Helen J Warburton

Helen J Warburton
University of Canterbury | UC · School of Biological Sciences

About

24
Publications
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193
Citations

Publications

Publications (24)
Article
The generalizable functional attributes of organisms (traits) relate strongly to their environment across multiple levels of biological organization, making trait‐based approaches a powerful mechanistic framework to understand species distributions and community composition in relation to environmental change. To investigate how a wide range of str...
Article
Riparian plants provide an important source of energy for freshwater food webs through inputs of leaf litter. Planting riparian buffers with mixed species could enhance the detrital resource supply for invertebrates through varied leaf breakdown rates. To quantify leaf breakdown rates and invertebrate colonisation, we used leaves from eleven grass,...
Article
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Mechanisms linked to demographic, biogeographic and food-web processes thought to underpin community stability could be affected by habitat size, but the effects of habitat size on community stability remain relatively unknown. We investigated whether those habitat size-dependent properties influenced community instability and vulnerability to pert...
Article
Full-text available
Globally benthic invertebrate biotic indices are widely used to assess stream health. In New Zealand, the response of biotic indices to high nitrate-nitrogen (hereafter nitrate) concentrations has not been rigorously tested. We conducted a field survey of benthic invertebrates in 41 lowland intensively farmed Canterbury streams representing a wide...
Article
Traditionally, resistance and resilience are associated with good ecological health, often underpinning restoration goals. However, degraded ecosystems can also be highly resistant and resilient, making restoration difficult: degraded communities often become dominated by hyper-tolerant species, preventing recolonization and resulting in low biodiv...
Article
Biotic interactions perform an important role in structuring freshwater communities, however these are rarely considered during stream restoration. Degraded stream communities are often dominated by organisms with shell or case protections, such as snails, which are less vulnerable to predation than desired organisms, such as mayflies. Unprotected...
Article
Describing trophic structure within freshwater food webs can be a useful tool for understanding relationships to make ecological inferences and to inform management action. A complementary analysis examining both stable isotope (SI) and biomass community components may be useful, because these two responses may be influenced differently by habitat...
Article
In Aotearoa New Zealand, agricultural land-use intensification and decline in freshwater ecosystem integrity pose complex challenges for science and society. Despite riparian management programmes across the country, there is frustration over a lack in widespread uptake, upfront financial costs, possible loss in income, obstructive legislation and...
Article
Full-text available
In animals with indeterminate growth, such as predatory fishes, mouth size is related to, and increases with, body mass of the organism. As fishes grow in body size, they can consume larger-bodied prey items at potentially-higher trophic levels. Therefore, body size should predict trophic position. Trophic position (TP) is useful for describing ene...
Article
• Understanding risks to aquatic systems posed by changing drought regimes is particularly important for the conservation of already threatened taxa. However, little is known about how local environmental conditions, especially those in heavily human‐influenced situations, interact with regional shifts such as droughts to alter realised impacts on...
Article
Full-text available
Introduced aquatic macrophytes can dominate small agricultural waterways in summer and autumn becoming a significant management problem. Excessive growth can clog waterways, causing drainage issues and reducing agricultural productivity while in-stream velocities are reduced and sedimentation increased. Consequently, water managers remove them by m...
Article
Abstractions and diversions are prevalent in river networks worldwide; however, specific mechanisms and measures reflecting changes in functional characteristics of aquatic assemblages in response to flow abstraction have not been well established. In particular, the influence of small takes on fish assemblages is poorly understood. Field surveys a...
Article
Excessive nutrient loading from small agricultural headwaters can substantially degrade downstream water quality and ecological conditions. But, our understanding of the scales and locations to implement nutrient attenuation tools within these catchments is poor. To help inform farm- and catchment-scale management, we quantified nitrate export in n...
Article
Both disturbance history and disturbance type act to structure communities through selecting for particular species traits but they may also interact. For example, flooding selects for species with flood‐resistant traits in streams, but those traits could make communities susceptible to other disturbances and so could cause shifts in community comp...
Article
For freshwater systems, climate change‐induced alterations to drought regimes are a considerable threat to already threatened species. This is particularly poignant for kōwaro (or Canterbury mudfish, Neochanna burrowsius), a critically endangered fish largely restricted to drying‐prone waterways on the Canterbury Plains, New Zealand. By comparing t...
Article
Full-text available
• Food web properties can be used in bioassessment as indicators of ecosystem stress, although logistical constraints restrict their widespread use. Size spectra (body mass–abundance relationships) are easier to produce, still incorporate much of the variation in feeding interactions and indicate the strength of the energy transfer efficiency. • He...
Article
Full-text available
Habitat reduction could drive biodiversity loss if the capacity of food webs to support predators is undermined by habitat-size constraints on predator body size. Assuming that (i) available space restricts predator body size, (ii) mass-specific energy needs of predators scale with their body size, and (iii) energy availability scales with prey bio...
Article
Characterisation of food webs, by summarising energy transfer and trophic relationships, allows more functional measurement of ecosystems and may reveal threats (e.g., land‐cover change) in sensitive environments that are not obvious from conventional biomonitoring. However, typical methods used to achieve this are time‐consuming and expensive. The...
Article
Excessive macrophytes can cause significant problems in agricultural waterways requiring active management. Conventional control techniques can have a range of adverse effects. We investigated several control tools in two experiments: firstly, we tested eight treatments at a small-scale (2 m × 2 m). We found intensive hand weeding, weed mat and her...
Presentation
Full-text available
A segment of my PhD research exploring the hypothesized relationship between the body size of omnivorous and predatory fishes and their stable isotope-derived trophic position
Article
Full-text available
Globally intensive agriculture has both increased nitrogen pollution in adjacent waterways and decreased availability of terrestrially derived carbon frequently used by stream heterotrophs in nitrogen cycling. We tested the potential for carbon additions via leaf litter from riparian restoration plantings to act as a tool for enhancing denitrificat...
Article
Biodiversity in running waters is threatened by an increased severity and incidence of low-flow extremes resulting from global climate change and a growing human demand for freshwater resources. Although it is unknown how and to what extent riverine communities will change in the face of these threats, considerable insight will be gained from effor...

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