fg dm−3and for the surface water of the Sea of Japan was 230 fg dm−3. Based on these analyses four water masses were deduced in the Sea of Japan during the summer months. It is shown for the first time in the Sea of Japan that polychlorinated biphenyls are excellent chemical indicators of not only the anthropogenic pollution, but also water masses.

Description: Epibiosis on four marine benthic invertebrate species was found to be reduced relative to other nearby surfaces, suggesting the existence of an underlying protection against fouling. In all four cases, toxic chemical antifouling defenses were wanting or inconsistent. However, the lack of epibionts could be attributed to the existence of non‐toxic protective properties in all instances, viz. periodic emergence and mutual grazing in the gastropod, Littorina littorea, cumulative filtration and an as yet unidentified fouling‐reducing property of the periostracum of the bivalve Mytilus edulis, repellency and, possibly, mucus secretion in the colonial ascidian, Cystodytes lobatus, burrowing, periodic emergence (intertidal individuals) and moulting in the crustacean, Carcinus maenas. It seems that such protective systems are often multiple, consisting of several, more or less overlapping, adaptations to reduce fouling. Characteristics of these non‐toxic, multiple protection systems and their significance for potential epibionts are discussed.

Description: Octopuses ( Eledone cirrhosa (Octopoda: Cephalopoda)) held in an aquarium were subjected to varying conditions of feeding and starvation to evaluate putative indices of feeding and growth. Specific growth rate (%d −1 ) was linearly related to feeding rate (% of the body mass d −1 ) in animals with a mean body mass of 250 g at 15°C. Maximum growth rates varied between 〉 2% d −1 (body weights 〈 300 g) to 〈 1% d −1 (body weights ≤ 900 g) but specific growth rates were not related to body weight. Growth rates became negative (weight loss) after one week without food. The digestive gland index (DGI) was significantly correlated with short and long-term feeding and specific growth rates, and with body weight. Muscle RNA concentration was linearly correlated with growth rate during the previous 1–3 weeks but not with feeding rate. RNA:protein ratios were not different between mid-arm and mantle sample sites but arm tip values were significantly higher. RNA:protein ratio was related to body weight only in feeding animals. It is concluded that DGI is an index of feeding rate and that RNA:protein ratio can be used as an index of recent (~ 4 weeks) growth rate.

Description: Growth in Loliolus noctiluca (Myopsida: Loliginidae) in Western Port, Victoria, Australia was studied from statolith growth increments. Tetracycline staining experiments verified previous work on tropical forms of this species that showed growth increments to be deposited daily. A logistic growth function described the relationship between length and increment number. There appear to be major differences in the form of growth, longevity and life history pattern between tropical and temperate forms of this species. These are probably attributable to differences in environmental conditions.

Description: Seasonal distribution, size composition, age structure and growth of Berryteuthis magister juveniles (mantle length from 20 to 130 mm) were studied in the western Bering Sea (from 1700E to 179°W) between June and October 1994. According to the analysis of 1030 statoliths, the juveniles hatched from December to June with a peak in February and March. Growth data for different seasonally hatched groups were best fitted by an exponential function, summer-hatched juveniles demonstrated the fastest growth. B. magister attained the length at which it recruits (130 mm mantle length) at an age ranging from 140 to 200 days. Comparison of variability of both juvenile age structures and geostrophic currents in the region revealed that the Eastern Bering Slope Current (EBSC) was the main carrier of B. magister juveniles from the spawning grounds to the western Bering Sea. Seasonal variability of the EBSC determined the differences in juvenile migratory patterns. During its intense stage in May-June, the EBSC transported winter-hatched and spring-hatched juveniles first to the eastern part of the region and then westward along the slope. During its relaxed stage in July-September, the EBSC carried spring- and summer-hatched juveniles across the deep-water part of the Aleutian Basin directly to the western part of the region.

Description: Cephalopod eggs and egg masses turn up in samples taken during oceanographic cruises (including subsamples consisting of the stomach contents of marine predators); they are encountered by Scuba divers and crews of manned submersibles, and stranded egg masses can be found on ocean beaches around the world. If it is comparatively easy to identify such material as "squid eggs", it is much more difficult to recognize the group or species to which the eggs belong. There are various reasons why the identification of eggs and egg masses is often difficult or impossible, especially for the non-specialist. The lack of standardized illustrated keys showing both the embryonic stages and the corresponding aspects of egg capsules for well known species is a major impediment to identification or further developments needed to optimize the chances of finding hitherto unknown material...

Description: Two large (dorsal mantle length 42.5 and 47.5 cm), mated spent females of circum‐Antarctic bathypelagic cranchiid squid Galiteuthis glacialis were caught early in March 1992 at the surface of the ice hole in the western Weddell Sea over depths 1915‐1920 m by the team of the U.S.A.‐Russian Ice Station Weddell‐I. The structure of the reproductive system of adult females is described for the first time in detail. Both were gelatinous, devoid of tentacles, with empty or almost empty stomachs. The empty spermatangia (sperm reservoirs of spermatophores) 30‐35 mm in length were distributed in the mantle tissues parallel to the mantle surface and to each other in the dorso‐anterior part of the mantle: 13 in one female, parallel to the body axis, and 20 in the other, parallel (13) or perpendicular (7) to the body axis. In the latter case, they represented probably two mating events. The spermatangia lay nearer to the inner than the outer mantle side and opened by a round window on the inner side; the skin with chromatophores above them remained intact. The spermatozoa had one flagellum and rod‐like heads, length 5.0‐5.3 μm, width 1.2‐1.5 μm. The most characteristic features are: a very simple type of blood vessel branching making each micro‐gonad currant‐like, not grape‐like; a very compact disposition of oviducal, nidamental glands and gill, forming a united complex located on both sides of the mantle cavity; and an ovary connected by mesentery along all its length with the continuation of the stomach from the caecum to the end of the gastrogenital ligament. Only immature degenerating trophoplasmatic oocytes, length 0.9‐1.4, av. 1.0‐1.2 mm, were contained in ovaries; only one mature egg (length 3.3 mm, width 2.4‐2.5 mm) was found in each female. The absence of oocytes 〈0.9 mm and 1.5‐3.2 mm indicates that the maturation of oocytes proceeds rather synchronously, one large portion of eggs (some tens of thousands) matures in a short time while others degenerate. The residual fecundity is assessed to be approximately 20,000 eggs. It is hypothesized that mating occurs shortly before spawning and that mature males do not undergo gelatinous degeneration and do not lose tentacles. Spermatophores are placed on the inner side of the female's mantle with the aid of the male's tentacles and/or arms (less probably by the penis), but the exact mode of implantation is unclear. Spawning probably occurs at depths of adult habitat (approx. 500–2500m), may be multiportional but short; the exhausted female loses neutral buoyancy, rises to the surface and dies. Rising to the surface after spawning is a common feature of females of many meso‐ and bathypelagic squids undergoing gelatinous degeneration during maturation (Onychoteuthidae, Gonatidae, Histio‐teuthidae, Cranchiidae, etc.) and may explain the common occurrence of large deep‐water squids in the stomachs of seabirds, including those incapable of diving, and marine mammals.

Description: A total of 57 comparative hauls using a rectangular midwater trawl with a fishing mouth area of 50 m 2 (RMT 50) were carried out along the sides of an imaginary triangle south of Madeira in 1986. A total of 1258 cephalopods were caught, giving a mean of 22 per haul with a range from 0 to 67. The nets were used with a diver's light on the top bar which was either switched off or was operated with a 20, 70 or 150 W bulb, powered by a car battery. A significantly greater number of individuals per haul was caught with lights on than without lights, increasing from a mean of 13·5–25·1, a factor of 1·8. Similarly, the number of species caught was increased from a mean of 7 to 10·4, a factor of 1·5 and the volume of cephalopods was increased from a mean of 41·1–162·3ml, a factor of 3·9. Similar comparisons made for catches during day or night separately and on the three courses separately also showed marked increases with the lights. Samples show that increase in power of the lights increased the total number of cephalopod individuals caught. In the 12 species with more than ten individuals, in 33 of the 36 comparisons (of number of individuals, species and volumes) there is an increase with the light. The most influenced species was Taonius pavo which increased in numbers by a mean factor of 3·9 times with 20W, 4·0 times with 70W and 6·1 times with 150W when compared with the numbers caught with no light.

Description: A specimen of Chaunoteuthis mollis (Cephalopoda: Onychoteuthidae), a mature mated female, from the Straits of Messina was examined. Measurements and indices were compared with those of Onychoteuthis banksii reported by previous authors. The differences found were attributed to the degeneration of the C. mollis specimen, due to sexual maturation. Two subocular (one under each eye) and two visceral photophores, similar to those of O. banksii , were present in the C. mollis specimen. The size of the posterior visceral photophore of C. mollis fit the regression line correlating posterior photophore diameter to mantle length in O. banksii. These results corroborate the hypothesis, put forward by other authors, that C. mollis represents the mature female of O. banksii.

Description: Three specimens of the giant squid Architeuthis were by-caught in demersal trawls to the west of Ireland, between April and June 1995. All three specimens were mature males, of mantle length 975–1084 mm. Although some intraspecific variation in fin, beak and gill were noticed, all three specimens were tentatively assigned to the species A. dux. The three specimens had food remains in their stomachs and food items identified included Micromesistius poutassou, Trachurus trachurus, Nephrops norvegicus and Eledone cirrhosa . Age estimates were made by counting putative daily growth increments in ground statoliths, and ranged from 294–122 d, giving percentage daily growth rates of 2·96–4·25% indicating a short life cycle and extremely rapid growth.

Description: The highly active squid which inhabit the pelagic zones of continental seas are characterized by high energy requirements and have been termed invertebrate athletes. In this paper, the physiological and biochemical background of muscular performance in squid from different environments is reviewed and the physiological and environmental factors limiting performance levels are addressed. One important factor is the highly concentrated haemocyanin which, in ommastrephid squid, and by virtue of their extreme pH dependence, helps to load oxygen efficiently in the gills and unload it fully into the tissues. Squid regulate their extracellular pH more efficiently than intracellular pH, so protecting the haemocyanin from fatal pH changes. However, a large proportion of the oxygen requirement in the mantle muscle must still be provided by oxygen uptake through the skin. Anaerobic mechanisms become involved beyond critical swimming speeds once oxygen supply to mitochondria becomes limiting. Onset of anaerobiosis also characterizes the limits of long-term tolerance to progressive hypoxia at a critical P O2 and to high, above-critical temperatures. In general, anaerobic energy production reflects an inability to meet oxygen demand and indicates transition to a time-limited situation. The development of energy-saving locomotion strategies therefore shifts critical thresholds and extends tolerance periods in species exposed to environmental extremes, typically in coastal areas. There, negatively buoyant squid make greater use of the fin for economical swimming, which is also advantageous because of the complexity of the environment. In Lolliguncula brevis, the rate at which anaerobic resources are used above the critical swimming velocity is minimized by oscillating between periods of high and low pressure jets, thereby extending the period during which the animal can dive into hypoxic or warm water. However, only jet propulsion can economically attain the high velocities necessary in the open sea. Accordingly, the highest performance levels are seen in squid inhabiting the open sea, and they are only made possible by the uniform environmental parameters. Some squid may be able to operate at their functional and environmental limits, revealing a trade-off between oxygen availability, temperature, performance level and, possibly, body size.

Description: A peculiar squid paralarva from Hawaiian waters was described by Young (1991, Bull. mar. Sci. 49(1–2): 162–185), but it could not be assigned to any known family. Two larger juvenile specimens have now been obtained, one collected near the surface in the eastern Pacific Ocean and the other rehydrated from a dried specimen originally recovered from the stomach of an Alepisaurus. A photograph of the latter specimen before dehydration was found among the unpublished notes of S. S. Berry. The squid are characterized by very large fins that dwarf the rest of the animal. The fins are terminal in position, mostly posterior to the mantle muscle. The tentacles are similar to the arms in general form, but are much more robust. Tentacle suckers are in eight series, whereas the crowded arm suckers constitute more than two series on some arm pairs. The distal portions of the arms and tentacles taper abruptly to thin vermiform filaments. The funnel cartilage of the net-collected juvenile is oval and the buccal connectives to Arms IV are ventral. Although some characters indicate a likely relationship with the chiroteuthid/mastigoteuthid group of families, the brachial crown differs from that found in any known family. Based upon these three specimens and the photograph, it is concluded that the squid represent a family not previously recognized by science. This family is named Magnapinnidae, with the type species Magnapinna pacifica n. gen., n. sp., the holotype of which is the net-collected juvenile. Although all three specimens are included in the family and genus, the possibility exists that the paralarva and the rehydrated specimen are not conspecific with the holotype. Therefore, paratypes are not designated.

Description: A brief summary of the current capabilities of a high resolution global numerical prediction model towards resolving the life cycles of hurricanes is first presented. Next, we illustrate the results of season long integrations for the years 1987 and 1988 using the observed sea surface temperature (SST) anomalies over the global oceans. The model being used here is the FSU atmospheric global spectral model at the horizontal resolution of T42 and with 16 vertical layers. The main emphasis of this study is on hurricane tracks for these and for global warming experiments. The global warming scenarios were modeled using doubled CO2 and enhanced SST anomalies. The model being atmospheric does not simulate the ocean, and SST anomalies need to be prescribed. It is assumed in these experiments that the SST anomalies of the doubled CO2 world appear similar to those of the current period but that they are slightly warmer over the global tropics. That is determined using a simple proportionality relationship requiring an enhancement of the global mean SST anomaly over the tropics. Such an enhancement of the SST anomaly of an El Nino year 1987 amplifies the SST anomaly for the El Nino of the double CO2 atmosphere somewhat. The La Nina SST anomalies were similarly enhanced for the double CO2 atmosphere during 1988. These hurricane season experiments cover the period June through October for the respective years. It was necessary to define the thresholds for a model simulated hurricane; given such a definition we have compared first the tracks and frequency of storms based on the present day CO2 simulations with the observed storms for 1987 and 1988. Those comparisons were noted to be very close to the observed numbers of the storms. The doubled CO2 storms show a significant enhancement of the frequency of storms for the La Nina periods, however there was no noticeable change for the El Nino experiments. We have also run an experiment using the SST anomalies from a triple CO2 climate run made at the Max Planck Institut at Hamburg, This experiment simulated some 7 hurricanes over the Atlantic Ocean. The intensity of hurricanes, inferred from maximum winds at 850 mb, show that on the average the storms are slightly more intense for the double CO2 experiments compared to the storms simulated from current CO2 conditions. The triple CO2 storms were slightly stronger in this entire series of experiments.

Description: Deep-water trawling for fish species on the shelf slope off Scotland results in a by-catch of rare cephalopod species. The cirrate octopus Opisthoteuthis grimaldii is normally present below 800 m; at least one other species of cirrate and five species of incirrate octopus are found; significant extensions of range and depth are recorded. An incidental catch of the ommastrephid squid, Todarodes sagittatus , included a fully mature specimen and is indicative of its probable breeding locations. The results highlight the many taxonomic and systematic uncertainties surrounding the rarer cephalopod forms, and emphasize the utility of the fishing by-catch.

Description: Cephalopod prey of several cetacean species from Hawaiian waters were identified and quantified from the beaks in stomachs of stranded individuals. The different species of cetaceans all appear to target different species and sizes of cephalopods. Beaks from two sperm whales ( Physeter catodon ) included a total of 312 upper and 292 lower beaks (mandibles) of cephalopods. All of the cephalopods represented by lower beaks were oceanic squid belonging to 20 or more species in 14 families. The major constituents of the whale diet were Histioteuthis hoylei (45% by number and 10·9% by dry weight), Ommastrephes bartrami (7·6% by number, 30·6% by weight) and Architeuthis sp. (only 0·7% by number, but 26·5% by weight). In a Risso's dolphin ( Grampus griseus ) stomach, 1051 upper beaks and 1349 lower beaks were present. Eighteen or more genera of cephalopods in 15 families were present. The major constituents of the Grampus diet were Enoploteuthis spp. (36·1% by number and 30·1% by dry weight) and Abraliopsis spp. (23·6% by number, but only 4·9% by weight) and O. bartrami (1·3% and 32·1% respectively). The melon-headed whale ( Peponocephala electra ) eats fish as well as cephalopods which are represented by only six lower beaks belonging to five genera, Enoploteuthis, Teuthowenia, Abraliopsis, Abralia sp. and Bathyteuthis abyssicola . The beaked whale (unidentified) contained two lower beaks which were O. bartrami. Stenella attenuata also eats fish and the sample contained lower beaks, one of Enoploteuthis sp. and seven of an Abraliopsis sp.

Description: Observations on samples from Spanish trawlers between September and November of 1995 revealed the presence of mated females of Loligo gahi (Cephalopoda: Loliginidae) from 164–285 m depth, in the Western area of the Falkland Islands Conservation Zone. 93.8% of the mature females, and 31.0% of the maturing ones, were mated. Deposition of spermatophores always took place in the oral membrane between the connectives of arms IV. The relationships between sexual maturation and copulation have been analysed, and the hypothesis of mating acting as a ‘trigger’ of the final sexual maturation in Loligo gahi females is proposed and discussed.

Description: This paper gives morphometric variations and dorsal mantle length–total weight (DML-TW) relationships for Illex coindetii in the eastern Central Atlantic area. Positive allometry was observed in males and negative in females of the species. The most variable body measurements between males and females were width and perimeter of the head. In the study area, divergence of morphometric measurement starts at 95 mm. The point of divergence, however, varies with latitude; fluctuating from 104 mm in the north (Morocco and Sahara) to 76 mm in the central area (Mauritania and north of Senegal) and 73 mm in the south (Gulf of Guinea). The relationships between DML and TW showed that sexual dimorphism due to differential growth between males and females starts to occur at 56 mm ML. The starting point of sexual dimorphism (56 mm) varies according to the zone; the higher the latitude, the later it occurs. Thus, sexual dimorphism occurs at 49 mm in the south (Gulf of Guinea), at 54 mm in the central area (Mauritania and north of Senegal) and at 74 mm in the north (Morocco and Sahara). Females grow larger than males, but males were heavier at any given length. As latitude decreased, a slow down in the increase in weight-at-length was observed in both sexes.

Description: A study of the echo peak amplitudes from known nodule areas is initiated to observe the acoustic response for varying nodule abundances and number densities. A statistical study of the peak amplitudes from different nodule areas confirms that the coefficient of variation is the highest for medium nodule abundance and number density. Echo fluctuation study based on the Rician probability density function (PDF) establishes that the non‐nodule sediment bottom contributes to less scattering, i.e., it is a microtopographic type, whereas scattering is dominant in the nodule‐bearing areas. The spectral studies are conducted on depth data of different areas. This study ensures that the signal scattering in the nodule bottom area is due to the nodules lying on the seabed rather than the large / small‐scale topographic variations. The study based on Poisson PDF for nodule area confirms this fact again. Agreement between the nodule distribution and the Poisson distribution parameter is clearly seen. Such a relation is not observed in the case of Rician density functions.

Description: Plastic debris accumulates in the marine environment following its use in agricultural, industrial and social activities. Its ultimate fate is accomodation in sediments where it may persist for times up to centuries or longer. There appears to be an increasing flux of materials with time and an increased areal coverage of the benthos. Impacts upon bottom organisms can take many forms. Systematic monitoring tactics for the extent of seafloor coverage by plastics are yet to be incorporated into national programs.

Description: A description of egg masses from Gonatus frabricii (Lichtenstein) caught with pelagic trawl in the Norwegian Sea is given. The eggs were kept together in a single layer between two mucous membranes, and the pieces collected appeared to be fragments of more extensive structures torn apart by wear from the sampling gear. No embryos were observed in the eggs, and none of the eggs showed any staining for five enzyme systems analyzed by isoelectric focusing. Either the eggs were caught shortly after spawning and fertilization, or the lack of embryonic tissue reflects the fact that most of the eggs were caught in water colder than 0°C. The development rate at this temperature is expected to be very slow.

Description: The South Tasman Rise is a large submarine plateau of continental origin, located south of Tasmania. In the light of satellite‐derived gravity data and shipboard swath‐bathymetry and magnetic data collected in 1994 in the South Tasman Rise region, this paper re‐examines the sea‐floor spreading history of the surrounding ocean basins (northeastern Australian‐Antarctic Basin and southwestern Tasman Sea). This information is synthesised in seven plate tectonic reconstructions of the South Tasman Rise region from the mid‐Cretaceous (95 Ma) to the Early Oligocene (34 Ma). Our interpretation and model confirm that the South Tasman Rise is composed of two distinct terranes. A western domain, limited to the west by a transform margin along the Tasman Fracture Zone and to the east by a N170°E oriented boundary at 146.5°E, was initially attached to Antarctica. The western terrane rifted away from Antarctica in the Late Paleocene/Early Eocene and underwent severe wrench deformation as the Antarctic plate moved southward relative to the Australian plate. Shear motion continued to shape the Tasman Fracture Zone transform margin until the Early Miocene (chron 6B, 23 Ma) after which the Southeast Indian Ridge axis cleared from the western edge of the South Tasman Rise. An eastern domain limited to the east by a boundary at 146.5°E, rifted off from Tasmania and the East Tasman Plateau. After an initial phase of stretching between Tasmania, the East Tasman Plateau and the Lord Howe Rise that lasted until the mid‐Cretaceous, sea‐floor spreading in the Tasman Sea started in the Late Cretaceous (chron 34y) north of the East Tasman Plateau. Seismic, magnetic and gravity profiles between the eastern South Tasman Rise and the East Tasman Plateau suggest that sea‐floor spreading began between the two microcontinental blocks in the Late Cretaceous (ca chron 33y) and failed shortly after (chron 30y).

Description: Changes in the molecular structure of a highly ordered kaolinite, intercalated with urea and potassium acetate, have been studied using Raman microscopy. A new Raman band, attributed to the inner surface hydroxyl groups strongly hydrogen bound to the acetate, is observed at 3605 cm (super -1) for the potassium acetate intercalate with the consequential loss of intensity in the bands at 3652, 3670, 3684 and 3693 cm (super -1) . Remarkable changes in intensity of the Raman spectral bands of the low-frequency region of the kaolinite occurred upon intercalation. In particular, the 144 and 935 cm (super -1) bands increased by an order of magnitude and were found to be polarized. These spectroscopic changes provide evidence for the inner surface hydroxyl group-acetate bond being at an angle approaching 90 degrees to the 001 face. Decreases in intensity of the bands at 243, 271 and 336 cm (super -1) were observed. The urea intercalate shows additional Raman bands at 3387, 3408 and 3500 cm-1 which are attributed to N-H vibrations after formation of the urea-kaolinite complex. Changes in the spectra of the inserting molecules were also observed.

Description: Recent attention to members of the sepiolid squid genus Euprymna and symbiotic associations with luminescent bacteria ( Vibrio fischeri strains) has prompted a review of this poorly-resolved group of squids. Twelve nominal species have been placed in this genus of which the majority are ill-defined, known only from their original descriptions and separated on the basis of inadequate characters. As a first step in resolving this group, a temperate Australian species, the Southern dumpling squid, Euprymna tasmanica , is here redescribed in detail. As the genus Euprymna currently stands, most members are only distinguished on the number and position of enlarged suckers in mature males. No diagnostic characters are available to identify females. All nominal species placed in this genus are reviewed and a key to proposed valid species is presented. Six species are considered here to be valid: Euprymna berryi, E. hoylei, E. morsei, E. scolopes, E. tasmanica and an undescribed species treated here as Euprymna sp. 1. Euprymna similis is a synonym of E. morsei of Japan. Due to inadequate original descriptions, and lost or poor type material, two species are considered here to be nomen dubia ( E. schneehageni and E. pusilla ), while the taxonomic status of four additional species remain unresolved ( E. albatrossae, E. bursa, E. phenax and E. stenodactyla ).

Description: Records of unusual cephalopods, taken as by-catch in Irish and Scottish waters in the years 1985–1995, are presented. Of most interest are three specimens of giant squid (Architeuthis) that were caught in bottom trawls off the west of Ireland between April and June 1995, all were mature males of mantle length ∼1000 mm. Other records include a large mature female Histioteuthis bonnellii from the west of Ireland and three specimens of the gelatinous incirrate octopus, Haliphron atlanticus.

Description: The female of the harpacticoid Cholidya polypi Farran, 1914, is redescribed and the male is described for the first time. This copepod parasite of octopuses, reported previously only from Benthoctopus (= Polypus) ergasticus off Ireland, is here documented from the North Atlantic east of Florida on Tetracheledone spinicirrus and off North Carolina and New Jersey on Bathypolypus anticus, and from the northeastern Pacific west of Oregon and Washington on Graneledone pacifica and off central California on Graneledone spp.

Description: Statolith morphology of the giant squid Architeuthis sp. from southern African waters is illustrated. The most characteristic features are identified, particularly the wing shape and position, which are described for the first time.

Description: The statolith microstructure was studied in 142 females (mantle length, ML, ranging from 77–402 mm) and 119 males (72–328 mm ML) of Martialia hyadesi caught on the Patagonian and Falkland shelves and at the Antarctic Polar Frontal Zone between 1989–94. The statolith microstructure dark zone in this species, contains narrower and more numerous growth increments than the dark zones of other ommastrephid squids. Assuming daily production of putative growth increments within statoliths males live up to 12 months, and females live up to 13 months. It is likely that the life cycle lasts c. 1 yr, but immature squids with ages 〉330–340 d suggest that a part of M. hyadesi populations could have life span 〉1 yr. Growth in length was best described by the Gompertz function, whereas growth in weight was best described by the logistic function. M. hyadesi is characterized by slow juvenile growth (〈100 mm ML), fast growth of immature squids and a sharp decrease in growth rates during maturation. M. hyadesi mature later (at ages 〉270 d) than other temperate ommastrephids, but maturation is rather rapid (2–3 months). In the south-west Atlantic, M. hyadesi hatch throughout the year.

Description: The morphology of a preserved octopod is significantly affected by the condition of the animal at the time of fixation, whether live or dead. When unknown, this condition can be assessed by examining the degree of contraction of the radula support muscle. Specimens fixed post‐mortem have a relaxed radula support muscle. This muscle is contracted in specimens plunged into preservatives alive. The degree of contraction of this radula support muscle facilitates identification of both fixation‐induced and fixation‐independent character states in octopod systematics.

Description: An uncritical compilation of New Zealand Mollusca by Spencer & Willan in 1996 cites 90 species of cephalopod as recorded from New Zealand waters (excluding the Kermadec Islands) to 31 December 1993. Seventeen of these 90 species are octopods and the status of five is in need of immediate revision. Pareledone sp. and Octopus sp. have since been transferred to the genera Graneledone and Benthoctopus, respectively, although both species await description. Haliphron atlanticus Steenstrup, 1860 (as Alloposus mollis Verrill, 1880), Ocythoe tuberculata Rafinesque, 1814, and Octopus dofleini (Wulker, 1910) are cited as occurring within New Zealand waters solely on the basis of identification of beaks or tissue remains from gut contents of longdistance foraging marine predators. The appropriateness of including these three species in the New Zealand fauna is evaluated in the light of thorough examination of extensive cephalopod collections from New Zealand waters.

Description: A total of 1,014 measures of sediment shear strengths were measured by means of miniature vane shear and fall cone tests on five gravity cores collected in Eckernfo‐erde Bay, Baltic Sea. Paired t test was used to compare the shear strengths measured by the two methods. It was found that fall cone strength calculated with Wood's K60value (0.29) overestimates the vane shear strength by 0.15 kPa (a = 0.001) and the sample mean of the fall cone strength is 4.1% higher than the mean of the vane shear strength. However, fall cone strength calculated with Hansbo's K60 value (0.24) underestimates the vane shear strength by 0.88 kPa (a = 0.001), and the sample mean of the fall cone strength is 13.8% less than the mean of the vane shear strength. Both calculated fall cone strengths are significantly different from the vane shear strength, with a p value of less than 0.001. Regression analysis of the Echernfoerde Bay data indicates that a new K60 value is 0.275 with a confidence interval (a = 0.01) from 0.2704 to 0.2786. Paired t test shows that there is no significant difference between miniature vane shear and fall cone tests for these samples if the fall cone strength is calculated with K60 = 0.275.

Description: The natural feeding of the two most abundant ommastrephid squid (Cephalopoda: Ommastrephidae) in Galician waters was studied and compared. A sample of 334 stomach contents of Todaropsis eblanae (34–222 mm ML) and 267 stomach contents of Illex coindetii (50–379 mm ML) caught by commercial trawlers was examined. A total of 21 (T. eblanae) and 23 (I. coindetii) different prey items, belonging to three zoological groups (Teleostei, Crustacea and Cephalopoda), were taken by these cephalopods. However, 43% of the T. eblanae diet comprised only one fish species, Micromesistius poutassou. The diet of these squid species was significantly influenced by the geographical area (both species), size (T. eblanae) and maturation (I. coindetii). Feeding rate of both species decreased with size, but the percentage of stomachs with food remains increased in maturing and mature females. Weight of prey captured was dependent on available prey sizes and, in small individuals, maximum prey weight was very close to the squid weight. Both squid species are mainly neritic nekto-benthic predators, but I. coindetii seems to have a broader and more pelagic diet.

Description: A mineralogical and 4OAr/39Ar study of 13 amphibole samples in the Kamila Amphibolite Belt and Kamila Shear Zone in northern Pakistan has found a correlation between the degree of greenschist facies alteration and quantity of excess 40Ar. Additionally, there is a north–south divide with amphibole samples from the northern region showing larger degrees of gree schist facies alteration, brittle deformation, and excess 40Ar incorporation compared to the predominantly plastically deformed, less altered, amphibole samples from the Kamila Shear Zone in the south. Acid leaching of two amphiboles from the Kamila Amphibolite Belt indicates that a large proportion of the excess 40Ar is correlated with later greenschist facies alteration hases, and can be easily removed by acid etching, thus revealing acceptable regional 40Ar/39Ar plateau ages.

Description: The size distribution of benthic nematodes was investigated along different gradients of food availability in various regions of the north-eastern Atlantic: I, across the continental margin and II, with increasing distance from the continental rise. An overall trend for miniaturization with increasing distance from the food source was found. Moreover, our results indicate that seasonally varying food supply or a periodically pulsed input of organic matter to the sea floor affects nematode size spectra. The hypothesis is proposed that the life cycle of deep-sea nematode species and hence the size structure of their populations are related to seasonal energy availability. This dependence might result in one year life spans of deep-sea nematodes and probably other meiofauna.

Description: The free surface version of the GFDL model is used to study inflow and outflow through the Danish Straits, which connect the Baltic with the North Sea. Three problems are addressed: (i) the piling up of inflowing water in the Arkona basin; (ii) the transport ratios between Belt and Sound; (iii) the dominance of hydraulic or geostrophic control. Model results show that a cyclonic eddy (dome) is formed by the inflowing saline water that prevents this water from passing rapidly into the Bornholm basin. This eddy is enforced with increasing inflow due to a sea level difference between Kattegat and western Baltic. If density gradients along the straits are weak and the flow is dominantly driven by sea level differences between Kattegat and Baltic, the well-known ratio of 70% : 30% for the transports through Belt and Sound are confirmed. Strong density gradients can change this ratio considerably, especially in the outflow case, when the light water of the Baltic flows against the heavier water of the Kattegat. Under variable wind conditions, no fixed ratio is found. The flow in the Straits is geostrophically controlled; however, the strong baroclinic density field does not allow us to derive the transport simply from sea level inclination.

Description: Density-dependent effects of Anguillicola crassus larval infections in the copepod intermediate host were examined experimentally. Three species of copepods (Cyclops vicinus, C. viridis and C. fuscus) were subjected to a range of doses of larval A. crassus within infection arenas. Prevalence, intensity and parasite dispersion (variance: mean abundance) values increase and then approach an asymptote as infection dose increases. Infection parameters differ between species of copepod. Increasing temperature has a negative effect on the establishment of the parasite population within the intermediate host. Parasite-induced host mortality increases with dose. These mechanisms have the potential to regulate populations of A. crassus larvae within the copepod population and hence the whole suprapopulation.

Description: For the purpose of this study, 5 311 post recruit of Illex coindetii were collected from the fishery of the Galician shelf, with sizes ranging from 32 to 379 mm dorsal mantle length (ML). Samples were taken monthly from November, 1991 to October, 1992. Sexual maturation, spawning season and population structure of Illex coindetii were analyzed. The spawning season extended throughout the year reaching a peak in July-August, with size at first maturity in males, 128 mm ML and in females, 184 mm ML. Males mature at a smaller size and attain lower size (279 mm ML) than females (379 mm ML). The sex ratio of the whole population sampled was slightly biased towards males, nevertheless monthly variations observed and the ratio obtained (1.09 : 1) does not suggest that there is spatial segregation by sexes in the fishing ground. From the total sample, 185 males and 281 females, covering the whole range of ML's, were randolmy separated out to calculate maturation indices. A correlation between the subjective scales and the values of these indices was established in both sexes. The nidamental gland length proved to be a reliable parameter for distinguishing between stages of maturity in females. The fecundity of the species varied between 3 500 and 285 000 oocytes, (the most frequent range being from 30 000 and 200 000 oocystes) in the ovary and the oviducts. The principal axis in the oviduct contained 2 331 ± 912 eggs. The number of spermatophores in the spermatophoric sac varied between 81 and 1 555, and it was observed that the number and the length of the spermatophores tended to increase with size of the males. Illex coindetii may be considered as an intermittent spawner.

Description: The size of fish and squid prey of Loligo forbesi was investigated using otoliths, beaks and statoliths collected from stomach contents analysis of samples obtained from Scottish and Irish waters between 1990 and 1993. Loligo forbesi was found to consume a large range of prey sizes, but prey size was always less than the predator size. Season was shown to significantly influence the predator size-prey size relationship for sprat and sandeel prey, but this itself could be influenced by seasonal changes in the size of prey. Fish prey size increased with increased predator size up to a mantle length (ML) of 200 mm. Loligo forbesi of mantle length 〉200 mm consumed a range of prey sizes, with no clear increase in the size of prey. For most prey taxa the relationship between prey size and squid size was similar, the exceptions being dragonets and silvery pout. Cannibalism by L. forbesi was mostly limited to larger L. forbesi (〉150 mm ML) feeding on smaller (20–50 mm ML) conspecifics.

Description: Statolith microstructure was studied in 162 specimens of Illex coindetii (mantle length ranging from 48 to 300 mm) captured on the shelves of Sierra Leone and Western Sahara between May and November 1987. Growth increments were revealed in all statoliths studied, but they were not well-resolved as in other congeneric species Illex illecebrosus and Illex argentinus . Age and growth rates were estimated assuming that growth increments within statoliths were produced. In both regions, differences in growth rates between sexes (females become larger than males) occurred first in length and then in weight. Geographical differences in sex-specific growth (Western Sahara squid grow faster and attain larger sizes than Sierra Leone squid) was apparent after 150 d in females and 120 d in males. Illex coindetii in Sierra Leone started maturing at smaller sizes but at approximately the same age as the Western Sahara squid. Small sized early maturing groups of I. coindetii with a life span of ~0.5 y occurred in both regions. However, large sized late maturing squid with a life span of ~1 y were encountered only in the Western Sahara. In waters of the west African shelf, I. coindetii spawn throughout the year.

Description: Most cephalopods are voracious and very mobile predators with highly developed sense organs that rival the equivalent vertebrate sense organs in complexity. A brief description is given of cephalopod predation and the sense organs that are directly, or indirectly, involved: (i) the vertebrate‐like lens eyes with their complex extraocular eye muscle system; (ii) the epidermal head and arm lines which are analogous to the lateral lines of fishes and aquatic amphibians; (iii) the vestibular analogue statocysts with receptor systems for linear (gravity) and angular accelerations; (iv) the proprioceptive neck receptor organ which controls head‐to‐body positions; (v) the sucker and muscle mechanoreceptors; and (vi) the contact and distance chemoreceptors. In addition, the possibility of hearing is discussed.

Description: Parasites were collected from 1,200 short-finned squid (Illex coindetii, Todaropsis eblanae) caught as by-catch in a multispecies trawling fishery in the northwest Spanish Atlantic waters in 1992-1993. Parasites found included six species of helmiths, three tetraphyllidean cestodes (Phyllobothrium sp., Pelichnibothrium speciosum, Dinobothrium sp.), two trypanorhyllidean cestodes (Nybelinia yamagutii, Nybelinia lingualis), and one ascarioid nematode (Anisakis simplex B). Two of these parasites (Phyllobothrium sp., A. simplex B) which could be recognised as component species, were used in analyses of host-parasite relationships. Levels of infection varied significantly with host size or stage of maturation for both squid species. Regional variation in infection level seems attributable to geopgraphical variation in variability of prey, discreteness and movements of host populations and to size or age-related changes in the prey selection of their host. Parasite evidences suggest that both ommastrephid squids are sympatric species sharing similar econiches, and serve as diet for large top predators (selachians and marine mammals) of Northeast Atlantic. Parasites may also be useful as an indirect indicator of the migratory habits of the squid.

Description: Metazoan meiofauna were studied in replicated multiple-corer samples obtained at a bathyal site (1320–1360 m depth) in the Porcupine Seabight (51°36′N 13°00′W) before (April) and after (July) the delivery to the seafloor of a phytodetrital pulse originating from the 1982 spring bloom. In all samples the metazoan meiofauna was dominated by nematodes; harpacticoid copepods and their nauplii were the second most abundant taxon. Population densities and biomass were very similar in both sample sets, the only significant differences being in the numbers of ostracods (higher in April) and nauplii (higher in July). Furthermore, vertical distribution patterns in the top 5 cm of sediment indicate that the meiofauna did not migrate towards the sediment surface following the phytodetrital pulse. The lack of a metazoan meiofaunal response contrasts with published evidence, based on the same samples, for a substantial increase in the foraminiferal abundance following the sedimentation event. Thus our results suggest that metazoans (as a whole) fail to exploit and utilize phytodetritus as rapidly as foraminifera. This probably reflects the energetic expense of egg production coupled with frequently slower rates of somatic growth among metazoans. In addition, foraminifera may outcompete metazoans for detrital food because they possess extremely efficient food-gathering organelles (granuloreticulate pseudopodia) and are able to raise their levels of metabolic activity very rapidly. However, metazoan responses at the species level, or over longer time periods (〉3 months), would not have been detected and so remain a possibility.

Description: Squid (Lolliguncula brevis) were exercised in a tunnel respirometer during a stepwise increase in water velocity in order to evaluate the anaerobic treshold, i.e. the critical swimming speed above which anaerobic metabolism contributes to energy production. The average anaerobic treshold was found at speeds of 1.5-2 mantle lenghts s-1. Above this velocity, α-glycerophosphate, succinate and levels fell and phospho-L-arginine was progressively depleted, while the levels of glucose 6-phosphate and inorganic phosphate rose. The finding of a simultaneous onset of anaerobic metabolism in the cytosol and the mitochondria indicates that a limited oxygen supply to the mitochondria elicits anaerobic energy production. This finding is opposite to the situation found in many other vertebrate and invertebrate species, in which energy covered by anaerobic energy production. This finding is opposite to the situation found in many other vertebrate and invertebrate species, in which energy requirements in exvess of aerobic energy production are covered by anaerobic metabolism, with mitochondira remaining aerobic. In L. brevis, swimming at higher speeds is associated with a small factorial increase in metabolic rate based on a high resting rate of oxygen cnsumption. Pressure recordings in the mantle cavity support this finding, indicating a high basal level of spontaneous activity at rest and a small rise in mean pressure at higher swimming velocity. Bursts of higher pressures from the jet support elevated swiming speeds and may explain the early transition to anaerobic energy production which occurs when pressure rises above 0.22-0.25kPa. The finding f mitochondrial hypoxia at a low critical speed in these squid is interpreted to be related to their life in shallow coastal and bay waters, which limits the necessity to maintain high swimming velocities. At increased swimming velocities, the animals oscilliate between periods of high and lo muscular activity. This behaviour is interpreted to reduce transport cost and to permit a longer-term net use of anaerobic resources when speed exceeds the critical value or when the squid dive into toxic waters. The simultaneous onset of anaerobic metabolism in the cytosol and the mitochondria emphasizes that squid generally make maximal use of available requirements are the highest among marine invertebrates.

Description: This study shows that calcium carbonate plays an important role as a cementing agent of various marine sediments. The measured vane shear strength of marine soil samples is shown to vary with depth and is strongly correlated with the calcium carbonate content. The results show that an increase in calcium carbonate of 1% causes an increase in shear strength of about 10 kPa. Moreover, under accumulating self‐weight, consolidation is found to be enhanced by calcium carbonate. It was also found that both the cementation and condensation due to calcium carbonate are the major factors accounting for the strength development of marine sediments, beside consolidation. These effects are often greater than those due to grain size effects.

Description: A model is presented which tests the representation of the maturity process in terms of gonadosomatic indices (GSI) in chokka squid Loligo vulgaris reynaudii. It assumes that the true maturation process is reflected by the results of histological investigation, which cannot be used in large-scale ecological work in the field. However, the maturity scales used in ecological studies define some morphological categories which can be linked directly to microscopic development. Therefore, the overlap of GSI ranges for each morphological maturity category may be used to judge how well the GSIs represent the histological stages. Results have shown that the overlap is large and that GSI cannot be recommended as adequately reflecting the maturation process in squid. A morphological scale of maturity with possible broad applications in exploited families of squid is proposed as a better representation of the maturation process than GSI.

Description: Morphological differences between paralarvae of two loliginid squid species common in southern African waters (Loligo vulgaris reynaudii and Lolliguncula mercatoris) are described. The differences are: Loligo — "cheek patches" consisting of four dark chromatophores, nine large dark dorsal chromatophores on the mantle, tentacular clubs broad and much wider than tentacle stalks, proximal row of three club suckers with others tetraserial, suckers large enough to appear crowded on the club surface; Lolliguncula — "cheek patches" with three dark chromatophores, two pairs of" large, dark dorsal chromatophores on the mantle, tentacular clubs narrow, proximal club suckers arranged in three pairs, suckers small, not particularly crowded. Relationships with other myopsids are briefly discussed.

Description: The genus Illex is likely to constitute a large portion of the annual world ommastrephid squid catches (Roper et al, 1984), even though specific official statistics are difficult to obtain. The broad-tail short-fin squid Illex coindetii is a widespread species ranging from the western to the eastern Atlantic (Roper et al., 1984) and east through the whole Mediterranean Sea (Mangold & Boletzky, 1987). Usually a by-catch of important fisheries, it is caught mainly by trawlers. Although its economic value is lower than that of other squid species (i.e. Loligo spp.), in the Sicilian Channel Illex coindetii may represent a valuable resource due to its abundance. In Italian waters, the available statistics (Cingolani et al., 1986) report that 2680 tonnes of ommastrephid squid were landed in 1982 (0.5% of the total landed catch). The main component of these was landed in Sicily (2183 tonnes), a consistently large part of which was no doubt Illex coindetii (Ragonese & Jereb, 1992). The catches came mainly from southern Sicilian waters (Sicilian Channel) where one of the major Mediterranean landing places is in Mazara del Vallo. Large trawlers (up to 200 gross tonnage) usually carry out long fishing trips (15–20 d), and Illex coindetii is caught mainly by those targeting Parapenaeus longirostris and Merluccius merluccius (Jereb & Ragonese, 1991).

Description: This communication presents the first records of mated female Loligo gahi in Falkland Island waters. In October 1993 fully mature mated female L. gahi were identified in samples taken from the commercial fishery in waters east of Lively Island, East Falkland, at depths of 145–174 m. Spermatophores were found in both the mantle cavity and buccal sites of deposition. These records, combined with past records of spent females, suggest spawning periods in late October/early November and April/May. These concur with two of the three periods of spawning suggested from previous studies of juvenile and adult L. gahi.

Description: Age, growth and maturation of Loligo vulgaris were studied by examination of growth increments within statoliths of 294 specimens (mantle length, ML, ranging from 31 to 498 mm) caught on the west Saharan shelf between 1985 and 1988. Maximum age was 335 d (290 mm ML) for females, and 396 d (498 mm ML) for males. Growth rates varied considerably among individuals with a greater range in males. Sexual dimorphism in length was apparent after about 210 d. Males and females diverged considerably in weight, with males reaching a greater weight after about 180 d. Growth in length between 124 and 396 d was best described by a power function, while growth in weight was best described by the Gompertz function. Males started maturing at 180–210 d and mature males ranged in age between 250 and 396 d; while females started maturing at 240–270 d and mature females ranged between 285 and 335 d. Loligo vulgaris hatched throughout the year with two distinct peaks; in winter (December - early March) and summer (June-July). The life cycle of L. vulgaris populations on the west Saharan shelf lasts ~1 y, with large males (〉450 mm ML) living slightly longer.

Description: The reproductive strategies of male and female Loligo forbesi Steenstrup, 1856 were investigated from samples obtained from commercial catches and research cruises in Irish waters. In females maturity increased with size, but in males two modes in the size at maturity were identified, with approximately 40% mature at small size (180–200 mm mantle length), and the remainder mature at 〉250 mm mantle length. The difference in estimated age of the two modes of mature males was small, so size differences were probably due to different growth rates. Growth and maturation proceeded together in both sexes over much of the life-cycle. The effect of maturation on relative growth of somatic tissues was examined using analysis of covariance and multivariate regressions. In males there was a significant decline in total mass, and in mass of mantle, head and viscera, relative to mantle length with maturation. In females total mass was not significantly affected by maturation, but relative masses of head, mantle and viscera declined with maturation, indicating that energy was diverted from somatic growth to gonad production. Potential fecundity estimates were obtained by counting eggs and ova in the oviduct and ovary of mature females and were in the range 2500 to 10,500 (mean 5800). Fecundity was positively related to mantle length. The ovaries of mature females contained a range of egg sizes and developmental stages, indicating that spawning probably occurs intermittently.

Description: The mean pressures required to collapse gas vesicles in turgid cells of cyanobacteria from the Baltic Sea were 0·91 MPa (9·1 bar) in Aphanizomenon flos-aquae, 0·83 MPa in Nodularia sp. collected from the main deep basins and 0·34 MPa in Nodularia from shallower coastal regions. The gas vesicles were strong enough to withstand the depth of winter mixing, down to the permanent halocline (60 m in the Bornholm Sea, 90 m in the Eastern Gotland Sea) or to the sea bottom (30 m or less in the shallow Arkona Sea and Mecklenburg Bight). The cyanobacteria had low cell turgor pressures, within the range 0·08–0·18 MPa. The colonies were highly buoyant: the Aphanizomenon colonies floated up at a mean velocity of 22 m per day and the Nodularia colonies at 36 m per day. The colonies remained floating when up to half of the gas vesicles had been collapsed. In summer the cyanobacteria were mostly restricted to the water above the thermocline and in calm conditions their concentration increased towards the top of the water column. A series of colony concentration profiles indicated that, following a deep mixing event, the population of colonies moved upward with a net velocity of 22 m per day, similar to the colony floating velocity. This demonstrated that the buoyancy provided by gas vesicles would give a selective advantage to populations of cyanobacteria by enabling them to float into the higher irradiance of the near-surface water.

Description: PEEM allows ‘real-time’ observations to be made of solid-state transformations and other high-temperature processes taking place during vacuum-heating up to c. 2000°C The solid state transformations of an amphibole-rich hornblendite specimen have been observed in the temperature range of 750–1000°C (± 50°C Between c. 970–990°C a rapid change in orientation contrast was observed, indicating a structural rearrangement from an oxyhornblende crystal lattice to a clinopyroxene structure. This phase retains the original amphibole shape and texture (including two 120°C intersecting cleavage traces), but possesses a clinopyroxene crystal structure. At higher temperatures this phase is seen to decompose, forming iron oxides and other fine-grained products. PEEM has provided useful information on both the nature and rates of transformation of natural amphiboles which has proved invaluable in our understanding of the mineralogically-controlled mechanisms of argon release during 40Ar/39Ar dating of amphibole samples.

Description: In this study the antifouling activity was investigated of a series of chemically related, halogenated furanones isolated from Delisea pulchra (Greville) Montagne, a red alga which is rarely fouled in the field. The metabolites were tested in laboratory assays against representatives of the three major groups of fouling organisms, the barnacle Baianus amphitrite amphitirite Darwin, the macroalga Ulva lactuca Linnaeus and a marine bacterium (strain SW 8). Settlement of barnacle cyprid larvae was strongly inhibited, with an EC50 of 〈 25 ng·mr1 (25 ppb) for some compounds. The settlement and growth of algal gametes was also strongly inhibited, in some cases at concentrations as low as 25 ng·cm-2 • Growth of the marine bacterium SW8 was inhibited more strongly than by the common antibiotic gentamicin. Overall, activity of the D. pulchra metabolites was comparable to that of the heavy metals and biocides currently used in antifouling paints. However, no single compound was most active in all tests and some metabolites effective against one organism showed Iittle or no activity a·gainst the others. The high but variable level of activity of the D. pulchra metabolites, coupled with their small size, relative stability, and ability tobe synthesized suggest their potential use as active ingredients in antifouling coatings.

Description: Simulations with an ocean general circulation model and a hybrid coupled model reproduce well the observed principal spatial mode (PSM) of variation of the tropical Pacific ocean/atmosphere system. The model results show the origins of the PSM to be a coupled ocean/atmosphere mode and suggest this phenomenon is not a natural mode of the tropical Pacific Basin alone. Air-sea interactions amplify the mode variability by a factor of 5–6 over the strength it would have in a purely random atmosphere and so it obtains climatological importance. These same interactions introduce the PSM to the atmosphere. The PSM of interannual variability is not directly driven by the annual cycle. But its time scale does depend importantly on the fact that the ocean-atmosphere coupling strength varies with respect to the annual cycle. The mode appears to be rather sharply peaked in wave number space but broadbanded in frequency space so that identifying it with a temporal designator, as has been done in the past is apt to be misleading.

Description: Megafauna on bioherms (large biological structures) of the scleractinian coral Lophelia pertusa at 240-290 m depth in the Haltenbanken- Fmyabanken area was investigated by video-recording. Sixteen transects from soft bottom with scattered patches of stones below bioherms to top of bioherms were analysed. Fauna patterns were related to the near-bottom currents. The orientation of the gorgonianParamuricea placomus was used as an indicator of the direction of the main currents at the bioherms. The bioherms were 2 to 31 m high, and had a basal area ranging from 1 500 to 50 600 m2. 36 taxa were identified, of which five taxa only occurred on the bioherms, and five only on the soft bottom with scattered stones. The diversity, H', was highest in the zone of dead Lophelia, and lowest on the silty clay. None of the 26 taxa observed on stones were spesific for this habitat, but occurred also on the bioherms or the soft bottom. The area with Lophelia rubble, near the basis of the bioherms, had the lowest number of taxa (15), but the highest average density of individuals (7.92 ind./1Om2). Different sponges, gorgonians (Paragorgia arborea, Paramuricea placomus, Primnoa resedaeformis), squat lobsters (Munida sarsi), redfish (Sebastes spp.) and saithe (Pollachius virens) dominated in terms of individuals per area. Diversity, density of sponges and density of gorgonians were highest on the down-current side of the bioherms. Saithe were observed with highest densities near the basis of the bioherms, on the up-current side, while redfish had highest densities on the parallel-current side of the bioherm top. These results indicate that near bottom currents and turbulence are factors affecting the fauna on Lophelia bioherms.

Description: Arabian Sea sediments record changes in the upwelling system off Arabia, which is driven by the monsoon circulation system over the NW Indian Ocean. In accordance with climate models, and differing from other large upwelling areas of the tropical ocean, a 500,000-yr record of productivity at ODP Site 723 shows consistently stronger upwelling during interglaciations than during glaciations. Sea-surface temperatures (SSTs) reconstructed from the alkenone unsaturation index (U K′ 37) are high (up to 27°C) during interglaciations and low (22-24°C) during glaciations, indicating a glacial-interglacial temperature change of 〉3°C in spite of the dampening effect of enhanced or weakened upwelling. The increased productivity is attributed to stronger monsoon winds during interglacial times relative to glacial times, whereas the difference in SSTs must be unrelated to upwelling and to the summer monsoon intensity. The winter (NE) monsoon was more effective in cooling the Arabian Sea during glaciations then it is now.

Description: The current status of Antarctic Odontocetes – sperm whales Physeter catodon , killer whales Orcinus orca , long-finned pilot whales Globicephala melaena , hourglass dolphins Lagenorhynchus cruciger and poorly known species of beaked whales (family Ziphiidae)–were studied in Anatarctic waters using data gathered in sighting surveys conducted from 1976/77 to 1987/88. Temporal variation in density demonstrated the different migration patterns by species, especially between sperm whale and killer whale. Spatial distributions during mid-summer demonstrated different peaks of occurrence for each species by latitude that suggest possible segregation between the species. Killer whales occur mainly in the very southernmost areas, sperm whales in the southern half of the study area, beaked whales (mostly southern bottlenose whales Hyperoodon planifrons ) ranged over a wide area, and long-finned pilot whales and hourglass dolphins were mainly in the northern regions of Antarctic waters. Several longitudinal peaks of occurrence and apparent distribution gaps were identified for sperm, beaked and killer whales. Abundance estimates for south of the Antarctic Convergence in January are based on line transect theory and were 28 100 animals (coefficient of variation CV 0.18) sperm whales, 599 300 (0.15) beaked whales (mostly southern bottlenose whales), 80 400 (0.15) killer whales, 200 000 (0.35) long-finned pilot whales, and 144 300 (0.17) hourglass dolphins. Based on this, biomass of these species were estimated as 0.77 (sperm whales), 2.70 (beaked whales), 0.32 (killer whales), 0.16 (long-finned pilot whales) and 0.01 (hourglass dolphins) million tonnes. Consumption of food (mostly squid) by the Odontocetes is estimated as 14.4 million tonnes with 67% of the total consumed by beaked whales. Indirect consumption of Antarctic krill through the predation of squid by beaked whales is estimated to be c . 24 million tonnes. This value is similar to the estimate of krill consumption by penguins in the Antarctic (33 million tonnes). Odontocetes, especially southern bottlenose whales, are suggested to have a much greater role in the Antarctic ecosystem than has previously been considered.

Description: Subantarctic Marion Island is one of the few localities where the congeneric albatrosses Phoebetria fusca and P. palpebrata breed sympatrically. Chicks of both species at Marion Island were induced to regurgitate their stomach contents after being fed. Liquid formed over half the diet by mass. Cephalopods occurred most frequently in both species' diets. In terms of mass, cephalopods formed the larger part of the diet of sooty albatrosses, whereas fish was more important to light-mantled sooty albatrosses. Crustaceans and birds were also recorded for both species. Squid of the families Onychoteuthidae, Histioteuthidae, Chiroteuthidae and Cranchiidae occurred most abundantly in both species. Most squid taken by both albatrosses were of species known to float after death, suggesting that scavenging plays an important role in the species' foraging behaviour. Light-mantled sooty albatrosses consumed more squid restricted to the south of the Antarctic Polar Front than did sooty albatrosses, supporting a trend to latitudinal segregation of the two species while foraging.

Description: There have traditionally been strong ties between physiology and ecology and between ecology and systematics. Although the connection between physiology and systematics has not been adequately realized, there are important reasons to strengthen it. Much of physiology has been based on the comparative method, which implies a knowledge of evolutionary relationships. Systematics, on the other hand, relies on the distribution of characteristics among groups of organisms, and should include characteristics of their lifestyles, including performance. Lifestyle characteristics, which are studied by physiologists, ecologists, or behavioral scientists, may be comparatively recent adaptations or may be constrained by evolution similarly to the morphological characters traditionally studied by systematists. Working together, these disciplines can provide better explanations of adaptations and evolutionary constraints about which not much is known for the great majority of cephalopod taxa.

Description: The morphological and physiological adaptations that the cephalopod sensory organs and nervous system underwent during the course of evolution are briefly summarized. Special emphasis is paid (i) to the vertebrate‐like lens eyes with their complex extraocular eye muscle system, (ii) to the vestibular analogue statocysts with hair cell receptor systems for linear and angular accelerations and an elaborate afferent and efferent nerve supply, (iii) to the epidermal head and arm lines which are analogous to, and as sensitive as, the lateral lines of fishes and aquatic amphibians, (iv) to the giant fibre system for escape jetting, and (v) to the highly centralized brain which is capable of different forms of learning and memory.

Description: Statolith microstructure was studied in eight specimens of the boreal sepiolid Rossia pacifica (mantle length ranging from 45to 90mm) caught on the continental slope of Northwest Bering Sea. Growth increments were presented in all ground statoliths and were narrow and uniform width (average 3.2 - 3.3µm). They were grouped into inner opaque and outer translucent growth zones. The total number of growth increments within the statoliths of mature males (75-78) was lower than of mature females (95-117 increments). Assuming growth increments to be laid down daily, the life span from hatching to death of R. pacifica in the Bering Sea may be 4-5 months.

Description: The distribution and abundance of six species of Sepia and one of Rossia were studied during six west coast and three south coast bottom trawl surveys off South Africa. The two most common species on both coasts were Sepia australis and S. hieronis. Both were most abundant on the northern West Coast (Orange River and Port Nolloth areas) and were sparsely ditributed over the rest of the region. The depths of greatest abundance were 60-190m (S. australis) and 110-250m (S. hieronis). The highest biomass indices were recorded on the species also peaked in May 1988 on the South Coast (803 tons). The environmental factors most influencial in the distribution of the two species were bottom oxygen concentrations between 1,5 and 3,5ml-l-1. The two species were most abundant at relatively low temperatures: on the West Coast catches peaked when the S. simoniana and S. typica) are usually found in shallow water (〈100m), mainly on the South Coast. Rossia enigmatica, a sepiolid, is most abundant in 400-500m of water, generally on the West Coast.

Description: A new type of epibenthic sledge is presented, which possesses an additional supranet above the epinet. Both nets are closed by an opening/closing device in the water column. The new construction allows a selective catch ofhigher suprafauna, which swims 1–1.33m above the seafloor, and a good discrimination between real suprafauna and epifauna. In total, 79581 Peracarida were sampled at 8 stations at about 75°N and 12°W, off Greenland. Of these, Isopoda were usually the most abundant group in the epinet, Amphipoda in the supranet. At the stations where suprafauna was abundant, the numbers of Mysidacea were usually higher in the epinet than in the supranet, probably due to differences in food supply, i.e. the enrichment of food in the benthic boundary layer.

Description: Observations of the dinoflagellate Dinophysis norvegica in the Baltic Sea during the summers of 1991–1993 indicate that maximal abundances (c 40–150 × 103 cells l-1) were found at the thermocline, typically at 12°C. Maximum densities were usually between 12 and 15 m where 2·9% and 1·5% of surface photon irradiances, respectively, were measured. No diel vertical migration was observed, and cell densities in the mixed layer were always low. Photosynthesis versus irradiance measurements with an oxygen electrode indicated that these populations had a P max of 2·47 [coefficient of variation (CV) 7·3%] and 3·4 (CV 4·7%) mg O2 mg Chl a -1 h-1, and compensation values of photon irradiance were 16·5 and 83 μmol m-2 s-1 in 1992 and 1993, respectively. Both oxygen electrode and 14C light/dark bottle measurements indicated that D. norvegica had very little net photosynthesis at the depths where it was most abundant; it would have had about 2·5-fold greater capacity at photon irradiances present closer to the surface. Calculated carbon doubling times via photosynthesis averaged 4–11 months. There was no observable diel rhythym of DNA synthesis, suggesting that either D. norvegica was not dividing synchronously (asynchronous division is common in heterotrophs) or not dividing at all. Electron microscopy did not reveal the presence of food vacuoles, but feeding and digestion could have been extracellular. The data suggest that this species is a mixotroph which received its primary nutrition via heterotrophic means during our observation periods in the summers of 1991–1993.

Description: Larvae of Siboglinum poseidoni were reared in the laboratory. About 6 weeks after recovery from the central Skagerrak the larvae develop a small tentacular bud. On the opposite side a stomodaeum is formed. Electron microscopy of suitable sections shortly in front of the tentacular bud reveals a ciliated opening and tract. In the trunk this tract is reduced to a small tube by bulging endoderm cells containing large amounts of yolk. The lumen is obscured by densely packed cilia. In more advanced stages extracellular symbiotic bacteria occur within this transient digestive tract. They appear to be taken in via the transient mouth. As development progresses the mouth and ciliated foregut close. In the trunk of adult specimens the space between the dorsal and the ventral vessel is occupied by bacteriocytes forming the trophosome. The lumen ofthe digestive tract is reduced to small ciliated spaces. The tentacle develops opposite to the transient mouth and hence dorsally, while the main nerve trunk is ventral. More advanced larval stages closely resemble an elongated annelidian metatrochophora. A relationship between Vestimentifera (Obturata) and Pogonophora (Perviata) is confirmed and the placement of both groups within the phylum Annelida suggested.