Coastal-offshore ecosystem interactions

Coastal-offshore ecosystem interactions


195KB Sizes 0 Downloads 35 Views





Coastal-Offshore Ecosystem Interactions. Bengt-Owe Jansson (Editor). Lecture Notes on Coastal and Estuarine Studies, 22. Springer, Berlin, 1988. xvI + 368 pp., DM69.00. ISBN 3-540-19051-1. The book is based on the proceedings of a symposium sponsored by the Scientific Committee on Oceanic Research together with U N E S C O and a n u m b e r of other institutions, which was held at San Francisco State University, 7-12 April 1986. The meeting concentrated on six aspects considered to be most general and crucial for further studies: 1, c o a s t a l / o f f s h o r e boundaries and water exchange; 2, nutrient exchange between coastal and offshore systems; 3, transport of matter across the c o a s t a l / o f f s h o r e boundary; 4, c o a s t a l / o f f s h o r e relations in terms of animal populations; 5, relative biological productivity in coastal and offshore systems; and 6, effects of man-made disturbances. Chapter I deals with problems of water exchange between coastal and offshore areas. J. Dronkers considers shallow coastal systems where tide, wind and buoyancy are responsible for exchange between coastal areas and the shelf zone. A classification is suggested relating major mixing zones to mixing agents and geomorphological characteristics. The simplifications pertinent for each case are discussed. T.A. McClimans looks at narrow, deep shelf areas. In this case, the common-density front is suggested as a dividing line between coastal and offshore waters, and the motions of these fronts and the processes in frontal regions are considered. The time and space scales for exchange processes are studied. The effects of wind, turbulence, transport and entrainment are discussed. In contrast with the previous paper, the speculations are mostly qualitative. U. Horstmann demonstrates how coastal-offshore processes can be traced with the present state-of-the-art of satellite remote sensing. Pictorial examples from the Baltic Sea are presented. In Chapter 11 mass balance is the method of analysis. J.N. Gearing presents an extensive review of the method of stable isotope ratios for tracing and quantifying the amounts of organic matter in marine environments. All major tracers (hydrogen, carbon, nitrogen, sulfur) are considered. The following papers are concerned with some particular types of ecosystems. H. Postma summarizes the present knowledge for tidal flats, paying special attention to the cycle of organic matter and its possible role in eutrophication processes. C.S. Hopkinson Jr. considers salt-marsh/estuarine ecosystems, starting with a critical analysis of the mass balance approach and then illustrating it with five case-studies, presenting conceptual models of carbon cycle for each of them in terms of Odum's flow diagrams. The main conclusion is that generally there is an 'outwelling' of carbon from the



estuary but its source is not yet known. R.R. Twilley takes into consideration the mangrove ecosystem as an additional source of nutrients and organic matter in the estuary. The outwelling concept seems to be more justified in this case than in salt marshes. This is further confirmed by P.L. Gomez, who studied mangroves in The Philippines. The energy flow through fjordic ecosystems is analyzed by T.H. Pearson. Boreal well-mixed fjords are shown to export considerable amounts of nutrients to adjacent coastal waters, whereas stagnant fjords are nutrient and carbon sinks. A general energy-flow model is presented. S.V. Smith treats the mystery of 'extreme productivity' of coral reefs and argues that reefs are not metabolically different from other shoal-water systems. Their limited metabolic interaction with the surrounding ocean is stressed. D.H. Peterson, S.W. Hager, L.E. Schemel and D.R. Cayan present an overview of riverine C, N, Si and P transport to the coastal ocean, considered on a coarse temporal and spatial scale with reference to major estuarine recycling processes. The ratio of river-basin area to estuarine area is treated as a measure of the leakage of riverine organic matter from an estuary to the coastal ocean. Riverine/ estuarine nutrient sources to coastal waters are considered secondary to the ocean, except locally. In Chapter III, the active transport between coast and ocean is analyzed through reviews of fish and crustacean case-studies. J.J. Zijlstra concentrates on fish migrations as a form of coastal/offshore transport of matter and energy. Significant transports are only due to fishes who exploit the inshore zone as a nursery and due to seasonal visitors. In general, this type of transport is proved to be mostly significant in terms of its quality rather than its quantity. Larval transport mechanisms of three coastal Crustacea are presented by P.C. Rothlisberg as three case histories. He concludes that all three species are active vertical migrators but they have different transport trajectories. Therefore, detailed dynamic analysis is necessary to estimate their overall role in matter transport. C.E. Epifanio considers the transport of crab larvae between estuaries and the continental shelf, and describes the behavioral traits of three species which allow control of horizontal advection to keep larvae in areas near favorable adult habitats. Possible models for transport back to the estuary are considered. Chapter IV by R.J. Uncles is devoted to numerical modelling, with special attention to techniques of coupling of hydrodynamic and ecological models in large ecosystem simulations of tidal estuaries. He gives an overview of one-, two- and three-dimensional models, and concludes that the fixed-element, tidally-averaged model is the most suitable for ecosystem simulations. Finally, in Chapter V, B.-O. Jansson, A.D. McIntyre, S.W. Nixon, M.M. Pamatmat, B. Zeitzschel and J.J. Zijlstra give some recommendations for future research concerning all the main topics of the Symposium.



In general there is not much modeling in the book and most of the papers may give only conceptual insights. However, practically all of them present an excellent overview of the relevant literature and provide extensive bibliographies. Therefore the book may be considered as a good survey of the topic. A.A. V O I N O V

Laboratory of Mathematical Ecology, Institute of Atmospheric Physics USSR Academy of Sciences Pyzhevsky 3, Moscow 109017, USSR



Interregional Migration. W. Weidlich and G. Haag (Editors). Springer, Berlin, 1988. Hardcover, 387 pp., DM148.00. ISBN 3-540-18441-4. The book is devoted to the modelling of processes related to migrations in human societies. Assuming that these processes can be described by probability methods, the authors construct a scheme of population migrations between several regions, based on the master equation. The idea of the construction may be briefly described as follows. An isolated population is distributed in a finite number of regions in each of which it can be considered as homogeneous. The individual migratory behavior in a given region can be represented by several functions, describing the probability of migrating to any other region during a unit of time. These time-dependent probabilities are presented in the product form of two functions: mobility and push/pull activity. The first is symmetric with respect to regions and depends on the 'distance' between them. The second function depends on individual utilities of the given regions which, by regression, may be identified with such characteristics as employment, income, etc. The authors parametrise the basic functions and evaluate the regional characteristics in the following way. Basing on individual probabilities, they construct a dynamic system which describes the migratory behavior at the population level (Chapter 1). This system is considered in two forms: stochastic (master equations) and deterministic (mean value equations) (Chapter 2). The solution may be compared with heuristic ones by regression methods, in the result of which one can get necessary estimations (ch.3). These three chapters constitute the first part of the book, devoted to basic methods. The second part represents an application of the concepts of Part 1 to different countries. Note that in spite of the unity and comparability of results concerning different countries, these approaches may be considered as supplementing each other in individual details. (e.g. in the case of France