David Dudgeon:

Patterns and processes in stream ecology

A synoptic review of Hong Kong running waters

1992. VIII, 147 pages, 40 figures, 9 tables, 16x24cm, 450 g
Language: English

(Die Binnengewässer, Band 29)

ISBN 978-3-510-40040-9, bound, price: 48.00 €

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Content Description top ↑

There are at least two ways of approaching the study of nature. One tactic is to investigate a habitat or any convenient local environment with the aim of producing an inventory of the type of organisms found there, preferably with some indication of their relative abundance or population densities. The second approach concentrates upon what the organisms are doing in the habitat, and might involve measuring attributes of groups of animals which tend to exhibit similar interactions or use the same resources — such as predators or the animals which eat plant foliage — but which are not necessarily closely related. In the first case we are asking a descriptive question: "Which organisms live in the habitat?" We label them using a scientific name, but without additional information this does not provide us with any understanding of the habitat. In the second case we ask: "What are the organisms doing?" — a functional question. The two approaches are complementary, with the descriptive approach often preceding the functional one, but they are nonetheless distinct. The ecological literature exhibits a clear dichotomy between these approaches, and books tend to focus on either one or the other. If the main goal is to introduce the reader to descriptive studies, an identification manual (with keys and line drawings) would be the usual publication. If the functional approach is adopted, an introduction to ecological patterns and the processes bringing them about would be the subject of the text.

Rather little is known about the ecology of seasonal tropical freshwaters in general, and Hong Kong's freshwaters in particular. Moreover, there has been no attempt to synthesize the material that is available in the primary scientific literature. This book outlines the main ecological patterns, both temporal and spatial, which characterize Hong Kong streams and rivers. Attempts are made to account for the observed patterns by recourse to characteristics of the populations that comprise freshwater communities, and the properties and interactions of the individual organisms constituting those populations. Attention is centred upon animals although they are not considered to the exclusion of plants. The intention here has not been to produce an identification guide; indeed, it is worth emphasizing that our taxonomic knowledge of Hong Kong running-water fauna is restricted, as reflected in this text by the use of letters or numbers to designate as yet undescribed species within genera.

Contents top ↑

Preface VII
I Communities 1
River zonation and classification schemes 1
Functional classification of stream animals 2
The River Continuum Concept 5
General features of Hong Kong running waters 6
Longitudinal zonation along the Lam Tsuen River 7
The river valley 7
Characterisation of the river fauna 8
Spatial arid temporal variations in benthic communities 12
Functional organisator of benthic communities 18
The stream and its valley 21
Tai Po Kau Forest Stream 21
General characteristics: the abiotic environment 21
Microdistribution of benthic animals 24
General characteristics: the biotic envirronment 26
The tropic basis of production 27
Riparian vegetation and stream communities 28
Comity composition 28
Functional organisation 32
Land-water interactive systems 34
II Populations 37
Life cycles and population dynamics in a seasonal tropical environment 37
The Hong Kong climate 37
Mollusca 40
Crustacea 44
Insecta 46
Fishes 50
Herpetofauna 52
Recapitulation: seasonality of lotic populations 53
Drift of the stream fauna 54
Diel periodicity 54
Seasonal fluctuations 57
Population implications of drift 59
Interspecific competition and niche dimensions 61
Odonata 61
Fishes 63
Is competition important in Hong Kong streams? 65
Biotic versus abiotic influences on lotic populations 66

III Individuals 68
Adaptation and optimal animals 68
Feeding 69
Foraging behaviour: predators 70
Foraging behaviour: primary consumers 76
Feeding apparatus and diet: mayfly larvae 79
Feeding apparatus and diet: net-spinning caddisflies 87
Morphological adaptations for life in running waters 93
Optimal animals revisited 98
IV The human factor 100
Stream vulnerability 100
Pollution 100
River regulation 101
Exotic invaders: overview 103
Attributes of invasive species 105
Ecological effects of exotic species 107
Where are exotic species most successful? 108
Is there reason for concern over exotic species 109
The future 109
V Synthesis 111
Acknowledgements 115
References 117
Index 141