Lipid composition and diet inferences in abyssal macrourids of the eastern North Pacific

The lipid compositions of 2 abyssal macrourids, Coryphaenoides armatus and C. yaqui- nae, from the eastern North Pacific were examined and used to infer diet. The resulting fatty acid (FA) profiles are the first published for C. yaquinae and among the first for abyssal fishes. They indicated a greater proportion of polyunsaturated FAs and lower monounsaturated FAs than shallower living con- geners, suggestive of homeoviscous adaptations to great pressure. Cholesterol was the predominant sterol, which is frequently the case for exclusively car- nivorous species. Comparisons of macrourid FA pro- files were made to those of benthic prey and epipelagic carrion sources, including the Humboldt squid Dosidicus gigas captured in surface waters of the abyssal study site. The FA profiles of macrourid muscle were very similar to those of squid mantle muscle. The FA profiles of macrourid liver and swim- bladder were similar to benthic crustaceans, whole squid, squid digestive gland and the epipelagic fish Trachurus symmetricus. For both tissues, the FA pro- files of echinoderms were the most different. These comparisons suggest a strong link to carrion and ben- thic crustaceans and a weak one to echinoderms, the dominant megafauna at the study site and in most of the abyssal ocean. These results support previous stomach content and stable isotope analyses, reinforc- ing the hypothesis that there are closer food web ties between abyssal fishes and epipelagic nekton than to many abyssal benthic groups.

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abstract: The proximate chemistry of the white muscle and liver of 18 species of demersal fish from the eastern North Pacific was studied to determine trends with depth, locomotory mode and buoyancy mechanism, foraging strategy and to elucidate energetic strategies. Data for 24 species from shallow water were taken from the literature and included for analysis of muscle water content. Benthopelagic species, primarily gadiforms, have significantly larger lipid-rich livers than benthic species. The benthopelagic species may use this lipid to add buoyancy, but it is also used as energy storage. Buoyancy mechanism was directly related to proximate composition. Fishes using gasbladders had normal muscle composition. The two species of benthopelagic fishes without gasbladders have either very high muscle lipid content ( Anoplopoma fimbria ) or gelatinous muscle ( Alepocephalus tenobrosus ) to aid in achieving neutral buoyancy. The macrourid, Albatrossia pectoralis , has a very small gasbladder and also has gelatinous muscle. Both of these benthopelagic fishes with gelatinous muscle feed on pelagic organisms. Gelatinous muscle was also found in two flatfishes that inhabit the oxygen minimum zone. For these fishes, high water content may serve to lower metabolic costs while maintaining large body size. Scavengers such as Coryphaenoides armatus and Coryphaenoides acrolepis have lipid rich livers and others such as A. fimbria and Pachycara sp. have high and variable muscle lipid content. Thus foraging mode also acts to influence proximate composition. Several depth-related trends in proximate composition were found. White muscle water content increased significantly with depth, and all four gelatinous species occurred at bathyal depths. This adds evidence in support of the hypothesis that decreasing light levels shorten reactive distances and relax the selective pressure for high locomotory capacity. In addition significant declines in liver protein content were observed, suggesting that the rates of metabolism in this organ also decline with depth. There was little evidence for food availability affecting proximate composition. There were no significant changes in either muscle or liver lipid or caloric density with depth. Total lipid stores actually increased significantly, but they were driven primarily by the abyssal scavenger C. armatus suggesting that foraging strategy rather than depth may be the most important factor determining total lipid stores.

title: A rapid method of total lipid extraction and purification.
abstract: Lipid decomposition studies in frozen fish have led to the development of a simple and rapid method for the extraction and purification of lipids from biological materials. The entire procedure can be carried out in approximately 10 minutes; it is efficient, reproducible, and free from deleterious manipulations. The wet tissue is homogenized with a mixture of chloroform and methanol in such proportions that a miscible system is formed with the water in the tissue. Dilution with chloroform and water separates the homogenate into two layers, the chloroform layer containing all the lipids and the methanolic layer containing all the non-lipids. A purified lipid extract is obtained merely by isolating the chloroform layer. The method has been applied to fish muscle and may easily be adapted to use with other tissues.

title: Thin-layer chromatography — flame ionization detection and the quantitation of marine neutral lipids and phospholipids
abstract: A method is described whereby a complete analysis of individual neutral lipid and phospholipid classes in marine animal total lipid can be achieved using an latroscan TLC-FID analyser. The method involves separate analyses of two samples of total lipid in solvents designed to separate neutral and polar lipid classes, together with calibration by a composite standard similar in composition to the sample under analysis. The method does not depend on the degree of unsaturation of the fatty acids present, is rapid and compares well in accuracy with conventional combined gravimetric, colouritnetric, and densitometric procedures.

title: Vertical stratification of fatty acids in the blubber of southern elephant seals (Mirounga leonina): implications for diet analysis.
abstract: Fatty acid signature analysis (FASA) is a powerful ecological tool that uses essential fatty acids (FA) from the tissues of animals to indicate aspects of diet. However, the presence of vertical stratification in FA distribution throughout blubber complicates the application of FASA to marine mammals. Blubber biopsy samples were collected from adult female southern elephant seals (Mirounga leonina) from Macquarie Island (n=11), and blubber cores were divided into inner and outer sections to determine the degree to which the blubber layer was stratified in FA composition, we found 19 FA from both blubber layers in greater than trace amounts (>0.5%). The inner and outer blubber layers could be separated using principal components analysis based on the relative proportion of FA in each layer. Dietary polyunsaturated fatty acids (PUFA) were also observed in significantly higher proportions in the inner blubber layer. Due to the degree of FA stratification in southern elephant seals, we concur with other marine mammal studies that sampling only the outer blubber layer will result in a loss of recently accumulated information regarding diet structure (as indicated by 'surplus' PUFA from the diet). This finding suggests that differential mobilization/deposition of certain FA may result in a modified signature from prey to predator. Thus, sampling animals to recover the inner blubber layer is important for studies attempting to describe aspects of marine mammal diet. This can be achieved in animals such as pinnipeds where the whole blubber layer can be readily sampled.

title: Temporal variations in the diet of the squid Moroteuthis ingens at Macquarie Island: stomach contents and fatty acid analyses
abstract: The onychoteuthid squid Moroteuthis ingens was collected as by-catch from a commercial trawl fishery in the vicinity of Macquarie Island, within the Pacific sector of the Southern Ocean. Squid were collected during 3 austral summers and 1 austral winter between January 1995 and June 2000. Stomach contents and fatty acid profiles of both mantle and digestive gland tissues were used to determine if the diet of M. ingens was subject to temporal variations in this region. Discriminant analysis (DA) of stomach contents data and digestive gland fatty acid data indicated that the diet varied significantly on an interannual basis, most likely due to an increase in the consumption of the myctophid Gymnoscopelus nicholsi during the summer of 1999 relative to the summers of 1995 and 2000. Comparisons with oceanographic data reveal that the summer of 1999 was a period of warmer sea-surface temperatures and reduced primary production compared to the summers of 1995 and 2000. Fluctuations in oceanographic conditions may have underpinned variations in the availability of prey during the study period. DA of digestive gland fatty acid data also indicated that the diet varied significantly between the summer and winter of 2000. Stomach contents data indicate that the myctophid Electrona carlsbergi replaced Krefftichthys anderssoni as a key prey species for M. ingens during the winter period, as has been observed for other marine predators in the sub-Antarctic Southern Ocean. A comparison of methods reveals that, while fatty acid analyses greatly aid the interpretation of stomach contents data, both techniques are subject to limitations and are best used in combination.

title: Distribution and abundance of epibenthic megafauna at a long time-series station in the abyssal northeast Pacific
abstract: Abundance and dispersion of epibenthic megafauna were examined at an abyssal site (4100 m depth) in the northeast Pacific (Sta. M, 34°50'N, 123°00'W). Photogrammetric techniques and line-transect theory were used to analyze photographs from nine towed camera-sled transects made on six cruises between June 1990 and October 1991. The megafaunal assemblage was dominated numerically by the tube-dwelling polychaete Paradiopatra sp. and echinoderms, representing 26–48% and 24–41 % of the total, respectively. Megafaunal densities were remarkably similar among the nine transects, ranging from 26,594 to 39,913 individuals 10 −4 m −2 . While the overall assemblages in the nine transects were ⩽80% similar, based on pairwise comparisons, the relative contribution of each faunal category varied significantly between transects; densities of individual species from pairs of synoptic transects were significantly different ( p

title: Abundance and size distribution dynamics of abyssal epibenthic megafauna in the northeast Pacific.
abstract: The importance of interannual variation in deep-sea abundances is now becoming recognized. There is, however, relatively little known about what processes dominate the observed fluctuations. The abundance and size distribution of the megabenthos have been examined here using a towed camera system at a deep-sea station in the northeast Pacific (Station M) from 1989 to 2004. This 16-year study included 52 roughly seasonal transects averaging 1.2 km in length with over 35600 photographic frames analyzed. Mobile epibenthic megafauna at 4100 m depth have exhibited interannual scale changes in abundance from one to three orders of magnitude. Increases in abundance have now been significantly linked to decreases in mean body size, suggesting that accruals in abundance probably result from the recruitment of young individuals. Examinations of size-frequency histograms indicate several possible recruitment events. Shifts in size-frequency distributions were also used to make basic estimations of individual growth rates from 1 to 6 mm/month, depending on the taxon. Regional intensification in reproduction followed by recruitment within the study area could explain the majority of observed accruals in abundance. Although some adult migration is certainly probable in accounting for local variation in abundances, the slow movements of benthic life stages restrict regional migrations for most taxa. Negative competitive interactions and survivorship may explain the precipitous declines of some taxa. This and other studies have shown that abundances from protozoans to large benthic invertebrates and fishes all have undergone significant fluctuations in abundance at Station M over periods of weeks to years.

title: A seasonal analysis of the nutritional condition of deep‐sea macrourid fishes in the north‐east Pacific
abstract: Of three common macrourids Coryphaenoides armatus and Coryphaenoides yaquinae were collected from 1995 to 1998 at an abyssal station, c. 220 km west of Point Conception, California in the north-east Pacific (4100 m depth). Coryphaenoides acrolepis was collected from 1997 to 1998 in the San Diego Trough (1200 m depth). Energy storage in all three species was primarily in the liver, which was up to 56% lipid (wet mass) and up to 96% triglyceride. No seasonal variation in nutritional condition was found for C. armatus or C. yaquinae. There was, however, a significant increase in muscle water content and liver lipid content and a significant decline in muscle lactate dehydrogenase activity for C. armatus between 1996 and 1998. Potential mechanisms for these interannual shifts are proposed. No seasonal variation in parameters was found for C. acrolepis but a small seasonal periodicity in feeding activity may have existed. The seasonal deposition of phytodetritus in the deep sea is of little or no consequence to these fishes.

title: Amount of Squalene and Fatty Acid Composition of Triacylglycerols and Phospholipids in Flesh and Liver Lipids of Some Deep-sea Teleost Fish, Morid Cods and Whiptails
abstract: Examination was made of the amounts of squalene and fatty acid compositions of triacylglycerols (TG) and phospholipids (PL) in the flesh and liver lipids of five species of deep-sea teleost fish: the Pacific flatnose Antimora microlepis and the black mora Halargyreus johnsonii of morid cods and the roughscale rattail Coryphaenoides acrolepis, the pop-eye grenadier C. cinereus and the pectoral rattail C. pectoralis of whiptails. Liver specimens of these deep-sea teleost fish contained copious amounts of lipids (19.5-65.1%) which were composed almost entirely of TG (72.6-95.9%). Flesh samples contained small amounts of lipids (0.3-0.5%) with lower TG (0.9-1.4%) and higher PL (53.8-76.0%) content. In the livers and flesh, unsaponifiable matter from the neutral lipids comprised squalene (42.4-57.7% and 3.7-10.3%) and sterols (22.8-51.0% and 84.0-95.3%), respectively, and the squalene content of liver lipids corresponded to 0.57-1.76%. Component fatty acids in TG from liver lipids were characteristically rich in monoenes (59.5-73.0%) with 22:1n-11 (15.7-24.1%), 18:1n-9 (11.2-16.6%) and 20:1n-11 (8.7-10.9%) acids. Nevertheless, component fatty acids in PL from flesh lipids were rich in polyenes (37.6-44.2%) with 22:6n-3 (23.1-28.4%) and 20:5n-3 (8.7-8.8%) acids.

title: Energy budgets and feeding rates of Coryphaenoidesacrolepis and C. armatus
abstract: This study develops energy budgets and estimates feeding rates for two macrourid fishes, Coryphaenoidesacrolepis, dominant in the bathyal eastern North Pacific, and the abyssal cosmopolitan species, Coryphaenoidesarmatus. Daily energy expenditure by C. acrolepis was nearly twice that of C. armatus. C. acrolepis allocated nearly equal amounts of energy to metabolism and growth. Once sexual maturity was reached reproduction became the dominant energetic cost. Either these costs are necessary to retain adequate numbers of eggs and larvae on the continental slopes, or this fish does not reproduce on an annual basis and the calculated costs are an overestimate. C. armatus allocated relatively more energy to metabolism than growth. It may be semelparous, and this strategy would be of great energetic savings in its food-poor but stable environment. Individual daily ration for C. acrolepis decreased from 0.31% to 0.07% of body weight (BW) and for C. armatus from 0.12% to 0.02% BW with increasing fish length. These rates are substantially lower than those for fishes living in cold waters on the continental shelves. The population feeding rates for C. acrolepis ranged from 0.8 to 15 kg km–2 day–1 and for C. armatus from 5 to 2,800 g km–2 day–1. The scavenging behaviour of C. acrolepis was used to investigate the role of carrion as a food supply to the deep-sea benthos. It was estimated that the carrion eaten by C. acrolepis is equivalent to 0.04 mg C m–2 day–1 or only 0.2–0.4% of the average small particulate flux. Carrion consumption is important for scavengers like C. acrolepis, but it is not an important component of the carbon flux into the deep-sea benthic environment.

title: Lipid, sterols and fatty acid composition of abyssal holothurians and ophiuroids from the North-East Pacific Ocean: food web implications.
abstract: The lipid, fatty acid (FA), and sterol composition of two ophiuroids and four holothurians from the abyssal eastern North Pacific were analysed to assess their feeding habits and to ascertain their composition for use in a larger study to examine food web dynamics and trophic ecology. Holothurians were rich in phytosterols and algal derived FA such as docosahexaenoic acid and eicosapentaenoic suggesting tight trophic coupling to phytodetritus. Large proportions of stanols were found, probably a result of enteric bacteria but they may come from sterol metabolism in the holothurians themselves. Oneirophanta mutabilis was distinct with much higher levels of stanols and bacterially derived FA suggesting specific selection of bacteria rich detrital particles or the activity of enteric and integumental bacteria. The ophiuroids sterol and FA compositions differed greatly from the holothurians and reflected consumption of animal material in addition to phytodetritus. Large proportions of energy storage lipids suggested a sporadic food supply. Several unusual fatty acids were found in these abyssal echinoderms. Tetracosahexaenoic acid, 24:6omega3, in ophiuroids and 23:1 in holothurians may be good biomarkers for food web studies. We report the first occurrence of alphaOH 24:1 in holothurians with none detected in ophiuroids. Its function is presently unknown.

title: Lipid, sterols and fatty acids of abyssal polychaetes, crustaceans, and a cnidarian from the northeast Pacific Ocean: food web implications
abstract: The lipid, sterol, and fatty acid compositions of the abyssal anemone Bathyphellia aus- tralis, the 3 polychaetes Laetmonice sp., Paradiopatra sp. and Travisia sp., 3 crustaceans (Munidopsis sp. and 2 lysianassid amphipods), and an unidentified caridean shrimp were determined from a site in the northeast Pacific Ocean. Lipid composition was dominated by phospholipids in most species. However, energy storage lipids (triacylglycerols and wax esters) contributed >50% to the total lipids in the lysianassid amphipods and the unidentified caridean shrimp, and lipids made up 19 and 45% of amphipod and 14% of shrimp dry mass, suggesting sporadic feeding and the need for energy stor- age. The dominant sterol was cholesterol. The presence of phytosterols in the anemone, the poly- chaetes and Munidopsis sp. suggested consumption of phytodetritus, but none of the specimens had levels suggesting that phytodetritus was their main food resource. The levels of essential photo- synthetically derived polyunsaturated fatty acids (PUFA) corroborated the sterol results. The ratio of 18:1ω9/18:1ω7 further suggested carnivory as the predominant mode of foraging in the abyssal ani- mals, although to varying degrees. Some distinct differences in the fatty acid (FA) composition of these animals allowed for their separation, confirming that FA profiles will be useful in future bio- marker approaches to deep-sea food web studies.

title: Composition of lipid foams from swim bladders of two deep ocean fish species.
abstract: Lipid-containing deposits within the swim bladders of Coryphaenoides acrolepis and Antimora rostrata were investigated. Lipid analysis of this material, which was quite uniform from the two species, yielded the following data: neutral lipids, 36.0-41.7%; phospholipids, 53.6-56.7%; and glycolipids, 4.3-8.9%. Cholesterol (mainly in the free form) constituted 60.4%-77.8% of the neutral lipids. Sphingomyelin and phosphatidylcholine were the principal phospholipids, with sphingomyelin highest in the material from C. acrolepis and phosphatidylcholine predominant in that from A. rostrata. The overall pattern of lipids shows a resemblance to that of plasma membrane, particularly in the relatively high levels of free cholesterol, sphingomyelin, and phosphatidylserine. The lipid-to-protein ratio of the material is approximately 1.5-2 to 1. The lipids of the fine inner lining (tunica interna) of the swim bladder from a shallow water fish, the kelp bass (Paralabrax clathratus), had essentially the same composition as the much more abundant swim bladder material from the deep ocean fishes.

title: The membranous lining of the swimbladder in deep sea fishes. I. Morphology and chemical composition.
abstract: Cholesterol-rich swimbladder foams from Coryphaenoides (cf. fernandezianus ) and Parabassogigas sp. collected from 3400 to 4575 m depth appear as sheets of layered membranes having typical bilayers. 2. 2. Sphingomyelin was the major phospholipid in Parabassogigas swimbladder foam (48.7 and 63.0 per cent) whereas phosphatidylcholine (39.1–44.8 per cent) was the major phospholipid in Coryphaenoides . 3. 3. Although percentages of both cholesterol and phospholipids were lower in Parabassogigas than in Coryphaenoides , the ratio of cholesterol to phospholipid was close to one to one in both fish. 4. 4. Total fatty acid unsaturation in the swimbladder foams was high (71.4–80.5 per cent) despite the presence of hyperbaric oxygen.

title: Lipid and fatty acid composition of the mantle and digestive gland of four Southern Ocean squid species: implications for food-web studies
abstract: Lipid content, lipid class and fatty acid composition of four Southern Ocean cephalopod species – the myopsid Sepioteuthis australis and three oegopsids, Gonatus antarcticus, Moroteuthis robsoni and Todarodes spp. – were analysed. The lipid content of the digestive gland was consistently greater than that of the mantle, and was an order of magnitude greater in oegopsid species. The lipid class and fatty acid composition of the mantle and digestive gland also differed markedly in each species. Digestive gland lipid is likely to be of dietary origin, and large amounts of lipid in the digestive gland of oegopsids may accumulate over time. Thus the digestive gland is a rich source of fatty acid dietary tracers and may provide a history of dietary intake. However, the absolute amount of dietary lipid in the digestive gland of oegopsid species exceeds the absolute lipid content of mantle tissue. Therefore the overall lipid “signature” of an oegopsid may more closely resemble its prey species rather than its mantle tissue. When lipid techniques are used in dietary analysis of teuthophagous predators, squid may not be represented by a unique signature in analyses and their importance in the diets of predators may be underestimated.

title: Lipids in selected abyssal benthopelagic animals: links to the epipelagic zone?
abstract: A detailed study of the lipids of selected zooplankton species and scavenging amphipods in the near-bottom water layer (15–100 m above bottom, mab) was carried out at the BENGAL site in late summer 1998. Copepoda were the main contributors to the zooplankton, comprising 75% of the total abundance, followed by Ostracoda and Chaetognatha. Calanoid copepods of the family Metridinidae were predominant and accounted for more than 50% of all copepods. Two types of storage lipids were distinguished: triacylglycerols and wax esters. Ostracoda and the polychaete Vanadis sp. stored exclusively triacylglycerols whilst the bulk of the Copepoda accumulated wax esters, with the exception of the family Aetideidae. In the amphipods both lipid classes were found: Eurythenes gryllus stored wax esters and Paralicella spp. and Orchomene sp. triacylglycerols. The fatty acid composition was characterized by a high level of monounsaturated 18:1 (n—9), which is described as characteristic for animals living in the deeper layers of the water column, and to a lesser degree by 16:1 (n—7) and 20:5 (n—3), which are typical components of diatom lipids, and 22:6 (n—3), typical of dinoflagellates. The ratio of 18:1 (n—9):18:1 (n—7) fatty acids was between 5 and 10 in the copepods and indicates a carnivorous/omnivorous feeding behaviour in this group, whereas the higher ratios of 8–18 in the amphipods confirm their necrophagy. The fatty alcohols of the animals storing wax esters were dominated by the monounsaturated isomers 18:1 (n—9) and 18:1 (n—7). The predominance of wax esters as storage lipids in the deep-sea copepods indicates a strong seasonality in the availability of food. This is supported by the high levels of 16:1 (n—7), 20:5 (n—3) and 22:6 (n—3) fatty acids, which point to there being a direct link between the surface primary production and deep-sea copepods, probably via the rapid deposition of phytodetritus.

title: Lipids of Antarctic Ocean amphipods: food chain interactions and the occurrence of novel biomarkers
abstract: Antarctic hyperiid ( Themisto gaudichaudi , Hyperia macrocephalus , and Primno macropa ) and gammarid amphipods ( Eusirus perdentatus and Orchomene rossi ) were collected near Elephant Island, located in the South Shetland Islands, during January and February 1997 and 1998. Polar lipid (PL) was the major lipid class in all amphipods (58–88% of total lipid), except for T. gaudichaudi in which triacylglycerol (TAG) was dominant (62%). Cholesterol was the major sterol in the gammarid amphipods (89–91% of total sterols), and the hyperiid P. macropa (70%). The hyperiids T. gaudichaudi and H. macrocephalus had a more diverse sterol composition including trans -dehydrocholesterol, desmosterol, 24-nordehydrocholesterol, 24-methylcholest-5,22 E -dien-3β-ol, 24-methylenecholesterol, and stanols (mostly cholestanol). Eicosapentaenoic acid [EPA, 20:5( n −3)] and docosahexaenoic acid [DHA, 22:6( n −3)] were the major polyunsaturated fatty acids (PUFA) in all amphipods. The PUFA octadecapentaenoic acid [18:5( n −3)] was not detected in 1997 samples, but comprised 0.3–1.2% in all 1998 samples. The PUFA 18:4( n −3) comprised 0.2–4.2% in all samples from both years. Very long chain PUFA (VLC-PUFA) (C 24 and C 26 ) were not detected in the one 1997 sample but comprised 0.6–2.8% of total fatty acids in almost all 1998 amphipods. Monounsaturated fatty acids included 18:1( n −9)c, 18:1( n −7)c, and 16:1( n −7)c. Principal saturated fatty acids in all amphipods were 16:0, 14:0, and 18:0. Examination of biomarker lipids has helped clarify trophic interactions for these Antarctic amphipods, and revealed annual differences in their food sources.

title: Feeding ecology of eastern North Pacific killer whales Orcinus orca from fatty acid, stable isotope, and organochlorine analyses of blubber biopsies
abstract: Blubber biopsy samples from eastern North Pacific killer whales Orcinus orca were ana- lyzed for fatty acids, carbon and nitrogen stable isotopes and organochlorine contaminants. Fatty acid profiles were sufficiently distinct among the 3 reported ecotypes ('resident,' 'transient' or 'offshore') to enable individual animals to be correctly classified by ecotype and also by mitochondrial DNA (mtDNA) haplotype. Profiles of PCBs also enabled unambiguous classification of all 3 killer whale ecotypes, but stable isotope values lacked sufficient resolution. Fatty acid, stable isotope and PCB profiles of the resident and transient ecotypes were consistent with those expected for these whales based on their reported dietary preferences (fish for resident whales, marine mammals for transients). In addition, these ecotype profiles exhibited broad similarity across geographical regions, suggesting that the dietary specialization reported for resident and transient whales in the well-studied eastern North Pacific populations also extends to the less-studied killer whales in the western Gulf of Alaska and Aleutian Islands. Killer whales of the same ecotype were also grouped by region of sample col- lection. The mean stable isotope ratios of various regional groups differed considerably, suggesting that the prey preferences of these North Pacific killer whales may be both region and ecotype spe- cific. Furthermore, 3 specific ecotypes of killer whales were found to have measured stable isotope values that were consistent with dietary preferences reported in the literature. Finally, although the offshore population had blubber fatty acid profiles implicating fish as its primary prey, contaminant and stable isotope results were equally congruent with predation on marine mammals.

title: Evidence of abalone (Haliotis rubra) diet from combined fatty acid and stable isotope analyses
abstract: Abalone are common herbivores throughout temperate and tropical waters, and yet the contribution of red and brown macroalgae to the diet of wild abalone remains unclear. In the northern hemisphere, adult abalone are considered to consume predominantly brown algae, but in the southern hemisphere abalone are thought to prefer red algae. Conventional methods such as gut content analysis and feeding trials provide some insight into diet choice, but the associated biases of these techniques create uncertainty surrounding the aforementioned variability in abalone diet. We use combined stable isotope and fatty acid analysis to determine the relative contribution of red algae, brown algae and detritus/microalgae to the diet of wild abalone in Tasmanian waters. Stable isotopes of carbon suggest that brown algae and/detritus are a more important source of carbon than red algae. Fatty acid analysis confirmed the larger contribution of brown algae to the diet of abalone, and also identified the bacterial and diatom component of detritus to be an important contributor to abalone diet. These results show combined use of chemical tracers to be a promising technique for resolving abalone diet, and challenge current perceptions regarding spatial variability in abalone diet choice.

title: Membrane biosynthesis in swimbladders of deep sea fishes Coryphaenoides acrolepis and Antimora rostrata.
abstract: 1. 
1. Excised tunica interna from the swimbladder of an abyssal fish (Coryphaenoides acrolepis) incorporated acetate-1-14C and squalene-4-3H into membrane lipids, cholesterol, phosphatidyl ethanolamine, phosphatidylcholine, cardiolipin, and to a lesser extent sphingomyelin. 
 
2. 
2. Ultrastructural study of the tunica interna of the swimbladder of another abyssal fish (Antimora rostrata) revealed large cytoplasmic vacuoles lined and filled with “bilayer” membrane. 
 
3. 
3. The membrane-lined vacuoles in the tunica interna cells may be an assembly point for the biosynthesis of the gram quantities of pure “bilayer” membrane found on the interior of the swimbladder.

title: The sequential mobilisation and restoration of energy reserves in tissues of Atlantic cod during starvation and refeeding
abstract: Summary1.In the early stages of starvation in cod (Gadus morhua L.), liver lipids and the glycogens of liver and white muscle were mobilised simultaneously, but liver lipids were exhausted first. At about that point, proteins began to be mobilised in red and white muscle, and red muscle glycogen also began to decrease. After about 20 weeks at 9°C, the latter was virtually exhausted, leaving muscle proteins as the only source of energy.2.Starvation caused a significant fall in the glucose, lipids and nonesterified fatty acids (NEFA) of the blood. Ketone bodies seemed to be unimportant as sources of energy in starving cod, in contrast to elasmobranchs and mammals. Little change was observed in blood proteins or ninhydrin-positive substances.3.When the cod were refed after starvation, overcompensation occurred in several metabolites, levels rising temporarily to values much higher than in continuously-fed controls. These comprised the glycogen contents of liver, red muscle and white muscle, NEFA in plasma and the RNA/DNA ratios of liver, red muscle and white muscle. Other constituents simply increased until their levels approached those of the controls. Liver lipids during refeeding did not rise above the low levels of starvation until the water content of the white muscle had dropped below about 82%.4.When fish were refed after a shorter starvation period with squid muscle or herring muscle, only those refed with squid showed a significant rise in the muscle glycogen concentrations. Those fed on herring increased their liver lipids the more.5.The differing periods of refeeding which gave rise to maximum values of red muscle glycogen and white muscle glycogen coincided respectively with maximum RNA/DNA ratios, suggesting that the purpose of unusually high glycogen values was to supply the energy for muscle regeneration.

title: Gonatid Squids in the Subarctic North Pacific Ecology, Biogeography, Niche Diversity and Role in the Ecosystem
abstract: This review is based on the author's own data and all available published data (mostly Russian and Japanese) on the ecology, biogeography and role in the ecosystem of gonatid squids in the northern North Pacific. For the best studied species, Berryteuthis magister , information is given on size, horizontal and vertical distribution, diel and ontogenetic vertical migrations, maturation, mating, spawning, fecundity, population structure, age, growth, life cycle, horizontal migrations, underwater behaviour, food and feeding, and predators. The assessed biomass and its interannual dynamics and the fisheries importance are also covered. For other, less studied, species of the genera Berryteuthis (B. anonychus), Gonatopsis (three species) and Gonatus (seven species) all available ecological and biogeographical data are included. All species are compared according to their size, horizontal and vertical distribution, spawning habitats, diel vertical migrations and gelatinous degeneration associated with maturation. The “ecological individuality” of each species is evaluated. It is shown that each occupies its own ecological niche but these niches overlap to different degrees. The history of niche divergence in North Pacific gonatids during the Neogene-Pleistocene period is briefly reviewed. Common features are described of the horizontal and vertical distribution, relative abundance and biomass of North Pacific gonatids in general. Their roles in the ecosystem, as predators, prey, competitors and hosts of parasites is evaluated. The total biomass of gonatid squids in the whole subarctic North Pacific and the Russian Far Eastern seas is estimated as approximately 15–20 million t. They contribute some 10–15% of the total production of mesopelagic cephalopods in the World Ocean. Their yearly food consumption is assessed at 100–200 million t. The life cycle of gonatids is shorter and their P/B-coefficient much higher than that of subarctic mesopelagic fishes. As a result, though the squid biomass (calculations for the Okhotsk Sea) is less than 10% of the total mesopelagic fish and squid population, they form 58–67% of annual total fish and squid production. Thus gonatid squids have an important place in the ecosystem of the northern North Pacific and the Far Eastern seas of Russia.

title: FOOD AND FEEDING OF JUMBO SQUID DOSIDICUS GIGAS IN THE CENTRAL GULF OF CALIFORNIA DURING 2005 -2007
abstract: Stomachcontentswereanalyzedfor249jumbosquid (Dosidicus gigas ) of 35‐80 cm mantle length. All squid were sampled in the central Gulf of California in 2005‐07, primarily on the commercial fishing grounds ofSantaRosaliaduringdifferenttimesoftheyear.Diet offSantaRosaliawasmainlycomposedofmesopelagic micronektonic organisms, mostly the myctophids Benthosema panamense , Triphoturus mexicanus,andthesquid Pterygioteuthis giardi.Pteropodsandcrustaceansmadeup a smaller portion of the diet. Squid sampled elsewhere revealed that the pelagic red crab, Pleuroncodes planipes, and northern anchovy, Engraulis mordax , could also be major dietary items. Cannibalism incidence increased withsquidmantlelength.Weproposethatthemainprey ofjumbosquidinthecentralGulfofCaliforniaderives from the mesopelagic community associated with the upper boundary of the oxygen minimum layer, a welldeveloped midwater feature in this region. In addition, opportunistic foraging on a variety of organisms sup plements their dietary intake. These data are discussed in conjunction with recent electronic tagging data that revealed vertical and horizontal movements of jumbo squid. This work demonstrates a need to study the dynamics of the oxygen minimum layer and the com positionofthedeep-scatteringlayerovertheupperslope

title: Towing large nets by single warp at abyssal depths: methods and biological results
abstract: Adequately sampling deep-water nekton is difficult because of the great time required for tows, avoidance of nets by larger animals, and the sparse fauna. These problems have been compounded by the small nets usually used for such sampling. This paper describes the equipment, techniques, difficulties, and results of towing large midwater and bottom trawls single warp at depths below 2000 m from chartered commercial fishing vessels. Use of large nets (107 m 2 mouth pelagic rope trawl and 29.6 m headrope otter trawl) is a method which minimizes the effects on sample sizes and compositions of the above factors. Tows with large opening-closing midwater trawls and otter trawls between 2000 and 4300 m off northern California collected specimens of rare species and unusually large individuals of other species. Included among these are five fish species not previously reported from off California: Bathysaurus mollis (Synodontidae), Barathronus pacificus (Aphyonidae), Echinomacrurus occidentalis (Macrouridae), Dysalotus oligoscolus (Chiasmodontidae), and Bellocia alvifrons (Alepocephalidae). Fishes decreased with depth by numbers of species, numbers of individuals, and by weight. Decapod crustaceans did not show similar trends. Cephalopods were uncommon at all depths sampled. Coryphaenoides filifer (Macrouridae), a nominally benthic fish species, was unexpectedly abundant in midwater between 2000 and 3100 m. It constituted 54.6% of the fish biomass collected at these depths. Its abundance did not appear to be related to sex, size, or reproduction. Food habits of Coryphaenoides armatus and C. yaquinae (Macrouridae), the most abundant benthic fish species, differed. The former ate primarily nekton; the latter, benthic infauna. Occurrence in stomachs of beaks from shallow living squid and of epipelagic barnacles suggests that carrion may form a significant part of the diets of these species. One ripe and five ripening female C. armatus , all longer than 740 mm TL, were collected. Estimated fecundity of the ripest was 6.2 × 10 6 eggs. Based on these and previous captures, C. armatus females mature at a large size, have a high fecundity relative to other macrourids, may not spawn simultaneously, and may be semelparous.

title: Diets and standing stocks of benthopelagic fishes at two bathymetrically different midoceanic localities in the northeast Atlantic
abstract: Deep-sea benthopelagic fishes were sampled by trawl and free-fall longline at two latitudinally and bathymetrically separated stations in the northeastern Atlantic. The catch structure and the contents of the fish stomachs were analysed. The northern, 3000 m deep station in the Iceland Basin exceeded the deeper (4500 m) site in terms of demersal fish biomass and abundance by factors of 5 and 10, respectively. Synaphobranchidae of the species Histiobranchus bathybius and several species of Macrouridae contributed to the samples, the latter dominating with Coryphaenoides (Nematonurus) armatus most abundant in the north and with Coryphaenoides (Chalinura) leptolepis in the south. Diet composition was studied for numerical abundance and wet weight of prey organisms. In the Iceland Basin, where two size classes of C. (N.) armatus could be analysed separately, an ontogenetic change in diet was noted. Individuals shorter than 30 cm in length fed mainly on benthic and epibenthic Crustacea whereas the larger specimens showed a high proportion of fish and Cephalopoda in their stomachs. At the southern site (BIOTRANS station in the West European Basin) Amphipoda, fish and Cephalopoda were the main food source. Coryphaenoides (Chalinura) leptolepis fed on Malacostraca and fish at the northern site, but on Polychaeta and Cephalopoda at the southern station. Stomachs of H. bathybius contained food only in the Iceland Basin. Their diet consisted mainly of Malacostraca and Cephalopoda. Despite their state of digestion, most Cephalopoda could be identified by means of their beaks, which also allowed a recalculation of their original size. The taxonomic composition and the size structure led to the assumption that most Cephalopoda were epi- or mesopelagic and had been preyed upon near the bottom as carcasses. The possible trophic position of the predominant benthopelagic fishes in the benthic boundary layer is discussed.

title: Deep-sea food web analysis using cross-reacting antisera
abstract: The high incidence of unrecognizable prey in the stomachs of deep-sea predators prompted the application of serological methods for identification of trophic connections. Antisera to whole-organism extracts of estuarine taxa cross-reacted with antigenic protein extracts of mid-water and deep-sea taxa along phylogenetically correct lines, indicating their potential as tools for gut contents immunoassay. Stomach, intestine, and rectum contents of grenadiers (Coryphaenoides armatus) trapped at 2500 m in the North Atlantic were analyzed visually and with 32 antisera representing taxa from 10 common deep-sea phyla. While visual analysis only revealed the presence of fluids, parasites, crustacean exoskeletons, and gastropod opercula, the immunoassay indicated the presence of antigenic proteins from holothurian, anemone, gastropod, decapod, and foraminiferan prey in the same samples. This qualitative serological identification of prey at non-specific taxonomic levels provides evidence that benthic predation may be important within deep-sea communities. The immunoassay technique, although not a panacea for elucidating food web dynamics in remote environments, may be useful when other methods fail to identify trophic pathways.

title: Toxins from sea cucumbers (holothuroids): chemical structures, properties, taxonomic distribution, biosynthesis and evolution.
abstract: Studies on structures, biological activities, chemical properties, taxonomic distribution, biosynthesis, and evolution of toxins from sea cucumbers (the phylum Echinodermata, the class Holothurioidea) were reviewed with special emphasis on recent results from our laboratory. These toxins are triterpene oligoglycosides having very often one or several sulfate groups in carbohydrate moieties. Their aglycones belong to lanostane derivatives and sometimes contain shortened side chains. Many aglycones are labile in the acid medium. There is a relationship between structures of the glycosides and taxonomic positions of corresponding animals, producers of these toxins. Toxins from sea cucumbers act on delta 5-sterol-containing biological membranes with the formation of glycoside-sterol complexes followed by the disturbance of membrane permeability and inhibition of activities of some membrane enzymes. The presence of the toxins causes the alterations in membrane sterol compositions of toxic sea cucumbers in comparison with non-toxic species. These alterations include the change of delta 5-sterols for those having 7(8)- and 9(11)-double bonds as well as biotransformation of a part of free sterol fractions into sterol sulfates and sterol xylosides.

title: Benthic boundary layer communities and carbon cycling at abyssal depths in the central North Pacific
abstract: Cycling of carbon through the benthic boundary layer (BBL) community in the deep sea is poorly understood. Until now, attempts to summarize the flow of organic C in these communities have relied primarily on data collected from various deep-sea areas. The one BBL community where the organic C pools and fluxes are best defined is in the central North Pacific, north of the Hawaiian Islands. This data base was combined with new estimates of standing stocks and organic C fluxes to construct an organic C budget for the bottom 600 m of the water column and the sediments, using net input from sinking particulate organic C (POC) and exchanges between 12 compartments. The largest standing stocks of C (dissolved organic C, suspended POC, and POC) were in the water and surface sediments (9.1 x lo8 g C km-2), exceeding that in the 10 consumer groups by almost four orders of magnitude. Of the consumer groups, the sediment nanobiota, meiofauna, and epibenthic megafauna had the most organic C and the macrofauna had the least. Fluxes into the consumer groups, as estimated from respiration rates, were highest in the sediment community, bacterioplankton, and epibenthic megafauna. The net flux of POC into the BBL (supply) ranged from -74 to + 1,268 g C km 2 d-l, which was generally insufficient to match the combined fluxes into the BBL consumer groups (demand) of 998-3,3 15 g C krnm2 d I. Other sources of organic C to fuel the demand of the BBL community are analyzed, including active transport by migrating abyssopelagic animals which might significantly augment the POC flux into the BBL at this oligotrophic midgyre station.

title: Changes in fisheries discard rates and seabird communities
abstract: It is clear that discards from commercial fisheries are a key food resource for many seabird species around the world. But predicting the response of seabird communities to changes in discard rates is problematic and requires historical data to elucidate the confounding effects of other, more ‘natural’ ecological processes. In the North Sea, declining stocks, changes in technical measures, changes in population structure and the establishment of a recovery programme for cod (Gadus morhua) will alter the amount of fish discarded. This region also supports internationally important populations of seabirds, some of which feed extensively, but facultatively, on discards, in particular on undersized haddock (Melanogrammus aeglefinus) and whiting (Merlangius merlangus). Here we use long-term data sets from the northern North Sea to show that there is a direct link between discard availability and discard use by a generalist predator and scavenger—the great skua (Stercorarius skua). Reduced rates of discarding, particularly when coupled with reduced availability of small shoaling pelagic fish such as sandeel (Ammodytes marinus), result in an increase in predation by great skuas on other birds. This switching of prey by a facultative scavenger presents a potentially serious threat to some seabird communities.