Tipping points in ecosystem structure, function and services
We investigated how marine ecosystems respond to change, and identified tipping points, risks and ways of managing them.
Project Leader
Duration
Budget
Simon Thrush (University of Auckland)
April 2016 – June 2019
$3,470,000
Overview
We investigated the effects of multiple stressors and cumulative impacts on marine ecosystems. Stressors can be caused by unexpected events (such as earthquakes) or impacts of human activities (such as increased sediment, nutrients or contaminants in the water), or climate change. These stressors can lead to ‘tipping points’ when rapid transformations occur, and an ecosystem loses its capacity to cope with change. Tipping points often involve the loss of valuable marine resources, or ecosystem services.
This was the first nationwide assessment of how estuaries and harbours in Aotearoa New Zealand respond to change. Our results show that as coastal waters become more turbid and nutrient levels increase biodiversity and ecosystem function decline. Rocky shores and kelp forests are also affected, with elevated turbidity decreasing the ability of these systems to respond to change and recover from disturbance.
Coastal and marine ecosystems deliver multiple benefits and services, so it is important to deal with the cumulative impacts of stressors and develop management strategies to reduce their impact. Our research suggests there is a growing need to apply an ecosystem-based management framework to manage risk and sustain New Zealand’s coastal ecosystems. This is even more important given the ongoing impacts of climate change.
eDNA metabarcoding offers a sensitive, cost-effective and fast way to detect nutrient enrichment effects in estuaries. Marine ecologist Dana Clark explains in this short video.
Evidence of bias in assessment of fisheries management impacts
Academic publication
Slooten E, G Simmons, SM Dawson, G Bremner, SF Thrush, H Whittaker, F McCormack, BC Robertson, N Haworth, PJ Clarke, D Pauly and D Zeller (2017)
PNAS 114:E4901-E4902.
Kaikōura earthquake: Summary of impacts and changes in nearshore marine communities
Academic publication
Schiel DR, Gerrity S, Alestra T, Pirker J, Marsden I, Dunmore R, Tait L, South P, Taylor D and Thomsen M (2018)
Book chapter in: Shakey Shores- Coastal impacts & responses to the 2016 Kaikōura earthquakes. Henlass C, Borrero J, Neale D and Shand T (eds)
Old tools, new ways of using them: harnessing expert opinions to plan for surprise in marine socio-ecological systems
Academic publication
Gladstone-Gallagher RV, Hope JA, Bulmer RH, Clark DE, Stephenson F, Mangan S, Rullens V, Siwicka E, Thomas SF, Pilditch CA, Savage C and Thrush SF (2019)
Frontiers in Marine Science 6:696
Cumulative stressors reduce the self-regulating capacity of coastal ecosystems
Academic publication
Thrush SF, Hewitt JE, Gladstone-Gallagher RV, Savage C, Lundquist C, O’Meara T, Vieillard A, Hillman JR, Mangan S, Douglas EJ, Clark DE, Lohrer AM and Pilditch C (2020)
Ecological Applications 31(1):e02223
[Open access]
Managing the impact of turbidity, nutrients and sea level rise on coasts and estuaries
Guidance
This guidance explains the cumulative effects of three significant coastal stressors and likely impact on ecosystem function, and provides management recommendations.
This document provides an ecological perspective on how to overcome ecological issues related to the use of national environmental limits. Hewitt J, Bulmer R, Clark D, Couzens G, Ellis J, Gladstone-Gallagher R, Lohrer D, Pilditch D, Thrush S (May 2022)
Conference presentation: eDNA reveals estuarine benthic community to nutrient enrichment – evidence from an in-situ experiment
Presentation
Conference presentation by Dana Clark summarising research from authors Dana Clark, Conrad Pilditch, Joanne Ellis, Angel Borja, Javier Atalah, John Pearman, and Anastasija Zaiko, November 2021, (12 mins).
Cumulative effects erode resilience in coastal ecosystems
Summary
This summary gives the main points of three articles published between 2021 and 2023, which highlight how cumulative effects can induce an overarching snowball effect, and how understanding this mechanism is crucial to predicting ecological shifts.
We studied initiatives to create economic value from sustainable marine activities that are based on healthy ecosystems. We used the findings to map and model a blue economy.
Participatory processes for marine ecosystem restoration
We examined how the Kaituna River re-diversion strategy was developed, to identify success factors in stakeholder and iwi engagement that could be applied in other marine resource contexts.
