ALBERT

Description: An estimate of average river particulate matter (RPM) composition was bàsed on analyses of more than 40 elements in the Amazon, Congo, Ganges, Magdalena, Mekong, Parana and Orinoco rivers, to which were added literature data for 13 other major world rivers, covering the whole spectrum of morphoclimatic features. Geographic variations of major elements in RPM are mostly linked to weathering types and to the balance between weathering rate and river transport. As a result of chemical erosion, Al, Fe and Ti are enriched in RPM with respect to the average parent rock, while Na, Ca, Mg and Sr are strongly depleted. These figures are directly related to the relative importance of dissolved and particulate transport in rivers; this has been computed for each of 40 elements. In order to study weathering on a global scale, the total observed elemental fluxes (dissolved + particulate) have been computed and compared to theoretical ones. The latter were derived from the elemental content in the average parent rock and the total quantity of weathered material, computed from the Al ratio in RPM and in parent rock. Observed and theoretical fluxes are balanced for the less mobilized elements (rare earths, Co, Cr, Cs, Fe, Mn, Rb, Si, Th, Ti, U and V) for which no enrichment relative to Al is noted in RPM, and for B, Ba, Ca, K, Mg, Na, Sr which are relatively depleted in RPM due to their high dissolved transport. Additional fluxes have been found for Br, Sb, Pb, Cu, Mo, Zn and are possible also for Ni and P. This is reflected by marked enrichments in RPM relative to Al for the poorly or moderately dissolved transports (Pb, Cu, Zn). Several hypotheses involving either the natural origin (volcanic dust, marine aerosols, geochemical fractionation) or the artificial origin (worldwide pollution) are discussed to explain these discrepancies, assuming river transport and weathering either to be in a steady state on a global scale or not. However, none of them can fully account for these additional fluxes. It is most likely that these excesses have multiple origins, anthropogenic or natural or both. The comparison between RPM and deep-sea clay compositions emphasizes the prime influence of river input on oceanic sedimentation of Si, Al, Fe, Ti, lanthanides, Sc, Rb, V, etc. A few elements such as Zn, Sb, occur in excess in RPM as compared to deep-sea clays; in order to balance this excess, a remobilization of these elements out of the sediment can be considered. Finally, the enrichment of Co, Cu, Mn and Ni in deep-sea clays compared to RPM is discussed and attributed to several sources and processes.

Description: This chapter discusses the Maillard reaction. Results of the many investigations into the mechanism of the Maillard reaction support one of two main theories. The first assumes the formation of glycosylamines that undergo the Amadori (or, for ketoses, the Heyns) rearrangement. The 1-amino-l-deoxyketose derivative (or 2-amino-2-de- oxyaldose derivative) formed may be dehydrated and cyclized to form furan derivatives, or it may enolize. In either case, intermediates that are readily transformed into brown compounds are formed. A third possibility is for the deoxy sugar derivative to react with more amino acid to form colored products. The many workers who have supported this mechanism found also that optimum conditions for occurrence of the Maillard reaction are (1) fairly low water content, (2) a pH of 7 to 10, and (3) a high temperature. Nevertheless, some reaction occurs under conditions far removed from these, but in the absence of moisture there is no reaction. The formation of an acyclic Schiff base as an initial step is not very likely, since replacement of the aldose by salicylaldehyde caused only a very small loss of amino groups. The second theory of the mechanism of the browning reaction is of recent origin and maintains that the browning reaction and the Maillard reaction are separate and distinct. Browning, according to this school of thought, is due to the effect of pH on the sugar and can occur over a wide range of pH, whereas the Maillard reaction proceeds only in alkaline media.

Description: Several types of abyssal bedforms have been discovered during surveys with a deeply towed instrument package at water depths of 1.5–6 km in the Pacific and Atlantic Oceans. Cores and current-meter records obtained at the same sites provide data for interpreting their dynamics. Wave and current ripples are best portrayed in bottom photographs, but medium-scale bedforms, including sand waves, mud waves and erosional furrows, are described by interpreting high-resolution side-looking sonar records. The largest examples affect surface-ship echograms, though their shape and structure can seldom be resolved without near-bottom observations. Wave ripples are common on the slopes of seamounts and ridges, while current ripples and sand waves occur beneath some fast thermohaline currents whose beds are shallower than the foraminiferal compensation depth. Depositional and erosional bedforms in cohesive sediment have been found beneath the deepest thermohaline currents; they may be restricted to areas where the flow is unusually steady in direction.

Description: Fourteen instances of whales entangled in submarine cables are reported. Ten entanglements occured off the Pacific coast of Central and South America. Six cases occured in about 500 fathoms, with 620 fathoms the maximum depth reported. Five entanglements occured in the period, Februray-March-April. All whales positively identified were sperm whales. The submarine cable was generally wrapped around jaw and often around the flukes and fins. The cable was rarely broken but always badly mauled. The entanglements often occured near former repairs where there is a chance for extra slack cable on the bottom. Two photographs of a sperm whale entangled in a cable and one photograph of a whale-jaw entangled in a cable are presented. It is concluded that sperm whales often swim alog the sea floor in depths as grat as 620 fathoms. It is suggested that the whales become entangled while swimming along with their jaw plowing through the sediment in search of food. It is possible that the whales attack tangled masses of slack cable mistaking them for items of food.

Description: The effects of hydrostatic pressure and dissolved oxygen concentration on oxygen consumption rates were examined in the mesopelagic, vertically migrating squid Histioteuthis heteropsis from southern California offshore waters. Elevated hydrostatic pressure (to 136 atm) had no significant effects on oxygen consumption rates at 5°C. Lox oxygen concentrations (〈0.5 ml O2 liter -1) depressed rates of oxygen consumption. These findings suggest that biosis may be necessary to supply the total nergy needs of this species at daytime depths in the oxygen minumum layer off southern California.

Description: A complete set of linearly independent relationships among the different cross spectral components obtained from pairs of moored instruments is derived which can be utilized to test whether or not the observed fluctuations within the internal wave frequency band represent a field of propagating internal waves. A further complete set of relationships is derived which enables to test whether or not the internal wave field is horizontally isotropic and (or) vertically symmetric. These relations are compared with corresponding relations for alternative models (standing internal wave modes, three-dimensional isotropic turbulence) and their capability to discriminate between the various models is investigated. The tests are applied to a set of data for which it is found that the observed fluctuations are consistent with both propagating and standing internal waves whereas isotropic turbulence must be rejected for the most part of the internal wave frequency band.

Description: This chapter discusses the carbon turnover, calcification, and growth in coral reefs. Carbon turnover within a total reef community is a function of two distinct, biochemically interacting cycles. The first is the metabolic cycle consisting of the photosynthetic fixation of CO2 and the release of CO2 by respiration and decomposition processes. Superimposed on this are the direct incorporation of organic compounds (dissolved or particulate; living or non-living) originating outside the reef systems (in the adjacent ocean waters), and the loss of organic compounds from the reef system into the out-flowing water. The second is the inorganic carbonate cycle involving the biological and non-biological precipitation and dissolution of carbonates. Superimposed on this is the loss of particulate carbonates in suspension in the out-flowing water. The main chemical component of a coral-reef system is calcium carbonate, which occurs either as high-Mg calcite, aragonite, or low-Mg calcite. The mean calcification values in various environments at One Tree Reef are presented in the chapter. These data may be converted to an implied vertical growth rate potential assuming that accrual is dominantly aragonite (density = 2.89 g cm–3) and that there is 50% porosity after normal compaction.

Description: In brackish water the variety of marine and freshwater parasite species is considerably reduced. The distribution in brackish water of most marine endoparasites is restricted by the salinity tolerance of their hosts, most of the parasite species are more tolerant than their hosts. The influence of salinity and temperature on nine species has been examined; first stage larvae of Contracaecum aduncum develop in 0-32‰ salinity; Cryptocotyle lingua proved to be infective at salinities down to 4‰. The greatest resistance was found in Anisakis larvae from herring Clupea harengus, which survived for more than half a year. Parasites in the fish intestines appear to be unaffected by changing water salinities, as the osmolarity in the intestines stays nearly constant. Marine ectoparasites (Acanthochondria depressa, Lepeophtheirus pectoralis) survive about three times longer than freshwater species (Piscicola geometra, Argulus foliaceus) when salinity is 16‰. High temperature increases the effects of adverse salinities on parasites. There is evidence that none of these ecto-parasitic species can develop within the range of 7-20‰ salinity.

Description: Using the fault plane mechanisms of the shallow earthquakes occurring along the Hellenic arc and the extent of the intermediate seismic belt, we make a quantitative estimate of the relative motion occurring between the Hellenic arc and the adjacent sea floor. This estimate is then used to evaluate the deformation in the Aegean area and to reconstruct the pattern of motion over the Eastern Mediterranean region for the last 13 m.y. It is shown that this pattern is compatible with the neotectonic and seismicity studies in Aegea. We then discuss the dynamics of the area and propose that, since Serravallian-Tortonian time, Aegea has been spreading gravitationally in front of the southwestward advancing Turkey. The reasons for this gravitational spreading are discussed.

Description: Some of the basic assumptions implied in the theory of limiting similarity of coexisting competitors were investigated experimentally in the case of three congeneric, deposit feeding snails. The species show character displacement with respect to size when coexisting. In experimental containers with a natural substrate, interspecific, exploitative competition between snails of the same size range is as intense as intraspecific competition. Diatoms of a given size range, which constitute the most important food, show a "logistic" growth response to grazing, and individual growth of the snails is linearly related to diatom density. The previous observation that the snails show size dependent selection for ingested particle sizes is extended to show that this mechanism leads to a real resource partitioning between snails of different sizes. Size frequency distribution of diatoms in the sediment is a function of the sizes of grazing snails. Size selection of ingested sand grains may also be significant for resource partitioning since the migration rate of the attached microflora between sand grains seems to be slow relative to its growth on the individual sand grains.