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1. Quantitative palaeolimnology has traditionally sought to quantify species-environment relationships to use alterations in biological assemblages to reflect past environmental change. Transfer functions have used regression techniques, such as weighted averaging, to define taxon optima and tolerance for a single chemical or biological variable. 2. Cladoceran assemblages and their sub-fossil remains in shallow lakes are shaped by a combination of interacting factors. Partial constrained ordination of sub-fossil cladoceran assemblages from 39 shallow lakes (29 in Norfolk, U.K. and 10 in Denmark) indicated that both zooplanktivorous fish (ZF) density and submerged macrophyte abundance significantly influenced community composition. These dual structuring forces precluded the use of a transfer function as one of the key assumptions of this approach was not met, namely that environmental variables apart from the variable being modelled have negligible influence on species distribution or that there is a linear relationship between the two. Separate transfer functions for ZF and macrophyte abundance were developed but had poor performance diagnostics with low bootstrapped r 2 , high root mean square error of prediction (RMSEP) and large bias. 3. To obviate the problem of multiple structuring forces a multivariate regression tree (MRT) was employed, which allows for more than one explanatory variable within a model. The MRT analysis defined six groups with discrete ranges of ZF and macrophyte densities. The technique identified critical values or 'break points' in ZF and macrophyte abundances which result in significant alterations in the sub-fossil cladoceran assemblage. In addition, the MRT groups had different summer mean values for chlorophyll-a, Secchi depth, total phosphorus and nitrate-nitrogen. 4. The predictive abilities of the model were assessed by comparing the observed versus predicted MRT group membership. In general group membership was reliably predicted, suggesting sub-fossil cladoceran assemblages reliably reflect ZF and macrophyte density in shallow lakes. For a relatively small number of sites there were differences between the observed and predicted MRT group membership. These failures of prediction may result, at least in part, from the disparity of the time Correspondence: Thomas Davidson, Environmental period represented by the environmental data and the surface sediment cladoceran assemblage.

Abstract— This study investigated interactions between zooplanktivores (roach and perch) and piscivorcs (pike and large perch) in experimental ponds (16 m2) with open water habitat and three densities of natural macrophytes. Fish habitat selection was determined both day and night and was supported by daytime observations to study anti‐predator behavioural patterns. Diel migration out from among macrophytes was seen in the absence of predators, particularly for roach, which changed from 13% of individuals being in open water during the day to 90% at night. The risk of predation from piscivores influenced the habitat selection of the zooplanktivores. Roach seemed to be the most vulnerable to predation from pike and selected the open water (90‐92%) during daylight hours, but kept a 1‐m distance from the macrophytes edge. The presence of pike thus reduced the use of macrophytes by roach, which in turn may improve macrophytes and the edge area as a refuge for zooplankton. Pike appeared to have less impact on the gross habitat selection of O+ perch, which were associated with the macrophytes (58–89%), though they were still vulnerable to predation. Adult perch, which was a generally less effective predator than pike, showed subdued behavior, concealing them selves in the macrophytes most of the time. No effect of the simultaneous presence of two predator species was found.

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Interactions between coot (Fulica atra) and submerged macrophytes: the role of birds in the restoration process. Perrow, M.R.; Schutten, J.; Howes, J.R.; Holzer, T.; Madgewick, F.J.; Jowitt, A.J.D. Published in: Hydrobiologia Link to publicationCitation for published version (APA): Perrow, M. R., Schutten, J., Howes, J. R., Holzer, T., Madgewick, F. J., & Jowitt, A. J. D. (1997). Interactions between coot (Fulica atra) and submerged macrophytes: the role of birds in the restoration process. Hydrobiologia, 242/243, 241-255. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. AbstractGrazing by herbivorous birds is often cited as an important factor in suppressing macrophyte development in shallow lakes undergoing restoration, thus delaying the attainment of the stable clear water state. Development and succession of macrophyte communities and size, diet and grazing pressure of coot (Fulica atra) populations upon macrophytes, were monitored over the seasonal cycle at ten shallow lakes of varying nutrient status, in the Norfolk Broads in eastern England. In spring, territorial breeding birds were at relatively low density and included only a small proportion of macrophytes in their diet, resulting in low grazing pressure on macrophytes. In summer, there was a significant relationship between macrophyte cover and bird density, illustrating the importance of macrophytes in the dispersion phase for birds following breeding. Macrophytes comprised the bulk of bird diet where they were available and the consumption of macrophytes was up to 76 fold higher than in spring. However, losses to grazing in both periods were negligible when compared to potential growth rates documented in the literature. Grazing experiments at two biomanipulated lakes confirmed that birds were not responsible for limiting macrophytes during the spring colonisation phase or in the summer growth period. During the period of autumnal senescence and over the winter months where some macrophyte species remain available, e.g. as developed individuals or dormant buds, grazing by birds may conceivably have an impact on the development and structure of macrophyte populations in subsequent growing seasons.The relative importance of bird grazing compared to other factors limiting the development of macrophytes...