Effects Of Water Motion Research Articles

Effect of water motion on coral photosynthesis and calcification

Water motion effects on metabolism of a common reef-building coral, Acropora formosa Dana, were studied utilizing laboratory incubations. Net photosynthesis and respiration were significantly reduced (≈ 25% lower) in unstirred conditions compared with stirred conditions. Dark calcification was reduced by ≈60% in unstirred conditions. Light-enhanced calcification appeared to be reduced by ≈ 25% in unstirred conditions; however, this effect was not statistically significant. A possible diffusion limitation on exchange of dissolved gases was indicated by a lack of stirring effect on net photosynthesis when photosynthesis was near the light compensation point. A boundary layer of unstirred water adjacent to the surface of the animal could account for the observed metabolic responses to stirring regimes. Comparisons of water motion measured in the field with rates of water motion in the laboratory incubations indicate that coral growth and reef development are influenced by the metabolic responses of corals to water motion over and around coral reefs.

Hydrodynamic streamlining of Laminaria saccharina Lamour. in response to mechanical stress

Application of mechanical stress to laboratory-grown Laminaria saccharina Lamour. provided insight into the effects of water motion on natural populations. Plants subjected to constant longitudinal tension had significantly narrower blades and higher rates of blade elongation than plants grown with no stress. Rates of biomass production, however, were similar for the two treatment groups. Mechanical stress imposed by currents and waves, therefore, may enhance hydrodynamic streamlining by influencing thallus morphology without affecting productivity.

Minerals From the Marine Environment

The current interest in minerals centering on, among other things, potential shortages, long‐term needs, and deep seabed nodules, accentuates the usefulness and timeliness of this little book authored by a former chairman of the British National Environmental Research Council.In less than 100 pages, the author puts into perspective the potential for producing minerals from offshore areas of the world. After introducing the reader to the ocean environment and the extraordinary variety of the nature of the seabed, the author describes in some detail the variety of minerals found there. This is done in seven separate chapters entitled ‘Bulk and Non‐Metallic Minerals From the Seas’; ‘Metals From the Shallow Seas’; ‘Metals From the Deep Oceans’; ‘Minerals From Solution’; ‘Oil and Gas from the Shallow Seas’; ‘Oil and Gas From Deep Waters’; and ‘Coal Beneath the Sea.’ The remaining chapters give a brief regional review of marine minerals distribution for eight areas of significant socioeconomic structure, and a short recapitulation of special problems of mineral recovery in the marine environment including such matters as the effect of water motion on mineral processing and of international law on investments. Glossaries of geological periods and technical terms, a short list of references, and an index completethe work.

Effects of water motion on reef corals

The Hawaiian reef coral Pocillopora meandrina Dana is restricted to turbulent environments. P. damicornis (L.) is most abundant on semi-protected reefs, while Montipora verrucosa (Lamarck) is characteristic of very calm environments. These species were grown in the laboratory under various conditions of water motion. Water motion influenced the growth, mortality, and reproductive rate, of each species differently. The differences may be attributed to morphological adaptations of the corals to their normal hydrodynamic environment. Water motion appears to influence corals by controlling the rate of exchange of material across the interface between the sea water and the coral tissue.

THE EFFECT OF WATER MOTION ON ALGAL SPORE ADHESION1,2

The effects of water motion on the attachment of algal germ cells to benthic substrates were studied. Water motion was measured in the field and the forces on a germ cell attached to a substrate surface computed. Laboratory apparatus for simulating wave surge was developed, calibrated, and used for experiments on the spore attachment process. A“waterbroom,” producing water motion over the surface of a submerged substrate in a laboratory aquarium, closely simulates wave surge; it was calibrated by measuring static and dynamic pressures in the substrate’s boundary layer and determining whether the layer was laminar or turbulent.Preliminary tests with the waterbroom indicate that the adhesion of carpospores of Agardhiella tenera to a clean glass surface increases wih residence time, while that of Cryptopleura violacea decreases. Improved experimental data on Gracilariopsis sjoestedtii showed an increase in adhesiveness with residence time, from 10 hr to an asymptotic limit at 20. Once attached, the Gracilariopsis spores adhere firmly, resisting removal by shear forces nearly 100 times their weight.

On the effects of water motion on marine organisms in the mesolittoral and infralittoral zones of the Rumanian shore of the Black Sea

Abstract Water movements and their influence on marine meso- and infralittoral organisms on the Rumanian shore of the Black Sea are discussed. Marine currents distribute water from the River Danube over a wide area and alter the salinity and temperature, the nutrients, the relationship between positive and negative ions, the distribution of the water masses, transparency and colour, and the composition of the fauna and flora. It is established that wave action is the dynamic factor with the most devastating effect on meso- and infralittoral organisms on the Rumanian shore of the Black Sea. Changes in sea level, which are less important in the Black Sea, are discussed. Brief reference is also made to several other aspects of the influence of water movements on marine organisms.

A time‐sequence oceanographic investigation in the North Pacific trade‐wind zone

The Bureau of Commerical Fisheries Biological Laboratory in Honolulu initiated an oceanographic investigation to gain an understanding of the mechanisms producing changes in the properties and water masses of the trade‐wind zone of the North Pacific Ocean. The Bureau undertook this study because changes in the distribution of water masses near Hawaii directly affect the availability of skipjack tuna (Katsuwonus pelamis) in a predictable manner [Seckel, 1963]. Therefore, both for ecological studies and for predicting favorable environmental conditions, it is important to understand first the basic structure and mechanism of change in the ocean.A study dealing with changes in the distribution of properties and water masses in the sea requires consideration of the theory of the distribution of variables for heat, salt, and momentum budgets [Sverdrup et al., 1942]. Involved are heat and water exchange at the sea surface, the wind stress, and the effects of water motion in advection and mixing; also essential is a knowledge of the local time change of properties.

Principles and Performance Analysis of Doppler Navigation Systems

The fundamental concepts of a Doppler navigation system are described. The theory of operation, design considerations, performance characteristics, and limitations of a Doppler radar are discussed along with the basic principles and major characteristics of navigational computers and heading references. The over-all performance characteristics of a Doppler navigation system and their dependence on the various characteristics of its major components are analyzed. It is shown that the over-all system accuracy of a Doppler system is a function of the accuracies of all three major components of the system?the Doppler radar, the computer, and the heading reference. Thus, the over-all system accuracy is shown to be no better than that of its weakest link. In most current systems, it is the heading reference error which swamps the other errors in the system. The performance capabilities of typical modern Doppler navigation systems are outlined. Such systems are shown to provide information on ground speed, drift angle, present position, and course and distance to destination. Complete Doppler navigation systems have been or being built which will produce maximum (95 per cent probability) position errors of less than 1.5 per cent of distance traveled over land and average sea state (neglecting unknown water motion effects). The maximum position error over water of any sea state is likely to be less than 2 per cent of distance traveled. Over-all position errors in per cent of distance traveled tend to decrease with distance.