ALBERT

Description: The chemical composition (alkalinity, pH, NH4+, PO43-, Si, H2S, Cl-, Ca2+,and SO42-) of interstitial water was studied in the sediments of the Sea of Okhotsk at sites of methane emission. Variations in alkalinity were observed in the sediments from a typical seawater value (2.3 mM/kg) to 63 mM/kg. It is demonstrated that they are caused by the processes of sulfate reduction and methane generation. Based on the balance relationships, an equationwas constructed connecting changes in alkalinity with variations of Ca2+, SO42- and NH4+ in interstitial solutions.

Description: A new mandibular sensor is presented here based on the use of a Hall sensor, attached to one mandible, opposite a magnet, attached to the other mandible. Changes in sensor voltage, proportional to magnetic field strength, and thus inter-mandibular angle, are recorded in a logger. This system was tested on seven captive Adélie penguins (Pygoscelis adeliae) and three gentoo penguins (Pygoscelis papua) during: (1) feeding trials on land, where birds were given known quantities and types of food; and (2) trials in water where birds were allowed to swim and dive freely. In addition, six free-living Magellanic penguins (Spheniscus magellanicus) were equipped with the system for single foraging trips. Angular signatures were looked for in instances when both captive and free-living birds might open their beaks, and it was discovered that five major behaviours could be identified: ingestion, breathing, calling, head shaking and preening. Captive feeding trials showed that prey mass could be determined with reasonable accuracy (r 2=0.92), and there was some indication that prey type could be resolved if recording frequency were high enough. Vocalisations in Adélie penguins (arc calls) took 〈0.7 s for mean maximum beak angles of 4.2° (SD 1.3), and were distinguished by their relatively gradual change in beak angle and by their high degree of symmetry. Beak shakings were distinguishable by their short duration (multiple peaks of 〈0.5 s) and minimal maximum angle (〈0.5°). Preening behaviour was apparent due to multiple decreasing peaks (angles 〈8°). Breathing could be subdivided into that during porpoising, where a characteristic double peak in beak angle was recorded, and that during normal surface rests between dives. During porpoising, only the primary peak (mean maximum beak angle 25.1°, SD 4.7) occurred when the bird was out of the water (mean maximum for second peak 5.9°, SD 4.1). During normal surface rests in free-living birds, breaths could be distinguished as a series of beak openings and closures, showing variation in amplitude and frequency according to an apparent recovery from the previous dive and preparation for the subsequent dive to come. The mandibular measuring system presented shows considerable promise for elucidating many hitherto intractable aspects of the behaviour of free-living animals.

Description: The responses of Gracilaria lemaneiformis, an easily epiphytized host, and the relatively resistant G. cornea mutant, to the green alga Ulva lactuca were studied using biculture experiments with and without antibiotics. Both Gracilaria species grown with and without U. lactuca showed different levels of growth rate, release of hydrogen peroxide and of halogenated hydrocarbons. These quantitative differences led to a successful response against Ulva lactuca in the case of G. cornea mutant and to a failure in response in the case of G. lemaneiformis. The response of each Gracilaria species to U. lactuca was qualitatively similar to its response to bacteria. This suggests the involvement of oligosaccharide elicitors produced in the presence of epiphytes and bacteria. A clear Gracilaria inhibition was demonstrated with extracts of the culture medium. It appears that hydrogen peroxide, halogenated hydrocarbons and oligosaccharides may be components of the inhibitory activity of the extracts. The responses of Gracilaria species to the presence of U. lactuca suggest the characterization of a defence response.

Description: To determine whether stable isotope measurements of bird feathers can be used to identify moulting (interbreeding) foraging areas of adult seabirds, we examined the stable-carbon (δ13C) and nitrogen (δ15N) isotopic composition of feathers of chicks and adults of black-browed albatrosses (Diomedea melanophrys) from Kerguelen Islands, southern Indian Ocean. Albatross chicks are fed primarily fish (75% by mass), the diet being dominated by various species of the family Nototheniidae and Channichthyidae which commonly occur in the shelf waters in the vicinity of the colony. δ13C and δ15N values in chick feathers, which are grown in summer in the breeding area, were lower than values in adult feathers, which are grown in winter (δ13C: –19.6‰ versus –17.6‰ and δ15N: 12.4‰ versus 15.7‰, respectively). No differences in δ13C and δ15N values were found in adult wing feathers moulted in 1993 and 1994 and in adult feathers formed at the beginning, middle and end of the 1994 moulting period. These data are consistent with adults moulting in the same area and feeding at the same trophic level from one year to the next and with no major changes in foraging ecology within a given moulting season; they suggest that foraging grounds were different in summer and winter and that these differed in their stable-isotope signature. Changes in both feather δ13C and δ15N values indicated feeding south of the Subtropical Front (STF) during chick rearing, which is in agreement with the known foraging ecology at this time and feeding north of the STF during moult. This, together with band recoveries from adult birds, indicates that black-browed albatrosses from Kerguelen Islands wintered in subtropical waters off southern Australia. The stable-isotope markers in feathers, therefore, have the potential for locating moulting areas of migratory seabird species moving between isotopically distinct regions and for investigating seabirds’ foraging ecology during the poorly known interbreeding period. Such information is needed for studies of year-round ecology of seabirds as well as for their conservation and the long-term monitoring of the pelagic environment.

Description: The food of three closely related and sympatric species of mollymawks (Diomedea spp.), the black-browed (BBA, D. melanophrys), grey-headed (GHA, D. chrysostoma) and yellow-nosed (YNA, D. chlororhynchos) albatrosses, was compared at Iles Nuageuses, Kerguelen, during the chick-rearing period. BBA preyed almost equally upon cephalopods (39% by fresh mass), fish (31%) and penguins (31%), while GHA fed more on squids (52%, 16% and 28%, respectively) and YNA fed more on fish and not on penguins (13%, 84% and 0%, respectively). Crustaceans were always a minor component of the diet (〈3%). Patagonian toothfish was the main fish prey, and Todarodes sp. the main cephalopod prey for the community. Accumulated beaks emphasise the importance of juvenile ommastrephid squids in the diet of mollymawks, accounting for 81%, 71% and 55% of the total number of beaks in BBA, GHA and YNA samples, respectively. BBA preyed also upon a significant number of the octopod Benthoctopus thielei (12%) and of the cranchiid squid Galiteuthis glacialis (4%), while GHA fed more on G. glacialis (18%) and on the onychoteuthid Kondakovia longimana (8%). When feeding on the same prey, prey size was similar for the albatross species. Comparison of overall prey biogeography together with the presence/absence of prey species indicators of water masses indicates segregation through different foraging areas among the three mollymawks. BBA forage almost exclusively over the shelf and upper slope waters surrounding the Kerguelen Archipelago. By contrast, GHA and YNA feed mainly in oceanic waters, YNA favouring the warm subtropical waters, and GHA the cold Antarctic waters. It is thus remarkable that birds from the same breeding grounds forage over such a wide latitudinal range, from about 35–40°S to 60–65°S, encompassing the Subtropical Zone for YNA, the Antarctic Zone for GHA and the Antarctic Polar Frontal Zone (where Kerguelen is located) for the three species.

Description: The Caucasian orogenic wedge formed as a consequence of the closure of the Tethyan Ocean, and numerous fields of active mud volcanoes pepper the area adjacent to the Black and Caspian Seas. Stable isotope ratios of boron, helium, and carbon have been measured for gas, fluid and sediment samples from active mud volcanoes of Taman Peninsula and Georgia to estimate the sources and mobilization depths of the fluid phase and mud. Boron concentrations in mud volcano fluids were found to be 5–35× higher than seawater. Fluid isotope ratios vary between δ11B=22 and 39‰, while isotope ratios of the smectite- and illite-rich extruded mud are considerably depleted in heavy 11B (δ11B=−8 to +7‰). B contents of these muds are ~8× higher than modern marine sediments. This suggests that liquefaction prior to mud volcanism was accompanied by both B enrichment and isotope fractionation, most likely at an intermediate depth mud reservoir at 2–4 km. The hydrocarbon-generating source beds to the mud volcanoes are located at 7 to 〉10 km depth in the folded Maikop Formation and are of proposed Oligocene–Miocene age. The most likely mechanism is re-hydration of these shales by both hydrocarbons and a geochemically mature fluid from greater depth within the orogenic wedge. Such a deep fluid source is supported by our results from gas analyses, which imply an admixture of minor amounts (less than 1%vol) of 3He (Georgia), thermogenic 13C in methane as well as "ultraheavy" 13C in CO2 (both Taman and Georgia). The overall results attest active local flow of geochemically different fluids along deep-seated faults penetrating the two study areas in the Caucasian orogenic wedge, with the waters as well as the gases coming from below the Maikop Formation.