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Stephen Juggins:

Diatoms in the Thames Estuary, England

Ecology, palaeoecology, and salinity transfer function

1992. 216 pages, 38 figures, 28 tables, 14x22cm, 420 g
Language: English

(Bibliotheca Diatomologica, Band 25)

ISBN 978-3-443-57016-3, paperback, price: 46.00 €

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Contents

Contents top ↑

Summary
Acknowledgements
Contents
Chapter One Introduction 1
Chapter Two The Thames Estuary 3
2.1 Hydrography 3
2.2 Water chemistry 7
2.3 Bottom sediments 8
2.4 Pollution 14
2.5 Ecology 15
2.6 Previous diatom studies 16
2.7 Archaeology and palaeoecology 17
Chapter Three Diatom Analysis and Palaeosalinity
Reconstruction 21
3.1 Review of methods 21
3.1.1 Salinity classification 21
3.1.2 Allochthonous valves 26
3.1.3 Quantitative palaeosalinity reconstruction 28
3.1.4 Comparative methods 29
3.2 Factors influencing the composition of estuarine
surface sediment diatom assemblages 31
3.2.1 Ecological factors 32
3.2.1.1 Habitat type 32
3.2.1.2 Environmental gradients 32
3.2.1.3 Seasonal variation 34
3.2.2 Physical processes 34
3.2.2.1 Erosion 34
3.2.2.2 Transport 35
3.2.2.3 Deposition and sediment mixing 36
3.3 The transfer function approach 36
3.3.1 Basic method 36
3.3.2 Assumptions of the transfer function approach 37
3.3.2.1 Changes in the ecological system 38
3.3.2.2 Changes in the hydrological system 39
3.3.2.3 Post-burial dissolution 40
3.3.3 Rationale of the present study 40
Chapter Four Methods 41
4.1 Sample site location and sample collection 41
4.1.1 Sample site location 41
4.1.2 Sample collection 43
4.1.2.1 Surface sediment samples 43
4.1.2.2 Periphyton 44
4.1.2.3 Archaeological samples 45
4.2 Sample preparation 48
4.3 Identification and counting 49
4.4 Water chemistry 49
4.5 Data presentation and analysis 50
Chapter Five Pilot Study 52
5.1 Introduction 52
5.2 Methods 53
5.3 Results and discussion 54
5.3.1 Surface sediment diatom assemblages 54
5.3.2 Periphyton 62
5.4 Implications for the sampling programme 67
Chapter Six Periphyton 70
6.1 Sample classification 70
6.2 Habitat composition 91

6.3 Salinity classification 97
Chapter Seven Surface Sediment Diatom Assemblages 101
7.1 Species classification 101
7.2 Sample classification 116
7.3 Within-site sample variability 123
7.4 Estimates of the allochthonous and autochthonous
components 126
7.5 Provenance of the allochthonous component 129
Chapter Eight Diatom / Salinity Transfer Function 133
8.1 Theoretical background 133
8.1.1 Species response models 133
8.1.2 Maximum likelihood methods 134
8.1.3 Weighted averaging methods 137
8.1.4 Comparison of methods 140
8.2 The Thames training data set 141
8.2.1 Data screening 141
8.2.2 Choice and scaling of the environmental variable(s) 142
8.3 Estimation of species' optima and tolerances 143
8.4 Comparison of the distribution patterns of
taxa in the life and death assemblages 153
8.5 Application of the transfer function to the
training and test data sets 161
Chapter Nine Application of the Transfer Function to the
Archaeological Diatom Assemblages 167
9.1 Introduction 167
9.2 Species composition of the subfossil assemblages 167
9.2.1 Changes in planktonic taxa over the last 2000 years 170
9.2.2 Changes in benthic taxa over the last 2000 years 171
9.3 Palaeosalinity estimates 173
9.4 The changing nature of the Thames in central
London over the last 2000 years 177
9.5 Conclusions 180
Chapter Ten Conclusions 183
1O.1 Sampling strategy 183

10.2 Periphyton 183
10.3 Surface sediment assemblages 184
10.4 Transfer function 185
10.5 Palaeosalinity estimates 186
References 188
appendix List of taxa with authorities and descriptions
of unidentified forms 206