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Emma L Johnston

Emma L Johnston
UNSW Sydney | UNSW · School of Biological, Earth and Environmental Sciences (BEES)

Ph.D.

About

230
Publications
72,561
Reads
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9,133
Citations
Citations since 2017
99 Research Items
5914 Citations
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Introduction
My research group investigate human disturbances in marine communities. We approach this research from both an ecological and ecotoxicological perspective using field experimentation wherever possible.
Additional affiliations
January 2012 - present
Sydney Institute of Marine Science
Position
  • Director, Sydney Harbour Research Program
January 2006 - December 2012
UNSW Sydney
January 1997 - August 2002
University of Melbourne

Publications

Publications (230)
Article
Stormwater drains act as a pathway for anthropogenic debris from land to sea, particularly in urbanised estuaries where impervious surfaces expedite the process. Debris type and abundance in stormwater drains may vary due to land use and human activity, and knowledge of this variation is necessary to manage the growing threat of debris. Surveys of...
Article
Full-text available
Records of anthropogenic marine debris and the threats it poses are increasing worldwide, yet we know relatively little about the distribution of benthic debris. The seafloor is the final destination for a large proportion of debris due to the degradation and sinking of items. A more detailed understanding of debris distributions in hotspots such a...
Article
1 – The influence of habitat complexity on biodiversity is a central theme in ecology, with many studies reporting positive relationships. Reconciliation approaches in urbanised areas, such as eco‐engineering, have increasingly focused on ‘re‐building’ the complexity of degraded and/or homogenised habitats to support biodiversity. Yet the effects o...
Article
Full-text available
Four drivers of global change are acting in concert to speed up the ecology of our coastal and open ocean ecosystems. Ocean warming, nutrient pollution, disturbance, and species additions increase biological and ecological rates, favoring weedy communities and causing pervasive human impacts. Ocean warming via greenhouse gas emissions is accelerati...
Article
Novel combinations of climatic conditions due to climate change and prolonged fire seasons have contributed to an increased occurrence of “megafires”. Such large-scale fires pose an unknown threat to biodiversity due to the increased extent and severity of burn. Assessments of wildfires often focus on terrestrial ecosystems and effects on aquatic h...
Article
Large-scale desalination is used increasingly to address growing freshwater demands and climate uncertainty. Discharge of hypersaline brine from desalination operations has the potential to impact marine ecosystems. Here, we used a 7-year Multiple-Before-After-Control-Impact experiment to test the hypothesis that hypersaline discharge from reverse...
Article
Full-text available
This is a synopsis of the 2021 State of the Environment report for Australia. As chief authors of the report, we present some of the key findings here, including new chapters dedicated to extreme events and Indigenous voices.
Book
Full-text available
Australia state of the environment 2021 (SoE 2021) is written by a panel of independent authors, using the best available evidence, assured through consultation, peer‑review and fact‑checking processes, and building on 25 years of experience in national environmental reporting. This is the first time the report has included Indigenous voices, highl...
Article
Estuaries are one of the most valuable biomes on earth. Although humans are highly dependent on estuaries, anthropogenic activities have impacted estuaries worldwide, altering their ecological functions and ability to provide a variety of important ecosystem services. Many anthropogenic stressors combine to affect the soft sedimentary habitats that...
Article
Marine artificial structures such as pilings are replacing natural habitats, and modifying surrounding areas, often resulting in local decreases in species diversity and facilitation of bioinvasion. Most research on the impacts of artificial structures in marine ecosystems has primarily focused on rocky bottom habitats and biodiversity, overlooking...
Article
Full-text available
Coral reefs are amongst the most biodiverse ecosystems on earth, and while stony corals create the foundational complexity of these ecosystems, octocorals and anemones contribute significantly to their biodiversity and function. Like stony corals, many octocorals contain Symbiodiniaceae endosymbionts and can bleach when temperatures exceed the spec...
Article
Antarctic sea-ice forms a complex and dynamic system that drives many ecological processes in the Southern Ocean. Sea-ice microalgae and their associated microbial communities are understood to influence nutrient flow and allocation in marine polar environments. Sea-ice microalgae and their microbiota can have high seasonal and regional (>1000 km ²...
Article
Ocean decision-makers are tasked with balancing social, economic, and environmental considerations when addressing complex policy challenges and achieving strategic objectives, such as conservation targets, or sustainable and ocean-based economic development agendas. Like many common environmental assets, oceans have been impacted by a history of i...
Article
Anthropogenic marine debris is a persistent threat to oceans, imposing risks to ecosystems and the communities they support. Whilst an understanding of marine debris risks is steadily advancing, monitoring at spatial and temporal scales relevant to management remains limited. Citizen science projects address this shortcoming but are often critiqued...
Article
Full-text available
Coastal systems such as estuaries are threatened by multiple anthropogenic stressors worldwide. However, how these stressors and estuarine hydrology shape benthic bacterial communities and their functions remains poorly known. Here, we surveyed sediment bacterial communities in poorly flushed embayments and well flushed channels in Sydney Harbour,...
Preprint
Full-text available
Exploring the theoretical links between marine spatial planning and ocean accounting. In press - Marine Policy.
Article
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Ocean warming driven bleaching is one of the greatest threats to zooxanthellate cnidarians in the Anthropocene. Bleaching is the loss of Symbiodiniaceae, chlorophyll, or both from zooxanthellate animals. To quantify bleaching and recovery, standardised methods for quantification of Symbiodiniaceae and chlorophyll concentrations have been developed...
Article
Full-text available
Humans depend on earth’s ecosystems and in the Anthropocene, ecosystems are increasingly impacted by human activities. Sustainability—the long-term integrity of social–ecological systems—depends on effective environmental stewardship, yet current conceptual frameworks often lack empirical validation and are limited in their ability to show progress...
Article
Eutrophication is an increasing problem worldwide and can disrupt ecosystem processes in which macrobenthic bioturbators play an essential role. This study explores how intraspecific variation in body size affects the survival, mobility and impact on sediment organic matter breakdown in enriched sediments of an infaunal bivalve. A mesocosm experime...
Article
Widespread wastewater pollution is one of the greatest challenges threatening the sustainable management of rivers globally. Understanding microbial responses to gradients in environmental stressors, such as wastewater pollution, is crucial to identify thresholds of community change and to develop management strategies that protect ecosystem integr...
Article
Aim The shape of the diversity–disturbance relationship is context dependent, but the mechanisms driving this context dependence are unclear due to limited standardized empirical assessments across different environmental and ecological settings. At seven sites and over 20° of latitude, spanning both temperate and tropical systems, we measured comm...
Article
We describe the design and structure of a web-based visualization tool for an Australian marine debris database and its application in environmental research, management and science communication. We give examples of its use in generating hypotheses regarding processes driving the distribution of marine debris, identifying source reduction opportun...
Article
Full-text available
Marine protected areas (MPAs) are a primary tool for the stewardship, conservation, and restoration of marine ecosystems, yet 69% of global MPAs are only partially protected (i.e., are open to some form of fishing). Although fully protected areas have well-documented outcomes, including increased fish diversity and biomass, the effectiveness of par...
Article
The marine environment is being increasingly modified by the construction of artificial structures, the impacts of which may be mitigated through eco-engineering. To date, eco-engineering has predominantly aimed to increase biodiversity, but enhancing other ecological functions is arguably of equal importance for artificial structures. Here, we man...
Article
Full-text available
The sprawl of marine construction is one of the most extreme human modifications to global seascapes. Nevertheless, its global extent remains largely unquantified compared to that on land. We synthesized disparate information from a diversity of sources to provide a global assessment of the extent of existing and projected marine construction and i...
Article
Full-text available
This method develops a local environmental stewardship indicator (LESI), which represents the level of stewardship action of a person at a place. The goal of the indicator is to quantify stewardship activity and allow it to be compared and modelled. LESI requires a brief interview to ascertain an individual's past and current stewardship activities...
Article
Urbanised estuaries, ports and harbours are often utilised for recreational purposes, notably recreational angling. Yet there has been little quantitative assessment of the footprint and intensity of these activities at scales suitable for spatial management. Urban and industrialised estuaries have previously been considered as having low conservat...
Article
Abstract Aim: Topographic complexity is widely accepted as a key driver of biodiversity, but at the patch-scale, complexity–biodiversity relationships may vary spatially and temporally according to the environmental stressors complexity mitigates, and the species richness and identity of potential colonists. Using a manipulative experiment, we asse...
Article
Full-text available
The human footprint on earth is now so great that we must become environmental stewards. To encourage stewardship and achieve better conservation outcomes, research is needed to connect practice with sound theory, and to empirically measure stewardship so we can identify its predictors and motivators. In this study, we use mixed methods to develop...
Article
Full-text available
Contaminants may affect ecosystem functioning by reducing the fitness of organisms and these impacts may cascade through ecosystems, particularly if the sensitive organisms are also habitat‐forming species. Understanding how sub‐lethal effects of toxicants can affect the quality and functions of biogenic habitats is critical if we are to establish...
Article
Full-text available
Real-world observational datasets that record and quantify pressure-stressor-response linkages between effluent discharges and natural aquatic systems are rare. With global wastewater volumes increasing at unprecedented rates, it is urgent that the present dataset is available to provide the necessary information about microbial community structure...
Article
Full-text available
Background: Sequencing of 16S rRNA genes has become a powerful technique to study microbial communities and their responses towards changing environmental conditions in various ecosystems. Several tools have been developed for the prediction of functional profiles from 16S rRNA gene sequencing data, because numerous questions in ecosystem ecology...
Article
Sea-level rise is an inevitable consequence of climate change and threatens coastal ecosystems, particularly intertidal habitats that are constrained by landward development. Intertidal habitats support significant biodiversity, but also provide natural buffers from climate-threats such as increased storm events. Predicting the effects of climate s...
Article
Global growth in desalination industries has increased the need for an evidence-based understanding of associated environmental impacts. We completed a seven-year assessment of the responses of fish assemblages to hypersaline discharge from the large Sydney Desalination Plant. At 12 times before, eight times during, and four times following the ces...
Article
Full-text available
The sub-Antarctic islands of New Zealand are biodiversity hotspots in the Southern Ocean, containing numerous endemic species and providing breeding grounds for seabirds and marine mammals. However, due to their remoteness and harsh environments, many of their marine ecosystems are relatively unexplored and potentially at risk from alien invasive s...
Article
The replacement of natural marine habitats with less structurally complex human infrastructure has been linked to the homogenisation of epibenthic assemblages and associated changes in fish assemblages. To mitigate these impacts, eco-engineering efforts have focussed on increasing the physical and biogenic complexity of artificial structures, in th...
Article
Coastal ecosystems are under growing pressure from human activities such as pollution and climate change. Although the rapidly growing numbers of humans living in coastal areas is a large part of the problem, there is great opportunity to improve the resistance and resilience of biotic communities via creative changes to the engineering design of b...
Article
Intermittently Closed and Open Lakes and Lagoons (ICOLLS) are important coastal systems that are periodically separated from the ocean by a sand barrier or a berm. In urban ICOLLs, continuous inputs of organic material and nutrients into coastal lagoons are contributing to eutrophic conditions that, together with natural environmental factors have...
Article
Predation is considered an important structuring process in ecology; however, the effect size attributed to predation can vary across manipulative experiments. Complex interactions between predators of different sizes and trophic levels can confound observations in field-based experimental studies. Excluding large (macro) predators has demonstrated...
Article
Full-text available
Population growth is driving the demand for recreational marine infrastructure, resulting in extensive coastal habitat modification. Boat moorings, for example, are popular for vessel storage and are known to damage seagrass communities, yet little is known about how they influence unvegetated sediment habitats. Here we investigate the effects of b...
Article
Natural systems are threatened by a variety of anthropogenic stressors and so understanding the interactive threats posed by multiple stressors is essential. In this study we focused on urban stressors that are ubiquitous to urban estuarine systems worldwide: elevated nutrients, toxic chemical contaminants, built infrastructure and non-indigenous s...
Conference Paper
Full-text available
The human footprint on earth is now so great that we are in the position of stewards of nature-whether we like it or not. Researchers call on an urgent need for active stewardship of earth systems, yet stewardship is variously defined, and difficult to quantify. Stewardship takes many forms, operates at many scales from local to global, and spans i...
Conference Paper
Full-text available
Fishing is a major human disturbance to marine communities on temperate rocky reefs. The Hawkesbury bioregion, on the east coast of Australia, has one of the highest human population densities in the country, and a correspondingly-high level of fishing impact. The region also contains ten small Marine Protected Areas (MPAs), most of which are open...
Article
Rock pools provide a range of ecological niches that can support diverse assemblages on rocky shores. As intertidal shores are increasingly lost to developments, understanding the drivers of diversity in rock pools is important for the conservation and construction of these key habitats. In this study we investigated relationships between physical...
Preprint
Full-text available
Assessing the functional capability and redundancy of a microbial community is a major challenge in environmental microbiology. To address this challenge, we developed Tax4Fun2, a R-based tool for the rapid prediction of functional profiles and functional redundancy of prokaryotic communities from 16S rRNA gene sequences. By incorporating user-defi...
Article
Full-text available
Host-associated microbial communities play a fundamental role in the life of eukaryotic hosts. It is increasingly argued that hosts and their microbiota must be studied together as 'holobionts' to better understand the effects of environmental stressors on host functioning. Disruptions of host-microbiota interactions by environmental stressors can...
Article
Microbially mediated biogeochemical processes are crucial for climate regulation and may be disrupted by anthropogenic contaminants. To better manage contaminants we need tools that make real‐time causal links between stressors and altered microbial functions, and the potential consequences for ecosystem services such as climate regulation. In a ma...
Article
Coastal waterways are increasingly exposed to multiple stressors, e.g. contaminants that can be delivered via pulse or press exposures. Therefore, it is crucial that ecological impacts can be differentiated among stressors to manage ecosystem threats. We investigated microbial community development in sediments exposed to press and pulse stressors....
Presentation
Full-text available
Introduction Marine Protected Areas (MPAs) are a key management tool for the conservation of biodiversity and restoration of marine communities. While large, well-designed and enforced MPAs have been found to be effective, most MPAs are small with various levels of protection, and the conservation effectiveness of such MPAs varies. This study asses...
Presentation
Understanding the relationship between humans and ecosystems is more important than ever in an increasingly-urbanized, human-impacted world. Social Ecological System (SES) models provide a framework to understand and manage this relationship, but most SES models offer only partial representation of human-ecosystem interactions. Many SES models are...
Article
Desalination is an increasingly common method of meeting potable water demands, but the associated ecological risks are not well understood. Seawater desalination plants discharge large volumes of hypersaline brine directly into the ocean, raising concerns about potential impacts to marine life. In order to reduce impacts of brine, newer desalinati...
Article
Full-text available
Several reproductive strategies have been identified as key factors that contribute to the establishment and dispersal of invasive species in new environments. These strategies include early maturity, high reproductive capacity and flexibility in timing of reproduction. It is therefore critical to investigate the reproductive biology of target exot...
Data
Summary of GLMs of the effects of Sex and Month on gamete abundance. (XLSX)
Data
Results of post-hoc Tukey’s pairwise tests between adjacent months from GLMs of the effects of month on gamete abundance at Wirrina Cove (Table 1). (XLSX)
Data
Sabella spallanzanii in Gulf St Vincent. (CSV)
Article
Full-text available
Marine Protected Areas (MPAs) are a key management tool for the conservation of biodiversity and restoration of marine communities. While large, well-designed and enforced MPAs have been found to be effective, results from small MPAs vary. The Hawkesbury Shelf, a coastal bioregion in New South Wales, Australia, has ten small, near-shore MPAs known...
Article
Viruses are ubiquitous, abundant and play an important role in all ecosystems. Here we advance understanding of coastal sediment viruses by exploring links in the composition and abundance of sediment viromes to environmental stressors and sediment bacterial communities. We collected sediment from contaminated and reference sites in Sydney Harbour...
Article
Assessments of human impacts on natural habitats often focus on the abundance of component species, yet physiological and/or sub-lethal effects of stressors on functional attributes may be equally important to consider. Here we evaluated how artificial structures, an integral part of urbanisation in the marine environment, affects key functional pr...
Article
Habitat complexity is accepted as a general mechanism for increasing the abundance and diversity of communities. However, the circumstances under which complexity has the strongest effects are not clear. Over 20 degrees of Australia's east coast, we tested whether the effects of within‐site structural habitat complexity on the diversity and communi...
Article
Full-text available
Historical ecology can teach us valuable lessons on the processes and drivers of environmental change that can inform future monitoring priorities and management strategies. Environmental data to study environmental history, however, is often absent or of low quality. Even when studying changes occurring during the last few decades, monitoring effo...
Technical Report
Full-text available
This report summarises those field campaigns, details the datasets obtained and highlights the relevance of the data gathered to the overall modelling program for the Hunter River estuary water quality modelling project.
Article
Coastal urbanization has led to large-scale transformation of estuaries, with artificial structures now commonplace. Boat moorings are known to reduce seagrass cover, but little is known about their effect on fish communities. We used underwater video to quantify abundance, diversity, composition and feeding behaviour of fish assemblages on two sca...
Article
The global sprawl of urban centres is replacing complex natural habitats with relatively flat and featureless infrastructure that supports low biodiversity. In a growing countermovement, artificial microhabitats are increasingly incorporated into designs for “Green” and “Blue” infrastructure. In order to maximise the ecological value of such interv...
Article
Full-text available
There is the potential for climate change to interact with pollution in all of the Earth's oceans. In the fjords of Norway, mine tailings are released into fjords generating suspended sediment plumes that impact deep-sea ecosystems. These same deep-sea ecosystems are expected to undergo periodic warming as climate change increases the frequency of...
Article
Sandy beaches are unique ecosystems increasingly exposed to human-induced pressures. Consistent with emerging frameworks promoting this holistic approach towards beach management, is the need to improve the integration of social data into management practices. This paper aims to increase understanding of links between demographics and community val...
Article
Complexity in physical habitats may modify predation pressure by allowing differential access of predators to prey. Rocky subtidal environments are inherently complex with many cryptic micro habitats, such as overhangs and crevices. Here, we examine the influence of habitat complexity in mediating predation on sessile assemblages by experimentally...
Article
Full-text available
There is growing public concern about the global expansion of harmful algal bloom species (HABs), with dinoflagellate microalgae comprising the major portion of the harmful taxa. These motile, unicellular organisms have a lifecycle involving sexual reproduction and resting cyst formation whereby cysts can germinate from sediments and ‘seed’ plankto...