Copyright is owned by the Author of the thesis.  Permission is given for 
a copy to be downloaded by an individual for the purpose of research and 
private study only.  The thesis may not be reproduced elsewhere without 
the permission of the Author. 
 
  
 
 
Habitat determinants and predatory interactions of the endemic 
freshwater crayfish (Koura, Paranephrops planifrons) in the Lower 
North Island, New Zealand.   
 
A thesis presented in partial fulfillment of the requirements for the 
degree of 
 
Masters of Science 
in 
Ecology 
 
at Massey University,  Palmerston North, 
New Zealand. 
 
 
Logan Arthur Brown 
 
2009 
 
 
 
 
 
 
 
 i
 
Acknowledgements 
 
My gratitude goes to all those who helped me throughout my thesis. The 
completion of this has taken many years and is thanks to the efforts of many who 
have helped me with fieldwork, made suggestions on ways to carry out experiments 
and been there for general support. A special thanks must go to my partner Emma 
who has put up with me for three years trying to complete this, also to my family 
and friends for their support.  
 
Thanks to my supervisor Associate Professor Russell Death for helping come up 
with the original topic and the comments provided on drafts. Thanks also to Fiona 
Death for proof reading final drafts of my thesis. 
 
The following people gave up their time to come and help me in the field. Matt 
Denton-Giles, Emma Round, Charlotte Minson, Jono Tonkin, Nikki Atkinson, 
Travis Brown, Jan Brown, Ray Brown, Peter Bills, Hannah Bills, Caitlin Bills, 
Brayden Bills, Hannah Rainforth, Shaun Nielson, Jess Costall, Emily Atkinson, 
Nikki McArthur, Carol Nicholson, Abby Deuel, Amy McDonald, Kiryn Weaver, 
Cleland Wallace, and Lorraine Cook. Hopefully this covers you all but thanks to 
those I may have missed, there were so many helpers it is hard to remember you all. 
 
Thanks to Tracy and Arjan van der Straaten who lent me troughs and allowed me to 
carry out experiments on their property. Thanks to Peter Bills who spent many 
hours building the enclosures for the stream experiments. I think I got the good end 
of the deal offering to milk while you built the enclosures. Thanks also to all the 
land owners that allowed me access to streams on their private property. It is with 
your co-operation that such research is possible.  
 
This research was partly funded by a Massey University Masterate Scholarship and 
was carried out with approval from the Massey University Animal Ethics 
Committee (Protocol numbers 06/108, 07/08, and 07/19).    
 
 
 ii
Table of contents 
 
 
Title page                                                    
Acknowledgements    i
Table of contents                                        ii
List of appendixes  iii
List of figures iii
Introduction 1
CHAPTER 1: 
Distribution and habitat determinants of 
koura in the Lower half of the North 
Island, New Zealand. 
 
7
CHAPTER 2: 
The predatory interactions between 
introduced brown trout (Salmo trutta), the 
endemic freshwater crayfish (koura, 
Paranehrops planifrons) and Cran’s bully 
(Gobiomorphus basalis) 
                                                 
30
CHAPTER 3: 
The effects of eels (Anguilla spp) and 
brown trout (Salmo trutta) presence on the 
rate of leaf breakdown by freshwater 
crayfish (koura, Paranephrops planifrons). 
 
49
CHAPTER 4: 
Development of a leaf pack tool for 
estimating koura (Paranehrops spps) 
population density. 
 
61
Discussion 68
 
 
 
 iii
List of 
Appendixes 
  
Chapter 1:   
Appendix 1: Sites sampled in the lower North Island. 24, 25, 26
Appendix 2: Definitions of the abbreviations used in figures 3 and 
4 
 
27 
Appendix 3: Examples of some of the sites sampled 
Plate 1: Site 88 - Wainuiomata River. Koura 
present. 
Plate 2: Site 92 - Mangaaruhe Stream. Koura 
absent. 
Plate 3: Site 30 - Unnamed tributary of the 
Waiharuru Stream. Koura absent. 
Plate 4: Site 23 - Unnamed tributary of the 
Nguturoa Stream. Koura present. 
28 
 
 
29 
Chapter 2:   
Appendix 1:  
 
Examples of stream enclosure set up. 
Plate 1: Enclosure used for koura predation 
trials. 
Plate 2: Example of stream set up of enclosures 
used for koura predation trials. Note: actual 
streams used for this experiment were smaller in 
size. 
48 
Chapter 3:   
Appendix 1: Examples of trough experiment set ups. 
Plate 1: Experiment setup of troughs. 
Plate 2: Example of trough used in experiment. 
Mesh covered the troughs to stop both animals 
escaping and aerial predation. 
Plate 3: Close up of individual trough. Water is 
pumped to the top of the rocks (see top of 
picture).  
Plate 4: Close up of individual trough. Orange 
tags represent the placement of the leaf litter 
packs.  
 
59 
 
 
 
 
60 
   
List of 
figures: 
  
Chapter 1: 
 
Figure 1: Presence (red circles) and absence (black 
circes) of koura over the 104 study sites within the 
Lower North Island. Page 17 
Figure 2: Regression tree showing breakdown of the 
sites using habitat variable data collected at each of 
the sites. The first number in brackets represents the 
number of sites at which the variable is correctly 
classified and the second number the number of sites 
at which it is incorrectly classified. Cross validation 
17  
 
 
18 
 
 
 
 
 
 iv
104 - Kappa statistic 0.0602, Correct = 65/104, 
Incorrect = 39/104. Training set - Kappa statistic 
0.74, Correct 93/104, Incorrect 11/104. Page 18 
Figure 3: Regression tree showing breakdown of the 
sites using habitat variable data collected at each of 
the sites and from the FWENZ database. The first 
number in brackets represents the number of sites at 
which the variable is correctly classified and the 
second number the number of sites at which it is 
incorrectly classified. Cross validation 10% - Kappa 
statistic 0.0027, Correct = 61/104, Incorrect = 
43/104. Training set - Kappa statistic 0.7913, Correct 
95/104, Incorrect 9/104. 
 
 
 
 19, 20 
Chapter 2: 
 
Figure 1: Map showing the catchment boundaries of 
the Mangaore, Kahuterawa and the Turitea Stream, 
Manawatu. 
Figure 2: Map showing the Ngururoa Stream, 
Manawatu. 
42 
 
 
43 
Chapter 3: 
 
Figure 1: The average percentage of leaf matter 
consumed by koura at a density of 7 per square 
metre, in the presence of an introduced and native 
predator. The corresponding letters indicate a 
significant difference between the treatments. 
Figure 2: Map showing the catchment boundaries of 
the Mangaore, Kahuterawa and the Turitea Stream, 
Manawatu. 
53 
 
 
 
 
56 
Chapter 4: 
 
 
Figure 1: The average percentage (+/- 1SE) of leaf 
matter consumed in the various density trials. The 
corresponding letters indicate a significant difference 
between the different treatments. 
Figure 2: Map showing the catchment boundaries of 
the Mangaore, Kahuterawa and the Turitea Stream, 
Manawatu. 
64 
 
 
 
66