Drift Density Research Articles

A transient model integrating the nanoconfinement effect and pore structure characteristics of oil transport through nanopores

Understanding the integrated transport behavior of oil in shale nanopores is critical to efficient shale oil development. In this paper, based on the time-dependent Poiseuille flow momentum equation, we present a novel transient model to describe oil transport in unsteady and steady states. The model incorporates the effect of the critical shift density, apparent viscosity, slip length, and alkane property, as well as pore tortuosity and surface roughness. We evaluated our model through a comparison with other models, experiments, and molecular dynamics simulations. The results show that the development rates of the volume flows of C6–C12 alkane confined in inorganic nanopores and C12 alkane confined in organic nanopores were faster than that of the corresponding bulk alkane. In addition, the critical drift density positively promoted the volume flow development rate in the unsteady state and negatively inhibited the mass flow rate in the steady state. This effect was clearest in pores with a smaller radius and lower-energy wall and in alkane with shorter chain lengths. Furthermore, both the nanoconfinement effect and pore structure determined whether the volume flow enhancement rate was greater than or less than 1. The rate increased or decreased with time and was controlled mainly by the nanoconfinement effect. Moreover, as the wall energy increased, the flow inhibition effect increased; as the carbon number of alkane increased, the flow promotion effect increased. The results indicate that the proposed model can accurately describe oil transport in shale nanopores.

Heteronuclear Dual Single-Atom Catalysts for Ambient Conversion of CO2 from Air to Formate

Single-atom catalysts (SACs) can achieve the maximum metal atom utilization, which exhibit great potential for the chemical transformation of CO2. However, an isolated single active site is less satisfactory for catalyzing multiple molecule reactions involving CO2 hydrogenation. In this work, we propose heteronuclear dual SACs composed of Pd and 3d transition metals supported by covalent triazine frameworks (CTFs). Among these catalysts, the optimized Pd1–Co1/CTF catalyst exhibits up to 84.6% conversion of the captured CO2 from air into formate at 30 °C and 1 bar. The in situ DRIFT characterization and density functional theory calculations reveal that CO2 in air is captured by the Et3N solution as bicarbonate, which is then hydrogenated into formate via the Pd1–Co1 heteronuclear dual single atom with an energy barrier as low as 17.2 kcal/mol. The heteronuclear Pd and Co metal atoms act as the active site for H2 activation and CO2 adsorption, respectively, thus exhibiting enhanced activity for formate synthesis with a synergistic effect. These findings present an insight into the synthesis and application of heteronuclear dual SACs and pave an avenue for conversion of CO2 in the air by heterogeneous catalysts.

Which metrics drive macroinvertebrate drift in neotropical sky island streams?

Despite long-standing interest, the mechanisms driving aquatic macroinvertebrate drift in tropical streams remain poorly understood. Therefore, the objective of this study was to evaluate which environmental metrics drive macroinvertebrate drift in neotropical sky island streams. We evaluated whether altitude, the abundance of food resources, and variations in water quality influenced macroinvertebrate drift density, diversity, richness, and functional feeding groups. An hypothesis was developed to test whether increased altitude, lower food availability (particulate organic matter), and discharge would increase the density, taxonomic richness, and diversity of drifting invertebrates. Nine headwater stream sites were sampled in the rainy and dry seasons in the Espinhaço Meridional Mountain Range (EMMR) of southeast Brazil. Samples were collected using drift nets deployed from 5:00 p.m. to 8:00 p.m. The abundance of food resources was assessed through estimates of coarse (CPOM) and fine (FPOM) particulate organic matter, and primary producers. CPOM availability was an important explanatory variable for Gathering-Collectors and Scrapers, Altitude was important for Shredders and Predators, and Filtering-Collectors were linked to water discharge, suggesting that functional group drift masses were linked to different ecosystem components. Water temperature, conductivity, dissolved oxygen, current velocity, FPOM biomass and microbasin elevation range exerted little influence on macroinvertebrate drift. Regarding taxa composition, this study also found that Baetidae and Leptohyphidae (Ephemeroptera) and Chironomidae and Simuliidae (Diptera) were the most abundant groups drifting.

The overlooked contribution of a fish bypass channel to the density and diversity of macroinvertebrate drift in a heavily modified river system

AbstractThe freshwater biodiversity decline affects all trophic levels, prompting restoration efforts. While habitat restoration for fish is well‐studied, habitat restoration to benefit other sensitive taxa such as Ephemeroptera, Plecoptera, and Trichoptera (EPT) remains poor. Consequently, this study investigated the habitat function of a man‐made nature‐like bypass system for EPT taxa in a highly modified alpine river with several drift feeding fishes. Spatially and temporally distributed drift samples were used to test the hypotheses that the bypass (a) enhances the density of drifting individuals compared to the main river and (b) diversifies drift assemblages compared to the main river. Mean drift density of EPT taxa was lowest in the main stem of the river close to the inlet of the bypass (38.24 Ind./100m3) and significantly increased toward the downstream direction of the bypass, near the outflow (61.49 Ind./100m3). In addition, drift assemblages significantly changed from the main stem to the bypass and the number of EPT taxa detected more than doubled (main stem: 16 genera; last site in the bypass: 33 genera), indicating that the bypass can provide a macroinvertebrate source to the main stem. Seasonal and diel drift patterns were similar to those observed in natural streams, underpinning the finding that nature‐like bypass systems can feature an EPT community similar to natural rivers. This study aligns with a growing body of evidence on the habitat function of nature‐like bypass systems for aquatic taxa and highlights the importance of this restoration measure beyond the aspect of solely restoring habitat connectivity.

Ternary heterojunction in rGO-coated Ag/Cu2O catalysts for boosting selective photocatalytic CO2 reduction into CH4

Herein, the ternary catalyst of reduced graphene oxide (rGO)-coated Ag/Cu2O-octahedron nanocrystals (Ag/Cu2O@rGO) was successfully fabricated by method of water bath combining with gas-bubbling-assisted membrane reduction. Supported Ag nanoparticles with low fermi energy can enrich the photogenerated electrons originated from visible light-driven Cu2O octahedral nanocrystals. The surface extended π bond of coated rGO nanolayers on Ag/Cu2O can further capture photoelectrons and improve adsorption-activation capacities for reactants. Agn/Cu2O@rGO catalysts with ternary rGO-Ag-Cu2O heterojunction exhibit excellent performance during selective photocatalytic CO2 reduction with H2O into CH4. Ag4/Cu2O@rGO catalyst has the highest formation rate (82.6 μmol g−1 h−1) and selectivity (95.4%) of CH4 product. Combined with the results of in-situ DRIFT spectra and density functional theory calculations, the photocatalytic mechanism is proposed: the protonation of CO* intermediate is key step for selective photocatalytic CO2 reduction into CH4. It provides one novel strategy to development of high-efficient photocatalyst for selective CO2 conversion into C1 chemicals.

Study of Drifting behaviour of aquatic mites in the snow fed river Alaknanda from Garhwal Himalaya: Density, Diversity and Diel Pattern

Hydrachnida or water mites are most diverse group amongst Acari and they play an important role as bioindicator for their adjoining habitat. In the present study data for drift density, diversity and diel drift pattern was recorded from January 2018 to December 2018. Total 743 individuals belonging to 25 species were noted. Species Atractides panesari, Feltria gereckei, Feltria rubra and Lebertia glabra displayed nocturnal drift and species Torrenticola turkestanica, Monatractides garhwalensis, Sperchon indicus and Sperchon garhwalensis displayed both diurnal and nocturnal drift. Maximum 17 species exhibited diurnal drift throughout the course of the study. Presence of Hygrobates fluviatilis, a pollution tolerant species reflected the polluted condition of water.

Do legacy effects of deposited fine sediment influence the ecological response of drifting invertebrates to a fine sediment pulse?

The deposition of excess fine sediment and clogging of benthic substrates is recognised as a global threat to ecosystem functioning and community dynamics. Legacy effects of previous sedimentation create a habitat template on which subsequent ecological responses occur, and therefore, may have a long-lasting influence on community structure. Our experimental study examined the effects of streambed colmation (representing a legacy effect of fine sediment deposition) and a suspended fine sediment pulse on macroinvertebrate drift and community dynamics. We used 12 outdoor stream mesocosms that were split into two sections of 6.2 m in length (24 mesocosm sections in total). Each mesocosm section contained a coarse bed substrate with clear bed interstices or a fine bed substrate representing a colmated streambed. After 69 days, a fine sediment pulse with three differing fine sediment treatments was applied to the stream mesocosms. Added fine sediment influenced macroinvertebrate movements by lowering benthic density and taxonomic richness and increasing drift density, taxonomic richness, and altering drift assemblages. Our study found the highest dose of sediment addition (an estimated suspended sediment concentration of 1112 mg l−1) caused significant differences in benthic and drift community metrics and drift assemblages compared with the control treatment (30 l of water, no added sediment). Our results indicate a rapid response in drifting macroinvertebrates after stressor application, where ecological impairment varies with the concentration of suspended sediment. Contrary to expectations, bed substrate characteristics had no effect on macroinvertebrate behavioural responses to the fine sediment pulse.

Freshwater reefs as mesohabitats for the assessment of diel invertebrate drift patterns

Freshwater reefs (known as tufa barriers) are special karst features recognized for highly heterogeneous habitat structures, complex hydrogeological features, and unique macrozoobenthos drift (downstream dispersal) patterns. Our study objective was to investigate diel and seasonal drift patterns between barriers and pools, both composed of moss-rich and fishless mesohabitat types, aligned on a small spatial scale within the karst, tufa-precipitating Plitvice Lakes hydrosystem. We monthly sampled drift at the two mesohabitat types (barriers and pools) during midday and dusk and examined quantitative and qualitative drift compositions, including drifting invertebrates, moss, and associated particulate organic and inorganic matter (APOIM). Barriers displayed higher invertebrate drift densities than those of pools. The same pattern was observed for moss and APOIM. At both mesohabitat types, invertebrate drift showed peak but highly variable densities during late spring and summer (mean >100 individuals m-3), whereas during late winter and early spring the drift densities were 5-fold lower than those densities. The nonmetric multidimensional scaling analysis revealed that invertebrate drift seasonality was influenced by seasonal drift patterns of aquatic moss and moss-dwelling invertebrate taxa. Adult and/or larval Riolus spp. and larval Hemerodromia spp. were found to be the most significant for the separation of midday and dusk within the NMDS ordination of barriers and pools. At barriers, midday drift densities of invertebrates, moss, and APOIM were higher than the respective dusk records. Within pools, invertebrate drift was largely aperiodic. We suggest that increased midday and/or aperiodic drift are a consequence of the lack of fish between barrier- and pool-mesohabitats. Our results further indicated that aquatic invertebrates inhabiting fast-flowing barriers and slow-flowing pools mostly exhibit “passive drift” mediated by transport agents such as water flow and dislodged aquatic vegetation. The observed spatio-temporal drift patterns are also likely influenced by ontogenetic shifts in drift periodicity (i.e., shifts depending on the development stage and morphological characteristics of the individual taxa) as well as benthic distribution of moss-dwelling invertebrate taxa. We can conclude that biotic (vs. abiotic) controls of drift are likely minimized in the fishless case of the freshwater reefs and associated barrier–pool sequences within Plitvice Lakes hydrosystem.

The presence of rainbow trout reduces drift of aquatic insects in Yungas streams (Tucumán, Argentina)

The drift or transport of individuals downstream is an important phenomenon of rivers and streams, since most aquatic organisms participate in it at some period of their life cycle. This work describes the assemblage of macroinvertebrate drift from ten sites in eight mountain streams of Tucumán, and evaluates the effect of the presence of rainbow trout (Oncorhynchus mykiss Walbaum), an exotic fish and visual predator, on this fraction of the community. Thirty-one (31) families of drifting aquatic invertebrates were identified, mainly immature insects and to a lesser extent water mites (Acari: Hydrachnidia), oligochaetes (Annelida: Oligochaeta) and nematodes (Nematoda). The richness and diversity of the sites with trout did not differ from the others, except when comparing lower and upper reaches of a same stream. Samples from rivers without trout or with low density of trout did not show significant changes in drift density of macroinvertebrates. In contrast, in rivers with high trout densities, a notable decrease in insect taxa was observed (those with large sized individuals): Baetidae (Ephemeroptera), Gripopterygidae (Plecoptera) and Leptoceridae (Trichoptera). On the contrary, the density of small Diptera, water mites, oligochets and nematodes increased in trout-streams

Effects of prolonged sedimentation from permafrost degradation on macroinvertebrate drift in Arctic streams

AbstractRetrogressive thaw slumps are areas of unstable degraded permafrost that often drain into nearby watersheds, leading to increased sediment loads and changes in water quality. Thaw slumps are prevalent across the Arctic, including western Canada, Alaska, and Russia, and high‐altitude areas of western China. Over the past several decades, increased temperatures and precipitation in the Arctic have led to increases in the size and frequency of thaw slumps. Our study explored the effects of prolonged sedimentation from thaw slumps in the Peel Plateau, NWT, Canada on benthic macroinvertebrate drift, an important biological function of stream ecosystems. Though sedimentation is known to initiate a catastrophic drift response, studies have generally not considered the drift response to ongoing, long‐term perturbation. Drift densities and sediment loads were measured using drift nets and sediment traps at paired sites upstream and downstream of thaw slumps. We compared drift densities and sediment loads between sites and examined how drift differed over a fine‐sediment gradient. The amount of suspended and settling fine sediments increased significantly at downstream sites. Drift densities decreased at downstream sites; however, when drift was corrected for benthic abundance at each site, there was an increase in proportional drift density associated with increased fine sediments. These results indicate that prolonged impacts from thaw slumps result in lower macroinvertebrate abundance and higher proportional drift relative to undisturbed sites. Ultimately, increased sediment loads from thaw slumps represent a chronic stressor that will continue to prevent recovery of macroinvertebrate communities at impacted sites until these features stabilize.

STUDIES ON THE DRIFTING BEHAVIORAL PATTERNS OF MACROZOOBENTHOS IN KYUNJA GAD, A MOUNTAIN STREAM FROM GARHWAL HIMALAYA, INDIA

Macrozoobenthos displayed several interesting trends with regards to their occurrence and movement in the streams in response to various abiotic and biotic factors constituting the aquatic ecosystem. These are considered of great ecological significance in understanding the quality of the particular ecosystem. The present communication focused on understanding the spatial and temporal diel drifting patterns displayed by macrozoobenthos in different levels of stream orders at different duration round the clock. It was observed that there was a general preference of nocturnal and early evening hours of drifting. The drift by benthic species was performed mainly due to presence of predators, lack of proper food and breeding sites. The study revealed that highest diel drift density and diversity of macrozoobenthos was found in 3rd order in comparison to 2nd and 1st order of Kyunja Gad stream. Variations were also noted in the physico-chemical parameters of streams Kyunja Gad at different orders.

Making up the bed: Gravel cleaning as a contribution to nase (Chondrostoma nasus L.) spawning and recruitment success

Abstract Spawning substrate quality is a major factor influencing the early ontogeny of European nase (Chondrostoma nasus), a target species of conservation. Analogous to findings from salmonids, restoration of spawning grounds was hypothesized to enhance spawning, development and thus recruitment success of nase, by improving the substrate quality, and subsequently spawning site use, egg infiltration and protection of larvae in the interstitial zones before emergence. These assumptions were tested using a comparative approach by cleaning 50% of the area of each spawning ground in two Bavarian rivers. Substrate cleaning resulted in an immediate reduction of ~70% fine sediment content with improvements still detectable 2 months later. Spawning nase used the restored areas of spawning grounds preferentially, which was evident in the number of spawning fish and the significantly higher number of eggs laid. Infiltration of eggs into the interstitial zone was distinctly more successful in the opened interstices of the cleaned spawning substrate, where they were found down to a depth of 20 cm. The same was true for larvae, which could be found down to 30 cm and up to 13 days after hatching. Moreover, higher peaks in the drift density of emerging larvae from the restored spawning substrate were detected (2.5 compared with 1.7 larvae m−3 discharge for the River Mangfall and 0.3 compared with 0.03 larvae m−3 for the River Sims). These results clearly indicate that gravel cleaning is a successful short‐term restoration tool for nase spawning grounds. It is a quick, cheap and effective method for the conservation management of nase, which may also be applicable to other riverine species with a similiar ecology and incubation time, such as Barbus barbus, Squalius cephalus, Leuciscus leuciscus and Phoxinus phoxinus. This especially holds true if streams lack internal dynamics and suffer from high loads of fine sediment and colmation.

Land Subsidence Susceptibility Mapping in South Korea Using Machine Learning Algorithms.

In this study, land subsidence susceptibility was assessed for a study area in South Korea by using four machine learning models including Bayesian Logistic Regression (BLR), Support Vector Machine (SVM), Logistic Model Tree (LMT) and Alternate Decision Tree (ADTree). Eight conditioning factors were distinguished as the most important affecting factors on land subsidence of Jeong-am area, including slope angle, distance to drift, drift density, geology, distance to lineament, lineament density, land use and rock-mass rating (RMR) were applied to modelling. About 24 previously occurred land subsidence were surveyed and used as training dataset (70% of data) and validation dataset (30% of data) in the modelling process. Each studied model generated a land subsidence susceptibility map (LSSM). The maps were verified using several appropriate tools including statistical indices, the area under the receiver operating characteristic (AUROC) and success rate (SR) and prediction rate (PR) curves. The results of this study indicated that the BLR model produced LSSM with higher acceptable accuracy and reliability compared to the other applied models, even though the other models also had reasonable results.

Invertebrate drift densities in the Njoro and Kamweti Rivers in the Kenyan highlands that differ in the level of anthropogenic disturbances

Invertebrate drift is one of several fundamental ecological processes in streams. However, little is known about the dynamics of invertebrate drift in Kenyan streams. In this study, we assessed invertebrate drift in two rivers, i.e. Njoro and Kamweti, that differ in the level of anthropogenic disturbances, between February and March, 2016. The aim was to evaluate the effect of river sampling duration (5, 10, 15, 20 and 25 min) and sampling period (day or night) on invertebrate drift densities. The 5-minute sampling period resulted in significantly higher mean drift densities than the other time intervals in both rivers. The highest mean drift density (2.0 ± 0.9 individuals m−3) was recorded at the Njoro River during the day, whereas the lowest drift density (0.3 ± 0.2 individuals m−3) was recorded at the Kamweti River during the day. A strong nocturnal drift pattern was noted at the less disturbed river (Kamweti). The present results suggest that anthropogenic perturbations influence invertebrate drift densities, and sampling duration and sampling period are important factors to consider when sampling invertebrate drift.

Effect of drift sampler exposure time and net mesh size on invertebrate drift density in the Njoro River, Kenya

Although invertebrate drift is an important ecological process in lotic ecosystems, very little is known about it in Kenyan rivers. The primary aim of this study was to investigate the effect of driftnet mesh size and exposure duration on drift density in 2017. Drift samples were dominated by Chironomidae, Baetidae, Simuliidae, Caenidae and Culicidae. The 100 µm mesh driftnet had the highest mean invertebrate density, followed by the 250 µm and 500 µm nets. Invertebrate drift densities decreased with increased exposure time. This study demonstrates that sampler mesh size and exposure time should be taken into account when characterising invertebrate drift in streams. Future studies should consider sampling different biotopes and during different seasons.

Impacts of Recreational Flow Releases on Macroinvertebrate Drift at Different Distances Downstream from Abanakee Dam, New York

We examined macroinvertebrate drift at 4 sites downstream of Abanakee Dam on the Indian River, NY, on separate days at base-flow conditions and following days during recreational releases (rapid releases supporting white-water rafting enterprises). Macroinvertebrate drift rates were highest near the dam due to high numbers of drifting Simuliidae at both base flow and during a release. At the other 3 sites, Simuliidae were less abundant in the drift, and Chironomidae and Sphaeriidae had especially high drift densities during a release, suggesting a greater vulnerability to catastrophic drift. Macroinvertebrate drift was not affected by differences in stream gradients or shear forces that did differ between sites. Our drift densities during the recreational releases were higher than observations from other studies during natural floods, suggesting greater drift vulnerability to rapid increases (∼15 min) in discharge when flood gates are opened.

Crowded waters: short-term response of invertebrate drift to water abstraction

Water abstraction modifies the environmental conditions of stream ecosystems, which can affect invertebrate assemblages by altering drift. We examined this issue with a before–after–control–impact design experiment in which we diverted 90% of the natural flow from a headwater stream. We measured flow-reduction effects on drift densities (animals/m3), total drift rates (animals leaving the reach per hour) and net balance of invertebrates entering or leaving the Impact reach. We also identified the specific taxa and traits that drove these responses. The sudden decrease in flow promoted a 12-fold increase in overall drift density at the Impact reach, which was primarily driven by filterers, shredders and taxa associated with fast velocities, such as simulids. By contrast, drift densities of other abundant taxa, such as Baetis, Esolus and chironomids, increased less than what could be expected from the magnitude of flow reduction. While drift rates remained unchanged after water abstraction, the Impact reach became a net invertebrate exporter indicating that many taxa drifted actively as a response to stressful conditions rather than passively, which would be reduced by water abstraction. Therefore, our results suggest that water abstraction influences drift, with potentially important consequences for the invertebrate assemblages and ecosystem processes further downstream.

Diel periodicity of aquatic macroinvertebrate drift in a coastal stream in northern Venezuela

Aquatic macroinvertebrates and organic matter (OM) are transported downstream with the current, in a process that is modulated by different mechanisms in the ecosystem. Macroinvertebrate drift and OM transport are processes involving interactions between organisms and the environment at multiple spatial and temporal scales. The objective of this study was to describe benthic aquatic macroinvertebrate drift in one of the least disturbed streams of northern Venezuela during the dry season. Aquatic macroinvertebrate drift and OM transport were assessed on three different dates, sampling every three hours for each diel cycle using three drift nets. Aquatic macroinvertebrate drift exhibited a clear diel pattern, showing higher drift density values at night than those found during daylight, with significant differences among sampling times (two-way ANOVA, F7,48 = 33.51, p < 0.001) but not among months (F2,48 = 2.012, p > 0.05) with no interaction between factors (F14,48 = 1.152, p > 0.05). All sampling dates showed the same trend for diel aquatic macroinvertebrate drift patterns with mean values ranging from 0.19 to 14.81 org.m–3. Transported OM showed no significant differences for the interaction between factors (sampling time*month) (F14,48 = 0.727, p > 0.05) or among sampling times (two-way ANOVA, F7,48 = 1.25, p > 0.05) and months (F2,48 = 0.049, p > 0.05) with values ranging from 79.28 to 207.49 mg.m−3. The San Miguel stream showed a definite diel trend for aquatic macroinvertebrate drift with a peak at 20:00 h dominated by larval shrimp. Our results indicate that drift samples taken at different times along a diel cycle should be considered in bioassessment studies as an important part of any biodiversity survey. This study contributes to comprehend the importance of the integrity of the freshwater–estuarine–marine corridor for the conservation of aquatic fauna and management in tropical coastal streams.

Highly Selective Oxidation of Ethyl Lactate to Ethyl Pyruvate Catalyzed by Mesoporous Vanadia–Titania

The direct oxidative dehydrogenation of lactates with molecular oxygen is a “greener” alternative for producing pyruvates. Here we report a one-pot synthesis of mesoporous vanadia–titania (VTN), acting as highly efficient and recyclable catalysts for the conversion of ethyl lactate to ethyl pyruvate. These VTN materials feature high surface areas, large pore volumes, and high densities of isolated vanadium species, which can expose the active sites and facilitate the mass transport. In comparison to homogeneous vanadium complexes and VOx/TiO2 prepared by impregnation, the meso-VTN catalysts showed superior activity, selectivity, and stability in the aerobic oxidation of ethyl lactate to ethyl pyruvate. We also studied the effect of various vanadium precursors, which revealed that the vanadium-induced phase transition of meso-VTN from anatase to rutile depends strongly on the vanadium precursor. NH4VO3 was found to be the optimal vanadium precursor, forming more monomeric vanadium species. V4+ as the major valence state was incorporated into the lattice of the NH4VO3-derived VTN material, yielding more V4+–O–Ti bonds in the anatase-dominant structure. In situ DRIFT spectroscopy and density functional theory calculations show that V4+–O–Ti bonds are responsible for the dissociation of ethyl lactate over VTN catalysts and for further activation of the deprotonation of β-hydrogen. Molecular oxygen can replenish the surface oxygen to regenerate the V4+–O–Ti bonds.

Effects of food supply and stream physical characteristics on habitat use of a stream‐dwelling fish

AbstractIdentifying the environmental factors that affect freshwater fish can be crucial for their conservation and management. Despite the widespread investigation of relationships between fish habitat use and environmental variables, there is a paucity of knowledge on how abiotic and biotic factors jointly influence stream fish habitat use. Three New Zealand South Island streams were selected to investigate the habitat preference of a stream‐dwelling galaxiid, banded kokopu (Galaxias fasciatus). Fish abundance in several permanent pools was determined by spotlighting at night once a month from June 2008 to May 2009. Drifting invertebrates and key physical features of each pool were measured at the time of fish sampling. An information‐theoretic approach (AIC) indicated that the most parsimonious candidate model to predict banded kokopu biomass was the one that included pool area, undercut banks, water velocity, overhanging vegetation, invertebrate drift density and an interaction term between invertebrate drift density and water velocity. Banded kokopu biomass was positively related to pool area, undercut banks, overhanging vegetation and invertebrate drift density. Our study suggests that fish resource use patterns need to be understood in the context of multiple interacting ecological factors, including prey abundance.