Benthic and Hyporheic Macroinvertebrate Distribution Within the Heads and Tails of Riffles During Baseflow Conditions

The distribution of lotic fauna is widely acknowledged to be patchy reflecting the interaction between biotic and abiotic factors. In an in-situ field study, the distribution of benthic and hyporheic invertebrates in the heads (downwelling) and tails (upwelling) of riffles were examined during stable baseflow conditions. Riffle heads were found to contain a greater proportion of interstitial fine sediment than riffle tails. Significant differences in the composition of benthic communities were associated with the amount of fine sediment. Riffle tail habitats supported a greater abundance and diversity of invertebrates sensitive to fine sediment such as EPT taxa. Shredder feeding taxa were more abundant in riffle heads suggesting greater availability of organic matter. In contrast, no significant differences in the hyporheic community were recorded between riffle heads and tails. We hypothesise that clogging of hyporheic interstices with fine sediments may have resulted in the homogenization of the invertebrate community by limiting faunal movement into the hyporheic zone at both the riffle head and tail. The results suggest that vertical hydrological exchange significantly influences the distribution of fine sediment and macroinvertebrate communities at the riffle scale

Distribution of Channel Catfish Life Stages in a Prairie River Basin

To describe the pattern of use by age 0, juvenile, and adult channel catfish (Ictalurus punctatus) in a prairie river basin, we collected concurrent samples from tributaries and mainstem study sites in the Grand River basin of northern Missouri. Using standardized methods, we made collections in June, August, and October of 1997 and 1998. Age 0 channel catfish were found in all three streams in August, but rarely were observed in the tributaries during October. Juveniles (ages 1-3) and adults were observed in all three streams in all three months sampled. Tag returns suggested that age 2 and over channel catfish moved to overwintering locations in deepwater habitats in the mainstem river

Movement and habitat use by stream-dwelling smallmouth bass

We monitored the movement and habitat use of 34 stream-dwelling smallmouth bass(Micropterus dolomieui) in Jacks Fork River, Missouri, by radiotelemetry. Observations weremade 24 h/d in all seasons. Definite patterns of diel activity and habitat use were evident andwere modified by seasonal changes in water temperature. Fish remained in restricted homeranges for most of the year but tended to disperse in spring when all of the radio-tagged fish lefttheir home pool; 75% returned during the same season. Equal numbers of fish moved upstreamand downstream. However, the median distance moved upstream was greater. Intrapoolmovement of smallmouth bass peaked soon after sunrise and again after sunset in all seasons.Average intrapool movement was 120 m/d when water temperatures were lowest (4°C) and 980m/d when temperatures were highest (27.5°C). In the warmer seasons, fish preferred logjamsand root wads by day and increased their use of boulders at night. In cooler seasons, fish usedboulders almost exclusively. Regardless of season, open water without cover was used mostduring the period just after sunrise but was never used in proportion to its availability. Boulderswere the most preferred substrate, and gravel was the least preferred. Small mouth bass usedintermediate depths the most and showed no daily or seasonal changes in depth preferences.Fish preferred velocities less than 0.2 m/s at all times of day and in all seasons. Movements infloods did not differ from those observed during normal discharges; however, single logs wereselected in significantly greater proportion than logjams

Patterns of movement and habitat use by northern hog suckers in an Ozark stream

Although the northern hog sucker (Hypentelium nigricans) is widely distributedthroughout the Mississippi and Ohio river basins and is both ecologically and recreationallyimportant, much of its basic ecology is not known. We determined movement and habitat use for25 fish in the Current River, Missouri, for 1 year using radio telemetry. Seasonal movements wererecorded two or three times each week during daylight hours from January to November 1988.Diet movement and habitat use were recorded once each hour for 17 d in winter and 12 d insummer. Mean daily distance traveled was greater in summer (425 m) than in winter (276 m).Home range was greater in winter and spring (812 m) than in summer and fall (426 m). Habitatuse changed seasonally from slower, deeper water and smaller substrates during winter toincreasing use of taster, shallower water and larger substrates through warmer-water periods. Inboth seasons, fish had a consistent daily pattern, moving more during the day than at night. Dietpatterns of use were distinct. In winter, fish used pool habitat with moderate flow during the dayand riffle or edge habitat at night. In summer, fish used run habitat during the day and riffle oredge habitat at night. Patterns of habitat use indicated fish used one area of the river during theday to feed and another at night to rest. Fish remained in their home area during high-flow eventsbut used flooded riparian areas where current velocities were lower. Fish moved up- ordownstream short distances (mean = 497 m, N = 7) into spawning areas during late February andearly March. This study emphasizes the importance of habitat diversity to accommodate thisspecies\u27 diel and seasonal preferences and the necessity of a connected floodplain for the fish tosurvive catastrophic events

Resource use by stream-dwelling rock bass and smallmouth bass

We examined food and habitat use of sympatric smallmouth bass (Micropterusdolomieui) and rock bass (Ambloplites rupestris) in the Current and Jacks Fork rivers, Missouri.Use of food resources was similar between species and within a species. On a total caloric basis,the importance of prey ranked crayfish \u3e fish \u3e insects. The similarities of both prey types and thesize selection of prey indicated that food resources were not a mechanism of ecologicalsegregation between rock and smallmouth bass. Habitat use was evaluated by underwaterobservation. Location of both species was highly correlated with some aspect of cover, especiallywoody structure. Although cover use overlapped among size classes and species, rock basswere more often associated with rootwads and smallmouth bass with log complexes (aggregatesof logs and branches). Cover use was independent of rock bass size, but smallmouth bassshorter than 350 mm long more often used vegetation and boulders and were more often found inopen water than were smallmouth bass larger than 350 mm. Smallmouth bass used woodystructure associated with higher current velocities more often than did rock bass. A positiverelation between water depth and fish size was evident for each species, but water depthappeared unimportant in interspecific segregation