ALBERT

Description: Many of the difficulties of staining plastic embedded tissues for light and electron microscopy derive from physical exclusion of hydrophilic staining reagents by hydrophobic embedding media. Structures which stain most intensely with hydrophilic reagents usually contain less hydrophobic plastic than do non-staining structures. Such incomplete infiltration is apparently caused by exclusion of viscous, hydrophobic monomers by physically dense and/or well hydrated tissue elements. In keeping with this, generalized staining of tissues embedded in hydrophobic media does occur when hydrophobic reagents are used. Staining of plastic-free structures with single hydrophilic reagents or with sequences of such reagents, is, however, largely rate-controlled. The surprising similarity of hydrophilic and hydrophobic plastic embedding media is discussed. Limits of this simple model are explored, with a consideration of the roles of fixative and of monomer-tissue reactions

Description: 1 Zonation is often seen in environments with a strong physico-chemical gradient, such as salt marshes. It has been hypothesized that plant species are limited in their distribution by abiotic factors towards the more extreme end of the gradient, and by competition towards the more favourable end. Invasion of the native clonal grass genus Elymus in many Wadden Sea marshes may be due to increasing atmospheric nitrogen input into a nitrogen-limited environment. However, at Thmlauer Bay, Germany, Elymus athericus does not occur in lower salt marsh communities that are dominated by a dwarf shrub (Atriplex portulacoides). We therefore hypothesized that at this site the downslope (= more extreme) distributional boundary of E. athericus is a result of competition with A. portulacoides rather than of physiological limits. 2 A factorial experiment was set up to investigate the effects of removal of each competitor and fertilization. The reciprocal effects of the species on each other were measured in terms of vegetation cover and above-ground biomass. The impact of the tidal regime on plant zonation was investigated by calculating inundation frequencies at the boundary between the two plant populations from water level recordings. 3 Elymus athericus extended its distribution into the lower salt marsh when A. portulacoides was removed. The latter increased in cover but not in biomass after the removal of E. athericus. Neither species showed a response to nitrogen fertilization. The boundary between the two species in the control plots varied considerably in elevation and inundation frequency. 4 The lower distributional boundary of E. athericus can be interpreted as the result of competition with A. portulacoides. Improvement of nitrogen availability in concentrations of the same order of magnitude as annual atmospheric input had no detectable effect on plant zonation and growth. Elevation and inundation frequency were not strictly correlated with plant zonation.

Description: A new species of the holopodid genus Cyathidium was found on rocks off Grande Comore in a depth of around 200 m. Based on external morphology of resting animals, the new species Cyathidium plantei sp. n is described, with emphasis on comparison to the only other extant species (C. foresti) as well as to the four extinct representatives of the genus. Concerning morphological characters, the new species is almost identical to the Cretaceous C. depressum. A cladistic analysis of the entire family, including the genus Holopus, shares a peculiar pattern of bending of the arms, which in principle is an apomorphic character of the family and in detail shows variations within the family. In addition, stratigraphic data are used for the determination of the evolutionary direction. This analysis reveals that the two recent species are closely related to each other, and to the fossil C. depressum. from which the entire family is probably derived.

Description: The chapter gives an overview of marine plant relationships with their environment, wich is called ecology. The overview is a requirement to understanding the biology of marine plants because they do not live as isolated units. Consideration will be given to basic tenets of marine ecology including levels of organization (Populations to ecosystems), processes of community development (succession, energy transfer), strategies (evolutionary, plant responses), biological iunteractions (forms of symbiosis, competition, predation), and growth (rates and responses).

Description: A protein unique to phosphorus stress observed in Dunaliella tertiolecta Butcher was studied in the context of phosphate‐limited cell physiology and is a potential diagnostic indicator of phosphate deficiency in this alga. Cells were grown over a range of limited, steady‐state growth rates and at maximum (replete) and zero (phosphate‐starved) growth rates. The stress protein, absent in nutrient‐replete cells, was produced under all steady‐state phosphate‐limited conditions and increased in abundance with increasing limitation (decreasing growth rate). Cellular carbon: phosphorus ratios and the maximum uptake rate of phosphate (Vm) increased with increasing limitation, whereas the ratio of chlorophyll a: carbon decreased. Alkaline phosphatase activity did not respond to limitation but was measurable in starved, stationary‐phase cells. Fv/Fm, a measure of photochemical efficiency, was a nonlinear, saturating function of p, as commonly observed under N limitation. The maximum Fv/Fm of 0.64 was measured in nutrient‐replete cells growing at μmax, and a value of zero was measured in stationary‐phase starved cells. When physiological parameters were compared, the P‐stress protein abundance and Fv/Fm were the most sensitive indicators of the level of deficiency. The stress protein was not produced under N‐ or Fe‐limited conditions. It is of high molecular weight (〉200) and is associated with internal cell membranes. The stress protein has several characteristics that make it a potential diagnostic indicator: it is 1) unique to phosphorus limitation (i.e. absent under all other conditions), 2) present under limiting as well as starved conditions, 3) sensitive to the level of limitation, and 4) observable without time‐course incubation of live samples.

Description: Heavy mineral studies of East Siberian river sediments, Laptev Sea surface sediments, and a sediment core of the western Laptev Sea were carried out in order to reconstruct the pathways of modern and ancient sediment transport from the Siberian hinterland to the Laptev Sea. The modern heavy mineral distribution of Laptev Sea surface sediments reflects mainly the riverine input. While the eastern and central part of the Laptev Sea is dominated by amphibole, which is supplied by the Lena River, the western part is dominated by pyroxene imported from the Siberian Trap basalts by the Khatanga River. The distribution of garnet and opaque minerals is additionally influenced by hydrodynamic processes. As a consequence of their high density, these minerals are predominantly deposited close to the river mouths. Heavy mineral and sedimentological studies of a sediment core of the western Laptev Sea were applied to reconstruct the postglacial history of the shelf area during the last 11 ka. In the lowermost interval of the core (〉c. 10 ka), high accumulation rates and a heavy mineral composition similar to that of the modern Khatanga river indicate fluvial conditions. Additionally, the high mica content in this interval may indicate meltwater inflow from the Byrranga mountains. Strong variations in accumulation rates, grain-size distribution, and heavy mineral composition are observed in the time interval between c. 10 and 6 ka, which represents the main transgression of the Laptev Sea shelf. During the uppermost interval (〈6 ka), rather stable conditions similar to the modem situation prevailed.

Description: Before making a critical evaluation of the crude oil and natural gas prospects for the years to the end of the century, it is necessary to review the geology and structure of the three German hydrocarbon-producing provinces. Furthermore, past exploration, production and reserves should be discussed. The three hydrocarbon-producing provinces are: the NW German Basin, the Upper Rhine Graben and the Molasse Basin, which together make up about 41% of West German territory (Fig. 1). The NW German Basin contains a sedimentary sequence over 8,000 m thick ranging in age from Permian to Quaternary. Gas and oil, the two natural hydrocarbons, are generally confined to separate lower and higher stratigraphic levels respectively (Fig. 2). The NW German Basin is the most important prospective area in West Germany. It extends into the North Sea. The tectonic rift feature of the Upper Rhine Graben originated in the Eocene. The Tertiary fill is over 4,000 m thick. Oil is found mainly in Mesozoic, Eocene and Oligocene rocks; the Miocene and Pliocene reservoir rocks contain natural gas almost exclusively (Fig. 3). The Molasse Basin is part of the foredeep north of the Alpine and Carpathian mountain ranges. The basin is filled with Upper Eocene to Pliocene and Quaternary sediments which, near the Alpine nappes, reach a thickness of over 5,000m (Fig. 4). During this century there were peaks in annual oil-production in 1910, 1940 and 1968 (see Fig. 5). The 1910 peak was the result of drilling activity in the Wietze oilfield. During the period 1934–1945, government financial aid was made available for drilling exploration wells. The success of this collaboration is demonstrated by the oil output in 1940 of 1 × 106 t. After World War II, many different types of oil-bearing structure were found, particularly by reflection seismic techniques in conjunction with detailed stratigraphical and palaeogeographical investigations. The success achieved can be seen by the peak of 8 × 106 t oil production for 1968 (Fig. 5) and in the growth of oil reserves (Fig. 7). Intensive exploration also enabled many new gasfields to be developed, especially in the deeper horizons of the NW German Basin. In 1971, estimated gas reserves reached 360 × 109 m3 (Fig. 11), and annual gas production in 1979 was 20.7 × 109 m3 (731 Bcf) (Fig. 9). There is, no doubt, still scope for the discovery and exploitation of oil and gas in Germany, especially in the NW German Basin where the best prospects for the future lie. This is borne out by two recent offshore oil discoveries and also by the successful application of enhanced recovery methods in the oilfields. The chances of finding more gas at the lower stratigraphic levels are promising now that gas has been discovered in the deeper parts of the Permian basin. The results of massive-hydraulic-fracturing tests in low-permeability pay-horizons are also encouraging. The deeper parts of oil- and gas-producing basins contain interesting prospects and have yet to be tested by ultra-deep wells. Provided that the economic climate remains favourable, there should be no difficulty in finding and supplying German oil and gas in the future. Geologically and technically possible reserves should be converted into proven and/or probable reserves. German crude oil will be available for several years beyond the year 2000, and German natural gas for a far longer time. A production rate of 19 to 20 × 109 m3 of gas per annum is feasible over the next twenty years, and oil production will probably not sink below 3 × 106 t/a in this period.

Description: The influence of mixing frequency and depth on phytoplankton functional group composition (mobile versus immobile species) was studied by enclosure experiments in a shallow, stratified lake. Mixing events were artificially induced at intervals from 2–12 d. The mixing depth was increased from the natural level (4 m) to 6 and 9 m. The mobile phytoplankton in the experiments consisted of cyanobacteria and flagellates. Among the latter, large and rapid swimming species were represented by dinoflagellates. An increase of the relative abundance of gas vacuolated cyanobacteria occurred with increasing frequency of mixing. Additionally Reynolds' hypothesis predicting the occurrence of certain mobile phytoplankton genera in response to the mixing regime could be confirmed for the condition when mixing depth exceeds the euphoric depth.

Description: Ship speed may have an important effect on the results of seabird surveys. We counted seabirds on a 20.5 X 0.3 km transect in the Kattegat that was sailed nine times with the RV "Heincke." Ship speed alternated between 9 knots and 5 knots. The numbers of the most common species, the Lesser Black-backed Gull (Larusfuscus), were significantly higher when the ship was sailing at lower speed similar to that of commercial fishing vessel when trawling in the area. It is postulated that scavenging species( e.g., gulls) are attracte to the low speed of vessels whereas non-scavengers (e.g. auks) are not

Description: The identification of developmental stages in fish eggs from plankton samples is often complicated by deformation of the embryos due to mechanical stress during the sampling procedure and by dehydration during formaldehyde fixation. The effects of formaldehyde fixation and mechanical stress on Baltic cod eggs (Gadus morhua callarias L.) were examined separately by visually comparing the morphological features of treated vs. live eggs of identical ontogenetic age. Microphotographs were made concurrently for documentation. In stage IA eggs, mechanical treatment resulted in scattered blastodiscs surrounded by single cells, while in further advanced stages the yolk membrane collapsed entirely, the yolk coagulated and the embryo extending over the yolk shrank. Formaldehyde fixation caused the yolk and the blastodisc or embryo to darken, and in some cases crystalline enclosures occurred. Eggs mechanically deformed during handling were clearly distinguishable from those that died prior to catching; however, staging was generally less accurate for formaldehyde-preserved eggs when compared with living specimens.

Description: The holocene depositional setting of the Laptev Sea was studied using three marine sediment cores from water depths between 77 and 46 m. Based on sedimentary parameters (TOC content, delta(13)C(org) Sedimentation rates) controlled by radiocarbon age models the palaeoenvironment of a strongly coupled river-shelf system was reconstructed since similar to 11 ka SP. Caused by a transgressing sea after the last glaciation, all cores reveal progressive decreases in sedimentation rates. Using the sedimentary records of a core from the Khatanga-Anabar river channel in the western Laptev Sea, several phases of change are recognized: (1) an early period lasted until similar to 10 ka BP characterized by an increased deposition of plant debris due to shelf erosion and fluvial runoff; (2) a transitional phase with consistently increasing marine conditions until 6 ka BP, which was marked at its beginning near 10 ka BP by the first occurrence of marine bivalves, high TOC content and an increase in delta(13)C(org); (3) a time of extremely slow deposition of sediments, commencing at,6 ka BP and interpreted as Holocene sea-level highstand, which caused a southward retreat of the depositional centres within the now submerged river channels on the shelf; (4) a final phase with the establishment of modern conditions after similar to 2 ka BP.

Description: At a subtidal, soft-bottom site in the western Baltic Sea, mussel (Mytilus edulis) patches co-occur with high predator abundances. Sea star (Asterias rubens) biomasses, in particular, exceed reported values considered sufficient for restricting mussels to the intertidal zone. To determine how mussels can persist in the face of intense predation, we decomposed patch space occupancy into the relative contributions of newly arriving individuals (recruitment) and of increases in body size of the individuals already present in the patch over 13 mo. Sea stars, as major predators, were only able to control 77% of the potential per capita recruitment rate of 91 individuals/yr in 2 m depth. The remaining recruitment rate of 21 individuals/yr was sufficient to allow patches to occupy 1.6 times more space per year. Transplantation of patches to 6 m depth, where recruitment is negligible, revealed that sea stars were also ineffective in controlling mussel coverage through consumption of larger mussels (〉1 yr, 〉30 mm shell length). In deeper water, space occupancy of patches through increases in mussel body size was able to balance predation mortality, demonstrating that mussels attained a relative refuge in size at only 33 mm shell length. Based on the measured shell growth rates, mussels attain this size after ≈15 mo. In situ observations of Asterias feeding activity, the ratios between necessary predator sizes to attack prey of a given size, and predator size distributions suggest that sea stars were on average too small to feed effectively on adult (〉1 yr) mussels. Probably, Asterias cannot respond to abundant prey and increase its maximal body size at the site because salinities are at its lower tolerable limit (12–18 g/kg). Thus, bottom-up factors such as high prey productivity in concert with subtle size-based ineffectiveness of the predator population allow otherwise unstable predator–prey populations of a generalist predator and its preferred prey to coexist. Although mussel predators were unable to decimate mussels to local extinction, a release of experimental mussel patches from predation with strong recruitment (2 m depth) resulted in an approximately sevenfold yearly areal increase in shallow treatments, which would lead to a 100% mussel cover at the site within 1 yr. Given that mussels can dominate both rocky substratum and soft sediment, we also studied the effect of substratum quality in factorial combination with presence/absence of predation and water depth on mussel abundance. Attachment to stable substratum did not affect recruitment to the patches or patch space occupancy, but it completely prevented patch dislodgment and subsequent drift. In contrast to rocky shores, mussel patch dislodgment may represent the major mode of patch dispersal and new patch formation in soft-bottom environments as demonstrated by a drift collector fence.

Description: High-resolution reflection seismic data obtained around Gran Canaria allow a detailed and consistent correlation of seismic reflectors of the northern and southern Canary Basins with the lithology drilled by DSDP Leg 47A SSE of Gran Canaria, as well as with major phases of volcanic activity on Gran Canaria as mapped onshore. Two prominent reflectors were chosen as marker horizons and correlated with the drilled lithology. the results indicate that reflector R7 above the Miocene volcaniclastic debris flows V1-V3 reflects the shield-building phase of Gran Canaria. Reflector R3 is interpreted as corresponding with the Pliocene Roque Nublo formation. The top of the massive island flank of Gran Canaria, defined by seismically chaotic facies, extends 44 to 72 km off the coast of Gran Canaria. West of Gran Canaria the flank of Tenerife onlaps the steeper and older flank of Gran Canaria, which, in turn, is onlapping the older flank of Fuerteventura to the east in a similar way. Erosional channels, which can also be traced up to 50 km from the area between Gran Canaria and Fuerteventura into the deeper northern basin, have been identified in the bathymetry. The data presented provide new detailed information for modelling the submarine and subaerial evolution of the central Canary Islands of Gran Canaria and Tenerife, i.e. the timing of their shield-building phases and later stages of major volcanic activity, as reflected by the position of prominent seismic reflectors in the seismic stratigraphy.

Description: The growth of Fucus vesiculosus L, germlings in chemically defined culture media containing a range of Cu concentrations (20-1000 nM) was monitored simultaneously with measurement of the Cu speciation in the media by competitive equilibrium-adsorptive cathodic stripping voltammetry, Fucus vesiculosus germlings were found to exude Cu-complexing Ligands with conditional stability constants of the order of 1.6 x 10(11), Ligand concentrations increased with increasing total dissolved Cu concentrations (Cu-T) until a concentration of 500-800 neq Cu.L-1 was reached. Concentrations of the ligand exceeded Cu-T in treatments containing 20 and 100 nM Cu-T were similar to Cu-T in the 500-nM Cu treatment, but were less than Cu-T in the 1000-nM treatment. Therefore, [Cu2+] were calculated to be at concentrations of 10(-11) - 10(-10) M in the 20- and 100-nM treatments, 10(-9) M in the 500-nM treatment, and 10(-7) M in the 1000-nM treatment, Growth rates were lowest at Cu2+ concentration 〉 10(-9). These results are discussed within the context of the potential roles for exuded copper-complexing ligands

Description: There has been a widespread increase in the reporting of harmful and ‘nuisance’ algal blooms in the coastal ocean over the past few decades. On the global scale this is suspected to be a consequence of coastal eutrophication, however, on a case-by-case basis there is usually insufficient evidence to discriminate between the effects of human and natural causal factors. Intense blooms of the ‘Brown Tide’ unicellular algae (Aureococcus anophagefferens) have occurred sporadically since 1985 in coastal waters of Eastern Long Island and have devastated the local commercial scallop fishery. Analysis of an 11-year time-series dataset from this region indicates that bloom intensity is correlated with higher salinities and inversely correlated with the discharge of groundwater. Laboratory and field studies suggest that whereas salinity is unlikely to represent a direct physiological control on Brown Tide blooms, the addition of inorganic nitrogen tends to inhibit Brown Tide blooms. Budget calculations indicate that the inorganic nitrogen supply from groundwater is 1–2 orders of magnitude higher than any other external source of nitrogen for this ecosystem. Biweekly time series data collected in 1995 demonstrate that Brown Tide blooms utilize dissolved organic nitrogen (DON) for growth, as evidenced by a large decrease in DON parallel with an increase in cell abundance. On an interannual basis, bloom intensity was also positively correlated with mean DON concentrations. We hypothesize that bloom initiation is regulated by the relative supply of inorganic and organic nitrogen, determined to a large extent by temporal variability in groundwater flow. The 1980s and 1990s were characterized by exceptionally high and interannually variable groundwater discharge, associated with a large-scale climate shift over the North Atlantic. This, coupled with the time-lagged discharge of groundwater with high nitrate concentrations resulting from increased fertilizer use and population increase during the 1960s and 1970s, may have been a key factor in the initiation of Brown Tide blooms in 1985

Description: The biosynthesis of Pep5, a lanthionine-containing antimicrobial peptide, is directed by the 20-kbp plasmid pED503. We identified a 7.9-kbp DNA-fragment within this plasmid which covers the information for Pep5 synthesis in the homologous host Staphylococcus epidermidis 5 which has been cured of pED503. This fragment contained, in addition to the previously described structural gene pepA and the immunity gene pepl [Reis, M., Eschbach-Bludau, M., Iglesias-Wind, M. I., Kupke, T. & Sahl, H.-G. (1994) Appl. Env. Microbiol. 60, 2876–2883], a gene pepT coding for a translocator of the ABC transporter family, a gene pepP coding for a serine protease and two genes pepB and pepC coding for putative modification enzymes; the gene arrangement is pepTIAPBC. We analyzed the biosynthetic genes with respect to their function in Pep5 biosynthesis. Deletion of PepT reduced Pep5 production to about 10%, indicating that it can be partially replaced by other host-encoded translocators. Inactivation of PepP by site-directed mutagenesis of the active-site His residue resulted in production of incorrectly processed Pep5 fragments with strongly reduced antimicrobial activity. Deletion of pepB and pepC leads to accumulation of Pep5 prepeptide in the cells without excretion of processed peptide. A pepC-deletion clone did not excrete correctly matured Pep5 but it did produce fragments from which serine and threonine were absent. Only one of these fragments contained a single lanthionine residue out of three expected while the remaining, unmodified cysteine residues could be detected by reaction with Ellman's reagent. These results demonstrate that PepC is a thioether-forming protein and strongly suggest that PepB is responsible for dehydration of serine and threonine

Description: Tubificid and enchytraeid oligochaetes are common members of the interstitial fauna of sandy beaches. Their abundance dynamics, life cycles and distribution patterns were investigated at two beaches on the western Baltic Sea and at a North Sea beach (Isle of Sylt). Populations of 115,000 ind./m2 were found at protected Baltic beaches. Reproduction of the tubificids, Phallodrilus monospermathecus and Spiridion insigne takes place within a well defined breeding period once a year. The market horizontal and vertical distribution patterns of various tubificid and enchytraeid species are elucidated by preference reactions to several physiographic parameters, such as oxygen and water content of the sediment, and salinity.

Description: The aim of this study was to evaluate the potential of a compound diet as a live prey substitute for feeding European sea bass larvae (Dicentrarchus labrax L.). The effect of a commercial diet (Nippai ML feed) and live prey (Artemia nauplii) on tryptic enzyme activity, protein content, growth (standard length) and survival rates of sea bass larvae were tested during a 27-day rearing experiment. Sea bass larvae were divided into two groups. The live food group (control group) was fed exclusively on newly hatched Artemia nauplii (Inve AF grade), the test group was fed exclusively with the compound diet from day 15 onwards. As trypsin has been demonstrated to be a useful indicator for evaluating digestibility of food and the nutritional condition of fish larvae, individual tryptic enzyme activity was determined in both feeding groups. Larvae older than 14 days after hatching and fed on live food showed a significantly higher tryptic enzyme activity than larvae fed the compound diet. A similar relationship between tryptic activity and standard length in both test groups was detected only in small larvae (standard length 〈 7 mm). The usefulness of proteolytic enzyme activity measurements in larval fish research, as well as its use in aquaculture nutrition research, was confirmed. Protein content, increase in length and survival rates of the sea bass larvae were additionally determined in order to evaluate an influence on the diet. The protein content of larvae fed the Artemia nauplii was higher and the growth of larvae fed the compound diet was reduced. Larval mortality was not affected by the diet given.

Description: Microalgal biovolume is commonly calculated to assess the relative abundance (as biomass or carbon) of co‐occurring algae varying in shape and/or size. However, a standardized set of equations for biovolume calculations from microscopically measured linear dimensions that includes the entire range of microalgal shapes is not available yet. In comparison with automated methods, the use of microscopical measurements allows high taxonomic resolution, up to the species level, and has fewer sources of error. We present a set of geometric shapes and mathematical equations for calculating biovolumes of 〉850 pelagic and benthic marine and freshwater microalgal genera. The equations are designed to minimize the effort of microscopic measurement. The similarities and differences between our proposal for standardization and previously published proposals are discussed and recommendations for quality standards given.

Description: We have prevously shown that a marine chlorophyte expressed flavodoxin under iron limitation but not under other nutrient stress conditions. Here we use polyclonal antiserum raised against the diatom Phaeodactylum tricornutum Bohlin to show that a similar response is observed in this species. Using our antibody, western blotting techniques, and standard colorimetric detection (4‐chloro‐1‐naphthol), we can detect at least a 25–50‐fold increase in flavodoxin in iron‐depleted compared to iron‐replete cells. In iron‐limited batch cultures of P. tricornulum, flavodoxin accumulation was inversely proportional to growth rate and was not detectable in cultures containing initially more than 750 nm of iron. We demonstrated that the accumulation of flavodoxin under iron stress is widespread among marine diatoms and that it may be possible to use the presence or absence of flavodoxin in natural marine diatom assemblages to detect iron limitation. However, our polyclonal antisera appears to be specific for diatoms and did not cross‐react with Synechococcus sp., Micromonas pusilla (Butcher) Manton et Parke, Dunaliella tertiolecta Butcher, Chlorella sp., Emiliania huxleii (Lohm.) Hay et Parke, or Isochrysis galbana Parke. A reverse bioassay experiment was conducted with natural phytoplankton assemblages containing mainly diatoms from Long Island Sound and in shelf waters near Cape Hatteras, two areas not suspected to be iron‐limited. Although flavodoxin was not detected in situ in these areas, natural populations of diatoms driven into iron limitation expres.sed flavodoxin. Flavodoxin was detected in mats of the diatom Rhizosolenia castracanei Cleve collected from the Equatorial Pacific during a JGOFS cruise in 1992, consistent with the hypothesis that iron may be limiting in this high‐nutrient, low‐chlorophyll region.

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: Various discretization methods exist for the numerical simulation of multiphase flow in porous media. In this paper, two methods are introduced and analyzed—a full-upwind Galerkin method which belongs to the classical finite element methods, and a mixed-hybrid finite element method based on an implicit pressure–explicit saturation (IMPES) approach. Both methods are derived from the governing equations of two-phase flow. Their discretization concepts are compared in detail. Their efficiency is discussed using several examples.

Description: Current methods for the replacement of skeletal tissue in general involve the use of autografts or allografts. There are considerable drawbacks in the use of either of these tissues. In an effort to provide an alternative to traditional graft materials, a degradable 3-dimensional (3-D) osteoblast cell–polymer matrix was designed as a construct for skeletal tissue regeneration. A degradable amino acid containing polymer, poly[(methylphenoxy)(ethyl glycinato) phosphazene], was synthesized and a 3-D matrix system was prepared using a salt leaching technique. This 3-D polyphosphazene polymer matrix system, 3-D-PHOS, was then seeded with osteoblast cells for the creation of a cell–polymer matrix material. The 3-D-PHOS matrix possessed an average pore diameter of 165 μm. Environmental scanning electron microscopy revealed a reconnecting porous network throughout the polymer with an even distribution of pores over the surface of the matrix. Osteoblast cells were found attached and grew on the 3-D-PHOS at a steady rate throughout the 21-day period studied in vitro, in contrast to osteoblast growth kinetics on similar, but 2-D polyphosphazene matrices, that showed a decline in cell growth after 7 days. Characterization of 3-D-PHOS osteoblast-polymer matrices by light microscopy revealed cells growing within the pores as well as on surface of the polymer as early as day 1. This novel porous 3-D-PHOS matrix may be suitable for use as a bioerodible scaffold for regeneration of skeletal tissue.

Description: Methods for analysing fish stomach contents are listed and critically assessed with a view to their suitability for determining dietary importance—this term is defined. Difficulties in the application of these methods are discussed and, where appropriate, alternative approaches proposed. Modifications which have practical value are also considered. The necessity of linking measurements of dietary importance to stomach capacity is emphasized and the effects of differential digestion upon interpretation of stomach contents outlined. The best measure of dietary importance is proposed as one where both the amount and bulk of a food category are recorded.

Description: At the sub-Antarctic island of South Georgia 25 of the 29 breeding species are seabirds. Fifteen of these have recently been studied in some detail. By examining the timing of their breeding seasons and their diet and feeding ecology (especially feeding techniques and potential foraging ranges), the nature of their ecological isolating mechanisms, and in particular the way in which they partition the resources of the marine environment, are reviewed. Although breeding season adaptations occur (winter breeding in Wandering Albatross and King Penguin; out of phase breeding in two species-pairs of small petrels) these are less important than dillerences in food and feeding ecology. There is a fundamental distinction between the niche of pursuit-diving species (mainly penguins) and the remainder which are basically surface-feeders. The two abundant krill-eating penguins show clear differences in feeding zones. Three albatrosses and a petrel feed mainly on squid and there are differences in both the species and size of the prey of each. The remaining seabirds chiefly take krill (although the giant petrels are extensive scavengers and some smaller petrels specialize on copepods) and utilize different feeding methods and areas to do so. Various adaptations related to inshore and offshore feeding zones are discussed. Although most species possess a combination of ecological isolating mechanisms additional evidence for the particular importance of dietary differences is presented.

Description: A population dynamics analysis for planktonic diatoms is presented that allows estimates of the net rate of increase (k), the death rate (δ), the sedimentation rate (σ) and, in absence of grazing, the growth rate (μ). It requires counts of live and dead cells suspended in the euphotic part of the water column and accumulated in sedimentation traps. The application of the model is demonstrated for the three dominant summe diatom species in Lake Constance. Asterionella formosa Hass, Fragilaria crotonensis Kitton and Stephanodiscus binderanus Krieger. Only during the first two weeks of the summer bloom of diatoms the loss rates were unimportant in comparison to the growth rates. Thereafter diatom population dynamics was strongly influenced by sedimentation and mortality, which sometimes led to a decrease in population density even when cell division continued at high rates. There were two periods of extraordinarily high death rates, which were associated in the case of A. formosa with silicon depletion and in the case of F crotensis with fungal parasitism.

Description: The germination of spores of the endophytic brown algae Laminariocolax aecidioides and Laminarionema elsbetiae (Ectocarpales sensu lato) on their host Laminaria saccharina was studied using scanning electron microscopy. Zoids were the infective units in both taxa. Despite a large difference in size between spores of the species studied, the initial steps of infection were similar. Zoids settled on the host surface, and during secretion of adhesive material from their anterior end, the spores became elongated to rod-shaped and stood erect on the host. A single germ tube developed at the proximal end and penetrated the intact surface of the host. Sharp edges around the entrance hole and the absence of inward deformation of the host surface around the settled zoids suggest an enzymatic rather than a mechanical penetration mechanism.

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: Mesozooplankton production was estimated by using a new sampling technique and two alternative calculation methods. In essence, production estimates are based on significantly higher abundances. The contribution of juvenile stages to copepod and fish dynamics was generally low, so that the omission of juvenile stages in budgets will result in a small error. The situations reported in this study present a unique food web szenario, which in detail, however, was strongly dependent on methodology. Furthermore, relations between trophic levels were considered with respect to vertical distribution.

Description: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option

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: Seismic refraction velocity data from the acoustic basement (called layer 2A) have been compiled for different mid-ocean ridges. The data from post-1970 studies show a strong correlation between velocity and basement age. Importantly, velocities double in less than 10 Myr for all ridges, but for older crust, up to 160 Myr in age, velocities do not increase significantly.

Description: Broadband receiver functions developed from teleseismic P waveforms recorded on the midperiod passband of Regional Seismic Test Network station RSCP are inverted for vertical velocity structure beneath the Cumberland Plateau, Tennessee. The detailed broadband receiver functions are obtained by stacking source‐equalized horizontal components of teleseismic P waveforms. The resulting receiver functions are most sensitive to the shear velocity structure near the station. A time domain inversion routine utilizes the radial receiver function to determine this structure assuming a crustal model parameterized by many thin, flat‐lying, homogeneous layers. Lateral changes in structure are identified by examining azimuthal variations in the vertical structure. The results reveal significant rapid lateral changes in the midcrustal structure beneath the station that are interpreted in relation to the origin of the East Continent Gravity High located northeast of RSCP. The results from events arriving from the northeast show a high‐velocity midcrustal layer not present in results from the southeast azimuth. This velocity structure can be shown to support the idea that this feature is part of a Keweenawan rift system. Another interesting feature of the derived velocity models is the indication that the crust‐mantle boundary beneath the Cumberland Plateau is a thick, probably laminated transition zone between the depths of 40 and 55 km, a result consistent with interpretations of early refraction work in the area.

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: Records of demersal deep‐sea fish assemblages in waters around the Falkland Islands (Patagonian shelf area) are rare. Twenty deep‐water stations to the east and south of the Falkland Islands were sampled by commercial bottom trawl deployed in upper, middle and lower benthopelagic zones (depth range of approximately 500‐1000 m). Forty‐one species (22 families) of teleost fish were recorded, 10 species (two families) of elasmobranch and one species of agnathan. Different assemblages of fish were found to characterize each depth zone (e.g. Moridae in deeper waters, Bothidae and Rajidae in shallower waters), with diversity being greatest in the mid‐zone and biomass greatest in the upper and lower zones. Some species occurred in all zones but showed depth‐related abundance. Four species, namely the grenadiers Macrourus carinutus and Coelorhynchus fasciatus, the southern blue whiting Micromesistius australis, and the Patagonian toothfish Dissostichus eleginoides, accounted for 85% by weight of all fish caught. Quantitative sampling of selected species revealed depth‐related variations in their population structure. Length‐frequency analyses are presented for M. carinatus and D. eleginoides and show a tendency for larger individuals to inhabit deeper water. Discard rates from the commercial catch were sometimes high, particularly for the smaller species, raising concerns about the impact of a fishery on by‐catch species. The potential for deep‐sea fisheries in Falkland waters is discussed and further studies are suggested in the light of developing oil, gas and fishing industries. The presence of some invertebrate taxa is recorded.

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.

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: There was a seasonal biomodality in the distribution of breeding activities of King Penguins Aptenodytes patagonicus, studied from 1991 to 1994 at South Georgia, with peaks of courtship and egg-laying 2-3 months apart. The late peak was of birds that bred successfully the previous year, whereas the early peak was of birds that had failed. Successful birds were delayed because the median time for a complete breeding cycle, including moult, was 〉 14 month. Although most birds made a breeding attempt each year, none bred successfully in two consecutive seasons. Hence, in practice the cycle was biennial. The egg-laying period spanned four months but only pairs that laid within the first quarter of this period were successful. Parental quality, rather than laying date, strongly influenced the outcome of first quarter breeding attempts. No late breeding attempt was successful and why they are undertaken is unclear. At least they posed no measurable cost, either by delaying subsequent breeding or by increasing mortality; this may be important for balancing the low benefit. After the over-wintering fast the chick could be fledged by a single parent; but no sex-specific difference in invested time in the chick near to fledge was observed.

Description: When King Penguin Aptenodytes patagonicus males arrive on the breeding grounds to start courtship, their energy reserves must sustain them during a fast lasting about five weeks, including the first incubation shift. If the female is delayed in relieving the incubating male, he must make a state-dependent decision of how long to wait until abandoning the egg (i.e. breeding failure). This is ultimately a life-history trade-off between current reproduction and future survival, and includes consideration of the size of his remaining energy reserves and his ability to replenish exhausted body reserves (foraging skills). Experienced males that abandoned the egg weighed significantly less (9.49 kg) at departure than relieved males (10.43 kg), but inexperienced males abandoned the egg at a nearly significantly higher body mass (10.27 kg) than experienced males. I conclude that experienced birds can compensate for lower body reserves by being more proficient foragers.

Description: Observations of small schools of squids in captivity suggested that dominance relationships among males were based upon major differences in the frequency or duration of their agonistic behavior, but staged contests showed few differences. During staged contests, squids exhibited up to 21 separate behaviors. Some contests included a complex array of visual signals and side‐by‐side posturing (Lateral Display) followed by physical contact during Fin beating. There was behavioral variability and step‐wise escalation during the contests: squids performed either 1. long sequences of visual signaling followed by Chasing and Fleeing; or 2. short sequences of visual signaling followed by physical Fin beating and ending with Chasing and Fleeing. Size influenced outcome in all contests; larger males were more likely to win the contest. Size had no effect on contest duration, but contest duration was shorter when resource value was high, especially when a male established temporary ownership of a female. We speculate that when the perceived resource value is high, male squids are more likely to engage in a shorter yet riskier fighting tactic.

Description: 1. Monthly series of abundance indexes for the English Channel squid stock, based on fishery statistics of the United Kingdom (1980–93) and France (1986–96), were compared with water temperature data. The two objectives of the study were to test empirical predictive models and to analyse the stock–environment relationship at various time scales; both correlation and time-series statistical techniques were applied. Sea surface temperature (SST) showed inter-annual fluctuations and month-to-month auto-correlation in addition to the annual cycle. 2. Trends in squid landings and temperature at the annual scale were found to be related, whatever the statistical method used (moving averages, cumulative functions or regression using averaged data). 3. Variable selection applied in a ‘multi-month’ model suggested that fishing season indexes could be predicted from temperatures observed in the previous winter. The link between mild winter conditions and cohort success in winter/spring spawning species suggested that early life survival (and/or growth) was involved. This empirical model is a first step in the development of environment-predicted recruitment indexes useful for management advice. 4. Seasonal decomposition was performed on both the squid resource data and SST data in search of short-term relationships. In spite of the flexibility of the loliginid life-cycle, no significant relationship was found between squid seasonally adjusted indexes and temperature anomalies in the previous months. This underlined the conclusion that temperature effect on cohort success was not constant throughout the year.

Description: A 3 year study of the diets of breeding royal Eudyptes schlegeli and rockhopper E. chrysocome penguins was carried out at two nearby colonies on Macquarie Island. Diets of both species were dominated by euphausiids and myctophid fish, in particular Euphausia vallentini and Krefftichthys anderssoni. Prey items were those found in the region of the Polar Frontal Zone, confirming the importance of this zone to these penguins. Diets of both species before hatching of the chicks were variable between years, and differences in quantity of food brought ashore and degree of digestion of prey suggested inter-annual variation in distribution of prey resources. No dietary differences were detected in either penguin species across the breeding season, which reflected variability in diet at all stages, indicating that individual penguins foraged in separate areas. Significant differences between the two species were found, royal penguins consuming more myctophid fish and rockhopper penguins consuming more euphausiids. Differences were also found in the size class of prey items taken and the degree of digestion of food by both penguin species, indicating that prey were taken from different sectors of the ocean. It is concluded that the overlap in diet is small in individuals from these two spatially close colonies and, contrary to previous studies, indicates a separation in the resources used by both species. The contrast with previous studies is most likely a reflection of the different methods used to assess overlap and, to a lesser extent, the years and colonies in which the comparisons were made.

Description: Mastigophora brevipinnis Owen, 1856, is a ‘fossil teuthid’ presently considered to be a member of the coleoid cephalopod Suborder Loligosepiina Jeletzky, which in turn has been placed by various authors in or near the Vampyromorpha Grimpe. Recent morphological and biochemical analyses indicate that vampyromorphs are more closely related to the Octopoda than to the Decapodiformes. Fossils of Mastigophora from the Oxford Clay (Jurassic: Callovian) show soft-tissue preservation and evidence of arm crown specialization. Some of these fossils have up to eight short, thick arms with circular sucker-like structures and filiform distal extensions, plus what appear to be the bases of two thinner ventrolateral arms. The latter lack proximal suckers and curve medially to insert into the arm crown, similar to the tentacles that are the modified ventrolateral arms of living squids and cuttlefishes. This suggests that the thinner structures were decapod-like tentacles. If Mastigophora had tentacles homologous with those of modern decapods, then it was a decapod, because this synapomorphy defines the Decapodiformes. This indication of decapod affinities for Mastigophora brings into question the relationships of the other ‘fossil teuthids’. The inferred relationship of the Loligosepiina, including Mastigophora, with the Vampyromorpha, based largely on similarities of gladius morphology with that of living Vampyroteuthis, may reflect shared plesiomorphic characters.

Description: The filaria Litomosoides sigmodontis, which develops a patent infection in BALB/c mice, was used to determine the fate of a challenge inoculum following immunization of mice with irradiation attenuated infective larvae (3 subcutaneous inoculations at weekly intervals with 25 L3 irradiated at 60 krad, and challenge with 25 L3 two weeks after the final immunization). The adult worm burden of vaccinated mice was reduced to 50% of that of controls although the pattern of larval migration and microfilaraemia were not affected. Necropsies showed that the increased killing of the filariae of the challenge inoculum occurred at the L3 stage within the first 2 days of challenge. This result draws attention on the protective mechanisms operating very early and probably in the subcutaneous region.

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: Three time series of pelagic bird abundance collected in disparate portions of the California Current reveal a 90% decline in Sooty Shearwater (Puffinus griseus) abundance between 1987 and 1994. This decline is negatively correlated with a concurrent rise in sea‐surface temperatures; Sooty Shearwaters have declined while sea temperatures have risen. There is a nine‐month lag in the response by shearwaters to changing temperatures. The geographical scale of our study demonstrates that the decline of Sooty Shearwaters is not a localized phenomenon, nor can it be ascribed to a short‐term distributional shift. The Sooty Shearwater is the numerically dominant species of the California Current System (CCS) in summer (austral winter), with an estimated population in the late 1970s of 5 million individuals. If the observed warming of the waters of the California Current System is an irreversible manifestation of a changing global climate, then the impact upon Sooty Shearwater populations seems likely to be profound.

Description: Within the Australian-Antarctic Discordance (AAD), a boundary exists between isotopically defined “Pacific-type” and “Indian-type” mid-ocean ridge basalt (MORB) erupted along the Southeast Indian Ridge (SEIR). This boundary has migrated westward beneath the easternmost AAD spreading segment at a minimum rate of 25 mm/yr since 4 Ma; however, its long-term history remains a matter of speculation. To determine if Pacific-type upper mantle has migrated westward beneath the eastern Indian Ocean basin as Australia and Antarctica drifted apart during the last 70 m.y., we present new Sr-Nd-Pb isotope data, combined with trace element and 40Ar-39Ar radiometric age determinations, for samples from Legs 28 and 29 of the Deep Sea Drilling Project (DSDP). Basaltic basement at these DSDP sites provides a record of their upper mantle source composition and shows regional variations consistent with upper mantle flow in this region. East of the South Tasman Rise, all DSDP basalts have 87Sr/86Sr (0.7025–0.7029) and 206Pb/204Pb (18.80–19.48) ratios typical of Pacific-type MORB indicating that Pacific-type upper mantle existed east of the Australian-Antarctic continental margin and beneath the Tasman Sea during the early stages of seafloor spreading in this region. Basalts from DSDP sites west of the AAD have high 87Sr/86Sr (0.7030–0.7035), low 206Pb/204Pb (17.99–18.10) and trace element characteristics typical of present day Indian-type SEIR MORB. Between these two regions, DSDP basalts recovered along the western margin of the South Tasman Rise have isotopic characteristics that are, in one case consistent with an Indian-type MORB source (Site 280A) and, in the second case, transitional between Pacific-type and Indian-type mantle sources. The occurrence of seafloor basalts with transitional or Indian-type isotopic characteristics well to the east of the present Indian-Pacific MORB isotopic boundary within the AAD strongly implies that Pacific-type upper mantle has migrated westward into the region since the South Tasman Rise separated from Antarctica circa 40 Ma.

Description: Microsatellite DNA markers were applied for the first time in a population genetic study of a cephalopod and compared with previous estimates of genetic differentiation obtained using allozyme and mitochondrial DNA (mtDNA) markers. Levels of genetic variation detected with microsatellites were much higher than found with previous markers (mean number of alleles per locus=10.6, mean expected heterozygosity (HE)=0.79; allozyme HE=0.08; mtDNA restriction fragment length polymorphism (RFLP) HE=0.16). In agreement with previous studies, microsatellites demonstrated genetic uniformity across the population occupying the European shelf seas of the North East Atlantic, and extreme genetic differentiation of the Azores population (RST/FST=0.252/0.245; allozyme FST=0.536; mtDNA FST=0.789). In contrast to other markers, microsatellites detected more subtle, and significant, levels of differentiation between the populations of the North East Atlantic offshore banks (Rockall and Faroes) and the shelf population (RST=0.048 and 0.057). Breakdown of extensive gene flow among these populations is indicated, with hydrographic (water depth) and hydrodynamic (isolating current regimes) factors suggested as possible barriers to migration. The demonstration of genetic subdivision in an abundant, highly mobile marine invertebrate has implications for the interpretation of dispersal and population dynamics, and consequent management, of such a commercially exploited species. Relative levels of differentiation indicated by the three different marker systems, and the use of measures of differentiation (assuming different mutation models), are discussed.

Description: The diet of the white‐chinned petrel at Bird Island, South Georgia was studied during chickrearing in 1986 by quantitative analysis (by weight, frequency of occurrence and number of individuals) of regurgitated or lavaged adult stomach contents. Antarctic krill comprised over 90% of prey items and formed 47% of the diet by weight; fish and squid occurred in 67% and 35% of samples and formed 33% and 19% of the diet by weight, respectively. Decapods, amphipods and salps occurred in a few samples. The fish were mainly lanternfish (Myctophidae) of eight species (chiefly Electrona and Gymnoscopelus, forming 80% by number and 52% by mass of fish prey) and the nototheniid Patagonotothen guntheri (14% by number and 35% by mass). Of squid taken, the ommastrephid Martialia hyadesi comprised 57% by number and 52% by mass and the gonatid Gonatus antarcticus 14% by number and 42% by mass. These dietary data confirm white‐chinned petrel as the most important avian consumer of fish and squid at South Georgia (and the third most important consumer of krill). In 1986 the nototheniid fish were probably obtained via commercial fishing operations but the myctophids and squid were probably live‐caught, most likely at night. Meal size increased rapidly until chicks were three weeks old and then remained constant until the chicks were within 10 days of fledging, when it decreased. Meal delivery rate was high (one per day) for young chicks (1–10 days old) and thereafter fluctuated between 0.56 and 0.88 meals per day until close to fledging, when it was halved. These provisioning rates, and the proportion of krill in the diet, are higher than those recorded previously at South Georgia and Indian Ocean sites, probably reflecting high local availability of krill at South Georgia in 1986. In many respects, white‐chinned petrels at South Georgia are intermediate ecologically between prions and albatrosses, although specialized in their extensive consumption of myctophids. Because krill and all the main fish prey are currently the targets of substantial commercial fishing and the main squid prey (Martialia) is a potential target, the ecological role and status of white‐chinned petrels are of additional importance.

Description: Models of the giant squid (Architeuthis spp.) are probably unique in natural history exhibition: they are representations of a giant living animal that has never been seen in a healthy state by a human being. Since its discovery in the mid‐nineteenth century, the giant squid has remained one of the world's great zoological mysteries. In the attempt to introduce this fabulous creature, museums around the world have resorted to life‐sized models. Yale teuthologist A.E. Verrill was responsible for the first such models in 1882; then Ward's Natural Science Establishment in Rochester, New York, manufactured and sold them. In this century, various museums (and one zoo) have made their own models of these ten‐armed monsters of the deep. Their disparate attempts to re‐create Architeuthis for the museum public represent one of the most intriguing case histories in the annals of museum exhibition.

Description: Strong latitudinal gradients in species composition were revealed by two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA) of 41 species of epipelagic fishes and squids in 513 gillnet collections by research vessels of Hokkaido University over a huge area of the northern North Pacific during the summers of 1978-1993. Salmonids inhabited northern subarctic water and skipjack tuna (Euthynnus pelamis) and flying squid (Ommastrephes bartrami) inhabited the regon of the Subarctic Boundary, but distinct boundaries between species groups and sample groups were lacking, largely because abundant species, such as Pacific saury (Cololabis saira) and Pacific pomfret (Brama japonica), migrated across most of this region during the summer. Longitudinal differences were not pronounced, but some species, including Japanese sardine (Sardinops melanosticus) and Japanese anchovy (Engraulis japonicus), were only found in the western pacific. Pacific saury was more common in the western Pacific, whereas sockeye samlon (Oncorhynchus nerka) was concentrated in the eastern Pacific. Interannual flucuations in the latitude of species groups were most closely correlated with changes in sea surface temperatures. In the western Pacific, 1982, 1983, 1985, 1987-88, and 1992-93 were cool years when subarctic and transitional assemblages were found farther to the south than other years. Temperature and silinity at various depths were highly correlatied with each other with first-axis DCA ordinations scores. Long-term trends in community structure were not apparent during the 1.6 decades.

Description: Oxides of Fe and Mn in soils are capable of sorbing large amounts of trace metal ions and can therefore be important in controlling trace metal concentrations in soil solution, and hence trace metal bioavailability in soils. There is, however, relatively little information on the rates of desorption of trace metals from oxide materials or on the factors affecting desorption rates. The objective of this study was to examine the kinetics of desorption of Cd and Co from two Fe oxides, goethite and ferrihydrite, and from two Mn oxides, hausmannite and cryptomelane. The concentrations of Cd and Co specifically sorbed by the oxides at pH 6.0 were greater for the Mn oxides than for the Fe oxides. The metals were also much less readily desorbed from the Mn than the Fe oxides and, in general, Cd was more readily desorbed than Co from all four oxides. Increasing the initial sorption period from 1 to 15 wk substantially decreased the proportion of sorbed Cd or Co subsequently desorbed from goethite, with a similar but much smaller effect also observed with the Mn oxides. Desorption kinetics for both Cd and Co were found to be described well by assuming either the occurrence of two simultaneous first-order desorption reactions, or by a continuous distribution of reaction sites, distributed lognormally with respect to desorption first-order rate constant. With increasing initial sorption period, the parameters obtained from fitting either type of kinetic equation to the experimental data could be interpreted as indicating a movement of metal ions to sites with slower desorption reactions.

Description: Benthic microalgae and the herbivores Idothea chelipes (Isopoda) and Littorina littorea (Gastropoda) were used as an experimental model system to study the effect of herbivore type on primary producer diversity. Both herbivores enhanced diversity at intermediate grazing pressures, the enhancing effect being stronger with Littorina. This difference is explained by differences in the spatial heterogeneity of the grazed microalgal biofilm caused by behavioural differences in spatial grazing patterns. Idothea spreads its grazing pressure rather evenly in space (“lawn-mower” type), whereas Littorina creates pronounced spatial heterogeneity by moving slowly over the biofilm and decimating it within the grazing tracks (“bulldozer” type). Idothea grazing did not enhance biomass patchiness beyond the level of ungrazed controls (maximum/minimum from 1.7 to 5.5), whereas Littorina strongly increased patchiness (maximum/minimum from 45 to 850).

Description: Despite recognition that Fe availability is significant in regulating oceanic production in some regions, the biogeochemistry of this trace element is poorly understood. To complement contemporary methods of analytical chemistry, we have used an immunological approach to monitor theFenutrition of marine phytoplankton. In prokaryotes and numerous microalgae, the redox catalyst ferredoxin is functionally replaced by flavodoxin during periods of Fe deficiency. In this study, antibodies were raised against ferredoxin purified from a marine diatom, and their utility as a diagnostic indicator was assessed. A species survey demonstrated broad reactivity with both pennate and centric diatoms and additionally with several nondiatom taxa. In batch cultures of the diatom Phaeodactylum tricornutum Bohlin, in which Fe levels were varied, accumulation of ferredoxin varied with the physiological state of the culture; in unimpaired cells (Fv/Fm $ 0.65), ferredoxin levels were high, whereas levels dropped markedly in cells experiencing even slight photochemical impairment. Accumulation of flavodoxin varied inversely with that of ferredoxin. An experiment was performed to demonstrate the temporal pattern of accumulation of ferredoxin upon recovery from Fe limitation. Prior to Fe amendment,cells were physiologically impaired (chlorotic, Fv/Fm , 0.3) and contained flavodoxin but no detectable ferredoxin. Following addition of Fe, constraints on photochemistry were relaxed within hours. Coinciding with this, levels of flavodoxin declined, whereas ferredoxin was accumulated to high levels within 8 h.

Description: Three arrays of ocean bottom seismographs have been deployed to study the seismicity at the northern end of the Juan de Fuca ridge system off western Canada. Nearly 100 events were located with estimated accuracies generally better than ±10 km, all lying on or near the en echalon ridge-transform fault plate boundaries as defined in this area by the magnetic anomalies, the seafloor morphology and by other geophysical data. The depths of 12 events were determined to lie between 2 and 6 km below the top of the crust. The seismograms exhibit clear P and S wave arrivals along with phases that involve P to S and sometimes S to P conversion probably at the base of the sediments beneath the instruments. The event magnitudes have been estimated from signal duration using four calibration events that were well recorded by a land station. The magnitude estimates permit the determination of rough magnitude-frequency of occurrence relations over the magnitude range of 1 to 3 that are in surprisingly good agreement with the recurrence relations for the area at larger magnitudes from 75 years of land station data. The mean P wave velocity in the uppermost mantle from the earthquake data recorded by the sea floor arrays is 7.6 km s-1 and the mean Vp/Vs ratio is 1.71 or a Poisson's ratio of 0.24.

Description: Periphyton was grown on transparent plastic substrata in the Kiel Fjord and used for short-term laboratory experiments to study the feeding selectivity of the periwinkle Littorina littorea in response to the vertical structure of the periphyton. The susceptibility of algae to periwinkle grazing was assessed by comparing the species-specific biomass within the grazing tracks of the snails to the biomass outside the tracks. After 3 weeks of incubation, the periphyton consisted of a scattered monolayer of algal cells without vertical structure. No apparent grazing could be found. After 6 weeks of incubation, periphyton consisted of a tightly attached undergrowth (mainly Cocconeis scutellum, Bacillariophyceae, and Myrionema sp., Phaeophyceae) and canopy of filamentous (Melosira moniliformis, Bacillariophyceae) and stalked forms (Achnanthes longipes, Bacillariophyceae). The unicellular diatoms Fragilaria tabulata and Stauroneis constricta grew partly on the primary substratum and partly as epiphytes on the canopy species. The canopy species and the epiphytes were decimated inside the grazing tracks, while the tightly attached undergrowth species appeared ungrazed.