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Modeling the eutrophication process
304
Modeling the Eutrophication Process. E. Joe Middlebrooks, Donna H. Falkenborg and Thomas E. Maloney (Editors). J o h n Wiley, Chichester, 1974, 228 pp., £ 7.70.
This book is a collection rather than a synthesis and is likely to give any reader a rather low opinion of the value of modeling in the study of eutrophication processes. The question is whether such a collection provides any insight into h o w matters could be improved. There is one very large and complex model developed as part of IBP (Bloomfield et al.) which, however, shows a rather p o o r fit to the data. Further, it is not clear w h y the fit is poor and this is a basic fault of such large models. It may be one reason that this group has reverted to a much smaller and simpler simulation. A simpler model of p h y t o p l a n k t o n (Larsen et al.) applied to data from Shagawa Lake, Minnesota shows h o w the process of tuning (or fiddling) can successively turn an unrealistic o u t p u t to one showing the general features observed in the data. The critical factors appeared to be the rates of phytoplankton loss from the system and of the nutrient input from the bottom. Note that these are i n p u t - - o u t p u t terms rather than ones intrinsic to the system. A similar conclusion, that the critical factors are at the boundaries of the system, was derived by Welch et al. in a comparison of the changes in Lake Washington and Lake Sammamish. For the latter lake, problems of release of phosphorus from the sediment appear critical. A very simple simulation by Lorenzen shows h o w varying assumptions a b o u t the sediment-water interactions may produce quite different responses in the overlying systems. Thus, relatively simple models m a y have a use in exploring the implications of data for individual localities or particular problems. It may be generally relevant that the insights gained usually lie outside or at the edges of the system rather than in the internal workings. At present, this volume would indicate, models are n o t y e t of use for general management purposes and a more m o d e s t application of this technique as one of several components in research work is indicated. J.H. STEELE (Aberdeen)
Modeling the Eutrophication Process. E. Joe Middlebrooks, Donna H. Falkenborg and Thomas E. Maloney (Editors). J o h n Wiley, Chichester, 1974, 228 pp., £ 7.70.
This book is a collection rather than a synthesis and is likely to give any reader a rather low opinion of the value of modeling in the study of eutrophication processes. The question is whether such a collection provides any insight into h o w matters could be improved. There is one very large and complex model developed as part of IBP (Bloomfield et al.) which, however, shows a rather p o o r fit to the data. Further, it is not clear w h y the fit is poor and this is a basic fault of such large models. It may be one reason that this group has reverted to a much smaller and simpler simulation. A simpler model of p h y t o p l a n k t o n (Larsen et al.) applied to data from Shagawa Lake, Minnesota shows h o w the process of tuning (or fiddling) can successively turn an unrealistic o u t p u t to one showing the general features observed in the data. The critical factors appeared to be the rates of phytoplankton loss from the system and of the nutrient input from the bottom. Note that these are i n p u t - - o u t p u t terms rather than ones intrinsic to the system. A similar conclusion, that the critical factors are at the boundaries of the system, was derived by Welch et al. in a comparison of the changes in Lake Washington and Lake Sammamish. For the latter lake, problems of release of phosphorus from the sediment appear critical. A very simple simulation by Lorenzen shows h o w varying assumptions a b o u t the sediment-water interactions may produce quite different responses in the overlying systems. Thus, relatively simple models m a y have a use in exploring the implications of data for individual localities or particular problems. It may be generally relevant that the insights gained usually lie outside or at the edges of the system rather than in the internal workings. At present, this volume would indicate, models are n o t y e t of use for general management purposes and a more m o d e s t application of this technique as one of several components in research work is indicated. J.H. STEELE (Aberdeen)