Over the last 150 years, most large, easily accessible lakes and tarns in Aotearoa (New Zealand) have experienced trout introductions or incursions, leaving few salmonid‐free reference lakes. Using database information and field surveys, we characterized lake, pond/tarn, and wetland systems found throughout Aotearoa that support populations of kōaro ( Galaxias brevipinnis ) known or putatively believed to be trout‐free. These...

Managing New Zealand's diadromous Galaxias species and the associated whitebait fishery presents a complex challenge due to species‐specific differences in life‐history strategies, habitat requirements, and population dynamics that underpin responses to anthropogenic and environmental pressures. Consequently, effective management must balance the distinct vulnerabilities and dependencies of each species to ensure long‐term sus...

Complex landscapes are challenging to study because both the higher level contextual and interacting lower level mechanistic processes underpinning their ecological characteristics occur simultaneously. However, food‐web structures can provide process insight in such landscapes by identifying these processes in specific contexts. Here, we used stable isotopes to identify spatially separate resources and infer resource flows un...

Aim Fueled by the emergence of global‐scale databases, fish morphological traits are now routinely used as a proxy for trophic ecology when estimating functional diversity. Yet, a rigorous empirical validation of trophic‐morphology relationships is lacking. This study offers a global test of whether species' morphology is associated with a known indicator of trophic ecology, stable isotope ratios of carbon and nitrogen. Locati...

Ecological disturbances act as environmental filters by removing species with particular characteristics, resulting in community types associated with different disturbance histories. However, studies to date on community responses to disturbance have neglected the potential for different community assemblages to display different responses. Using lotic invertebrate communities as a study system, this study investigated the in...

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, shrub and tree species common along agricultural waterways in New Zealand. Brea...

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 perturbations caused by disturbance. This is particularly important given that huma...

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 mechanical clearance, chemical spray and cutting which can be costly and have neg...

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 herbicide spraying to be effective treatments, reducing macrophyte cover to

Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico‐chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulse...

Because smaller habitats dry more frequently and severely during droughts, habitat size is likely a key driver of survival in populations during climate change and associated increased extreme drought frequency. Here, we show that survival in populations during droughts is a threshold function of habitat size driven by an interaction with population density in metapopulations of the forest pool dwelling fish, Neochanna apoda ....

Food webs are strongly size‐structured so will be vulnerable to changes in environmental factors that affect large predators. However, mechanistic understanding of environmental controls of top predator size is poorly developed. We used streams to investigate how predator body size is altered by three fundamental climate change stressors: reductions in habitat size, increases in disturbance and warmer temperatures. Using new s...

Purposeful species introductions offer opportunities to inform our understanding of both invasion success and conservation hurdles. We evaluated factors determining the energetic limitations of brown trout ( Salmo trutta ) in both their native and introduced ranges. Our focus was on brown trout because they are nearly globally distributed, considered one of the world's worst invaders, yet imperiled in much of their native habi...

Ecology Letters (2010) 13: 881–890 Abstract The number of trophic transfers occurring between basal resources and top predators, food chain length (FCL), varies widely in the world’s ecosystems for reasons that are poorly understood, particularly for stream ecosystems. Available evidence indicates that FCL is set by energetic constraints, environmental stochasticity, or ecosystem size effects, although no single explanation ha...

Canterbury mudfish ( Neochanna burrowsius ) are endemic to a small region of Canterbury, South Island, New Zealand and classified as nationally endangered. We reviewed data from the New Zealand Freshwater Fish Database and trapped fish in July 2006, and January and February 2007 in the Waianiwaniwa Valley, Canterbury to determine the importance of this catchment for mudfish conservation. Mudfish were found in 19 of the 28 site...