Oceanographic Abstratcs 1033

BRACONNOT JEAN-CLAUDE, 1964. Sur le dhvelopment de la larve de Doliolum denticulatum Q et G. C. n. hebd. Sdanc. Acad. Sci., Paris, 259 (23): 4361-4365.

Pour la premiere lois la larve de Doliolum denticulatum a pu 8tre obtenue et 4levhe en laboratoire. Cette larve est tout "a fait diffdrente de celle qui est attribu6e habituellement "a cette esphce.

BRAUNSS G., 1965. Some remarks on gravitational interaction and gravitational waves. Z. Naturyl, 20a (4): 495-497.

A brief consideration of the problem of gravitational waves is given on the basis of the following assumption : The components of the metric tensor are functionals of a field by which, in the sense of HEISENBeRG'S nonlinear theory, all other fields resp. the corresponding interactions can be deduced. For the sake of mathematical simplicity a scalar field q~ (non-charged bosons) is considered instead of a spinor field. The condition gmn " gmn (4) resp. Rmn Rmn (4) leads to the statement that the concept of a free gravitational wave, i.e. a wave which is a solution of Rmn ~ 0 or Rklmn ~ O, cannot be accepted. A free wave is here by definition a wave which is so far from the origin that one can neglect in the field eqs. all terms which represent a strong interaction. A comparison with a spinor field leads, with regard to this definition, to the conclusion that a free wave may be considered as a neutrino wave and gravitation as the weakest interaction possible of neutrino fields.

BRISOU J., C. TYSSET, Y. DE RAUTL1N DE t.A ROY, R. CURCleR and R. MOREAU, 1964. l~tude sur la chitinolyse en milieu marin. Annls. Inst. Pasteur, Paris, 106 (3): 469-478.

The presence of chitinolytic bacteria in sea-water is well known, but their distribution and the relation- ships between this distribution and ecology have not so far been defined. The authors' paper is a further contribution to our knowledge of this very specialized sea-water microflora, which depends upon the geographical conditions, the climates and the nature of the animal population of the areas studied.

The selective part played by certain animals is unquestionable. Gram-negative bacteria, par- ticularly vibrios, Pseudomonas, are by far the richest ones in enzymes able to destroy chitin.

BROENKOW WILLIAM W., 1965. The distribution of nutrients in the Costa Rica Dome in the eastern tropical Pacific Ocean. Limnol. Oceanogr. 10 (1): 40-52. The distributions of salinity, dissolved oxygen, phosphate, nitrate, and silicate in the Costa Rica Dome are described from data collected during the Costa Rica Dome cruise November-December 1959. The dome is an area where nutrient-rich, oxygen-poor water is brought to the surface by upwelling.

The ratios of change of oxygen, phosphate, and nitrate are computed statistically from the observed data to 1,100 m depth.

A simple mixing model is used to explain the observed vertical distribution of oxygen above 65 m when allowances are made for photosynthetic oxygen production. The contributions of oxygen from various sources are estimated by use of tfie model. A similar model is used to compute the ratios in which nutrients are assimilated by phytoplankton.

BRUCKNER W. D. and H. J. MORGAN, 1964. Heavy mineral distribution on the continental shelf off Accra, Ghana, West Africa. In: Det, elopments in Sedimentolog)', L.M.J.U. Van Straatan, Editor, Elsevier Publishing Co., 1 : 54-61.

A quantitative study of the heavy minerals in sea bottom samples taken along a line across the continental shelf off Accra shows that their distribution on the inner shelf is governed by their specific gravities, the heavier minerals decreasing in quantity more rapidly outwards than the lighter ones, whereas their abundances on the outer shelf are closely related to those of the underlying (Pleistocene ?) rock, which has been amply reworked. The non-opaque heavies derived from the coast appear to indicate transportation in a west to southwest direction, opposite to the flow of the Guinea current which predominates at the surface of the sea.

BUCHANAN J. B., 1963. The bottom fauna communities and their sediment relationships off the coast of Northumberland. Oikos, 14 (2): 154-175. The distribution of the benthic communities and the bottom sediments is given for an area of 750 sq. mi. off the Northumberland coast. Three communities are recognised and their constitution is quantitatively described together with their variations. These are : (1) Amphiura filiformis - Amphiura chiajei community which in this area can be split into two sub-communities, one charac- terised by A. filiformis, which has four recognisable variations, and the other by A. chiaiei. (2) The Haploops tubicola community. (3) The Venus striatula community.

The communities are shown to be poorly correlated with the texture of the bottom sediments. When the sediments of the various associations are compared it is found that there is very broad overlapping of conditions which is not associated with a similar mixing of the fauna. Also similar sediments are shown to contain very different faunas.

The unreliability of sediment analysis as a guide to ecological conditions is discussed.