ALBERT

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

Description: Allozyme electrophoresis was used to investigate species boundaries and population genetic structure within the southern calamary Sepioteuthis australis Quoy and Gaimard. Samples collected from 17 localities around southern Australia and northern New Zealand were examined for allozyme variation at 49 loci. Of 13 polymorphic loci detected, 7 were sufficiently variable to be useful as routine genetic markers of population structure. There was little or no genetic differentiation across the entire range sampled at 5 of these 7 loci. In marked contrast, the allozyme data at 2 loci (Fdp and PepD) unequivocally sorted all individuals into 1 of 3 genetic types, the geographic distributions of which exhibited a markedly non-random pattern. One type was mainly found near the western and eastern limits of the sampled area, the other type predominantly in the intervening region. Where these 2 types overlapped, a third hybrid-type was found at frequencies predicted under Hardy-Weinberg expectations. The 2 most-likely explanations for these data are: (1) there are 2 taxa within S. australis which produce only F1 hybrids wherever they overlap, or (2) the 2 loci Fdp and PepD are tightly linked and thus are not independent measures of population structure. Preliminary morphological and reproductive data support the hypothesis of 2 taxa, while mitochondrial DNA-sequence data are inconclusive. It is argued that some combination of the 2 explanations may be operating. Regardless of the final outcome, the data indicate that there are a number of discrete stocks of S. australis in this region, a result at variance with current management perspectives on this important fishery.

Description: The cephalopod fishery in Eastern Central Atlantic waters, from Cape Blanc (21°N) to Cape Bojador (26" N), is economically very important for Spain, due to the high commercial values on the international market of the main species caught. octopus Oc t o p ~ ~vusl garjs Cuvier, 1797, cuttlefish Sepia hierredda Rang, 1837 and squid Loljgo rlulgaris Lamarck, 1798. After octopus, S. hie]-redda is the most important species for this f~sheryF.o r cuttlefish stock assessment, it is necessary to elucidate a key aspect of its biology, namely growth. In 1992, in order to view growth increments, statoliths were embedded in a clear fast-drying resin, and their surfaces were ground and polished Some were etched. Several mounting posltlons were analyzed, of \vh~ch2 were chosen for the study In polished statolith surfaces, thin growth increments were observed and assumed to be daily structures, because of their regular pattern and by analogy with validated results on the families Loliginidae. Ommastrephidae (order Teuthoidea) and ldiosepiidae (order Sepioidea). Thicker and more widely spaced growth rings were also observed and their periodicity is discussed. As this is the first study on the ageing of cuttlefish off the northwestern African coast using microincrements of statoliths, the results have not yet been validated. However, these hard parts seem to be very useful tools for direct age determination of cuttlefish (family Sepiidae) and of S. hjerredda in particular, as they reveal much information concerning individual growth.

Description: 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.

Description: 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.

Description: Bioaccumulation of 65Zn and 109Cd by the cuttlefish Sepia officinalis L. was studied at different stages of its life cycle, i.e. in embryos, juveniles and adults, following exposures via sea water, sediments and food. Cuttlefish eggs efficiently accumulated both elements from seawater with bioconcentration factors of 79 for 65Zn and 46 for 109Cd after 11 d exposure. Most of the radiotracers were found in the capsule membrane of the eggs, demonstrating that the capsule acts as a shield to protect embryos against metals. Juveniles and adults efficiently bioconcentrated both radiotracers from seawater, with the muscular tissues containing 84% of the total 65Zn and 62% of the total 109Cd. Loss kinetics followed a single exponential function for 65Zn, while for 109Cd loss was best described by a double exponential model. Biological half-lives for elimination were ca. 2 mo for both elements. After 29 d depuration in uncontaminated seawater, 76 to 87% of the radiotracers were found in the digestive gland. For both elements, the dissolved phase can be considered as a significant source of accumulation. In an experiment with radiolabelled sediments, transfer factors were very low, even after 29 d exposure. Food-chain transfer experiments demonstrated that both juveniles and adults assimilated 65Zn and 109Cd very efficiently. Moreover, loss of ingested radiotracers was much slower than elimination of 65Zn and 109Cd taken up from seawater, indicating a very strong retention of dietary Cd and Zn by juvenile as well as by adult cuttlefish. As with direct uptake from seawater, ingested radiotracers were mainly found in the digestive gland, with fractions reaching 82% for 65Zn and 97% for 109Cd after 29 d depuration. These tracer experiments indicate that (1) food is the likely primary pathway for Zn and Cd bioaccumulation in S. officinalis, and (2) the digestive gland plays a major role in the subsequent storage and presumed detoxification of these elements regardless of the uptake pathway.

Description: The diet of the sub-Antarctic onychoteuthid squid Moroteuthis ingens was assessed using stomach contents analyses and fatty acids as dietary tracers. The contents of 54 stomachs (50 from squid collected near Macquarie Island and 4 from squid collected near Heard Island) were examined visually, and prey remains were identified to species level where possible. Myctophid fish were the most common prey item in the stomach contents of M. ingens and were identified in 59% of stomachs. In total, teleost fish remains were found in 96% of stomachs. The lipid class and fatty acid profiles of the digestive gland and mantle tissue were analysed for 5 to 6 squid from each area, in addition to 4 stomach fluid samples taken from Heard Island animals. Mantle tissue was low in lipid, and contained high concentrations of phospholipids and polyunsaturated fatty acids. Digestive gland tissue had a high lipid content, with a mean value of 26.8 ± 12.9% wet mass in Macquarie Island squid and 41.7 ± 8.5% wet mass in Heard Island squid, and was rich in triacylglycerol (TAG) and monounsaturated fatty acids (MUFA). Stomach fluid generally contained high concentrations of TAG, although 1 sample was high in wax ester. Stomach fluid was also characterised by high MUFA concentrations. The digestive gland of M. ingens grouped with the fatty acid profile of stomach fluid and some myctophid species in cluster analysis and multidimensional scaling, and appears to be a source of fatty acid dietary tracers. Thus the fatty acid profile of the digestive gland supports findings from stomach contents analyses that myctophids, particularly TAG-rich species, are an important prey group of M. ingens at Macquarie and Heard Islands. This combination of techniques has a potential to increase our knowledge of the feeding ecology of squids in the Southern Ocean.

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