Absence Of Shelter Research Articles

Triggers affecting crayfish burrowing behaviour

Surface water inhabiting crayfish are well-known for the impact on their surroundings. This impact has been related to loss of biodiversity and deteriorating water quality for invasive crayfish. Crayfish dig burrows for various reasons like lack of natural shelters, avoiding an upcoming drought, or high crayfish density and this may lead to increased sediment transport and accelerated bank instability. All crayfish are considered to have burrowing capability, but not all species have been observed burrowing. Studies comparing this behaviour among different species in standardized ways are scarce. Crayfish burrowing was investigated under standardized laboratory conditions to reveal differences among species and their sex. All studied species occur in the Netherlands and were the native Astacus astacus (Linnaeus, 1758), the Eurasian Pontastacus leptodactylus (Eschscholtz, 1823) and the invasive North American Faxonius virilis (Hagen, 1870), F. limosus (Rafinesque 1817), Pacifastacus leniusculus (Dana, 1852), Procambarus acutus (Girard 1852), and P. clarkii (Girard, 1852). As burrowing triggers were evaluated presence of shelter, increased light intensity, increased water temperature, and increased crayfish density. Results showed species-specific and sometimes sex-specific differences in burrowing behaviour among crayfish. The response to burrowing triggers was also species-specific and no two species reacted identical to all triggers. Absence of shelter was a strong driver to burrow for A. astacus, F. limosus and F. virilis, while increased light intensity triggered burrowing behaviour in P. leptodactylus, P. acutus and P. clarkii and lowered activity of F. limosus. Burrowing behaviour of P. clarkii was mostly influenced by increased water temperature. Significant differences between females and males were observed for P. leptodactylus, P. leniusculus and P. acutus in the shelter, increased density and increased water temperature treatment, respectively. Understanding the triggers that invoke burrowing may help managing populations of these invasive species.

Diversified Bund Vegetation Coupled With Flowering Plants Enhances Predator Population and Early-Season Pest Control.

Insecticide overuse in crop production systems often results in detrimental effects on predators and parasitoids, which regulate important insect pests. The natural enemies are also unable to survive in monocrop landscapes with the absence of shelter or food sources. Diversified vegetation, especially with flowering plants, can enhance natural enemy abundance and diversity, thus strengthening biological control, enabling farmers to reduce insecticides. In this study, we conserved bund vegetation and manipulated the existing rice landscapes with flowering plants to provide food and shelter for the biological control agents. Our study revealed significant positive relationships between predator densities and bund plant diversity. The abundance of predators significantly increased in the eco-engineered plots, especially at the flowering peaks compared to the insecticide-treated and control plots, while parasitoids were more diverse in both the eco-engineered and control plots. There were no significant differences in planthopper and leafhopper densities among the treatments during the rice early and maximum tillering stages, suggesting effective natural control of these herbivore pests in the eco-engineered plots at the early rice-growing season. However, at the heading stage relatively higher planthopper and leafhopper populations in the control and eco-engineered plots than in the insecticide-sprayed plots were recorded, suggesting perhaps the need for insecticide interventions if exceeding the threshold at this time. Our study indicates that manipulating the habitats surrounding the rice fields to enhance natural enemies is a sustainable practice in rice production as it can enhance the natural suppression of pests and thus reducing the need for insecticide.

Does shelter influence the metabolic traits of a teleost fish?

Availability of shelter is an important component of habitat selection for animals as it can influence survival (protection against harsh physical conditions and predation) and growth (energy acquisition and expenditure). Few studies address the effect of shelter on metabolic expenditures associated with non-mechanical tasks (excluding station holding or movement). The main goal of this study was to investigate the influence of shelter use on metabolic traits of smallmouth bass (Micropterus dolomieu) from two populations (Kiamika River and Lake Long). Respirometry experiments on smallmouth bass were conducted to measure standard metabolic rate (SMR), resting metabolic rate (RMR), aerobic scope (AS), recovery time (RT) and excess post-exercise oxygen consumption (EPOC) in the presence or absence of shelter. The presence of shelter did not affect most metabolic traits, except for RMR, which was reduced in the presence of shelter for Lake Long fish. The results of this study also show that larger fish had lower SMR in the presence of shelter than when it was absent. When accounting for social hierarchy, there were no differences in most metabolic traits in dominant or subordinate fish in the presence or absence of shelter, except for RT, which was significantly lower in the presence of shelter for dominant fish. These results do not support the existence of an unequivocal relationship between individual metabolic traits and the presence of shelter. If physiological motives may influence the use of shelter, sheltering in itself might not have important consequences on energy expenditures required for non-mechanical tasks.

A combination of six psychoactive pharmaceuticals at environmental concentrations alter the locomotory behavior of clonal marbled crayfish

Pharmaceutically active compounds (PhACs) are ubiquitous in the aquatic environment worldwide and considered emerging contaminants. Their effects on growth, behavior, and physiological processes of aquatic organisms have been identified even at very low concentrations. Ecotoxicological investigations have primarily focused on single compound exposure, generally at a range of concentrations. In the natural environment, pollutants seldom occur in isolation, but little is known about the effects and risks of combinations of chemicals. This study aimed to investigate the effects of concurrent exposure to six psychoactive PhACs on locomotory behavior and life history traits of clonal marbled crayfish Procambarus virginalis. Crayfish were exposed to ~1 μg L−1 of the antidepressants sertraline, citalopram, and venlafaxine; the anxiolytic oxazepam; the opioid tramadol; and the widely abused psychostimulant methamphetamine. In the absence of shelter, exposed crayfish moved significantly shorter distances and at lower velocity and showed significantly less activity than controls. With available shelter, exposed crayfish moved significantly more distance, showed higher activity, and spent a significantly more time outside the shelter than controls. Molting, mortality, and spawning frequency did not vary significantly between the groups. Hemolymph glucose level did not vary among groups and was not correlated with observed behaviors. Results suggest that environmental concentrations of the tested compounds in combination can alter the behavior of non-target aquatic organisms as individual exposure of these compounds, which may lead to disruption of ecosystem processes due to their reduced caution in polluted conditions. Further research is needed using varied chemical mixtures, exposure systems, and habitats, considering molecular and physiological processes connected to behavior alterations.

Potential of marbled crayfish Procambarus virginalis to supplant invasive Faxonius immunis

Biological invasions are a growing threat to global biodiversity due to negative impacts on native biota and ecosystem functioning. Research has expanded from investigating native and alien species interactions to examining relationships among alien species. Invasive crayfish may have similar life histories, niche preferences, and adaptation strategies, but their mutual interactions are little understood. This study aimed to quantify interaction patterns of size-matched calico crayfish Faxonius immunis, established in the Rhine River catchment, and the parthenogenetic marbled crayfish Procambarus virginalis, currently spreading throughout Europe. During agonistic interactions in the absence of shelter, marbled crayfish won a significant majority of fights against calico crayfish, but in the presence of shelter there was no significant difference. When sex of calico crayfish was considered in the analysis without shelter, marbled crayfish won a significantly higher number of fights with female calico crayfish. In the absence of shelter, marbled crayfish dominated calico crayfish females in 83.3% and males in 60% of pairs. With available shelter, the dominance of marbled crayfish was 100% and 54.5% over female and male calico crayfish, respectively. The results suggested that sex and resource availability influence agonistic behaviour in the studied crayfish. Marbled crayfish are confirmed to be competitive against the calico crayfish, which has been shown to be dominant over another serious invader in the Rhine River catchment, the spiny-cheek crayfish Faxonius limosus. In natural sympatric populations, the situation may be affected by factors such as size, reproductive variables, water temperature, and predation pressure.

Impact resistance to ballistic ejecta of wooden buildings and a simple reinforcement method using aramid fabric

Many of the casualties in the phreatic eruption of Mt. Ontake, which is located in central Japan, on September 27, 2014, were climbers near the summit. The main cause of death was injury by lapilli and block ejecta (ballistic ejecta). The absence of shelters at the summit and along the climbing trails may be a major factor in the large number of casualties attributable to ballistic ejecta, and establishing and improving shelters on active volcanoes is an urgent need. The climbers who evacuated to wooden mountain huts survived the 2014 Mt. Ontake eruption, this research focuses on the impact characteristics of wooden materials. We therefore performed an experimental investigation into the safety of wooden materials under impact by simulated ballistic ejecta with a mass of 2.66 kg (equivalent to a diameter of 128 mm) as by assembling cylindrical abrasive travelling at up to 300 km/h (approximately 83 m/s). With abrasives acting as ballistic ejecta, the simulated shelter facility components serving as targets were wooden structures composed of Japanese cedar, which found on volcanoes at high elevations in Japan. The components of the fabricated roof were Japanese cedar with a thickness of 15 mm as roofboard installed on the surface waterproof sheet and 0.4 mm thick Galvalume® steel sheet with an additional rafter installed. The impact absorption energy of the fabricated roof increased with simulated ballistic ejecta impact velocity because the localization of bending deformation progressed at the impact part and the frequency of splitting failure increased with increasing impact velocity. This is attributable to variation in the mode of splitting failure of cedar boards and the dependence of the material strength on projectile velocity. We also experimentally investigated simple reinforcement methods in order to obtain basic data on conversion of mountain huts to shelters. The reinforced wooden structure could withstand simulated ballistic ejecta impacts of up to approximately 13 kJ by incorporating two layers of aramid fabric between a waterproof sheet and a cedar board. Review of the roof structures of existing wooden buildings based on these results promises further advances in safe impact-resistant design.

Ecological traits of sea cucumbers with commercial relevance from the north-eastern Atlantic coast

Ecological traits of sea cucumbers with commercial relevance from the north-eastern Atlantic coast

An enemy of your enemy is your friend: Impact of predators on aggregation behavior of gammarids

AbstractPredation pressure may affect many aspects of prey behavior, including forming groups and changes in social interactions. We studied the aggregation behavior of competing gammaridsDikerogammarus villosusandPontogammarus robustoides(Amphipoda, Crustacea) to check whether they modify their preferences for conspecifics or heterospecifics in response to predator (the racer gobyBabka gymnotrachelus) kairomones in the presence or absence of stone shelters (alternative protection source). Both species exhibited preferences toward shelters occupied by conspecifics over empty shelters and conspecifics apart from shelters, suggesting that their aggregation depends not only on habitat heterogeneity, but also on their social interactions. Moreover, gammarids in the presence of shelters (safer conditions) preferred conspecifics over heterospecifics, but predator kairomones made them form aggregations irrespective of species. In the predator presence,P. robustoidesincreased its aggregation level only in the sheltered conditions, whereasD. villosusexhibited this response only in the absence of shelters, suggesting that this behavior can protect it against predators. Therefore, we tested the antipredator effectiveness ofD. villosusaggregations by exposing them to fish predation. Gobies foraged most effectively on immobile single gammarids compared to moving and aggregated individuals. Fish also avoided aggregated prey, confirming the protective character of aggregations. We have demonstrated that the predator presence increases aggregation level of prey gammarids and affects their social behavior by reducing antagonistic interactions and avoidance between competing species. This is likely to affect their distribution and functioning in the wild, where predator pressure is a standard situation.

A serosurvey of selected cystogenic coccidia in Spanish equids: first detection of anti-Besnoitia spp. specific antibodies in Europe

BackgroundEquine besnoitiosis, caused by Besnoitia bennetti, and equine protozoal myeloencephalitis (EPM), caused by Sarcocystis neurona and Neospora hughesi are relevant equine diseases in the Americas that have been scarcely studied in Europe. Thus, a serosurvey of these cystogenic coccidia was carried out in Southern Spain. A cross-sectional study was performed and serum samples from horses (n = 553), donkeys (n = 85) and mules (n = 83) were included. An in-house enzyme-linked immunosorbent assay (ELISA) was employed to identify a Besnoitia spp. infection and positive results were confirmed by an a posteriori western blot. For Neospora spp. and Sarcocystis spp., infections were detected using in-house ELISAs based on the parasite surface antigens N. hughesi rNhSAG1 and S. neurona rSnSAG2/3/4. Risk factors associated with these protozoan infections were also investigated.ResultsAntibodies against Besnoitia spp., Neospora spp. and Sarcocystis spp. infections were detected in 51 (7.1%), 46 (6.4%) and 20 (2.8%) of 721 equids, respectively. The principal risk factors associated with a higher seroprevalence of Besnoitia spp. were the host species (mule or donkey), the absence of shelter and the absence of a rodent control programme. The presence of rodents was the only risk factor for Neospora spp. infection.ConclusionsThis study was the first extensive serosurvey of Besnoitia spp. infection in European equids accomplished by two complementary tests and gives evidence of the presence of specific antibodies in these populations. However, the origin of the infection is still unclear. Further parasite detection and molecular genotyping are needed to identify the causative Besnoitia and Neospora species. Finally, cross-reactions with antibodies directed against other species of Sarcocystis might explain the positive reactions against the S. neurona antigens.

Effect of density and shelter on growth, physiology, and biochemical composition of the crayfish Cambarellus montezumae

ABSTRACTWe analyzed the combined effects of population density and presence or absence of shelters on growth and physiological performance of the crayfish Cambarellus montezumae. Three different densities—64, 144, and 208 crayfish per m2—with and without shelters were used. Growth; survival; metabolic rate; tissue glucose; and total lipid, triglyceride, nitrogen, and energy content were measured. Animals stocked at 64 and 144 per m2 with shelter reached the highest body weight; those in groups without shelter had elevated levels of glucose (p < .05). Animals stocked at 144 per m2 retained the most nitrogen and energy (p < .05). Overall, the combination of medium density with shelters produced the best performance.

Finding a Place to Belong: The Role of Social Inclusion in the Lives of Homeless Men

This study explores the role of informal social support networks of male homeless shelter residents. Authors utilized ethnographic methods, relationality and reflexive research approaches and key informant interviews with 10 shelter residents to investigate perceptions of belonging in overcoming social exclusion and countering the stigmatization cast onto as a result of their condition of homelessness. Study findings challenge our normative conceptions of homelessness by discerning between “rooflessness” and “rootlessness” suggesting that homelessness is more than the absence of shelter, but rather denotes the absence of support and inclusion in one’s community. This research highlights a community within the shelter characterized by notions of acceptance and companionship. The associations shelter residents developed are creative and collaborative survival strategies allowing residents to negotiate their conditions of homelessness. As a result, some residents expressed reluctance to leave the shelter and (re)integrate into the community that had cast them off.

Comparative performance of wild juvenile mud crab (Scylla serrata) in different culture systems in East Africa: effect of shelter, crab size and stocking density

Grow-out culture of mud crabs Scylla serrata in East Africa is at an earlier development phase and is dependent on wild seed crabs. We assessed three different culture systems (net cages, ponds and pens) in three treatments (shelter, size and density) to evaluate survival and growth in small-scale culture of mud crabs in Kenya. In small nursery cages, we assessed how availability of shelter, stocking density and size-class separation affected cannibalistic rates in small juveniles (20-80 mm internal carapace width) in 7-day experiments. The result indicated that shelter and size-class separation decreased cannibalism and mortality with 26 and 31 %, respectively, whereas no significant effect was found for different stocking densities. Earthen ponds and mangrove pens were used to compare growth and survival in long-term studies (2-4 months) in the presence and absence of shelter. Treatments with and without shelter yielded low overall recovery of crabs (4-26 %) indicating high mortality rates, and there was no significant effect of shelter or culture system on survival. In contrast, growth rate was high in both pens and ponds, but significantly lower in pen systems without shelter. Generally, the results indicated that cannibalism is the largest source of mortality in different culture systems (net cages, ponds and pens), and use of shelter and size grading of crabs improved survival significantly. In contrast, growth rates were high and comparable to natural growth in both pond and pen culture when shelter was provided. Using growth models to compare growth and survival in mud crabs from aquaculture studies in the literature, we show that shelter may have a stronger effect on growth than has been previously thought, whereas crab density appears to impact more on crab survival. Thus, improving survival in grow-out culture systems is a challenge that remains to be solved for small-scale mud crab culture in East Africa.

Importance of bottom type and background color for growth and blind-side hypermelanosis of the olive flounder, Paralichthys olivaceus

When flatfishes are cultured at high-density in an artificial facility, the bright background color and the carpeted bottom substratum (sand or gravel) help significantly to enhance growth and prevent blind-side hypermelanosis. However, how the bright background and carpeted gravel enhance growth and prevent the hypermelanosis is unknown. Thus, we performed three experiments using the olive flounder, Paralichthys olivaceus. In the first, the acupressure of gravel to blind skin and the burrowing behavior of flounder were assessed to determine which eventually suppressed hypermelanosis. In the second experiment, we assessed whether the color of the carpeted gravel affected flounder hypermelanosis and growth. In the final experiment, we assessed whether hypermelanosis of flounder reared on a gravel bottom was continuously inhibited after removal of the gravel substratum, and whether tank color affected the hypermelanosis and fish growth. The results showed that the burrowing of flounder into gravel was more important than the stimulus of rough gravel on blind-skin to prevent blind-side hypermelanosis. The color of the gravel and tanks did not affect hypermelanosis. Removal of the gravel substratum resulted in enhancement of blind-side hypermelanosis. However, fish growth was enhanced by a bright-colored tank but not a bright-colored bottom substratum. In conclusion, these results confirm that the absence of shelter in which flounder can burrow or hide induces blind-side hypermelanosis, and that flounder consistently burrow beneath the substratum to prevent malpigmentation. Additionally, our results show that a bright-colored tank resulted in increased growth, indicating that flounder should be reared in a bright-background to enhance growth.

Preference of Syrian hamsters to nest in old versus new bedding

This study tested whether Syrian hamsters ( Mesocricetus auratus) have an aversion to old bedding (up to 14 days) by offering them the option to nest in a new cage. A secondary goal was to assess the relative value of shelters by testing whether the tendency to nest in the new cage was reduced when a shelter was present in the old cage. Individual hamsters were placed in two cages connected by a tunnel, and left to familiarize themselves with this set-up for 10 days. Then the bedding was changed in each cage, and for the next 3, 9, or 14 days the tunnel was blocked and each hamster lived in only one of the cages, either with or without a shelter (PVC pipe) present in that cage. Then the tunnel was unblocked and for the next 3 days the position of each hamster's nest in either of the two cages was noted. After 3, 9, and 14 days in the old cage, respectively 10, 11, and 8 out of 15 males and 6, 9, and 3 out of 15 females never nested in the new cage, whether the old cage had a shelter or not. Only 2, 1, and 4 out of 15 males, and only 5, 3, and 5 out of 15 females nested in the new cage more than in the old one in the absence of shelters. Of those males that nested in the new cage at least once, three out of five, three out of four, and five out of seven nested in the new cage less often when a shelter was present in the old cage than when no shelter was present. For females, the corresponding numbers were 8 out of 9, 5 out of 6, and 11 out of 12. These results indicate that access to a new (though still familiar) cage with fresh bedding holds only a small attraction for nesting hamsters, at least when their current bedding is up to 14 days old, and that shelters are valued.

The Exclusion of (Failed) Asylum Seekers from Housing and Home: Towards an Oppositional Discourse

"Housing" - the practical provision of a roof over one's head - is experienced by users as "home" - broadly described as housing plus the experiential elements of dwelling. Conversely, being without housing, commonly described as "homelessness", is experienced not only as an absence of shelter but in the philosophical sense of "ontological homelessness" and alienation from the conditions for well-being. For asylum seekers, these experiences are deliberately and explicitly excluded from official law and policy discourses. This article demonstrates how law and policy is propelled by an "official discourse" based on the denial of housing and the avoidance of "home" attachments, which effectively keeps the asylum seeker in a state of ontological homelessness and alienation. We reflect on this exclusion and consider how a new "oppositional discourse" of housing and home - taking these considerations into account - might impact on the balancing exercise inherent to laws and policies concerning asylum seekers.

Aspectos biológicos de Harmonia axyridis alimentada com duas espécies de presas e predação intraguilda com Eriopis connexa

O objetivo deste trabalho foi determinar os aspectos biológicos de Harmonia axyridis, alimentada com duas espécies de presas, e a ocorrência de predação intraguilda com Eriopis connexa. Larvas de H. axyridis foram alimentadas diariamente com ovos de Anagasta kuehniella ou com o pulgão Schizaphis graminum. Adultos da joaninha foram separados em dez casais que receberam o mesmo tipo de alimento da fase larval. Na avaliação da predação, uma larva de quarto instar de cada espécie foi mantida na presença ou ausência de abrigo e de ovos de A. kuehniella. A fase larval de H. axyridis durou 10,2 e 8,9 dias, quando alimentada com A. kuehniella e S. graminum, respectivamente. A sobrevivência do predador, em fase imatura, variou de 70 a 100%. A joaninha apresentou período de oviposição de 47,3 e 51,7 dias, com 887,6 e 822,5 ovos, ao se alimentar de A. kuehniella e S. graminum, respectivamente. A longevidade das fêmeas foi de 74,1 e 76,2 dias e a dos machos de 67,3 e 70,3 dias, em A. kuehniella e S. graminum, respectivamente. H. axyridis atuou como predador intraguilda e foi a espécie dominante na competição com E. connexa.

Direct and Indirect Effects of Channel Catfish (Ictalurus punctatus) on Native Crayfishes (Cambaridae) in Experimental Tanks

For the incised, sand-bed streams of north-central Mississippi, USA, fish predation is one plausible mechanism to explain both relatively low crayfish densities and differences in stream size occupied by various native crayfishes. I conducted two mesocosm experiments to test effects of a fish predator (channel catfish, Ictalurus punctatus) on the survival and size structure of native crayfishes (primarily Procambarus hayi and Orconectes chickasawae) in the presence and absence of shelter. I used predominantly the larger species, P. hayi, in the first experiment and the smaller species, O. chickasawae, in the second. Experiments lasted 19–21 d, and each consisted of four replicated treatments: crayfish without shelter, crayfish with shelter, crayfish and predator without shelter, crayfish and predator with shelter. In both experiments, catfish significantly reduced crayfish survival. Shelter significantly reduced catfish predation on the smaller, but not the larger, crayfish species. Comparisons between experiments showed that in tanks containing catfish, P. hayi had higher survival than O. chickasawae. In both experiments, the mean size of crayfish increased less in the presence than in the absence of catfish, and I argue that the effect is due largely to a reduction in crayfish growth. Channel catfish directly and indirectly influenced crayfish in experimental settings, with the degree of influence varying by crayfish species and presumably related to crayfish size. Thus, fish predation and shelter availability are likely important factors influencing densities of and macrohabitat use by these native crayfishes.

Testing the hypothesis of tolerance strategies in Hiatella arctica L. (Mollusca: Bivalvia)

The physiological and biocenotic optima of Hiatella arctica L. inhabiting shallow water fouling communities of the White Sea were compared. The biomass and proportion of H. arctica in communities were used for the estimation of biocenotic optima or community success. The physiological state of populations was assessed by means of the fluctuating asymmetry. The fluctuating asymmetry of H. arctica was calculated using the valve weights. It was determined that the shell of H. arctica possesses a slight directional asymmetry, the right valve usually being larger (and heavier) than the left one. The relationship between fluctuating and directional asymmetries is discussed. High biomass and proportion of H. arctica in the community generally correspond with high levels of fluctuating asymmetry. Thus, a discrepancy between physiological and ecological optima is observed, which is recognised as being characteristic of a tolerance strategy. However, in the absence of pressure from major filter-feeding competitors such as the mussel Mytilus edulis L. and the solitary ascidian Styela rustica L., populations of H. arctica possess a high biomass and low levels of fluctuating asymmetry. It appears that H. arctica prefers to inhabit shelters or depressions, or to be covered by other organisms. Populations of H. arctica existing in the absence of shelter had extremely high levels of fluctuating asymmetry despite the absence of filter-feeding competitors. Thus, the strategy adopted by H arctica L. in the investigated upper 5 m layer of water in the White Sea can be described as a stress- and competitor-tolerant strategy.

Acquired predator recognition by fathead minnows: influence of habitat characteristics on survival.

In this study we conditioned fathead minnows (Pimephales promelas) to recognize the odor of a perch (Perca flavescens) by exposing them to perch odor coupled with minnow alarm cue. We then staged encounters between the predator and prey in order to assess whether the predator odor training had any effect on survival of the prey. We tested for a survival effect in the presence and absence of shelter. Our results indicate that fish trained with alarm signals to recognize predators gained a survival benefit during staged encounters with a predator and that habitat characteristics influenced the survival of conditioned fish.

The use of artificial temporary streams with and without shelters by Japanese dace Tribolodon hakonensis

SUMMARY: In order to know how fish use temporary streams, we set up artificial temporary streams with and without shelters and investigated the fish that colonized there from connected permanent streams. A total of 220 fish belonging to six species were captured over four sampling periods from May to September, with Japanese dace Tribolodon hakonensis being the most abundant (75%). More Japanese dace colonized the stream with shelters than without shelters. The standard length and condition of Japanese dace tended to be greater in the stream with shelters than without shelters. Foraging behavior and area of Japanese dace differed significantly between the two streams; more Japanese dace employing drift feeding near the entrance of the shelterless stream. Japanese dace predominantly fed upon chironomid larvae, which became abundant in stream mud in July. However, in August and September, Japanese dace rarely preyed upon chironomid larvae and their digestive canal fullness was low, probably because most chironomid larvae had been consumed. This tendency was more prominent in the stream with shelters. The use of temporary waters by Japanese dace changed dynamically in response to the abundance of chironomid larvae and the presence or absence of shelters.