Validating cumulative impact methods in marine systems

Mr Jackson Stockbridge1, Dr Alice  Jones2, Prof Bronwyn Gillanders3

1The University Of Adelaide, Adelaide, Australia, 2The University of Adelaide, Adelaide, Australia, 3The University of Adelaide, Adelaide, Australia

Marine ecosystems are under threat from multiple stressors arising from human activities. When considered in isolation, the effects of human activities such as overfishing, pollution, climate change, invasive species and physical degradation can be measured and quantified to give an estimate of impact. However, these stressors rarely act in isolation, and as such an estimate of the cumulative impact is needed. The most commonly applied methods for assessing cumulative impacts involve mapping threats and using expert knowledge to determine vulnerability of a system to different threats. These methods rely on many assumptions and incorporate expert knowledge in the place of empirical data. To assess whether spatial cumulative impact maps correlate with actual impact, we used data from a seagrass condition survey. We assessed the relationship between measured seagrass condition and previously published cumulative impact scores for a study area in northern Spencer Gulf, South Australia. The results show that there is little correspondence between modelled cumulative impact scores and measured seagrass condition at 31 sites throughout northern Spencer Gulf. Using seagrass as a case study, we have highlighted that the current approach to assessing cumulative impacts in marine ecosystems does not adequately capture the actual impacts of human activities on marine ecosystems. This is likely to be the result of a lack of empirical data to support many of the assumptions used in cumulative impact assessment methods. The outcomes highlight the need to develop more robust approaches to cumulative impact assessment in marine ecosystems.


I completed my Bachelor of Science  with Honours was completed at The University of Adelaide under the supervision of Prof Bronwyn Gillanders and Dr Alice Jones. My Honours project aimed to quantify the condition of mangroves around South Australia in order to promote their status as important areas of carbon sequestration.

Now into my second year as a PhD candidate with the same supervisor, i am looking at how we model cumulative impacts in marine ecosystems.

Failures or nirvana? Building and upgrading coastal infrastructure

Mr Peter Halton1

1Wattle Range Council, Millicent, Australia

Coastal councils in regional South Australia are under increasing pressures from the community to invest in the upgrade and development of new coastal infrastructure.  Examples include high quality multi use pathways for walking and cycling, beach access by boardwalks or stairs, protection works from erosion or flooding, right through to upgrades to jetties and boat ramps.

Director of Engineering Services at Wattle Range Council, Peter Halton, will provide an overview of his learnings in the building and maintenance of coastal infrastructure in regional South Australia.  Topics will include engaging the local community, design, construction, approvals, interaction with State Government agencies and maintenance of assets.

Giving real life examples, this presentation will appeal to staff and elected members from local government, as well as anyone interested in managing coastal infrastructure and connecting with coastal communities.


Peter is a civil engineer with over 21 years in Local Government as well as proven experience in construction and project management for private industry.   As Director of Engineering Services for Wattle Range Council, Peter has overseen the construction and maintenance of coastal infrastructure including groynes, seawalls and the Beachport Boat Ramp.  He has also taken a lead role in engaging with local communities on coastal issues such as erosion and sea level rise.  Peter is the regional council’s representative on the Coastal Protection Board’s advisory committee.

Nearshore hydrodynamic measurements in the Gulf Saint Vincent

Dr Graziela Miot Da Silva1, Dr Paul Van Ruth2, Dr Mark Doubell2, Dr Noble Warwick3, Dr Tim Kildea4, Dr  Milena Fernandes4, Paul Malthouse2

1Flinders University, , Australia, 2South Australian Research and Development Institute – SARDI, , , 3Environment Protection Authority – EPA, , , 4SA Water, ,

Nearshore hydrodynamic measurements in Gulf Saint Vincent are limited. The longest wave data record consists of a ~2 year non-directional dataset measured off Seacliff Beach during 1981 and 1982. Directional wave data was produced during the Adelaide Coastal Waters Study but spans just over a month, while other sporadic measurements are not long enough to capture long frequency oscillations, and not readily available to the scientific community or the general public. Coastal research, which is the basis for well-informed management decisions, is therefore often limited to modeled wave and hydrodynamic data. There is an immediate need of long-term measurements of directional waves and nearshore currents in Gulf Saint Vincent that will generate critical information for current coastal management efforts, water quality monitoring programs, navigation, ocean model validation and broader coastal research. Flinders University, the South Australian Research and Development Institute (SARDI), SA Water and the South Australian Environment Protection Authority (SA EPA) are currently developing a partnership in wave and nearshore current data collection to address the significant, ongoing impact of suspended sediments into coastal waters and as a part of a broader monitoring program for the Australian Integrated Marine Observing System (IMOS), which represents a starting point in bridging this gap. The program will commence in July 2019, with the deployment of a Nortek Sig1000 ADCP off the Adelaide metropolitan coast to supplement quarterly IMOS biogeochemical sampling. All data will be made available online through the IMOS Australian Oceanographic Data Network (AODN).


Bio to come

Why you need to let go of planned retreat and embrace assisted transition

Mr Allan Young

The standard rule book suggests that there are two main options for coastal adaptation – stay and protect, or move away.

One of the options is more popular than the other – and it comes as no great surprise that retreat is the unpopular one. Yet it remains that case that we are unlikely to be able to protect all assets, in all locations, for all time. Retreat will be a necessary solution in some places.

This presentation is all about making the retreat option workable. It is based on the results of a Churchill Trust research project undertaken in 2017 across the US, Caribbean and UK. It draws on the experience and insights of dozens of coastal practitioners, academics and community groups internationally.

The presentation will reveal the root causes of our general inability to make ‘planned retreat’ work. We have allowed planned retreat to become mission impossible. It now creates a moral hazard that promotes maladaptive behaviour and invites risk escalation. We need a fresh approach to put retreat options on a more realistic and sustainable footing.

This presentation will describe an innovative and pragmatic option to make retreat feasible. It is, as far as can be established, a global first.

The US journal Coastal Management recently published Allan Young’s paper on this topic, and it is generating interest from a number of public authorities in Australia and internationally. With good reason. The difficult economic and social adjustments required of coastal communities need this conversation.


Allan Young is an urban planner with a career background spanning the public and private sector, locally and internationally.

He is the Planning Service Leader for EMM Consulting and previously held senior roles in the NSW Government. His work includes coastal planning projects in Australia and New Zealand. His work has been recognised through a Fulbright Scholarship and more recently a Churchill Fellowship.

Allan’s research looks at some of the most complex issues confronting coastal managers and then tries to offer some simple practical responses.

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