Christoph D. Matthaei

Christoph D. Matthaei
University of Otago · Department of Zoology

PhD (ETH/EAWAG); habil (Munich)

About

193
Publications
51,054
Reads
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6,236
Citations
Citations since 2017
66 Research Items
3579 Citations
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Introduction
For a comprehensive, up-to-date list of my publications (including the times each article has been cited), please see my Google Scholar Profile: http://tinyurl.com/cd-matthaei-scholar

Publications

Publications (193)
Presentation
Full-text available
The Stream Ecology Research Group at Otago University has won the ”River Story Award” at the 2017 New Zealand River Awards. A 3.5 min video made by the Cawthron Foundation tells a story about the multiple-stressor research done since 2007 in the ExStream System, an innovative research facility delevoped by Jay Piggott and Christoph Matthaei. The vi...
Article
Full-text available
Anthropogenic environmental changes, or 'stressors', increasingly threaten biodiversity and ecosystem functioning worldwide. Multiple-stressor research is a rapidly expanding field of science that seeks to understand and ultimately predict the interactions between stressors. Reviews and meta-analyses of the primary scientific literature have largel...
Article
Full-text available
See related 3-min video: https://vimeo.com/243219546 . Sustainable management of freshwater and pesticide use is essential for mitigating impacts of intensive agriculture in the context of a changing climate. To better understand how climate change will affect the vulnerability of freshwater ecosystems to chemical pollutants, more empirical evidenc...
Article
Full-text available
Pharmaceuticals are an important class of micropollutants within the freshwater environment. There is sufficient evidence of their impacts on exposed biota to warrant further research to better assess their risk. We reviewed ecotoxicological freshwater studies conducted from 2010-2020 on carbamazepine, diclofenac, and ibuprofen, three high-use phar...
Article
Multiple stressors are continuously deteriorating surface waters worldwide, posing many challenges for their conservation and restoration. Combined effect types of multiple stressors range from single-stressor dominance to complex interactions. Identifying prevalent combined effect types is critical for environmental management, as it helps to prio...
Article
Full-text available
This study addresses the primary factors driving young-of-the-year (YoY) brown trout Salmo trutta abundance and population dynamics through the Austral summer in an important spawning tributary of a large New Zealand river. We measured the key traits and spawning investment of spawners; YoY density and movement; and environmental characteristics im...
Article
Full-text available
When herbivore abundance is controlled by predators there may be an indirect positive effect on primary producers due to reduced grazing pressure, but the potential of predation refuges to modify such trophic cascades has rarely been studied. By experimentally manipulating substrate particle size and fish predation regime, we assessed the outcome o...
Article
Full-text available
• Use of invertebrate traits rather than species composition may facilitate large-scale comparisons of community structure and responses to disturbance in freshwater ecology because the same traits potentially occur everywhere. In recent years, comprehensive invertebrate trait databases have been established at different scales (e.g., regions, cont...
Article
Contamination of the environment with toxic chemicals such as pesticides has become a global problem. Understanding the role of chemical contaminants as stressors in ecological systems is therefore an important research need in the 21st century. In surface freshwaters, mixtures of neonicotinoid insecticides are being detected around the world as mo...
Article
Full-text available
Macroinvertebrate communities in running waters are commonly used as bioindicators of fine sediment pollution, but few studies evaluate impacts across multiple years. We used a 5-year dataset from 46 rivers in Southland, New Zealand to investigate the consistency of the relationship between deposited fine sediment and stream macroinvertebrates acro...
Article
The global intensification of agriculture has resulted in pesticides playing an increasingly important role as anthropogenic stressors and drivers of environmental change. There is also a growing need to determine if other environmental stressors, especially those predicted to worsen with climate change, interact with pesticides to alter their effe...
Article
Full-text available
Ensuring the provision of essential ecosystem services in systems affected by multiple stressors is a key challenge for theoretical and applied ecology. Trait-based approaches have increasingly been used in multiple-stressor research in freshwaters because they potentially provide a powerful method to explore the mechanisms underlying changes in po...
Article
Natal homing and straying are behavioural tactics of migratory animals that return to nursery habitats to breed as adults. Straying has evolutionary and ecological importance for species flexibility, interpopulation connectivity and success of invasive species in new environments. This study aimed to estimate the relative importance of straying and...
Article
Full-text available
Freshwater ecosystems face many simultaneous pressures due to human activities. Consequently, there has been a rapid loss of freshwater biodiversity and an increase in biomonitoring programs. Our study assessed the potential of benthic stream bacterial communities as indicators of multiple-stressor impacts associated with urbanisation and agricultu...
Article
Full-text available
The integrity of freshwater ecosystems worldwide is under threat from agriculture and invasive species. Past agricultural activity can have persistent effects on aquatic diversity even decades after restoration, and the spread of invasive species is increasingly difficult to prevent due to globalisation. In the South Island of New Zealand, the inva...
Article
Despite the progress made in environmental microbiology techniques and knowledge, the succession and functional changes of the microbial community under multiple stressors are still poorly understood. This is a substantial knowledge gap as microbial communities regulate the biogeochemistry of stream ecosystems. Our study assessed the structural and...
Article
• Determining the factors driving population dynamics of stream salmonids across broad landscapes is important for understanding stream ecosystem functioning and for the management and conservation of the populations of such fish. A few studies have described the determinants of the early life history of salmonids across catchments, but none of the...
Article
Anyone clicking on this link before April 03, 2020 will be taken directly to the final version of this article on ScienceDirect, which they are welcome to read or download: https://authors.elsevier.com/c/1aZddB8cco9YD ABSTRACT: Agricultural development has resulted in the degradation of freshwater ecosystems worldwide. Two key stressors impacting s...
Article
Full-text available
Note: 50 free online copies of this article are available here: https://www.tandfonline.com/eprint/PYRVE58ZKPHETDXXJXAS/full?target=10.1080/00288330.2019.1703015 Microplastic pollution in aquatic systems has been reported globally at an alarming rate, with an increasing number of documented negative biological consequences. Research on microplastic...
Article
Many streams and rivers worldwide are restored with the intention to mitigate degradation caused by human activities, but these rehabilitation projects often involve physical instream work with diggers or other heavy machinery. The short-term effects of such restoration works on stream ecosystems are rarely investigated. The primary aim of our stud...
Article
Full-text available
Stable isotope values of primary consumers have been proposed as indicators of human impacts on nitrogen dynamics. Until now, these values have been related only to single-stressor gradients of land-use intensity in stream ecology, whereas potential interactive effects of multiple stressors are unknown. It also remains unknown whether stable isotop...
Article
Full-text available
Interactions of pesticides with biotic or anthropogenic stressors affecting stream invertebrates are still poorly understood. In a three-factor laboratory experiment, we investigated effects of the neonicotinoid imidacloprid, food availability, and population density on the New Zealand mayfly Deleatidium spp. (Leptophlebiidae). Larval mayflies (10...
Article
Freshwaters worldwide are affected by multiple stressors. Timing of inputs and pathways of delivery can influence the impact stressors have on freshwater communities. In particular, effects of point versus diffuse nutrient inputs on stream macroinvertebrates are poorly understood. Point-source inputs tend to pose a chronic problem, whereas diffuse...
Article
Full-text available
Neonicotinoid insecticides have been shown to have high chronic relative to acute toxicity, therefore short‐term toxicity tests of ≤ 96 hours in duration may underestimate their environmental risks. Among non‐target aquatic invertebrates, insects of the orders Diptera and Ephemeroptera have been found to be the most sensitive to neonicotinoids. To...
Article
Agricultural practices often result in multiple stressors affecting stream ecosystems, and interacting stressors complicate environmental assessment and management of impacted streams. The nitrification inhibitor dicyandiamide (DCD) is used for nitrogen management on farmland. Effects of leached DCD on stream ecosys- tems are still largely unstudie...
Article
Anyone clicking on this link before September 27, 2019 will be taken directly to the final version of your article on ScienceDirect, which they are welcome to read or download. No sign up, registration or fees are required: https://authors.elsevier.com/c/1ZXEIzLNSODMD New Zealand uses more than a ton of pesticides each year; many of these are mobi...
Article
Increased temperatures and exposure to agricultural insecticides are increasingly threatening freshwater ecosystems worldwide. However, their combined effects are still poorly understood. We investigated the individual and interactive effects of water temperature and imidacloprid, the most widely used neonicotinoid insecticide, on larvae of two New...
Article
Full-text available
Species reintroductions-the translocation of individuals to areas in which a species has been extirpated with the aim of re-establishing a self-sustaining population-have become a widespread practice in conservation biology. Reintroduction projects have tended to focus on terrestrial vertebrates and, to a lesser extent, fishes. Much less effort has...
Article
Mechanically reshaping stream banks is a common practice to mitigate bank erosion in streams that have been extensively channelised and lowered for land drainage. A common perception regarding this activity is that fish populations will be largely unaffected, at least in the short term, because the low‐flow wetted channel remains undisturbed. Howev...
Article
Global patterns of biodiversity have emerged for soil microorganisms, plants and animals, and the extraordinary significance of microbial functions in ecosystems is also well established. Virtually unknown, however, are large-scale patterns of microbial diversity in freshwaters, although these aquatic ecosystems are hotspots of biodiversity and bio...
Article
Tropical streams are one of the most endangered ecosystems in the world due to the constant pressures from human activities. Among these activities, agriculture represents a land use that is crucial for human development but also a key driver of stream degradation and biodiversity decline in the tropics. Against this background, we investigated ind...
Chapter
In this chapter, we summarize the available information on the main stressors affecting running water ecosystems in Australia and New Zealand (NZ). Four major habitat types (MHT), or biomes, are found within this region of the Southern Hemisphere (Fig. 13.1). The four biomes comprise 11 freshwater ecoregions, which were judged to represent distinct...
Article
Freshwater biodiversity provides important ecosystem services and is at the core of water quality monitoring worldwide. To assess freshwater biodiversity, genetic methods such as metabarcoding are increasingly used as they are faster and allow better taxonomic resolution than manual identification methods. Either sampled organisms are used directly...
Article
Interactions among multiple anthropogenic stressors threaten freshwater fish and pose challenges for fisheries management and conservation. Previous studies of multiple‐stressor effects on freshwater fish suggest a prevalence of antagonistic interactions. However, taxonomy, life stage and/or environmental context likely modify the magnitude and dir...
Article
Maintaining or restoring productive freshwater fisheries is a key challenge for resource managers. However, the inherent uncertainty and complexity of managing fisheries, often based on scant environmental data, make it difficult for managers and the public to reach consensus on appropriate actions. To help deal with this issue, we created a litera...
Article
Full-text available
Traditionally, taxonomic characterisation of organisms has relied on their morphology; however, molecular methods are increasingly used to monitor and assess biodiversity and ecosystem health. Approaches such as DNA amplicon diversity assessments are a particularly useful tool when morphology-based taxonomy is difficult or taxa are morphologically...
Article
Multiple stressors affect stream ecosystems worldwide and their interactions are of particular concern, with gaps existing in understanding stressor impacts on stream communities. Addressing these knowledge gaps will aid in targeting and designing of appropriate mitigation measures. In this study, the agricultural stressors fine sediment (ambient,...
Article
Emerging organic contaminants (EOCs) in New Zealand freshwaters are not well documented for regulatory assessments. We collected water and sediment samples for measurement of 26 EOC compound concentrations at four waterways within the city of Dunedin (Otago province). Compounds measured ranged from stimulants and depressants to pain-killers and ins...
Article
Stream ecosystems are impacted by multiple stressors worldwide. Recent studies have shown that the effects of multiple stressors are often complex and difficult to predict based on the effects of single stressors. More research is needed to understand stressor impacts on stream communities and to design appropriate counteractions. We carried out an...
Technical Report
Full-text available
Executive Summary Introduction. Northland Regional Council with support from Auckland Council and Ministry for the Environment have contracted a consortium led by Streamlined Environmental Ltd and consisting of Streamlined Environmental, Landcare Research, NIWA and the University of Otago, to conduct the Kaipara Harbour Sediment Mitigation Study (t...
Article
Full-text available
Natural hydrological disturbances in streams may reduce biomass and species richness and change community composition within streams. Disturbances can also affect beta diversity among streams if their effects are species specific or vary across sites. We investigated the effect of a natural flood on species richness, community composition and among...
Technical Report
Full-text available
This document is the final written output from the Ministry for the Environment funded project on benthic macroinvertebrate indicators of ecosystem health (Contract 21630). The project was designed to address a recognised need to include macroinvertebrates in the National Policy Statement for Freshwater Management (NPS-FM) 2014. Benthic macroinvert...
Technical Report
Full-text available
In this document we provide a literature review to underpin a Bayesian Belief Network-based (BBN) limiting factor analysis (LFA) for stream brown trout fisheries. This document is not intended to be a stand-alone report. A detailed background, methodology and an example application of the BBN to the Horokiri Stream (Wellington, New Zealand) can be...
Article
Agricultural land use results in multiple stressors affecting stream ecosystems. Flow reduction due to water abstraction, elevated levels of nutrients and chemical contaminants are common agricultural stressors worldwide. Concurrently, stream ecosystems are also increasingly affected by climate change. Interactions among multiple co-occurring stres...
Article
Deforestation in New Zealand has led to increased soil erosion and sediment loads in rivers. Increased suspended fine sediment in water reduces visual clarity for humans and aquatic animals and reduces penetration of photosynthetically available radiation to aquatic plants. To mitigate fine-sediment impacts in rivers, catchment-wide approaches to r...
Article
Full-text available
Despite the importance of small tropical streams for maintaining freshwater biodiversity and providing essential ecosystem services to humans, relatively few studies have investigated multiple-stressor effects of climate and land-use change on these ecosystems, and how these effects may interact. To illustrate these knowledge gaps, we reviewed the...
Article
Catchment land-use intensification and conversion of native vegetation to farmland threatens aquatic ecosystems worldwide by increasing exports of nutrients and fine sediment into streams, rivers and estuaries, resulting in a decline of aquatic biodiversity and ecosystem health. Using a survey approach, we studied the effects of catchment land-use...
Article
Full-text available
Disentangling the individual and interactive effects of multiple stressors on microbial communities is a key challenge to our understanding and management of ecosystems. Advances in molecular techniques allow studying microbial communities in situ and with high taxonomic resolution. However, the taxonomic level which provides the best trade-off bet...
Chapter
The book containing this chapter is available via orders through the New Zealand Hydrological Society for $90 (NZD) plus postage and packaging - see http://www.hydrologynz.org.nz/index.php/nzhs-publications/nzhs-books With 34 chapters and over 100 contributing authors, this book represents a significant review of the current state of New Zealand fr...
Chapter
PLEASE NOTE: The book containing this chapter is available via orders through the New Zealand Hydrological Society for $90 (NZD) plus postage and packaging - see http://www.hydrologynz.org.nz/index.php/nzhs-publications/nzhs-books With 34 chapters and over 100 contributing authors, this book represents a significant review of the current state of N...
Article
Using a space-for-time substitution design, we investigated the response of structural instream habitat and fish populations to different riparian management practices throughout a Dairy Best Practice Catchment. We found a significant negative correlation between the upstream area of stock exclusion fencing and deposited instream fine sediment cove...
Article
Dairying is an intensive form of agriculture influencing stream ecosystems worldwide via increased levels of nutrients, deposited fine sediment and other contaminants. However, it is not fully understood how dairy farming affects food supply for stream fish. We investigated relationships between dairy farming prevalence in the catchments of nine tr...
Article
Agricultural land use commonly exerts multiple stressors on the functioning of stream ecosystems, including leaf litter decomposition and the utilization of this resource in stream food webs. If stressors interact, their cumulative effects on biotic responses cannot be predicted from knowledge of individual stressor effects, posing challenges for m...
Conference Paper
Full-text available
Note: A manuscript based on this conference presentation is currently in revision in Scientific Reports. Recent advances in molecular techniques allow studying entire microbial communities in their environment, with a resolution down to Operational Taxonomic Units (OTUs). Should we therefore investigate OTUs, or can we simply look at common phyla?...
Presentation
Full-text available
Despite the importance of small tropical streams for maintaining freshwater biodiversity and providing essential ecosystem services to humans, relatively few studies have investigated multiple-stressor effects of climate and land-use change on these ecosystems, and how these effects may interact. To illustrate these knowledge gaps, we reviewed the...
Article
Land-use changes have degraded ecosystems worldwide. A particular concern for freshwater biodiversity and ecosystem function are stressors introduced by intensified agriculture. Typically several stressors affect freshwater ecosystems simultaneously. However, the combined effects of these multiple stressors on streams and rivers are still poorly un...
Chapter
Full-text available
Freshwater fish are one of the most diverse groups of vertebrates, but are also amongst the most threatened. With contributions from leaders in the field, this is the first assessment of the global state of freshwater fish diversity, synthesising the opportunities, challenges and barriers facing the conservation of freshwater fish biodiversity. The...
Article
Pesticides and deposited fine sediment have been associated independently with changes in relative abundance and number of sensitive species in aquatic ecosystems, but the interplay between these stressors in agricultural streams is poorly un- derstood. We used a 28-d experiment in outdoor streamside mesocosms to examine the effects of varying leve...
Article
Full-text available
The use of trait-based approaches to detect effects of land use and climate change on terrestrial plant and aquatic phytoplankton communities is increasing, but such a framework is still needed for benthic stream algae. Here we present a conceptual framework of morphological, physiological, behavioural and life-history traits relating to resource a...