University of Canberra

This thesis is available in print format from the University of Canberra Library. If you are the author of this thesis and wish to have the whole thesis loaded here, please contact the University of Canberra Library at e-theses@canberra.edu.au Your thesis will then be available on the www providing greater access.

The role of carp (Cyprinus carpio L) size in the

degradation of freshwater ecosystems

A thesis submitted in fulfilment of the requirements

of the degree of Doctorate of Science in Applied Science

Patrick Driver BSc (MSc prelim.)

Cooperative Research Centre

for Freshwater Ecology

R E S E A R C H

FRESHWATER ECOLOGY

Division of Science and Design

University of Canberra

December 2002

Frontispiece. One of the many carp (Cyprinm carpio} captured for the field experiment

described in Chapters 2 and 3 (at Lake Moodemere, near Rutherglen, Victoria).

Copyright in relation to this thesis

Under Section 35 of the Copyright Act of 1968, the author of this thesis is the owner of

any copyright subsisting in the work, even though it is unpublished.

Under section 31(I)(a)(i), copyright includes the exclusive right to reproduce the work

in a material form. Thus, copyright is infringed by a person who, not being the owner of

the copyright, reproduces or authorizes the reproduction of the work, or of more than a

reasonable part of the work, in a material form, unless the reproduction is a 'fair dealing'

with the work 'for the purpose of research or study' as further defined in Sections 40 and

41 of the Act.

This thesis must therefore be copied or used only under the normal conditions of

scholarly fair dealing for the purposes of research, criticism or review, as outlined in the

provisions of the Copyright Act 1968. In particular, no results or conclusions should be

extracted from it, nor should it be copied or closely paraphrased in whole or in part

without the written consent of the author. Proper written acknowledgment should be

made for any assistance obtained from this thesis.

Copies of the thesis may be made by a library on behalf of another person provided the

officer in charge of the library is satisfied that the copy is being made for the purposes

of research or study

IV

Acknowledgments

This PhD research was funded by the Cooperative Research Centre for Freshwater

Ecology (CRCFE), and was based at the University of Canberra (UC). Thanks to these

organizations for the training and support I received.

Thanks to my supervisors Dr. John H. Harris (formerly of the New South Wales

Fisheries Research Institute (FRI)), Dr. Gerry Closs (University of Otago, New

Zealand) and Ass. Prof. Richard Norris (UC)) for their support throughout my

candidature. Also thanks to Gerry for encouraging me to apply for the CRCFE

scholarship.

Terry Koen (NSW Department of Infrastructure, Planning and Natural Resources

(DIPNR), Cowra), Ross Cunningham (Australian National University (ANU)), Cathy

Hale and Arthur Georges (UC), Geoff Gordon and Dennis Reid (FRI) all helped me

with various aspects of statistics.

Numerous people and institutions helped make the pond experiment possible. The

Narrandera Inland Fisheries Research Centre and the FRI provided a boat electrofisher,

a fish transportation vehicle and staff for the transportation of carp to the experimental

pond. Andrew Bruce, Karen Markwort, Justen Simpson and Ian Wooden helped

transport the carp into the experimental enclosures. The Department of Conservation

and Natural Resources, Victoria approved (by permit) my use of their land and pond.

Mike Shirley shared his experience in designing a large pond experiment. Steve

Balcombe helped me access La Trobe University (Wodonga) field equipment. Fabian

Death helped collect field experiment samples. The Sydes family, particularly Fay

Sydes, gave me a place to live in Benalla and nearly all Sydes family members helped

with the construction of the ponds. Terry was an indispensable trouble-shooter who,

amongst other things, helped prime a troublesome pump. Additionally, Travis helped

me through the drudgery of digging trenches. Frank Krikowa and Lira Woo (UC) aided

me in my nutrient analyses. Sue Nichols provided various bits of information, including

instructions on the Chlorophyll analyses. Invertebrate identification was more endurable

because of the company of, and occasional help from Melissa Parsons, Phil Sloane, Mat

Allanson and Sean Grimes. Chris Wilson (ANU, now Trent University, Ontario) also

helped with zooplankton identification.

The CRCFE, UC and the North American Benthological Society helped fund my

conference tour to the United States of America where I presented aspects of this thesis.

Because of this trip, I made contact with Dr. John Rinne and colleagues (Rocky

Mountain Forest and Range Experimental Station and Northern Arizona University,

Flagstaff, Arizona), who took me into the field and broadened my understanding of carp

and other introduced fishes. Also special thanks to Dr. Rinne and Pam Sponholtz for

sending me various government publications.

The data from the NSW River's Survey (NSWRS) was made possible by the support of

the New South Wales Resource and Conservation Assessment Council, the CRCFE, the

FRI, UC and the ACT Parks and Conservation Service. I am very grateful for the

support from the NSWRS team. In particular Dr. John H. Harris, Dr. Peter Gehrke,

Simon Hartley, Andrew Bruce and Craig Schiller.

Chapters 4 and 5 are an expansion upon and partial re-analysis of a previously published

work that my supervisors and I authored. This work, Driver et al. (1997), was primarily

the result of my analyses of NSWRS data and my interpretation, but my supervisors

provided important contributions that improved the analyses and text within this paper.

Ass. Prof. Bill Maher (UC), my supervisors, an anonymous examiner and D r . Bruce

Chessman (DIPNR), Ian Cowx (University of Hull, UK), Chris Driver (a.k.a. Dad,

National Ageing Research Institute), Peter Gehrke, Melissa Parsons (UC), Marita Sydes

(ANU) and Jane Roberts (formerly CSERO) provided their thoughts on either drafts of

this thesis, drafts of Driver et al. (1997) or the submitted thesis that, ultimately,

improved the quality of this thesis.

A support network is essential to surviving postgraduate studies. I am therefore indebted

to Marita, Aaron, Eric (the last two were born during the completion of this thesis!),

Megs, Cosi, the rest of my family and my 'old' Melbourne friends, particularly Neil,

Shirley, Paul and Jimbo. I have also benefited intellectually and emotionally from the

support of fellow postgraduates and friends at UC and ANU. Finally, I finished this

thesis while working full time at the DIPNR office in Forbes. Therefore, thanks to my

work colleagues, in particular Greg Raisin, Paul Wettin, Peter Lloyd-Jones and Lisa

Thurtell for their support during my studies.

VI

Abstract

Carp (Cyprinus carpio) are alien freshwater fish that are globally widespread and often

associated with highly degraded freshwater ecosystems. This study explored carp-

habitat interactions that could contribute to the worldwide distribution of, and

consequent ecological impacts by, carp. Particular emphasis was placed on the role of

carp size in these interactions. One component of this study involved a field experiment

that was used to quantify the effects of carp biomass density and size-structure on

freshwater invertebrate communities and water quality. The treatments in this field

experiment comprised different combinations of large (2 kg) and small (0.7 kg) carp,

and low (330 kg.ha-1), intermediate (570 kg.ha-1) and high (650 kg.ha-1) biomass

densities. Carp impacts were more carp size-dependent than described in previous

studies. In particular, carp size was more important than carp biomass density in

determining the concentration of total phosphorus and algal biomass. On the other hand,

a more even mix of carp sizes increased total nitrogen. The zooplankton and

macroinvertebrate taxa that were more abundant in the presence of carp were the taxa

most able to avoid carp predation and tolerate habitat changes caused by carp

benthivory. To complement the small-spatial scale field experiment, large-scale patterns

of carp distribution, biomass density and recruitment were explored among the rivers of

New South Wales (Australia) in relation to their physical habitat. In contrast to

expectations, and although most recruitment probably occurred at lower-altitudes, the

populations with a size structure and biomass density most likely to cause ecological

degradation occurred at intermediate altitudes. Furthermore, the distribution of smaller

carp (less than or equal to 100 mm, and less than or equal to 300 mm) indicated that the

regulation of river flows does not always favour carp populations, particularly during

drought conditions. Nevertheless, it was concluded in a review of the carp literature,

which incorporated the findings of this study, that invasion by alien carp is most

successful in streams with formerly highly variable flows that are now subject to flow

regulation. Moreover, carp are likely to enhance their advantage in these waters through

habitat modification.

vii

Table of contents

ACKNOWLEDGMENTS V

ABSTRACT VII

TABLE OF CONTENTS VIII

LIST OF FIGURES XII

LIST OF TABLES XIV

CHAPTER 1 INTRODUCTION: INCORPORATING SCALE AND COLONIZER SIZE INTO

MODELS OF INVASION 1

1.1 BACKGROUND ON INVASION BIOLOGY 1

7.7.7 The ecological and economic importance of biotic invasions 7

7.7.2 Freshwater ecosystems are especially vulnerable to biotic invasion 2

7.7J Conditions that increase the probability of successful invasion 2

1.2 THE ROLES OF SCALE AND ORGANISM SIZE IN BIOTIC INVASIONS 3

7.2.7 Overview 3

7.2.2 Ecosystems operate at multiple scales 4

1.2.3 The role of size structure in species-ecosystem interactions 5

1.3 THE STUDY SPECIES - COMMON CARP (CYPRINUS CARPIO L.) 61.4 RESEARCH OBJECTIVES 8

CHAPTER 2 IMPLICATIONS OF BENTHIVORE SIZE STRUCTURE AND BIOMASS FOR

TROPHIC STATE IN FRESH WATERS 12

2.1 INTRODUCTION: BENTHIVORE EFFECTS ON TROPHIC STATE IN FRESHWATER ECOSYSTEMS 122.7.7 General impacts of benthivorousfish 72

2.7.2 Population structure and benthivorous fish impacts 13

2.1.3 Aims, and hypotheses tested 14

2.2 METHODS 17

2.2.7 Site description and construction of enclosures '. 77

2.2.2 Fish sampling and treatment design 22

2.2.3 Field sampling and laboratory techniques 23

2.2.4 Analyses of the effects of carp on zooplankton communities and water quality 25

2.3 RESULTS 262.3.1 General observations: plant abundance, water clarity and surface scums 26

2.3.2 Water quality 27

2.3.3 Response of zooplankton 32

2.4 DISCUSSION 39

2.4.1 Carp shift the ecosystem from oligotrophy to eutrophy 39

vii i

2.4.2 The importance of reporting carp size 41

2.4.3 The role of carp size in nutrient regeneration 45

2.4.4 Taxa-specific responses to nutrient regeneration and sediment suspension 50

2.4.5 Taxa-specific responses of zooplankton to carp predation 50

2.4.6 Effects of more than one carp size on water quality and zooplankton communities 57

2.4.7 Changes in carp size-dependent effects on water quality and zooplankton over time 52

2.4.8 Zooplankton resistance to carp predation 53

2.5 CONCLUSION 54

CHAPTER 3 IMPLICATIONS OF BENTHIVORE SIZE STRUCTURE AND BIOMASS

DENSITY FOR A LITTORAL MACROINVERTEBRATE COMMUNITY 56

3.1 INTRODUCTION 56

3.1.1 Effects of carp on macroinvertebrate diversity 56

3.1.2 Effects of benthivore size on macroinvertebrate communities 57

3.1.3 Aims, and hypotheses tested 58

3.2 METHODS 59

5.2.7 Field sampling 59

3.2.2 Statistical analyses of the effects of carp on macroinvertebrate communities 59

3.3 RESULTS 62

3.3.7 Description of taxa collected 62

3.3.2 Effects of carp on macroinvertebrate community structure 65

3.4 DISCUSSION 73

3.4.1 The infauna generally gain numerical dominance over non-infauna under carp effects... 73

3.4.2 Selective predation by carp and the importance of carp size 75

3.4.3 Large carp at high biomass densities have greater indirect effects on the

macroinvertebrate community 76

3.4.4 Gastropod removal by carp does not advantage herbivorous macroinvertebrates 77

3.5 CONCLUSION 78

CHAPTER 4 THE ROLE OF THE NATURAL ENVIRONMENT AND HUMAN ACTIVITIES IN

DETERMINING THE DISTRIBUTION OF CARP IN RIVERS OF NEW SOUTH WALES,

AUSTRALIA 79

4.1 INTRODUCTION 79

4.1.1 The factors that determine carp distribution at large spatial scales are not well understood

79

4.7.2 Abiotic features of rivers associated with carp 79

4.7.3 Human activities likely to be associated with carp 80

4.1.4 Carp in Australia 81

4.1.5 Aims, and hypotheses tested 81

4.2 METHODS 82

4.2.7 Site selection 82

4.2.2 Field collection of data 88

ix

4.2.3 Data collection and preparation 88

4.2.4 Analyses of carp presence-habitat relationships 92

4.3 RESULTS 95

4.3.1 Environmental factors that enable prediction of carp presence 95

4.3.2 Differences in physical habitat and climate between carp and no-carp sites 99

4.4 DISCUSSION 102

4.4.1 The importance of lowland habitat 102

4.4.2 Temperature is unlikely to be an important factor for determining carp distribution 104

4.4.3 Carp are favoured by human activities 104

4.4.4 Some factors not measured that could also have determined the observed patterns in carp

distribution 106

4.4.5 Less in-channel aquatic vegetation in association with carp probably has more to do with

carp impacts than carp dependencies 108

4.5 CONCLUSION 109

CHAPTER 5 BIOMASS DENSITY, POPULATION STRUCTURE AND THE VIABILITY OF

CARP POPULATIONS IN INLAND RIVERS OF NEW SOUTH WALES 110

5.1 INTRODUCTION 110

5.1.1 Measuring habitat quality; implications of scale and measurement HO

5.1.2 Aims, and hypotheses tested 772

5.2 METHODS 1125.2.7 Data collection and preparation 772

5.2.2 Calculation of carp biomass density 772

5.2.3 Rationale for choosing two definitions of 'young carp' 114

5.2.4 Analyses 775

5.3 RESULTS 120

5.5. 7 Variation in carp biomass density and the number of young carp across river types.

regions, seasons and years 720

5.3.2 Changes in carp biomass density and the number of young carp in relation to altitude and

turbidity 726

5.4 DISCUSSION 128

5.4.7 Conditions required for carp recruitment during the NSWRS 728

5.4.2 Effects of drought and flood on sampling efficiency and carp recruitment 130

5.4.3 Carp in slopes sites could be occasionally supplemented by upstream migration 757

5.4.4 Effects of a regulated flow regime on carp recruitment 752

5.5 CONCLUSION 134

CHAPTER 6 DISCUSSION AND REVIEW: A CONCEPTUAL MODEL FOR THE INVASION

AND ECOLOGICAL IMPACTS OF CARP 135

6.1 OVERVIEW 135

6.2 ORIGINS OF INVASIVE CARP 1386.3 THE BIOLOGY OF INVASIVE CARP 138

6.4 CARP COMPETE MOST SUCCESSFULLY IN FLOW-REGULATED TEMPERATE STREAMS 141

6.5 NATURAL PARASITES AND PATHOGENS OF CARP 145

6.6 ARE THE LOCAL ECOSYSTEM IMPACTS OBSERVED FOR CARP RELEVANT TO REGIONAL-SCALE

PATTERNS OF CARP INVASION? 146

6.6.7 Overview 146

6.6.2 A synthesis of the local impacts by carp 147

6.6.3 Do carp have large-scale impacts? 150

6.7 DIRECTIONS FOR FURTHER RESEARCH 152

6.8 CONCLUSION 154

CHAPTER 7 CONCLUSION: INCORPORATING SCALE AND COLONIZER SIZE INTO A

GLOBAL MODEL OF CARP INVASION 155

7.1 WHY STUDY CARP INVASION? 155

7.2 LOCAL IMPACTS BY CARP 155

7.3 LARGE-SCALE PATTERNS IN CARP PRESENCE, BIOMASS DENSITY AND SIZE STRUCTURE AMONG

RIVERS OF NSW 156

7.4 GLOBAL INVASION BY CARP 157

7.5 CONCLUSION 158

REFERENCES 159

XI

List of figures

Figure 2.1. Synthesis of carp impacts on water quality and zooplankton based on the available

literature and adopted for the formulation of hypotheses in the field experiment on carp impacts 16

Figure 2.2. Randomized block design for the experiment on the effects of carp biomass density

(kg.ha-1) and size (g) on a pond ecosystem 19

Figure 2.3. Field enclosures for the experiment on the effects of carp biomass density and weight on a

pond ecosystem 20

Figure 2.4. Carp weight and length shown for the carp sampled at Lake Moodemere, Victoria, for the

field experiment 20

Figure 2.5. Carp presence, size and biomass density impacts on water quality over time 30

Figure 2.6. Carp size and biomass density impacts on water quality 31

Figure 2.7. Carp presence and biomass density impacts on the abundance of zooplankton 35

Figure 2.8. Abundance of numerically dominant zooplankton over time for the less common taxa (A)

and most common taxa (B) in no-fish and carp treatments 35

Figure 2.9. Carp presence, size and biomass density impacts on zooplankton taxa over time. Carp size

effects on the abundance of Moina (A). Carp biomass density effects on the abundance of calanoid

copepods (B). Carp size effects on the abundance of Daphnia (C) 36

Figure 2.10. Carp size and biomass effects on cyclopoid copepod abundance over time 37

Figure 2.11. Revised synthesis (cf. Figure 2.1) of carp impacts on water quality and zooplankton based

on the available literature and results of the field experiment on carp impacts discussed in this chapter.

40

Figure 2.12. Approximate ranges for the size of carp (g) and biomass density of carp (kg.ha-1) used in

experimental research 43

Figure 3.1. Abundance of macroinvertebrate taxa in no-fish and carp enclosures for taxa between one

and ten percent (A), and taxa greater than ten percent (B) of total macroinvertebrate abundance 64

Figure 3.2. Carp size and biomass density impacts on macroinvertebrate taxonomic richness (A) and

the abundance of the tribe Tanytarsini (Chironomidae, Diptera) (B) 68

Figure 3.3. Carp size and biomass effects on tribe Chironomini species 1 (Chironomidae, Diptera)

abundance over time in a pond experiment 69

Figure 3.4. Carp size and biomass density impacts on abundance of non-infauna (pelagic, epibenthic

and periphyton and neuston) macroinvertebrates 71

Figure 3.5. Effects of carp presence over time on macroinvertebrates: abundance of non-infauna

(pelagic, epibenthic and periphyton) macroinvertebrates (A); the ratio of infauna to non-infauna (B)

and the abundance of Physa (C) 72

Figure 4.1. Map of New South Wales, Australia, showing the location, river type and region of the

eighty sampling sites used in the New South Wales Rivers Survey 84

Figure 4.2. The New South Rivers Survey sampling design 85

Figure 4.3. Percentage of sites with carp, within specified altitudes, at sites visited during the New

South Wales Rivers Survey in coastal and inland rivers (including montane sites) 96

Figure 5.1. Design of the New South Rivers Survey data analysed in this chapter 117

xii

Figure 5.2. Changes in carp biomass density (kg.ha'1) within river types over the two years of sampling

in the three river types (A), and the number of young carp equal to or less than 100 mm per site (YOY

carp) over the four sampling occasions (B) 122

Figure 5.3. Changes in the number of young carp equal to or less than 300 mm per site (juvenile carp)

over the four sampling occasions within the three river types (A), and all the region-river type

combinations over the two years of sampling (B) 125

Figure 5.4. Gradients in carp biomass density (kg.ha-1, A) and the number of young carp equal to or

less than 100 mm (YOY carp, B) and 300 mm (juvenile carp, C) in relation to altitude (m) in inland

rivers of NSW 127

Figure 6.1. Conceptual model for successful invasion and widespread ecosystem impacts by carp... 137

Figure 6.2. Synthesis of water quality, zooplankton and macroinvertebrate responses to carp biomass

density (kg.ha-1) and carp size (kg) based on literature and impacts observed in the pond experiment

(Chapters 2 and 3) 149

Xlll

List of tables

Table 2.1. Pond depth ± standard error of the mean (cm) within blocks at days 23 and 53 21

Table 2.2. Carp biomass densities ± standard error of the mean (kg.ha'1) within treatments over time....

21

Table 2.3. Carp weight ± standard error of the mean (g) within treatments over time 21

Table 2.4. The effects of carp size, density and their interactions on water quality in experimental field

enclosures, 23 and 53 days after the introduction of carp 29

Table 2.5. The effects of carp size and biomass density on zooplankton in experimental field

enclosures, 23 and 53 days after the introduction of carp 34

Table 2.6. Reported weights of carp (g) and biomass density of carp (kg.ha'1) used in experimental

research and some field studies on carp 44

Table 2.7. Reported effects of carp (g), carp size (kg) and biomass density of carp (kg.ha-1) on

phosphorus and nitrogen concentrations and turbidity (and/or sediment suspension) in the water

column from experimental research 46

Table 3.1. Macroinvertebrate taxa recorded in the pond enclosure experiment on carp impacts at days

23 and 53 61

Table 3.2. The effect of carp size, density, time, and their interactions in experimental field enclosures,

23 and 53 days after the introduction of carp on the taxonomic richness of macroinvertebrates 66

Table 3.3. The effect of carp size, density, time, and their interactions in experimental field enclosures,

23 and 53 days after the introduction of carp, on the abundance of macroinvertebrate taxa 67

Table 4.1. List of inland river sites used in the New South Wales River Survey (modified with

permission from Harris et al. 1996) 86

Table 4.2. Fish sampling methods used in the New South Wales River Survey in lowland and slopes

river types 90

Table 4.3. Conversion of class variables to ranked variables for statistical analysis 90

Table 4.4. Environmental variables describing the year and season of sampling, physical and

vegetation characteristics, climate and location , and human impacts associated with habitat 91

Table 4.5. Environmental variables that were related to differences between carp and non-carp sites in

New South Wales (excluding montane sites) selected using Discriminant Function Analysis 97

Table 4.6. Means of variables, in carp and no-carp sites, selected by the stepwise Discriminant

Function Analysis and used in the final model for predicting carp presence 97

Table 4.7. Environmental factors describing the physical habitat of inland non-montane sites versus

coastal non-montane sites 100

Table 4.8. Environmental factors describing the physical habitat of inland montane sites versus inland

non-montane sites 101

Table 5.1. Differences in carp biomass density (kg.ha'1) and the number of young carp per site in

inland rivers of New South Wales among different spatial and temporal scales 121

Table 5.2. Averages and 95 percent confidence limits for the biomass density of carp (kg.ha'1) in river

types of inland New South Wales 121

XIV