Substrate Particle Size Research Articles

Influence of abiotic factors on incubation of Baikal omul eggs in the Selenga River (Lake Baikal Basin)

Abiotic factors affecting the choice of spawning sites for the Baikal omul (Coregonus migratorius) in the Selenga River over 27 years were studied. A total of 3,450 samples were collected using the Dulkeit scraper in Decembers of 1987-2014, at 24 trans-sections in the Selenga River channel over a total length of 410 km. At each sampling site we recorded omul egg density, substrate particle size, water depth, water flow velocity, and ice thickness. Omul eggs were found mainly on hard substrates (sand, gravel, pebbles, and pebble-cobbles combinations). Omul has been found to avoid spawning at depths less than 1.5 m and greater than 6.0 m. Water velocity and ice thickness did not strongly influence the choice of site. Omul eggs were found at flow rates of 0.05-0.7 m/s with a maximum at 0.1 m/s.

Sand Particle Size and Phosphorus Amount Affect Rhizophagus irregularis Spore Production Using In Vitro Propagated Spore as a Starter Inoculum in Rhizosphere of Maize (Zea mays) Plantlets.

Microbial inoculants, particularly arbuscular mycorrhizal (AM) fungi, have great potential for sustainable crop management. In this study, monoxenic culture of indigenous R. irregularis was developed and used as a tool to determine the minimum phosphorus (P) level for maximum spore production under the in vitro conditions. This type of starter AM fungal inoculum was then applied to an in vivo substrate-based mass-cultivation system. Spore production, colonization rate, and plant growth were examined in maize (Zea mays L.) plant inoculated with the monoxenic culture of R. irregularis in sand graded by particle size with varying P levels in nutrient treatments. In the in vitro culture, the growth medium supplemented with 20 µM P generated the maximum number of spores (400 spores/mL media) of R. irregularis. In the in vivo system, the highest sporulation (≈500 spores g−1 sand) occurred when we added a half-strength Hoagland solution (20 µM P) in the sand with particle size between 500 µm and 710 µm and omitted P after seven weeks. However, the highest colonization occurred when we added a half-strength Hoagland solution in the sand with particle sizes between 710 µm and 1000 µm and omitted P after seven weeks. This study suggests that substrate particle size and P reduction and regulation might have a strong influence on the maximization of sporulation and colonization of R. irregularis in sand substrate-based culture.

Reactor Design for Biogas Production-A Short Review

Biogas is an alternative to gaseous biofuels and is produced by the decomposition of biomass from substances such as animal waste, sewage sludge, and industrial effluents. Biogas is composed of methane, carbon dioxide, nitrogen, hydrogen, hydrogen sulfide, and oxygen. The anaerobic production of biogas can be made cheaper by designing a high throughput reactor and operating procedures. The parameters such as substrate type, particle size, temperature, pH, carbon/nitrogen (C/N) ratio, and inoculum concentration play a major role in the design of reactors to produce biogas. Multistage systems, batch, continuous one-stage systems, and continuous two-stage systems are the types of digesters used in the industry for biogas production. A comprehensive review of reactor design for biogas production is presented in the manuscript.

Concurrent production of glycyrrhetic acid 3-O-mono-\u03b2-d-glucuronide and lignocellulolytic enzymes by solid-state fermentation of a plant endophytic Chaetomium globosum

Glycyrrhetic acid 3-O-mono-β-d-glucuronide (GAMG) as an important derivative of glycyrrhizin (GL) shows stronger biological activities and higher sweetness than GL. The biotransformation process is considered as an efficient strategy for GAMG production, due to its mild reaction, high production efficiency and environmentally friendly status. In this study, licorice straw was used for the first time as a medium for GAMG and lignocellulosic enzyme production via solid-state fermentation (SSF) of endophytic fungus Chaetomium globosum DX-THS3. The fermentation conditions including particle size, temperature, seed age, inoculum size, and moisture of substrate were optimized. Furthermore, additional nitrogen sources and carbon sources were screened for GAMG production by C. globosum DX-THS3 of SSF. Under optimal fermentation conditions, the percent conversion of glycyrrhizin reached 90% in 15 days, whereas the control needed 35 days to achieve the same result. The productivity of optimization (P = 2.1 mg/g/day) was 2.33-fold that of non-optimization (P = 0.9 mg/g/day). Meanwhile, high activities of filter paper enzyme (FPase) (245.80 U/g), carboxymethyl cellulase (CMCase) (33.67 U/g), xylanase (83.44 U/g), and β-glucuronidase activity (271.42 U/g) were obtained faster than those in the control during SSF. Our study provides a novel and efficient strategy for GAMG production and indicates C. globosum DX-THS3 as a potential producer of lignocellulolytic enzymes.

Fertilization methods and substrate particle size differentially affect growth and macronutrient status of Laelia anceps subsp. anceps

The effects of three fertilization methods (FM) using the Peters Professional® 30N-10P-10K water soluble fertilizer were analyzed: fertilization in irrigation water (FIW), foliar fertilization (FF), and their combination (FIW + FF), as well as two substrate particle sizes (SuPS): larger particle size (LPS) and smaller particle size (SPS), on the growth and macronutrient status of Laelia anceps subsp. anceps (Orchidaceae). A 3 × 2 factorial experiment was established. Aerial and root growth, dry weight and concentration of macronutrients N, P, K, Ca, and Mg in leaves, pseudobulbs, and roots were all evaluated. The interaction of the study factors resulted in a greater number of leaves, while by simple effects, greater leaf area, number of pseudobulbs, root volume, and dry matter of leaves and roots were obtained, when FIW and LPS were used. With FF, greater growth in root volume was observed. There were no differences in the concentration of N in the growth organs analyzed, but due to the interaction of factors, a higher concentration of P, K, Mg, and S was observed in roots, mainly with FIW + FF and SPS; although for P, there was a higher concentration in FIW and LPS. In the case of SPS, the concentrations of K and S were higher in leaves, and in pseudobulbs P, K, Ca, Mg, and S were higher. The results showed that there are positive effects on plant growth when FIW and LPS are used, while higher concentrations of nutrients in leaves, pseudobulbs and mainly in roots are observed when using SPS.

How head shape and substrate particle size affect fossorial locomotion in lizards.

Granular substrates ranging from silt to gravel cover much of the Earth's land area, providing an important habitat for fossorial animals. Many of these animals use their heads to penetrate the substrate. Although there is considerable variation in head shape, how head shape affects fossorial locomotor performance in different granular substrates is poorly understood. Here, head shape variation for 152 species of fossorial lizards was quantified for head diameter, slope and pointiness of the snout. The force needed to penetrate different substrates was measured using 28 physical models spanning this evolved variation. Ten substrates were considered, ranging in particle size from 0.025 to 4 mm in diameter and consisting of spherical or angular particles. Head shape evolved in a weakly correlated manner, with snouts that were gently sloped being blunter. There were also significant clade differences in head shape among fossorial lizards. Experiments with physical models showed that as head diameter increased, absolute penetration force increased but force normalized by cross-sectional area decreased. Penetration force decreased for snouts that tapered more gradually and were pointier. Larger and angular particles required higher penetration forces, although intermediate size spherical particles, consistent with coarse sand, required the lowest force. Particle size and head diameter effect were largest, indicating that fossorial burrowers should evolve narrow heads and bodies, and select relatively fine particles. However, variation in evolved head shapes and recorded penetration forces suggests that kinematics of fossorial movement are likely an important factor in explaining evolved diversity.

The effect of auxiliary complexing agent on silver crystallization and the application in SERS

<p indent="0mm">A crystalized nano-sized silver layer with large area uniformity and smoothness prepared by electrochemical deposition as surface-enhanced Raman scattering (SERS) active substrates was studied. The result shows that an effective binary complementary complex system can be formed to turn the silver’s nucleation mechanism from instantaneous one to progressive one when auxiliary complexing agent of hydroxyethylidene diphosphonic acid (HEDP) and main complexing agent of 5,5-dimethylhydantoin reach sufficient concentration of <sc>4 g/L</sc> and <sc>110 g/L</sc> in electrodeposition solution, respectively. The as-prepared crystalized nano-sized silver layer possesses excellent SERS properties. Its limit of detection (LOD) to Rhodamine 6G is as low as <sc>1.0×10^–13 mol/L,</sc> the relative standard deviation (RSD) of SERS uniformity is below 8%, and the averaged surface enhancement factor to methyl orange can reach 6.3×10⁶. Correspondingly, the particle size of silver-electrodeposited substrate is about <sc>10 nm</sc> and the particle spacing is less than 5 nm, which meets the requirements for generating SERS “hot spots”. Finally, the active substrate was applied to prohibit pigments of Sudan III and Sudan IV, and the LOD is as low as <sc>5.0×10^–12 mol/L</sc> and <sc>1.0×10^–11 mol/L</sc>, respectively, which shows great potential for applications.

Optimization of simultaneous dark fermentation and microbial electrolysis cell for hydrogen production from macroalgae using response surface methodology

In this study, H2 production from macroalgae by simultaneous dark fermentation (DF) and microbial electrolysis cell (MEC) in a single reactor, sDFMEC, was investigated, and the effects of particle size of substrate, temperature, initial pH, and substrate concentration on the sDFMEC performance was determined. The sDFMEC process were statistically optimized using a response surface method. The optimum substrate particle size achieved was 0.5–1.0 mm; however, it was not sufficiently significant because of the two-dimensional (2D) nature of the macroalgae substrate. However, the temperature, initial pH, and substrate concentration considerably affected the performance of sDFMEC. Based on the response surface analysis, the optimum conditions for a maximum H2 yield of 492.3 ± 5.1 mL/g-TS were as follows: temperature of 36.6 °C, initial pH of 7.44, and substrate concentration of 1.98 g/L. Under these operating conditions, the total energy efficiency achieved was 32.3 ± 0.2%. The results indicate that sDFMEC can be used as a promising method to produce H2 from macroalgae.

Habitat Partitioning in the Marine Sector of Karst Subterranean Estuaries and Bermuda's Marine Caves: Benthic Foraminiferal Evidence

Karst subterranean estuaries (KSEs) are created from the two- and three-way mixing of saline groundwater, rain, and oceanic water in the subsurface on carbonate landscapes, and this hydrographic framework promotes unique physical processes, biogeochemical cycling, and biological communities. Here we provide evidence that the source and quantity of particulate organic matter (POM) that is delivered to the benthos strongly correlates to benthic habitat partitioning in the oxygenated marine sectors of KSEs. A dataset of benthic foraminifera at 128 different locations from several large flooded cave systems in Bermuda were compiled and evaluated against common environmental characteristics (e.g., tidal exposure, substrate particle size, bulk organic matter, C:N, total organic carbon, and δ13Corg). Benthic areas receiving more carbon isotopically depleted organic matter sources (mean δ13Corg values &amp;lt; −23.2‰, C:N ratios &amp;gt;11), most likely from the terrestrial surface and some marine plankton, were dominated by Trochammina inflata, Bolivina spp., and Helenina anderseni. In contrast, benthic areas receiving more carbon isotopically enriched organic matter sources (mean δ13Corg values &amp;gt; −21.6‰, C:N ratios &amp;lt;10), most likely from marine plankton transported through marine cave openings cave from adjacent coastal waters, were dominated by Spirophthalmidium emaciatum, Spirillina vivipara, Patellina corrugata, and Rotaliella arctica. The benthic foraminifera most distal from any cave entrances were dominated by taxa also known from the deep-sea (e.g., Rotaliella, Spirophthalmidium) in sediment with the lowest bulk organic matter content (mean: 6%), or taxa that prefer hard substrates and are potentially living attached to cave walls (Patellina, Spirillina). While physical groundwater characteristics (e.g., salinity, dissolved oxygen) are expected drivers of benthic ecosystems in KSEs, these results suggest that POM source, quantity, and delivery mechanisms (e.g., groundwater-seawater circulation mechanisms, terrestrial flux) play an important role in benthic habitat partitioning and the spatial variability of biogeochemical cycles in the oxygenated marine sector of KSEs.

Isolation of Corncob Xylan-Degrading Fungi and Its Application in Xylobiose Production

In the present study, a potential corncob xylan degradation fungi was isolated and screened from soil to produce xylanase, and was identified as Fusarium oxysporum. The production of xylanase by F. oxysporum under solid state fermentation using corncob powder as the solid substrate reached the maximum xylanase activity when using particle size of substrate of 60 mesh, water content ratio of 2 mL/g substrate, incubation temperature of 30°C, initial pH of 6.0, size of inoculum of 5x107 spore/3 g substrate, and incubation time of 2 days. The xylanase activity increased about 4 times up to 7.92 U/mL after optimization. The potential application of xylanase of F. oxysporum in hydrolyzing alkali-treated corncob xylan to produce xylobiose was also demonstrated. Hydrolysis of 6% of corncob xylan using 100 U/g substrate of enzyme loading under optimum pH and temperature conditions (pH 5.5 and 50°C, respectively) achieved the yield of xylobiose up to 28.7 g/100 g pure xylan after 12 h incubation. The purification of hydrolysate could retain 91.1% of xylobiose. Further separation step using activated charcoal column chromatography was able to get a pure xylobiose, but could only recover 59.3% of xylobiose.

Effect of substrate particle size on burrowing of the juvenile freshwater pearl mussel Margaritifera margaritifera

Juveniles of the endangered freshwater pearl mussel (FPM, Margaritifera margaritifera) live burrowed in stream substrate for the first years of their life. Fine sediments block water exchange within substrate and may cause juvenile mortality and recruitment failure. To better understand the connection between success of juvenile FPM and substrate particle size, it would be important to understand behavioural responses of FPM to varying substrate sizes at this critical life stage. We placed newly detached FPM juveniles in a 7-mm layer of sieved sand sorted into five sizes (< 120, 120–200, 200–250, 250–500 and 500–650 µm) each with 10 replicate dishes, 10 juveniles per dish, with burrowing status monitored for 96 h. Mean dish-specific proportion burrowed (PB) was significantly affected by substrate size, increasing from 52% in the finest sand to 98% in the coarsest sand. Furthermore, the significant substrate × time interaction was observed due to dropped PB (30-34%) in finest sand at 2–4 h time points. Thus, results suggest a clear behavioural response by juvenile FPM to substrate size, with fine sediments triggering surfacing behaviour. Surfacing may indicate stress, can increase predation risk, and expose to drift and/or enable drift of juveniles.

Different trophodynamics between two proximate estuaries with differing degrees of pollution

Mangroves are complex ecosystems with widely varying abiotic factors such as salinity, pH, redox potential, substratum particle size, dissolved organic matter and xenobiotic concentrations, and a high biodiversity. This paper presents the trophodynamic pathways of accumulation and transfer of metals and metalloids (B, Al, V, Cr, Mn, Fe, Ni, Cu, Zn, Ag, As, Se, Rb, Sr, Pb and Hg), in three trophic chains (plant-crab-fish, plankton-shrimp-fish and plankton-oyster) of similar food webs, corresponding to two mangrove estuaries (Santa Cruz and Vitória Bay, separated by 70 km) in the Espírito Santo State (Brazil). Although the trophic transfer patterns are affected by physical variables, metal and metalloids were found in all trophic levels. We observed similar trophodynamics between both estuaries with some elements, but unequal transfer patterns in other cases, thus questioning the effectiveness of 15N to determine the food chain when the aquatic biota is affected by anthropogenic contaminants. Thus, in the Santa Cruz estuary, most metals were biomagnified through the food web. Conversely, Vitória Bay presented mostly biodilution, suggesting that metal/metalloid transference patterns in mangrove ecosystems may be affected by different anthropogenic contamination inputs. These results indicate the importance of knowing the complete food web when evaluating the trophic transfer of elements, including an evaluation of the differential impact of pollution on diverse components of the food chain.

Microbiological activities in the composting process : A review

Composting is a technological process of waste management that is, with the help of microbiological activities in aerobic conditions, organic material is decomposed and stabilized into a biodegradable mixture and transformed into compost. This process of decomposition of organic matter has recently attracted a lot of attention due to its environmentally friendly methods in which additional environmental pollution is avoided. The composting process follows four phases (first mesophilic phase, thermophilic phase, second mesophilic phase, and maturation phase). The most important factors influencing the decomposition success are C/N ratio, humidity, temperature, substrate particle size, pH, oxygen content and microorganisms. Microorganisms such as bacteria, fungi, and actinomycetes act as chemical decomposers in the process of decomposition of organic matter into carbon dioxide, heat, water, hummus, and a relatively stable final organic product - compost. In the process of composting, microorganisms decompose the complex molecules of lignin, cellulose, and hemicellulose. The presence of different types of microorganisms is influenced by the composition of composite mixtures and changes in temperature through the phases of the composting process. At the beginning of compression, the microbial activity increases significantly, which causes a temperature rise. The initial dominance of bacteria is replaced by fungi that are most active in the process of compost maturation.This scientific paper aims to present an overview of the composting process and the role of beneficial microorganisms in the process of decomposition of organic matter of the compost mixture.

KARAKTERISTIK HABITAT DAN STRUKTUR POPULASI KERANG BAMBU (Solen lamarckii, Chenu 1984) DI ZONA INTERTIDAL DESA APIAPI KECAMATAN BANDAR LAKSAMANA KABUPATEN BENGKALIS

The study about habitat characteristics and population structure razor clam (Solen lamarckii, Chenu 1984) in intertidal zone Apiapi Village Bandar Laksamana District Bengkalis Regency conducted on January 2020. The purpose of this study was to analyze about habitat characteristics and population structure of razor clam and the correlation between substrate particle size and population density of razor clam. The habitat parameters measured include the physical and chemical parameters of sea waters. Determination of the station using purposive sampling method. Razor clam samples were collected by using a 1 x 1 m2 frame that laid along a transect. There were 4 plots and 3 subplots along the transect as replications. The result showed, the sediment tipe was sandy substrate, organic material was low, total suspended solid was high. Population density of razor clams was 3.3-23.3 Ind/m2. The distribution pattern of razor clams through each plot was uniform. While, the most common size of razor clam 5.04-5.62 cm. The correlation between particle size and population density of razor clam was strong.

Production of Bio-Based Pigments from Food Processing Industry By-Products (Apple, Pomegranate, Black Carrot, Red Beet Pulps) Using Aspergillus carbonarius.

Food processing industry by-products (apple, pomegranate, black carrot, and red beet pulps) were evaluated as raw materials in pigment production by the filamentous fungi Aspergillus carbonarius. The effect of fermentation conditions (solid and submerged-state), incubation period (3, 6, 9, 12, and 15 d), initial substrate pH (4.5, 5.5, 6.5, 7.5, and 8.5), and pulp particle size (<1.4, 1.4–2.0, 2–4, and >4 mm) on fungal pigment production were tested to optimize the conditions. Pigment extraction analysis carried out under solid-state fermentation conditions showed that the maximum pigment production was determined as 9.21 ± 0.59 absorbance unit at the corresponding wavelength per gram (AU/g) dry fermented mass (dfm) for pomegranate pulp (PP) by A. carbonarius for 5 d. Moreover, the highest pigment production was obtained as 61.84 ± 2.16 AU/g dfm as yellowish brown at initial pH 6.5 with < 1.4 mm of substrate particle size for 15-d incubation period. GC×GC-TOFMS results indicate that melanin could be one of the main products as a pigment. SEM images showed that melanin could localize on the conidia of A. carbonarius.

Study on Spatial Interpolation Method of Marine Sediment Particle Size Based on Geostatistics

Sun, C.; Wang, N.; Jin, S., and Wang, M., 2020. Study on spatial interpolation method of marine sediment particle size based on geostatistics. In: Yang, D.F. and Wang, H. (eds.), Recent Advances in Marine Geology and Environmental Oceanography. Journal of Coastal Research, Special Issue No. 108, pp. 125–130. Coconut Creek (Florida), ISSN 0749-0208.To reflect continuously and appreciably on the distribution of the average particle size of marine sediments, the geostatistical interpolation method based on GIS is used to predict the particle size of offshore sediments in a certain sea area in Liaoning. The kriging interpolation, the inverse distance weighting method, and polynomial interpolation method were used to spatially interpolate the particle size data of the experimental sites, and the cross-validation method was used to appraise the interpolation accuracy of the results. According to the results, in the case of limited data, the kriging interpolation method is the best. Inverse distance weighting method is better than polynomial interpolation method, but the interpolation results of the three methods all show a certain probability accuracy and can be used to predict a certain area. The particle size of the ocean substrate can be predicted and used by others.

Measurements and modeling of infrared reflectance signatures of microparticle traces on surfaces

Standoff detection of hazardous materials using infrared backscattering spectroscopy shows promise due to its speed of detection, sensitivity, chemical specificity, eye safety, and the ability to perform detection in a stealthy manner. However, infrared diffuse reflectance spectra of trace particles on substrates exhibit a strong dependence on substrate type, particle size, and mass loading. This has a negative impact on the performance of detection algorithms and false alarm rates when using commercially available spectral databases. We present two models that are quickly computed yet capture most of the observed spectral features. Model I is best suited for calculating the diffuse reflectance spectra of trace amounts of particles on relatively smooth substrates, while model II extends the applicability of model I to particles on very rough substrates. The models can be used for algorithm development and training. The main inputs to the models are the analyte and substrate optical constants as a function of wavelength, and the particle size distribution and average mass loading. The accuracy of the models was checked by comparing to experimentally measured diffuse reflectance spectra of several carefully prepared samples.

Experimental and computational study on the microwave energy based regeneration in diesel particulate filter for exhaust emission control

The uncontrolled combustion and early-life failure of the Diesel Particulate Filter substrate during fuel-based regeneration has raised the requirement for an alternate regeneration technique. The Latest emission norms have made it a mandatory requirement to retrofit the Diesel Particulate Filtration system in the exhaust line of CI engines to bring down the Particulate emissions. In this work, a novel technique through application of microwave energy has been developed for active regeneration of soot particles accumulated in the filter channel. Modelling of soot layer formation and microwave regeneration were carried out using CFD software (COMSOL MULTIPHYSICS). Performance and emission characteristics of multi-cylinder CI engine were evaluated after retrofitting the developed after-treatment system comprising of Diesel Oxidation Catalysis (DOC) and microwave regeneration based Diesel Particulate Filtration (DPF) systems. Soot accumulation rate and regeneration rate were experimentally investigated at different engine loads and magnetron (microwave radiation source) power levels. The experimental results showed that the developed after-treatment system has an average filtration efficiency of 90% for brake specific particle number emissions and 55% for hydrocarbon emissions. The regeneration rate was observed to be a maximum of 0.21 g/min at 50% power levels owing to the non-linear behaviour of magnetron. Energy consumption pattern of other regeneration techniques has been compared with the developed microwave regeneration system. The effect of soot accumulation and regeneration on the morphology, microstructure, chemical composition and particle size of DPF substrate were examined using characterization studies like Scanning Electron Microscopy – Energy Dispersive X-Ray Spectroscopy (SEM-EDS), Fourier Transform Infra-Red spectroscopy (FTIR), Particle Size Analysis (PSA) and microscopic imaging.

Root morphology and exudate availability are shaped by particle size and chemistry in Brachypodium distachyon.

Root morphology and exudation define a plants’ sphere of influence in soils. In turn, soil characteristics influence plant growth, morphology, root microbiome, and rhizosphere chemistry. Collectively, all these parameters have significant implications on the major biogeochemical cycles, crop yield, and ecosystem health. However, how plants are shaped by the physiochemistry of soil particles is still not well understood. We explored how particle size and chemistry of growth substrates affect root morphology and exudation of a model grass. We grew Brachypodium distachyon in glass beads with various sizes (0.5, 1, 2, 3 mm), as well as in sand (0.005, 0.25, 4 mm) and in clay (4 mm) particles and in particle‐free hydroponic medium. Plant morphology, root weight, and shoot weight were measured. We found that particle size significantly influenced root fresh weight and root length, whereas root number and shoot weight remained constant. Next, plant exudation profiles were analyzed with mass spectrometry imaging and liquid chromatography–mass spectrometry. Mass spectrometry imaging suggested that both, root length and number shape root exudation. Exudate profiles were comparable for plants growing in glass beads or sand with various particles sizes, but distinct for plants growing in clay for in situ exudate collection. Clay particles were found to sorb 20% of compounds exuded by clay‐grown plants, and 70% of compounds from a defined exudate medium. The sorbed compounds belonged to a range of chemical classes, among them nucleosides, organic acids, sugars, and amino acids. Some of the sorbed compounds could be desorbed by a rhizobacterium (Pseudomonas fluorescens WCS415), supporting its growth. This study demonstrates the effect of different characteristics of particles on root morphology, plant exudation and availability of nutrients to microorganisms. These findings further support the critical importance of the physiochemical properties of soils when investigating plant morphology, plant chemistry, and plant–microbe interactions.

Substrate mediated predator\u2013prey interactions between invasive crayfish and indigenous and non-native amphipods

The increasing number of taxa being translocated across the globe is leading to many non-native species encountering indigenous taxa as well as other non-native species. Environmental heterogeneity may strongly influence the spatial distribution, habitat use and refuge availability for these taxa. Using a series of 24-h mesocosm experiments we examined the predator–prey interactions between an invasive crayfish (Pacifastacus leniusculus) and four amphipod taxa, one indigenous (Gammarus pulex) and three non-native species (Crangonyx pseudogracilis, Dikerogammarus villosus and Gammarus tigrinus) to Great Britain. The potential mediating effect of physical habitat on predator–prey interactions was examined via the use of different substrate particle sizes; cobbles, gravels and, sand. Survivorship of amphipods in response to crayfish predation varied significantly with the highest rates recorded for the non-native species D. villosus, followed by G. tigrinus, and C. pseudogracilis, with the lowest survivorship recorded for the indigenous species G. pulex for all substrates except cobble. However, total biomass consumption of the indigenous G. pulex and the non-native D. villosus by P. leniusculus were similar suggesting that crayfish may have been satiated by larger D. villosus individuals. Substrate size had a significant influence on the predation success of P. leniusculus, with larger substrate clasts typically resulting in increased survivorship rates for all species except C. pseudogracilis, which displayed lower predation rates for sand substrates. The findings of this study highlight the risks that naïve indigenous taxa may face from new invasive species and the importance of characterising physical habitat (complexity and refugia potential) when considering the potential ecological effects of invaders on predation success.