118 Book reviews

Gardner et al. on turbulent processes points to the importance of such detailed features as a bridge on the mixing. Normally these details would be lost in models of an estuary.

What price then numerical models ? It is obviously unrealistic to refuse to use them, but in many ways their predictive capability is little better than the box models reviewed by Officer. Perhaps their best use is in an iterative way with field experiments to understand the system. There are hints in this volume that this philosophy is gaining ground and that less and less are models being developed for their own sakes.

Several of the models described demonstrate the importance of wind in estuarine pro- cesses, yet the way in which the eddy coefficients are specified in terms of wind is relatively crude. The work should now be extended by field experiments, the results of which can be used to improve this specification and the refined models should then reveal new insights. Unless the physics is right there is little chance of ecological models being very valuable. A useful first step in ecological modelling is through multivariate analysis, such as that used by Jensen et al. for coliform bacteria. This should enable unimportant terms to be neglected and the problem simplified reasonably realistically. Show’s model of copepod movement in a lagoon off Galveston Harbour is, to my mind, a useful next step in the use of models as an additional learning tool, in that it demonstrates the validity of the hypothesis of plankton mobility minimizing losses on the estuarine circulation. Predictive ecological models are obviously still a long way off.

This book reflects the present state of the art, just as a selective choice of papers from a range of scientific journals would do. It is not a textbook and thus has to find its role as a reference book. Its success will be measured by the frequency of its citation. I suspect that the two papers which will be most lastingly referenced will be that of Officer on box models (slightly marred by a transposition of pages), and that by Nixon on 20 years of salt marsh research. These are more what a book should contain; a synthesis, a criticism of assumptions or accepted values, and an indication of where we ought to be going.

K. R. DYER

Fjord Oceanography Edited by H. J. Freeland, D. M. Farmer and C. D. Levings

Plenum Press, New York, London, 1980, 715 pp., 04.74

Fjords form a small but important part of the shoreline of the world’s ocean, indenting the western coasts of Scandinavia, North and South America, New Zealand and Scotland, as well aa much of the Arctic regions. Their study is prompted through concern over fisheries, pollution and navigation. They challenge the physical oceanographer to test and apply engineering or fluid dynamical concepts of hydraulics, especially turbulence and waves, in a stratified region where some success may be expected but in which, because of the presence of irregular topography and hence spatially variable dissipation, the outcome is uncertain.

The complexity of fjord phenomena is soon made apparent in this book. This is a collection of 66 papers (some extended reviews and some brief reports) of a NATO Advanced Study Institute held in Victoria, British Columbia in June 1979 and attended mainly by physical oceanographers and marine biologists, but including chemists and sedimentologists [a report of the meeting has been published by Huppert & Farmer (1979)]. The majority of papers came, naturally enough, from Canada and the U.S.A. (35); 21 came from Scandinavia. None came from the U.S.S.R. or other Eastern bloc countries.

Book revierus 119

As is common in such conference proceedings, the pages are typescript and lack the authority of set type, as well as that of a refereed set of papers. One does not mind scribbling marginal notes in such a book, which is good (but as such it is very expensive), but I feel that the reviews (Pickard and Stanton on Pacific Fjords, R. R. Long on Fluid Mechanics of Fjords, and Huppert on Topographic Effects) deserve more formal publication, whilst some of the other contributions are not yet ready for public exposure.

Perhaps the most exciting papers are those describing the investigations in Knight Inlet, B.C. Physical oceanographers have lagged behind other scientists (and the military) in their use of remote sensing and are only just becoming aware of the power of exploring the ocean by acoustics. The studies of Dugan Smith and Farmer using sonar have revealed large internal lee waves and mixing regions near a sill in the fjord. These features can be inter- preted quite successfully using laboratory models and known fluid dynamics. An important development reported by Gargett has been to survey the internal hydraulics with sonar and to make simultaneous in situ measurements from a submersible, thus partly overcoming the considerable difficulty of knowing enough of the general ‘environment’ in which turbulence measurements in stratified regions are made.

Deep-water renewal is a theme in several papers of which the most comprehensive is that of Gade and Edwards. Macrobenthos, productivity, fjord chemistry, and sediments are all discussed but the dominant subject is that of water movement. The book contains a subject index (‘Olympic Games-x968 is perhaps the most intriguing and unexpected subject!) as well as lists of geographic and taxonomic names which add to the book’s usefulness,

Much has been discovered about fjords but I suspect there is still a great deal of exciting and very useful science to be done, particularly concerning the processes of dissipation. This would give greater confidence in modelling the dynamics which influence pollution.

Reference Huppert, H. E. & Farmer, D. M. 1979 The oceanography of fjords. Nature 280, ~72-274.

S. A. THORPE

Estuarine Ecology-with Particular Reference to Southern Africa -- Edited by J. H. Day

A. A. Balkema, Rotterdam, Cape Town, Salem, N.H., 1981, viii- E22.50, $50.00

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This large book embodies the results of a review of the estuaries of Africa soul th of the Tropic of Capricorn initiated by the South African National Committee for Oceanographic Research (SANCOR) in 1976. The aims of the review are described as being twofold: to place existing knowledge of these estuaries in the context of recent knowledge of estuarine science gained outside South Africa (and thereby to identify gaps in local knowledge, to suggest areas for future research, to highlight peculiarities of South African estuaries, etc.); and to provide a basis for future management of the local estuarine systems.

These aims are reflected in the form of the book. Twelve of the first 13 chapters each adhere to a general pattern in which a worldwide review and summary of knowledge of their individual subject matters are given, followed by specific consideration of South African material. Chapters 13 and 14 respectively provide synoptic accounts of 43 southern African