Charles F. Rabeni

Effect of siltation on stream fish communities

SynopsisThe effect of siltation on stream fish in northeast Missouri was evaluated using community structural measurements and a functional approach that emphasized feeding and reproductive guilds. As the percentage of fine substrate increased, the distinction among riffle, run, and pool communities decreased, primarily because the number of individuals of typical riffle species decreased. Within the riffle communities the abundance of fish of two feeding guilds — benthic insectivores and herbivores — was reduced as the percent of fine substrate increased. The abundance of fish in other feeding guilds was not affected. The only reproductive guild to be similarly affected was the simple and lithophilous, whose members require a clean gravel substrate for spawning. Species within each guild affected by siltation had significantly similar trends in abundance. The guild analysis indicated that species with similar ecological requirements had a common response to habitat degradation by siltation.

Biomonitoring for deposited sediment using benthic invertebrates: a test on 4 Missouri streams

The response of stream benthic invertebrates to surficially deposited fine sediment was investigated in 4 Missouri streams. Twenty to 24 sampling sites in each stream were selected based on similarities of substrate particle-size distributions, depths, and current velocities but for differences in amounts of deposited sediment, which ranged from 0 to 100% surface cover. Deposited sediment was quantified 2 ways: a visual estimate of % surface cover, and a measurement of substrate embeddedness, which were highly correlated with each other and with the amount of sand. Invertebrates were collected using a kicknet for a specified time in a 1-m2 area. Five commonly used biomonitoring metrics (taxa richness, density, Ephemeroptera, Plecoptera, and Trichoptera [EPT] richness, EPT density, and EPT/Chironomidae richness) were consistently significantly correlated across streams to deposited sediment. Shannon diversity index, Chironomidae richness, Chironomidae density, a biotic index, and % dominant taxon did not relate to increasing levels of deposited sediment. Tolerance values representing taxa responses to deposited sediment were developed for 30 taxa. Deposited-sediment tolerance values were not correlated with biotic index tolerance values, indicating a different response by taxa to deposited sediment than to organic enrichment. Deposited-sediment tolerance values were used to develop the Deposited Sediment Biotic Index (DSBI). The DSBI was calculated for all samples (n = 85) to characterize sediment impairment of the sampled streams. DSBI values for each site were highly correlated with measures of deposited sediment. Model validation by a resampling procedure confirmed that the DSBI is a potentially useful tool for assessing ecological effects of deposited sediment.

Stream invertebrate community functional responses to deposited sediment

Abstract.We investigated functional responses of benthic invertebrates to deposited sediment in four Missouri USA streams. In each stream, invertebrates were sampled along continuums of deposited sediment (particles <2xa0mm in size) from 0 to 100% surface cover in reaches of fairly homogeneous substrate composition, current velocity, and water depths. Correlations, graphical representations, and the cumulative response curves of feeding and habit groups provided strong empirical support for distinct community functional changes due to deposited sediment. Feeding groups were more sensitive to deposited sediment than habit groups. Densities of all the feeding groups decreased significantly with increasing deposited sediment, while relative densities of gatherers increased significantly. Taxa richness also decreased significantly for all the feeding groups except for the shredders. Increases in deposited sediment were related to significant density decreases for only the clingers and sprawlers in the habit group, resulting in significant increases in the relative densities of both burrowers and climbers. Clingers, sprawlers, and swimmers also showed significant decreases in taxa richness.

Resource Use by Stream-Dwelling Rock Bass and Smallmouth Bass

Abstract We examined food and habitat use of sympatric smallmouth bass Micropterus dolomieui 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 > fish > insects. The similarities of both prey types and the size selection of prey indicated that food resources were not a mechanism of ecological segregation between rock and smallmouth bass. Habitat use was evaluated by underwater observation. Location of both species was highly correlated with some aspect of cover, especially woody structure. Although cover use overlapped among size classes and species, rock bass were more often associated with rootwads and smallmouth bass with log complexes (aggregates of logs and branches). Cover use was independent of rock bass size, but smallmouth bass shorter than 350 mm long more often used vegetation and boulders and were more often found in open wate...

Resource Partitioning by Stream-dwelling Crayfish: The Influence of Body Size

The crayfishes Orconectes luteus and 0. punctimanus are sympatric in over 200 km of the Jacks Fork and Current rivers in S-central Missouri. The combinations of substrate particle size, current velocity, depth and macrophyte cover used by youngof-the-year and adults of each species tended to be distinct. Orconectes punctimanus was more restricted in its use of habitats. Young-of-the-year were strongly associated with macrophyte cover and shallow water, and adults with larger substrate particles; both life stages preferred slow current velocities. Orconectes luteus was more evenly distributed over most of the habitats. Young-of-the-year used current velocities and substrate particle sizes somewhat more in proportion to their availability than did adults, which were concentrated within the higher ranges of both of these variables. Laboratory choice experiments involving combinations of species and size classes indicated that crayfish dominance was a function of body size and that habitat use by one size class could be modified when larger individuals of the same or a different species were present. The young of 0. punctimanus hatched earlier and grew faster than did those of 0. luteus. Orconectes punctimanus therefore maintained a distinct size advantage throughout its life cycle. Orconectes punctimanus probably inhabited its preferred set of microhabitat conditions and excluded 0. luteus from these areas. Because much of the remaining stream habitat was unsuitable for 0. punctimanus, competitive exclusion did not occur. Other factors, most notably fish predation, probably complement physical factors and species interactions in determining the distributional patterns of these crayfishes. INTRODUCTION The crayfishes of any particular aquatic habitat generally are limited to one or very few species, even if many species occur in the geographical region (e.g., Williams, 1954). Closely related species commonly exhibit disjunct distributions (see Bovbjerg, 1970, for a review) and an introduced species may rapidly replace one that occurred naturally (Capelli, 1982). The mechanisms involved in displacement or in maintaining species separation are not well understood, but crayfish behavior often gives insight into probable causes. It was well documented by Bovbjerg (1953, 1956), Penn and Fitzpatrick (1963) and Capelli (1982) that crayfish are aggressive, and Capelli and Munjal (1982) recorded interspecific encounters leading to attack in laboratory experiments. Intraspecific attacks are probably common either during the molting period, or by adults on juveniles after production of a maternal pheromone ceases (Little, 1976). Crayfish are mobile, and migrate (Momot, 1966; Flint, 1977), and disperse from areas of high density to areas of low density (Bovbjerg, 1964). Such behaviors have led several investigators to conclude that disjunct crayfish distributions were due to competitive exclusion (Aiken, 1965; Fitzpatrick, 1967; Crocker and Barr, 1968; Capelli and Magnuson, 1983). There are also situations where closely related species coexist in what appears to be a common habitat. Given their aggressive tendencies, different species existing in proximity is more surprising than is the exclusion of one species by another. The question why some crayfish are sympatric and others are not was the impetus for this study. In the Current and Jacks Fork rivers in S-central Missouri, Orconectes luteus (Creaser) and 0. punctimanus (Creaser) coexist in over 200 km of stream. The objectives 1 The Unit is sponsored by the U.S. Fish and Wildlife Service, the Missouri Department of Conservation and the University of Missouri.

Integrating biological realism into habitat restoration and conservation strategies for small streams

Successful habitat conservation or restoration must be biologically based, which requires an understanding of habitat variables most influencing fish; the relative influence of each habitat variable and the spatial scale over which each operates. Determining necessary habitat conditions requires examination from several perspectives, including observation of individual fish during all seasons and population analysis over a range of spatial scales. There is a definite spatial hierarchy of influences that must be addressed to separate those habitat conditions responsible for presence and abundance from those habitat conditions responsible for within-stream distribution. A case study of habitat factors influencing smallmouth bass (Micropterus dolomieu) in Missouri streams indicates that examination at the smallest spatial scales allows one to determine the influence of habitat conditions (depths, velocities, cover factors) relating mainly to the fishs distribution in a stream reach. Evaluation of populations at the stream-system level allows an understanding of how individual fish preferences relate to amounts of habitat as determined by geomorphic and fluvial dynamic forces and how this influences standing stocks throughout a stream system. Evaluation at the ecoregion level shows the overriding influence of physiographic variables on both the presence and abundance of fish across stream systems, as well as the importance of land use. Resume : La conservation ou la restauration de lhabitat se doivent, pour reussir, de reposer sur des fondements biologiques. Cela suppose de connaitre les variables de lhabitat qui influent le plus sur le poisson de meme que lincidence relative et lechelle daction spatiale de chacune de ces variables. La determination des conditions de lhabitat necessaires exige de realiser un examen sous des angles divers, notamment lobservation de poissons donnes pendant toutes les saisons et une analyse de population portant sur une gamme dechelles spatiales. Il existe une hierarchie spatiale nette des influences qui doit etre evaluee afin de distinguer entre les conditions de lhabitat regissant la presence et labondance et celles regissant la repartition au sein du cours deau. Une etude de cas des facteurs de lhabitat influant sur lachigan a petite bouche de cours deau du Missouri montre quun examen aux plus petites echelles spatiales permet de determiner linfluence des conditions de lhabitat (profondeur, vitesse du courant, couverture) qui ont surtout trait a la distribution du poisson dans un segment du cours deau. Levaluation des populations a lechelle des ramifications du cours deau permet de comprendre la relation entre les preferences de poissons donnes et le volume dhabitat, lui-meme determine par les forces geomorphiques et dynamiques fluviales, et comment elle influe sur les stocks presents dans le bassin du cours deau. Levaluation au niveau de lecoregion montre linfluence preponderante des variables physiographiques sur la presence et labondance du poisson dans les bassins de cours deau, de meme que limportance de lutilisation des terres. (Traduit par la Redaction)

Hypoxia and Hyperthermia Tolerances of Headwater Stream Fishes

Abstract We developed a reference base of relative hypoxia and hyperthermia tolerance rankings for many of the common fish species that inhabit small streams in Missouri. We also investigated the influences of geographic variation and of fish size on these tolerances. Fish collected from the wild were acclimated to laboratory conditions over a 63–160-d period. They were then exposed to either progressively increasing temperatures or to decreasing dissolved oxygen concentrations over a 4–6-h period. The temperature at which a fish lost equilibrium or the oxygen concentration at which it ceased ventilating was recorded as the end point. No significant differences in critical maximum temperatures (hyperthermia tolerance) or critical minimum oxygen concentrations (hypoxia tolerance) occurred in any of the five comparisons between fish of the same species collected from different locations in Missouri. Neither the hypoxia nor hyperthermia tolerance values varied with fish size for any species. Among the 35 spe...

Effects of crayfish (Paranephrops planifrons: Parastacidae) on in-stream processes and benthic faunas: a density manipulation experiment

Abstract The effects of New Zealand freshwater crayfish or koura (Paranephrops planifrons: Parastacidae) on organic matter processing, sediment accumulation, and benthic invertebrate communities were investigated using four replicate treatments of 0 (control), 4–5 (medium), and 8–11 (high) similar‐sized koura in 0.5 m2 artificial stream channels colonised by benthic invertebrates from a pasture stream, Waikato, New Zealand. Wineberry (Aristotelia serrata) leaf packs were placed in each channel and after 7 weeks the leaf matter remaining was significantly lower in both medium and high koura channels than in controls. The amount of sediment (surficial cover by fines and weight of suspendable sediment) was also significantly reduced in high koura density channels. Densities of invertebrates other than crayfish were not significantly different among treatments; however, taxa richness and invertebrate biomass were significantly lower in high koura channels than in controls. Our results suggest that freshwater ...

Patterns of Movement and Habitat Use by Northern Hog Suckers in an Ozark Stream

Abstract Although the northern hog sucker Hypentelium nigricans is widely distributed throughout the Mississippi and Ohio river basins and is both ecologically and recreationally important, much of its basic ecology is not known. We determined movement and habitat use for 25 fish in the Current River, Missouri, for 1 year using radio telemetry. Seasonal movements were recorded 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 in summer. 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). Habitat use changed seasonally from slower, deeper water and smaller substrates during winter to increasing use of taster, shallower water and larger substrates through warmer-water periods. In both seasons, fish had a consistent daily pattern, moving more during the day than at night. Diet ...

Evaluating techniques for sampling stream crayfish (paranephrops planifrons)

We evaluated several capture and analysis techniques for estimating abundance and size structure of freshwater crayfish (Paranephrops planifrons) (koura) from a forested North Island, New Zealand stream to provide a methodological basis for future population studies. Direct observation at night and collecting with baited traps were not considered useful. A quadrat sampler was highly biased toward collecting small individuals. Handnetting at night and estimating abundances using the depletion method were not as efficient as handnetting on different dates and analysing by a mark-recapture technique. Electrofishing was effective in collecting koura from different habitats and resulted in the highest abundance estimates, and mark-recapture estimates appeared to be more precise than depletion estimates, especially if multiple recaptures were made. Handnetting captured more large crayfish relative electrofishing or the quadrat sampler. to