E icolo fEstua ·ne Amphipod Paracorophium excavatum A thesis Submitted in partial fulfilment the requirements for Degree of Master of Science in Environmental Science at The University of Canterbury by Carol Wong Hee Ting University of Canterbury 1999 ABSTRACT The estuarine tube dwelling amphipod Paracorophium excavatum was investigated for its suitability as a bio-indicator and bio-monitor. Distribution patterns of P. excavatum were determined at 13 sites in the Canterbury region that differed in particle size distribution ranging from sandy to muddy sediment, with overall10w organic content. Low tide salinity ranged from 5 to 33 0/00 between sites and sediment moisture content ranged between 23 to 41 % moisture. Amphipods were absent from most sites within the Avon-Heathcote Estuary. The availability, life history and fecundity of P. excavatum were compared from intertidal mudflat sites in Brooklands Lagoon and Kairaki over a period of thirteen months. Four sediment core samples were collected at monthly intervals and P. excavatum IS population structure and life history pattern studied. The life history til· <: of P. excavatum can be characterised bY fast-growing, annual, iteroporous, bivoltine, females ovigerous throughout the year and thelygenous (female biased) population. P. excavatum showed relative consistency in abundance throughout the year with monthly densities ranging from 875.79 per 0.1 m-2 (July) to 1754.77 per 0.1 m-2 (December) at Brooklands Lagoon and 1031.83 per 0.1 m2 (November) to 1780.24 per 0.1 m2 (December) at Kairaki. There was a linear relationship between numbers of eggs per female and female length. P. excavatum show no statistically significant difference in brood mortality between the early and later development stages. P. excavatum was investigated for its potential use In short-term (acute) sediment toxicity tests. In 10-days sediment tolerance tests using sediment from nine sites (8 + control) in the Avon-Heathcote Estuary, amphipod survival was overall high in most sites (above 70%). However, low survival was found for site 7 and 9, indicating that P. excavatum may be a good discriminator of sediment quality. However, P. excavatum mortality was not ! 4 DEC 19!9 significantly correlated to sediment type (p = 0.99, / = 0.06) nor copper content of sediment (p = 0.99,/= 0.01). The effects of copper concentrations on the survival, emergence and reburial of P. excavatum were investigated. Amphipods were exposed to 10-days to 7 sub-lethal copper concentrations (2.7, 15.96, 20.45, 23.92, 32.02, 42.99 and 84.62 ~lg g-l wet weight sediment). The results show clear dose-dependent effects of copper on survival and behaviour on P. excavatum. Copper toxicity test indicates P. excavatum high sensitivity to the heavy metal copper. Median lethal concentration (LCso) was 53.026 J,tg g-l Cu (wet weight) and 1 median effect concentration (ECso) was 47.89 )lg t Cu (wet weight). Emergence increased with increasing metal concentrations indicating that the contaminants had a sublethal behavioural effect. Concentration of copper in P. excavatum tissues increased significantly with increasing metal sediment concentration. The ability of P. excavatum to accumulate heavy metals into their body tissues makes this species suitable for use used as a copper ..~ indicator. Further work should concentrate on the response of P. excavatum to yvL?J\' " ti ~ known contaminants and the influence of non-contaminant variables to better characterises P. excavatum's relative sensitivity. It is concluded that P. excavatum can be used as an effective tool for use in ecotoxicological studies. Natural behaviour, laboratory experiments, and sediment bioassays and its availability throughout the year has demonstrated that P. excavatum can be used as a bio-monitor. N Acknowledgements I wish to express my appreciation and gratitude to the many people who have helped me with this thesis. Firstly, I thank my supervisors Dr. Islay Marsden and Dr. Harry Taylor for. taking such an interest in my topic and my research. Thank you for your patient counsel, over these many months, valuable critique of this thesis and expertise in scientific literacy. Thanks also to Dr. Nadia AL-Mudaffar for her technical support, advice and her help in analysing metal. I am especially grateful for her encouragement at times when I really needed it. I am indebted also to those staff of the University of Canterbury who gave readily of their professional expertise, particularly the following: Graham, Jane, Bruce, Gavin and Tracey. I also wish to thank several friends for their practical help and encouragement, to Justin and Mogu for being there when I needed them, for my s,ummer assistant Clare, my spiritual advisor Pastor Jack and also to Jodie for her help and advice. I would like to take this opportunity to thank all my brothers and sisters from Christchurch Chinese Church. My gratitude to my parents for all they have done for me to make it possible to complete thesis. I treasure your love and support. Thanks to God for giving me good health, strength and even life and breathe itself. TABLE OF CONTENTS Abstract n Acknowledgments IV Jable of Contents V 1 Chapter One: General Introduction ..................................................................... 1 2 Chapter Two: Distribution Pattern of Paracorophium excavatum in the Avon-Heathcote Estuary 08 ..... 0 .........................................., ........... 9 2.1 Introduction ......................................................................................................... 9 2.2 General Infonnation: P. excavatum ................................................................. 11 2.2.1 Morphology ................................................................................................ 12 2.2.2 Habitat ......................................................................................................... 13 2.2.3 Development. .............................................................................................. 14 2.3 Study Sites General Sites Description ........................................................... 15 2.4 Sampling Methods And Procedure .................................................................. 19 2.5 Sediment Analysis ............................................................................................. 19 2.5.1 Data Analysis .............................................................................................. 20 2.6 Results ................................................................................................................ 20 2.6.1 Sediment Characteristics ............................................................................ 20 2.6.2 Temperature ................................................................................................ 22 2.6.3 Salinity ........................................................................................................ 22 2.6.4 Total Organic And Moisture Content.. ...................................................... 22 2.6.5 Paracorophium Excavatum Survey ........................................................... 23 2.7 Discussion.......................................................................................................... 25 3 Chapter Three: Study of the Life Cycle of P. excavatum ,............................. ,.. 30 3.1 Introduction ....................................................................................................... 30 3.2 Study Sites Physical Description ................................................................... 33 3.2.1 Brooklands Lagoon .................................................................................... 33 3.2.2 Kairaki ......................................................................................................... 34 3.3 Methods ........................................ ~ .................................................................... 35 3.4 Results ................................................................................................................ 38 3.4.1 Population Density ..................................................................................... 38 3.4.2 Population Structure ................................................................................... 39 3.4.3 Mean Population Length ............................................................................ 41 3.4.4 Size At Maturity ......................................................................................... 41 Table of Contents VI 3.4.5 Reproduction .............................................................................................. 42 3.5 Discussion .......................................................................................... ~ ............... 69 4 Chapter Four: Sediment Toxicity Test ............................................................... 73 4.1 Introduction .......................................................................................................... 73 4.1.1 Copper - An Overview ............................................................................... 78 4.2 Materials And Methods ............................................... :.................................... 79 4.2.1 Animal Collection ...................................................................................... 79 4.2.2 Experimental Set 1: lO-Day Sediment Tolerance Test.. ........................... 79 4.2.3 Experimental Set 2: P. excavatum Bioassay Protocol. ............................