ALBERT

Description: Major- and trace-element as well as Pb-isotope data are presented for greenschist- to amphibolite-facies greenstones from two locations: (1) metabasalt-breccias from the Galfipagos Rift at 100°W; and (2) metabasalt-breccias and unbrecciated greenstones from the Chile Ridge at 38°S. Greenstone-breccias from both locations display stockwork-like sulfide mineralizations related to the upflow portion of a hydrothermal convection system. Whereas Galfipagos Rift stockwork sulfides belong to the "normal" type containing Cu-Fe-sulfides, Chile Ridge stockwork sulfides are galena-rich Pb-Zn _ Cu-sulfides and represent a previously unknown type of sulfide mineralisation in a MORB environment. Geochemically, the greenstones can be divided into two types: (1) The unbrecciated galena-free greenstones from both Chile Ridge and Galfipagos Rift show at least a 10-20-fold Pb enrichment compared to fresh MORB. With respect to similar Pb enrichment measured in greenstones from two other locations, i.e. DSDP Hole 504B and Galfipagos Rift near 86°W, we suggest that this may be a general feature of all stockwork-mineralised oceanic greenstones. (2) The galena- and quartz-rich metabasalt-breccias from the Chile Ridge are up to 3000-fold enriched in Pb (up to 1000 Ixg/g Pb in the whole-rock analyses) compared to MORB and indicate Pb mineralisation two orders of magnitude higher than that of the "normal" greenstone-type. A mass-balance calculation carried out using crustal column thickness of 3000 m with a 200-m-thick greenstone layer and 0.15 m of galena-beating breccias shows that at the Chile Ridge ~ 42% of the entire Pb is concentrated in the greenstones. This suggests that the rest of the crustal column is depleted in 58% of its primary Pb content. This degree of depletion matches well with previous calculations that a 56% depletion of Pb in oceanic crust subjected to mantle-recycling via subduction would be necessary to yield a HIMU mantle source within 2 Ga. Despite the need for future investigations into the extent and volume of the Pb enrichment in Chile Ridge greenstones, we believe that this process of major Pb redistribution is capable of creating huge volumes of oceanic crust that on average are extremely Pb-depleted and which when recycled would produce the HIMU source. Keywords: Chile Ridge; Galfipagos Ridge; Hydrothermal alteration; Greenstones; Geochemistry; Mineralogy

Description: Distribution of elements in statoliths of squid Loligo vulgaris reynaudii d'Orbigny, 1845 was studied, using the true elemental imaging system (Dynamic Analysis) of the NAC nuclear microprobe. The analysis revealed various patterns of Ca and Sr distributions. The biological interpretation of the most frequent pattern is linked with the role of Sr in the statolith deposition process. Other patterns are linked with the technique used and the specific characteristics of the sample. Traces of other elements (Cr, Mn, Fe, Cu, Zn, Br, Pb) were also found. Likewise, their presence may have the biological interpretation (Zn, Cu and Br), or is an artefact linked to the methods and conditions of sample preparation and/or analysis. Methodical aspects of using proton backscattering for PIXE X-ray yield corrections are also discussed.

Description: 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.

Description: Longitudinal sections of statoliths were observed by light microscopy on 237 individuals (158–510 mm mantle length, ML) of Ommastrephes bartrami, obtained from the North Pacific (26 °–46 °N, 143 °E–149 °W) during 1991–1994. The width of each increment sharply decreased from 5–7 μm to about 1–2 μm between the 80th and 100th increment, with a transition zone where increments were inconspicuous. ML-age relationships were linear, and slope and intercept values differed by geographic area, hatch season and sex. Overall growth rates (mm day−1) were generally higher in females (1.1–2.5) than in males (1.1–2.1). Since these values were similar to the growth rates of four individuals which were tagged and recaptured (0.8–2.4), the increments were assumed to be formed daily. The growth rate was highest for individuals hatched in summer, followed by those hatched in spring. Growth rate obtained by length-based methods may be underestimated. The hatch dates of neon flying squid are almost year-round, and the life span is likely 1 year since mature individuals were 7–10 months old.

Description: This paper presents data on the diet of the squid, Loligo vulgaris (Lamarck, 1799) from the south coast of Portugal (Algarve) and from the Saharan Bank (Central-East Atlantic). A total of 964 squid was collected from the Algarve coast, between March 1993 and October 1994, from bottom trawling. An additional sample of 70 stomachs was obtained in the Algarve coast from the hand jigging fishery during 1991 and 1992. In the Saharan Bank, 848 squid were obtained, between June 1993 and January 1994, with bottom trawling. Stomachs with contents for trawled squid from the Algarve coast, and the Saharan Bank represented 28.1% and 40.8%, respectively. Fish was always the main component of the diet in both regions, representing 88.6% of the total weight of the prey found in the stomachs, for the Algarve coast, and 70.9% for the Saharan Bank. The occurrence percentage and the percentage in number indicated that Trachurus trachurus and fish belonging to the family Gobiidae were the most frequent fish found in the Algarve samples, while flatfish were the most common fish in the Saharan Bank samples. Loligo vulgaris was the dominant cephalopod found in the stomachs for both regions. No differences in the diet were found between males and females. The comparison between immature and mature squid showed that the importance of fish was higher in mature squid, for both regions. The squid captured from the Algarve coast by bottom trawling (at greater depths and offshore) fed primarily on fish, while those captured with hand jigging (inshore, at lower depths) contained an important percentage of crustaceans.

Description: Diet and feeding habits of the short-finned squid Illex argentinus were studied from the analysis of 729 stomachs of juveniles, subadults and adults caught with trawls on the continental shelf and slope off southern Brazil (26 °35′S–34 °31′S) from 1981 to 1992. Food, in different degrees of digestion, was found in 363 stomachs (49.8%). Feeding activity occurred at day and night and seemed to be most intense at dusk and early night. The proportion of stomachs with food increased with size and sexual maturity. Fish occurred in 43.8%, cephalopods in 27.5% and crustaceans in 18.7% of the stomachs with food. Identified prey included the fish Diaphus dumerilii, Maurolicus muelleri and Merluccius hubbsi, the cephalopods I. argentinus, Loligo sanpaulensis, Spirula spirula, Semirossia tenera and Eledone gaucha and the crustaceans Oncaea media and Euphausia sp. The occurrence of fish increased with squid size, but both cephalopods and crustaceans were equally important for all sizes. Cannibalism was observed at all sizes. The overall low proportion of stomachs with food, the high rate of cannibalism and the low frequency of occurrence of crustaceans for the juveniles and subadults in all seasons, but particularly in the summer and autumn, may reflect a limited availability of food in the region. If this is true, the main nursery grounds for the spawners off southern Brazil are likely to be off the Rio de La Plata Front or in the offshore confluence between the Brazil and Malvinas Currents, where primary and secondary production is higher than off southern Brazil.

Description: The distribution at sea of seabirds was studied in the North-East Water (NEW) polynya, Greenland, during transect counts in the summers of 1991, 1992 and 1993 on board the ice-breaking RVs Polarstern and Polar Sea. Data collected within the polynya ‘box’ (78–82°N; 5–18°W) concern observations of 8000 birds counted during 1350 half-hour counts. Distribution is presented as density (N/km2) and calculated daily food intake. Five bird species were selected for discussion, representing more than 95% of the total numbers encountered: Fulmar (Fulmarus glacialis), Ivory Gull (Pagophila eburnea), Kittiwake (Rissa tridactyla), Glaucous Gull (Larus hyperboreus) and Ross's Gull (Rhodostethia rosea). For these species, densities are comparable in the NE Greenland polynya and in other European Arctic seas. The main difference is the absence in NEW of the species playing the main role in Arctic seas: Brünnich's Guillemot (Uria lomvia) and Little Auk (Alle alle). In the absence of fish-eating birds and of birds consuming zooplankton in the water column, the NEW polynya ecosystem is thus dominated by surface feeders and, closer to the coast, by benthic feeders like eiders, Somateria mollissima and S. spectabilis, and walrus, Odobenus rosmarus. The density and daily food intake for all seabirds are one order of magnitude lower in the polynya than in the Arctic seas. The distribution and abundance of seabirds in the NEW polynya seems to reflect a very low density of pelagic fish and Zooplankton in the water column, while Zooplankton must be present at ‘normal’ concentrations in the upper layer.

Description: Residue levels of persistent organochlorines in deep-sea organisms collected from Suruga Bay, Japan, were determined. PCBs (polychlorinated biphenyls) were the predominant group of organochlorines ranging in concentrations from 380 to 2800 ng g−1 on a lipid weight basis. DDTs (DDT and its metabolises) were the next most abundant organochlorine compounds followed by CHLs (chlordane compounds), HCHs (hexachlorocyclo-hexanes) and HCB (hexachlorobenzene). In comparison with coastal shallow water organisms, higher concentrations of HCHs were found in deep-sea organisms, while no significant difference was noted for other organochlorines. Organochlorine residue levels in Suruga Bay were comparatively lower than those in other deep-sea organisms reported elsewhere. The deep-sea organisms showed no consistent trend between organochlorine concentrations and food chain relationships. Lipid-dependent accumulation of organochlorines by equilibrium partitioning may be attributable to this residue pattern. Among DDT compounds, p,p′-DDE was the highest in most deep-sea organisms. Trans-nonachlor and β-HCH were the major constituents of CHLs and HCHs, respectively, in these organisms.

Description: The development of phytoplankton biomass and composition was investigated on three occasions along a longitudinal transect (6°W) between 60°S and 47°S from October 13 to November 21, 1992 by measurement of photosynthetic pigments with high performance liquid chromatography (HPLC). Measured accessory pigment concentrations were multiplied by conversion factors to derive the proportions of phytoplankton groups contributing to the biomass indicator chlorophyll a. Phytoplankton blooms developed in the Polar Frontal region (PFr) and were dominated (80%) by diatoms. Other groups contributing to the phytoplankton included prymnesiophytes, green algae, autotrophic dinoflagellates, cryptophytes, pelagophytes and micromonadophytes, and their distributions varied with time. In contrast, phytoplankton biomass remained low in the southern Antarctic Circumpolar Current (ACC) and was dominated by flagellates, particularly green algae and prymnesiophytes. Green algae contributed more to total biomass than in previous investigations, partly attributed to “Chlorella-like” type organisms rather than prasinophytes. Cryptophytes decreased during the investigation, possibly due to salp grazing. No bloom was observed at the retreating ice-edge, presumably due to strong wind mixing. Only a slight increase in phytoplankton biomass, composed primarily of diatoms, was found at the ACC-Weddell Gyre front. Cluster analysis revealed that different phytoplankton communities characterised the different water masses of the PFr and southern ACC; the history of different water masses in the PFr could be reconstructed on this basis.