Tīmata whakaora, kickstarting recovery - Using bivalves to bioremediate degraded estuarine sediments
type: CreativeWork
description: Estuarine soft sediment ecosystems worldwide are increasingly threatened by anthropogenic, land-derived and marine stressors that compromise their health and functionality with cascading effects on ecosystem services that they provide. Once degraded, natural recovery can take years due to the loss of long-lived, functionally important benthic species. These species are important in maintaining internal feedback loops, thereby facilitating resilient communities that underpin critical ecosystem functions. In this thesis, I evaluated the role of two functionally distinct bivalve species, Austrovenus stutchburyi, a surface-dwelling suspension feeding bioturbator, and Macomona liliana, a deep-burrowing porewater-pressuriser, in supporting recovery of estuarine function following disturbance. Two field experiments in Tauranga Harbour, Aotearoa New Zealand were conducted, first a controlled disturbance-recovery translocation trial (after acute disturbance) and second, a large-scale translocation across a gradient of environmental (chronic) stress. In the first experiment bivalves were added to defaunated plots in single and combined species treatments and compared to ambient and defaunated no-addition controls. Measurements were taken over a period of 389 days (one year) and included influence of bivalve additions on sediment properties, nutrient cycling, benthic metabolism (Chapter 2), and community composition recruitment (Chapter 3). Results from the first research chapter (Chapter 2) demonstrate that A. stutchburyi consistently enhanced ecosystem function proxies, reducing sediment mud content, increasing oxygen consumption, and stimulating ammonium flux, even when survival was low, compared to unaided recovery. In contrast, M. liliana showed limited direct effects on the measured ecosystem functions and the co-addition of both species did not yield synergistic effects. The second research chapter (Chapter 3) elucidates that the presence of A. stutchburyi also altered …
abstract: Estuarine soft sediment ecosystems worldwide are increasingly threatened by anthropogenic, land-derived and marine stressors that compromise their health and functionality with cascading effects on ecosystem services that they provide. Once degraded, natural recovery can take years due to the loss of long-lived, functionally important benthic species. These species are important in maintaining internal feedback loops, thereby facilitating resilient communities that underpin critical ecosystem functions. In this thesis, I evaluated the role of two functionally distinct bivalve species, Austrovenus stutchburyi, a surface-dwelling suspension feeding bioturbator, and Macomona liliana, a deep-burrowing porewater-pressuriser, in supporting recovery of estuarine function following disturbance. Two field experiments in Tauranga Harbour, Aotearoa New Zealand were conducted, first a controlled disturbance-recovery translocation trial (after acute disturbance) and second, a large-scale translocation across a gradient of environmental (chronic) stress. In the first experiment bivalves were added to defaunated plots in single and combined species treatments and compared to ambient and defaunated no-addition controls. Measurements were taken over a period of 389 days (one year) and included influence of bivalve additions on sediment properties, nutrient cycling, benthic metabolism (Chapter 2), and community composition recruitment (Chapter 3). Results from the first research chapter (Chapter 2) demonstrate that A. stutchburyi consistently enhanced ecosystem function proxies, reducing sediment mud content, increasing oxygen consumption, and stimulating ammonium flux, even when survival was low, compared to unaided recovery. In contrast, M. liliana showed limited direct effects on the measured ecosystem functions and the co-addition of both species did not yield synergistic effects. The second research chapter (Chapter 3) elucidates that the presence of A. stutchburyi also altered …
author: Prinz, Natalie
keywords: restoration, disturbance-recovery, translocation experiment, Austrovenus stutchburyi, Macomona liliana, retention, ecosystem function
license: https://researchcommons.waikato.ac.nz/bitstreams/194ccc43-efd5-4c36-9e44-a812a6a87aa8/download
date published: 2025
date modified: 2026-07-24T05:57:44Z
provider: University Waikato
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: The University of Waikato