Deep current measurements near Bermuda

Deep current measurements near Bermuda

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346

t L;caiiographic .-\ bslra~;i.,,

with a longer average life span and lower proiiiicity fluctuations are o f more limited rdl;gc, of torige~

period, and are more sensible to overfishing. The importance of year classes, assumed so far to be random, in fact may be related to ccrtail; factors. The problem is difficult, and the method of multiple regression does not always lead to a correct prediction, Some clues are given by the existence of exceptional years, and also by the eventual synchronization of fluctuations in different places. The evidence furnished is meagre but points t~ plankton production, and hence to the availability and abundance of food as a major cause of fluctuation. Since inertia of seas can transform irregular yearly inputs and outputs of heat into more or less regular fluctuations by autoregression, the possible synchronization of short-term fluctuationmay be accepted. These fluctuations are superimposed on slower changes common to widely separated areas, and due to general modifications in the physical properties or seas. Spawning takes place when water conditions are suitable for the future brood. A ceriai, amoul~t of hydrographic heterogeneity is observed, but the timing mechanism is not understood Occasion~! lack of synchronization may be a supplementary cause of variations in the stock. Availability is related to changes in the internal distribution of the elements of the ccosystc~ Fishing techniques have developed so that in pelagic fishes availability is proportional to shoaling propensity. Shoaling is certainly related to feeding reactions and to small scale heterogeneity in the distribution of physical properties of water and of plankton, but only scanty direct evidence i~: available. MATSUMOIO, S., 1962. On some instability properties of multi-level geostrophi~: models

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Met. Soc. Japan. Ser. It, 40 (2): 116-125. Instability properties were compared among multi-level geostrophic models with ~artous number of freedom, to obtain some information on the number of levels at which the baroclinic development is well forecast within the hierarchy of quasi-geostrophic models. The growth rate is primarily a function of applied static stability and is not affected very much by the interaction between layers. The effect of a horizontal gradient of static stability was also studied numerically and the conic× type distribution of the vertical profile of zonal flow was shown to have a destabilizing effect ;w~ certain type of disturbances. A multiple parametric resolution is compared with corresponding multiple level rcsoltitiol'.. McALLISTER, R. Iz., 1962. Deep current measurements near Bermuda.

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lnstrum. Sot., Amer., Plenum Press, N.Y., l : 210-222. It has been customary for years to measure deep ocean currents indirectly, deducing them from dynamic topography. More recently the jog-log, parachute drogues and neutral density floats, along with anchored buoy recording stations, have been used. All of these methods suffer from the same difficulty : they filter out high frequency fluctuations in current speed and direction, either by the long time between successive recordings, by mechanical filtering due to the long connecting line to the surface, or by the difficulty in obtaining accurate geographic location. This is not to say that these are not excellent methods of measuring currents, but rather that they could not satisfy the objectives of this study, for which a continuous recording current meter with a high speed of response to current changes was needed. This report details the meter developed and some of the interesting results achieved. McLooN, C., 1962. The problems of reliable long-range transmission of remote oceanographic measurements, Mar. Sci. Instrum., lnstrum. Soc., .,Inter., Plenum Press, N.Y., 1:61--~64 Data telemetry transmission falls basically into two categories : line-of-sight and beyond-line-ofsight. When the transition to long range is made, entirely new telemetry techniques are required. This paper describes the problems involved with long range telemetry, together with some state-of the-art solutions. MENZIF.21, R. J., 1962. The Isopods of abyssal depths in the Atlantic Ocean. Abyssal Crustacea.

Vema Research Series. Columbia Univ. Press, New York and London, No. 1 : 7 9 - 2 0 6 In this monograph 176 species are described. Prior to this work only 66 species were known from the Arctic-Atlantic below 2000 meters and only 143 were known from the abyss of the world oceans, excluding probably pelagic species. This means that the results of this work based upon 84 abyssal trawl samples taken by the R. V. Vema and M. V. Theta increase by roughly one-fifth the number of abyssal species known for the entire world in the order lsopoda. The number of species from the Atlantic, where the fauna was best known previously, is increased by over two times. One hundred and seven new species are described from the Atlantic abyss and near abyss for the first time. Species new to the abyss but previously known elsewhere, are Antennuloniscus dimeroceras (Barnard), Stylomesus inermis (Vanh0ffen), Nannoniscus oblongus G. O. Sars, Eurycope antarctica VanhOffen, and Eurycope vicarius VanhOffen. Additionally five species previously recorded from the Atlantic abyss are excluded from this monograph due to the fact that they are too poorly known. These are Eurycope abyssicola Beddard, Acanthocope acutispina Beddard, Eurycope sp., Ischnomesus bacillus Beddard, and Storthyngura fragilis (Beddard). The list of the new species is contained in the table of contents. A total o f nine new genera is described. These are Antennuloniscus (formerly part Haploniscusj, Dendromunna, Spinianirelta, Notoxenoides, Xostyhts, Abyssijaera, Mesosignum, Glabroserolis, and Vemathambema. This brings the known abyssal Atlantic genera to 41 when one adds the five genera