ALBERT

Description: Two species of the family Bothidae (lefteye flounders), Mancopsetta maculata metadata and M. milfordi occur in the south‐west Atlantic but are caught rarely by commercial bottom trawlers. Little is therefore known about their general biology from this area. A total of 251 M. maculata and 276 M. milfordi were sampled during deep‐water exploratory fishing conducted in November 1994 within the Falkland Islands Interim and Outer Conservation Zones, at depths of 400‐1000 m, using standard commercial bottom trawling gear. The two species were found to have similar geographical distributions between 48.30′‐53.30'S and 55°‐62° W and were often obtained at the same stations in depths of 400‐900 m on the continental slope. Mancopsetta maculata maculata showed a uni‐modal cohort structure with a modal length at the 29‐cm total length size‐class. Males of M. m. maculata outnumbered females in a ratio of 3.5 : 1. Mancopsetta milfordi showed a tri‐modal length distribution, the main mode at the 37‐cm total length size‐class, with females outnumbering males in a ratio of 1.1 : 1. Length‐weight relationships and length‐at‐age information are presented for the two species. Diet was determined from the analysis of stomach contents and, although the major prey type for both species consisted of crustaceans, the morid fish Austrophycis marginata also formed an important part of the diet of M. milfordi. Key words: Mancopsetta maculata maculata; Mancopsetta milfordi; distribution; south‐west Atlantic; size; diet.

Description: We looked at the routes taken by Magellanic Penguins up the beach while moving between the sea and the colony at a breeding site in San Julian, Argentina. Birds swam parallel to the shore for a period before leaving the water to cross the beach but trajectories over the beach were not perpendicular to the water's edge but at an angle of 39°. We examined the premise that birds might be optimizing for a trade off between time or energy by adopting this procedure and found that birds can gain little or no time by walking obliquely but can, under particular circumstances, save energy. These circumstances require that the previously-calculated costs of transport for walking have been over-estimated by a factor of two

Description: Gracilaria conferta (Schousboe ex Montagne) J. ct G, Feldmann responded with an oxidative burst and rapid increases in respiration and halogenating activity when agar, agarose, or the agarose degradation products neoagarotetraose and neoagarohexaose were added to the growth medium, In contrast, carrageenan, oligocarrageenans, neoagarobiose, L-galactose, D-galactose, and several other mono- and oligosaccharides did not have any effect, Sixfold increases in respiration were observed 3 min after addition of neoagarohexaose. The response could only be induced in species of the genera Gracilaria and Gracilariopsis. Neoagarohexaose also elicited a release of hydrogen peroxide in less than 15 min, resulting in an immediate increase in algal brominating activity. Bleached thallus tips appeared a few hours after the addition of neoagarohexaose. This effect was dependent on the release of hydrogen peroxide and exposure to light, Exposure to light and oligosaccharide elicitors increased the production of reactive oxygen species, which reached destructive concentrations when both mechanisms were simultaneously active. Concentrations of 0.1 to 3.3 mu M agarose or agars were sufficient to trigger an increase in respiration, an oxidative burst response, and tip bleaching. However, higher concentrations of neoagarohexaose and neoagarotetraose were necessary to elicit the responses, indicating that the alga is more sensitive to oligoagars with degrees of biose-polymerization 〉 3, The extremely short reaction time and high specificity indicate that intermediates of agar degradation are recognized by Gracilaria as messengers when microbial degradation of its cell wall occurs, The physiological responses may represent the early stages of algal defense mechanisms involved in repression of pathogen ingress.

Description: Allocation processes play a central role in life history theories. Yet very few studies have been carried out on the link between foraging and life history in the context of allocation of resources. Here we report a study examining the relationship between foraging and allocation of resources in the Wandering Albatross Diomedea exulans of Crozet Islands. We simultaneously studied individual foraging strategies at sea and differential allocation to reproduction and storage by measuring the energy supplied to chicks and the variation of body mass of the adult. Satellite tracking and continuous monitoring of nest attendance by adults showed that while rearing a chick Wandering Albatrosses have two specific alternative foraging strategies. They either forage in short trips, short in duration and close to the colony over the southeastern slope of the peri‐insular shelf, or in long trips far from the colony in the oceanic waters north of Crozet. On average, birds made five successive short trips before making a long trip. Chicks received a meal every 1.8 d and were fed with fresh prey, 72% squid and 24% fish, and a liquid fraction composed of oil and water. During short trips birds appear to rely to a great extent on Moroteuthis ingens, a squid species probably available in large numbers at the southeastern edge of the Crozet shelf. The measure of energy flows indicates that 74% of the energy delivered to the chick comes from short trips, whereas only 33.8% of the total energy is gained at sea during these trips. Males spent a greater proportion of their time foraging in short trips than females, and consequently chicks received 61.3% of their meals from males and 38.7% from females. Adult birds tended to lose mass after short trips and to lose more mass with increased duration of short trips, whereas they gained mass after long trips. They initiated long trips when their body mass was low. Although Wandering Albatrosses are able to provision their chicks at a rapid rate because of the proximity of an abundant resource, birds still have to forage far from the colony to restore their body condition. Estimates of energy yield explain this paradox, as they suggest that the rate at which prey is caught during short trips in shallow waters is half that during long trips in oceanic waters. The significance of the twofold foraging strategy in relation to food availability and foraging efficiency is discussed.

Description: Stomach contents were analyzed from 85 Dall's porpoises, Phocoenoides dalli, taken in the southern Sea of Okhotsk during the summer of 1988. Thirteen species of fish and five species of cephalopods were identified. Fishes comprising 9 families were predominant and made up 79.9% of the total number of prey, with an overall occurrence in the stomachs of 100%. Three families of cephalopods made up 20.1% of the total number of prey ingested, with an overall occurrence of 74%. The Japanese pilchard, Sardinops sagax melanostictus, was the primary prey and represented 72.0% of the total prey in 97.3% of the stomachs examined. The gonatid squid, Berryteuthis magister, ranked second and made up 16.9% of the total prey in 61.6% of the stomachs. Walleye pollock, Theragra chalcogramma, was the third most abundant prey item consumed and represented 6.0% of the total, with an occurrence of 53.4%. Composition of the sample by the calculated total mass and caloric intake supports the numeric findings on the relative importance of the three major prey species to the DaIl's porpoise diet. The Japanese pilchard was clearly dominant using these indices and constituted 65.4% of the total mass and 80.7% of the caloric intake. Berryteuthis magister made up 26.8% of the mass and 15.5% of the caloric intake. Walleye pollock contributed the least to the diet with 7.9% of the total mass and 3.8% of the caloric intake. Volumetric data indicate that porpoises are feeding heavily on Japanese pilchard throughout the daylight hours. Berryteuthis magister was probably fed upon in the late night or early morning hours. Occurrence of both Dall's porpoise and Japanese pilchard in the coastal waters of the southern Sea of Okhotsk is seasonal. The summer movements of Dall's porpoise into this region may be related to the seasonal migration and abundance of the Japanese pilchard.

Description: Coupled three-dimensional (3-D) physical oceanographic modelling and field sampling programmes were carried out in May 1988 and August 1991 to investigate the potential drift of larval cod (Gadus morhua L.) in the Bornholm Basin of the Baltic Sea. The goals were to predict the transport of cod larvae, thus aiding the identification of physical processes influencing larval retention/dispersal. Numerical simulations were performed using a 3-D eddy-resolving baroclinic model based on the Bryan–Cox–Semtner code adapted for the Baltic Sea. Within the Bornholm Basin, the model was initialized with ground truth data of physical parameters obtained on the research cruises, and all simulations were forced with actual wind data. Outside the basin, generalized hydrographic features of the Baltic Sea were utilized by incorporation of simulated hydrographic fields from previous model runs typical for the time periods considered. Larval drift was simulated either by incorporation of passive drifters, or as the initial horizontal distribution of larvae implemented into the model. Drift model simulations of larval transport agreed relatively well with field observations. The influence of variations in the vertical distribution on a smaller scale, i.e. vertical deviations of ± 6 m from the observed mean centre of mass, on the drift was examined, revealing no significant differences in the drift of larvae depending on their vertical distribution. The different wind forcing during the investigated time periods was linked to a retention situation in May 1988 and to a dispersal situation in August 1991. Finally, observed spatial distribution patterns of 1-group cod based on Baltic Young Fish Surveys (BYFS) were compared with their predicted transport in the larval phase and examined with respect to recruitment.

Description: This paper presents quantitative analyses at the community level of the spatial dispersion of 44 species of pelagic birds in the South Atlantic Ocean. I have examined the extent to which assemblages of pelagic bird species are influenced by the combined influences of the abundances of other species and the physical structure of the pelagic environment. Results are based upon strip transects collected from oceanographic research vessels during the four consecutive austral summers of 1982–1986. The distributions of most seabird species were statistically independent of the distributions of other species. Species assemblages, however, did occur and were correlated with the physical structure of the ocean. The study area was divided into four zones, each defined by a distinctive assemblage of birds. Physical oceanography proved to be important in determining the species composition of each zone. These relationships were apparent despite the potentially confounding influence of large numbers of immatures and non‐breeding adults.