Craig R Johnson

Craig R Johnson
University of Tasmania · Institute for Marine and Antarctic Studies (IMAS)

About

269
Publications
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14,020
Citations
Citations since 2017
79 Research Items
5993 Citations
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Publications

Publications (269)
Preprint
Full-text available
Marine imagery is a comparatively cost-effective way to collect data on seafloor organisms, biodiversity and habitat morphology. However, annotating these images to extract detailed biological information is time-consuming and expensive, and reference libraries of consistently annotated seafloor images are rarely publicly available. Here, we presen...
Article
Tasmania is an island state in south-eastern Australia that has a long and rich history of seaweed use, research, and development. It is a cool-temperate system with 750 macroalgal species currently described. Tasmanian Aboriginal peoples have lived on this land for at least 40,000 years utilising seaweed as food, shelter, water carriers and medici...
Article
Full-text available
Ecosystem engineers often exert strong effects on the recruitment of other species through modification of the local abiotic and biotic environment. In 2015, artificial reefs in eastern Tasmania (− 42.64693, 148.01481) spanning seven different patch sizes (0.12–7.68 m ² ) and supporting four densities of transplanted kelp ( Ecklonia radiata at 0, 4...
Article
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View-only version accessible here: https://rdcu.be/cNqCu
Article
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1. The patch dynamics of foundation species profoundly affects community assembly and thus has important implications for ecosystem restoration. However, it is unclear how restored kelp patches that vary in size and density will influence the establishment of mid-trophic level (MTL) macroinvertebrates, a key functional group in coastal ecosystems....
Article
Across many temperate coastlines worldwide, kelp habitat has degraded to be replaced by alternative reef‐states with consequences to ecosystem functioning. Identifying both causes of decline and mechanisms of resilience of remnant kelp habitat is critical for managing and restoring these ecosystems. We use a combination of aerial imagery and field...
Article
The kelp, Ecklonia radiata, is an abundant subtidal ecosystem engineer in southern Australia. Density-dependent changes in the abiotic environment engineered by Ecklonia may feedback to affect reproduction and subsequent recruitment. Here we examined: 1) how the reproductive capacity of Ecklonia individuals in the field (zoospores released mm-2 rep...
Article
Nontrophic interactions can contribute to negative and positive feedbacks within a community, thus affecting likelihood of regime shifts; however, assessing the nature and importance of these effects in a network remains challenging, especially for pelagic ecosystems. Here, we present a qualitative modeling approach for assessing the importance of...
Article
Ecosystem engineering kelp forms habitat and influences associated communities by altering abiotic conditions. These conditions can also affect the engineer's own demographic rates but the mechanisms underpinning these feedbacks are not well known. Here, we tested the interactive effects of three abiotic factors engineered by the Australasian kelp...
Technical Report
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Dense giant kelp (Macrocystis pyrifera) forests were previously a conspicuous and iconic feature of the Tasmanian coast, but loss of ~95% of the species’ surface-canopies over recent decades has seen them listed by the Australian Government as an endangered community – the first such listing for a marine community in Australia. The decline of giant...
Article
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The ability to successfully transplant adult kelp has applications not only for ecological experiments, but also for habitat conservation and restoration projects. However, approaches to the long‐term transplanting of adult kelp (especially for stalked or ‘stipitate’ species), and the communication of these methods, has been relatively haphazard, o...
Data
NESP Marine Biodiversity Hub Project E7. Results from the outplanting of lab-selected and cultivated warm-adapted genotypes of giant kelp (Macrocystis pyrifera), at two trial restoration sites. -- Further details and data accessible at https://doi.org/10.25959/qmnc-h732
Data
NESP Marine Hub Project E7 - Intraspecific variation in the thermal tolerance of microscopic giant kelp (Macrocystis pyrifera) sporophytes was tested using a common garden experiment, where 49 unique family-lines were raised under four different water temperatures (12, 16, 20, and 24°C). -- Further details and data accessible at https://doi.org/10...
Article
Full-text available
Globally, collapse of ecosystems—potentially irreversible change to ecosystem structure, composition and function—imperils biodiversity, human health and well‐being. We examine the current state and recent trajectories of 19 ecosystems, spanning 58° of latitude across 7.7 M km2, from Australia's coral reefs to terrestrial Antarctica. Pressures from...
Article
Full-text available
Canopy‐forming macroalgae form the basis of diverse coastal ecosystems globally. The fucoid Hormosira banksii is often the dominant canopy‐forming macroalga in the temperate intertidal of southern Australia and New Zealand, where it is commonly associated with an understory of coralline turf. H. banksii is susceptible to both natural and anthropoge...
Article
Full-text available
• Fishing is a strong selective force and is supposed to select for earlier maturation at smaller body size. However, the extent to which fishing‐induced evolution is shaping ecosystems remains debated. This is in part because it is challenging to disentangle fishing from other selective forces (e.g., size‐structured predation and cannibalism) in c...
Article
Full-text available
Knowledge of long-term and multi-scale trends in ecological systems is a vital component in understanding their dynamics. We used Landsat satellite imagery to develop the first long-term (1986-2015) data set describing the cover of dense surface canopies of giant kelp Macrocystis pyrifera around the entire coastline of Tasmania, Australia, and asse...
Article
As foundation species, kelp support productive and species rich communities; however, the effects of kelp structure on mobile species within these complex natural systems are often difficult to assess. We used artificial reefs with transplanted kelp to quantify the influence of kelp patch size and density on fish assemblages including the arrival o...
Article
Full-text available
Kelp forests in many regions are experiencing disturbance from anthropogenic sources such as ocean warming, pollution and overgrazing. Unlike natural disturbances such as storms, anthropogenic disturbances often manifest as press perturbations that cause persistent alterations to the environment. One consequence is that some kelp forests are becomi...
Article
Full-text available
Kelp forests are highly productive foundation species along much of the world’s coastline. As a result, kelp are crucial to the ecological, social, and economic well-being of coastal communities. Yet, due to a combination of acute and chronic stressors, kelp forests are under threat and have declined in many locations worldwide. Active restoration...
Article
Areas that contain ecologically distinct biological content, called bioregions, are a central component to spatial and ecosystem‐based management. We review and describe a variety of commonly‐used and newly‐developed statistical approaches for quantitatively determining bioregions. Statistical approaches to bioregionalisation can broadly be classif...
Article
Full-text available
Patterns of abundance and shell morphology of intertidal gastropods are typically thought to depend on environmental conditions, but ecosystem engineers such as canopy-forming seaweeds can also influence these traits. The intertidal seaweed Hormosira banksii (H. banksii) is an abundant species and important ecosystem engineer on rocky shores and es...
Article
Full-text available
Kelp forests dominate the rocky coasts of temperate Australia and are the foundation of the Great Southern Reef. Much like terrestrial forests, these marine forests create complex habitat for diverse communities of flora and fauna. Kelp forests also support coastal food-webs and valuable fisheries and provide a suite of additional ecosystem service...
Article
Temperate marine systems are dominated by rocky reef macroalgal habitats, and there is now evidence that some seaweed communities are retreating in a manner consistent with climate change. Obtaining measurements of primary production across entire assemblages of algae over ecologically meaningful spatial scales is difficult, and acoustic techniques...
Article
Full-text available
ABSTRACT: Ecosystem engineers are important in shaping the composition of associated communities, including the abundance of species which exert additional influences on the ecosystem. Using an array of 28 artificial reefs supporting transplants of a dominant canopy-forming kelp (Ecklonia radiata) representing seven patch sizes (0.12 - 7.68 m2) cro...
Article
Opposing bottom-up ‘resource-driven’ and top-down ‘consumer-driven’ forces interact to shape the structure of ecosystems. While these counteracting forces are well recognised, debate remains regarding which of these forces is more influential across space and time. Here we explore bottom-up versus top-down control of macroalgal communities for temp...
Article
Characterising the spatial distribution and variation of species communities and validating these characteristics with data from the field are key elements for an ecosystem‐based approach to management. However, models of species distributions that yield community structure are usually not linked to models of community dynamics, constraining unders...
Article
This article recognizes that the impacts and effects of fishing are key to marine ecosystem management and explores the relationship between fisheries exploitation and sustainable harvests, and the collapse and depletion of stocks. A survey of 21 fisheries from around the world assessed key biological, environmental, social, economic, industry, gov...
Article
Full-text available
Habitat‐forming ecosystem engineers are the foundation of many marine ecosystems where they support diverse and productive food‐webs. A reduction in their patch size or density may affect the productivity, biodiversity, and stability of these ecosystems. We determined the effects of different densities and patch sizes of Ecklonia radiata (the domin...
Chapter
Full-text available
Ecklonia radiata is one of the most widespread kelps globally, dominating temperate reefs throughout much of Australasia and southeastern Africa. Throughout much of its range, it is the only laminarian kelp and hence plays a key role in facilitating biodiversity and driving food webs, and it underpins immense ecological and socioeconomic values. Th...
Article
Full-text available
Ecosystem engineers are species that influence the abiotic and biotic environment around them and may assist the restoration of associated species, including other habitat‐forming species. We deployed an array of 28 artificial reefs with transplanted Ecklonia radiata, the dominant canopy‐forming kelp species across southern Australia, to investigat...
Article
Full-text available
Development of global ocean observing capacity for the biological EOVs is on the cusp of a step-change. Current capacity to automate data collection and processing and to integrate the resulting data streams with complementary data, openly available as FAIR data, is certain to dramatically increase the amount and quality of information and knowledg...
Article
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Here we outline the genesis of Seamap Australia, which integrates spatial data of the seabed of Australia’s continental shelf (0–200 m depth) from multiple sources to provide a single national map layer of marine habitat. It is underpinned by a hierarchical classification scheme with registered vocabulary, enabling presentation of nationally consis...
Article
Full-text available
Sea urchins have the capacity to destructively overgraze kelp beds and cause a wholesale shift to an alternative and stable ‘urchin barren’ reef state. However, destructive grazing appears labile and contingent on behavioural shift. Changes in supply of allochthonous ‘drift-kelp’ food are hypothesised as a trigger of change in urchin grazing behavi...
Article
Full-text available
In coastal waters around the world, the dominant primary producers are benthic macrophytes, including seagrasses and macroalgae, that provide habitat structure and food for diverse and abundant biological communities and drive ecosystem processes. Seagrass meadows and macroalgal forests play key roles for coastal societies, contributing to fishery...
Article
Full-text available
Macroalgal forests provide the foundation for most shallow reef ecosystems in temperate environments; hence tools for accurately measuring primary productivity are integral for ecosystem management. This study compares estimates of production/potential production in an Ecklonia radiata kelp forest in Tasmania, Australia, using diel oxygen gross pri...
Article
Full-text available
Climate change is characterised by multiple abiotic forcings acting simultaneously on biotic systems. In marine systems, temperature appears to drive much of the observed change in biotic communities subject to climate change, but this may reflect the focus of most studies only on temperature without consideration of other environmental variables a...
Article
Biogenic marine habitats are threatened by a multitude of human stressors, and urbanised temperate coasts in particular are exposed to an intense and accumulating range of impacts. Here we use a 3-way factorial design to test the individual and combined effects of an approximate doubling of nutrients, sedimentation and sea urchin herbivory on rocky...
Article
Climate change is leading to shifts in species geographical distributions, but populations are also probably adapting to environmental change at different rates across their range. Owing to a lack of natural and empirical data on the influence of phenotypic adaptation on range shifts of marine species, we provide a general conceptual model for unde...
Article
Seamap Australia integrates seafloor maps with information on plant and animal habitats, environmental stressors, and resource management to create a first-of-its-kind resource.
Data
Kelp forests around the world are under increasing pressure from anthropogenic stressors. A widespread consequence is that in many places, complex and highly productive kelp habitats have been replaced by structurally simple and less productive turf algae habitats. Turf algae habitats resist re-establishment of kelp via recruitment inhibition; howe...
Article
Full-text available
Ensuring productive and sustainable fisheries involves understanding the complex interactions between biology, environment, politics, management and governance. Fisheries are faced with a range of challenges, and without robust and careful management in place, levels of anthropogenic disturbance on ecosystems and fisheries are likely to have a cont...
Article
Full-text available
Habitat forming ‘ecosystem engineers’ such as kelp species create complex habitats that support biodiverse and productive communities. Studies of the resilience and stability of ecosystem engineers have typically focussed on the role of external factors such as disturbance. However, their population dynamics are also likely to be influenced by inte...
Data
Results of preliminary analyses and abiotic analyses by season. Table A. Results of preliminary analyses. Table B. The experimental subsets into which macroscopic juvenile sporophytes were transplanted each season (N = total number of reefs). Winter sampling was attempted, but storms prevented the collection of sufficient data. Table C. Results of...
Article
Full-text available
Planning the Implementation of a Global Long-Term Observing and Data Sharing Strategy for Macroalgal Communities; Hobart, Tasmania, Australia, 24–26 September 2018
Data
Data accompanying "Layton et al. 2019, Resilience and stability of kelp forests: The importance of patch dynamics and environment-engineer feedbacks. PLOS ONE. doi: 10.1371/journal.pone.0210220" To explore how resilience and stability of kelp habitats is influenced by this habitat degradation, we created an array of patch reefs of various sizes an...
Technical Report
Full-text available
In Australia, the states and territories have the primary responsibility for coastal waters. However, the Environmental Protection and Biodiversity Conservation (EPBC) Act 1999 describes when the Australian Federal Government needs can assist. The EPBC focusses on nine matters of national environmental significance (MNES). These include World Herit...
Chapter
Full-text available
Kelp forests dominate the rocky reefs of temperate Australia and are the foundation of the Great Southern Reef that stretches 8,000km along the country's southern coastline. Much like terrestrial forests, kelp forests are complex habitats that support entire communities of associated flora and fauna. Unfortunately, in many places around Australia k...
Chapter
Full-text available
Kelp forests dominate the rocky reefs of temperate Australia and are the foundation of the Great Southern Reef that stretches 8,000km along the country's southern coastline. Much like terrestrial forests, kelp forests are complex habitats that support entire communities of associated flora and fauna. Unfortunately, in many places around Australia k...
Article
Full-text available
Understanding the strength and type of interactions among species is vital to anticipate how ecosystems will respond to ongoing anthropogenic stressors. Here, we examine the ecological function of native (Ecklonia radiata) and invasive (Undaria pinnatifida) kelps in resisting shifts to sediment-trapping turf on reefs within the highly urbanized tem...
Article
The invasion of SE Australia by the exotic New Zealand screwshell Maoricolpus roseus has sparked concern over its potential impact on native soft-sediment assemblages and, in particular, on commercially harvested molluscs. Here we quantify the impact of both live and dead and empty M. roseus shells on the growth, condition and survival of juvenile...
Article
Full-text available
The effects of climate-driven ocean change on reef habitat-forming species are diverse1,2 and can be deleterious to the structure and functioning of seafloor communities3–5. Although responses of shallow coral- or seaweed-based reef communities to environmental changes are a focus of ecological research in the coastal zone1,4–6, the ecology of habi...
Article
Hormosira banksii is an important intertidal habitat-forming seaweed in southern Australia that shows large variation in morphology. We examined the relationship between morphological variation in Hormosira and associated gastropod community structure, abundance and diversity in Tasmania, southern Australia. We sampled both Hormosira and gastropods...
Article
Timely detection of ecological regime shifts is a key problem for ecosystem managers, because changed ecosystem dynamics and function will usually necessitate a change in management strategies. However, currently available methods for detecting regime shifts depend on having multiple long time series data from both before and after the regime shift...
Article
A 3D ecosystem model was used to quantify changes in water quality brought about by salmon aquaculture in the D'Entrecasteaux Channel and Huon Estuary in southeast Tasmania. Macroalgae-based integrated multitrophic aquaculture (IMTA) was simulated and showed that IMTA is capable of reducing the increased chlorophyll concentration attributable to fi...
Article
Full-text available
Seafloor communities are a critical part of the unique and diverse Antarctic marine life. Processes at the ocean-surface can strongly influence the diversity and abundance of these communities, even when they live at hundreds of meters water depth. However, even though we understand the importance of this link, there are so far no quantitative spat...
Article
Full-text available
Benthic marine biodiversity on the Antarctic continental shelf is high and unique, yet its distributional patterns are still relatively poorly understood. Some of the main issues are that biological data are sparse, and that many species are rare and seem only weakly related to environmental conditions. Grouping species by taxonomic or functional s...
Preprint
Seafloor communities are a critical part of the unique and diverse Antarctic marine life. Processes at the ocean-surface can strongly influence the diversity and abundance of these communities, even when they live at hundreds of meters water depth. However, even though we understand the importance of this link, there are so far no quantitative spat...
Article
Heterogeneity in phytoplankton distribution is related to spatial and temporal variations in biogeochemical and ecological processes. In the open ocean, the interaction of these processes with meso- and submeso-scale dynamics (1-100 km, few days to months) gives rise to complex spatio-temporal patterns, whose characterization is difficult without e...
Article
Full-text available
URL: http://rdcu.be/A1wP <- this is the link to a free read-only version of the paper. Abstract: Most seafloor communities at depths below the photosynthesis zone rely on food that sinks through the water column. However, the nature and strength of this pelagic–benthic coupling and its influence on the structure and diversity of seafloor communitie...
Chapter
One of the purposes of biogeography is to identify areas within which a characteristic ecosystem is expected to occur. In the case of phytoplanktonic communities this knowledge is key to separate regions characterized by different biogeochemical processes, design efficient sampling strategies and recognize ecological hotspots. Meso- and submesoscal...
Article
Full-text available
Quantifying biological assemblages and their environment is a fundamental, yet statistically challenging task in conservation ecology. Here, we use a recently developed approach called Regions of Common Profile (RCP) to quantify and map the distribution of demersal fish assemblages in an ecologically significant region of the Southern Ocean to (1)...
Article
Marine reef habitats are typically defined subjectively. We provide a continental-scale assessment of dominant reef habitats through analysis of macroalgae and sessile animal taxa at sites distributed around Australia. Relationships between reef habitats and environmental and anthropogenic factors are assessed, and potential changes in the future d...
Article
Despite of over a century of intensive research on kelp (brown macroalgae of the order Laminariales), very few acoustic studies have been undertaken and much remains unknown about their species-specific acoustic properties, which are nevertheless essential for surveying and managing the respective habitats. In this paper, we discuss results of an i...