Susan B. Adams

Summer Movements within the Fish Community of a Small Montane Stream

Abstract We studied movements by fishes in Chamberlain Creek, Montana, from 24 July to 16 August 2001. We operated six weirs with two-way traps and one additional upstream trap, separated by 14–1,596 m, to quantify the timing, direction, and distance of movements and to estimate fish populations in the study reaches. We trapped and marked 567 fish of seven species, including 368 westslope cutthroat trout Oncorhynchus clarkii lewisi and 172 sculpin (slimy sculpin Cottus cognatus and an unidentified species similar to mottled sculpin C. bairdii). We recaptured 173 westslope cutthroat trout and detected net movements as long as 1,581 m (median, 91 m). Bidirectional movements for 116 westslope cutthroat trout ranged from less than 18 to more than 1,581 m (median, 64 m). Sculpin moved as far as 209 m (median, 26 m). We estimate that 14% of sculpin and 48% of westslope cutthroat trout were mobile during the study. We captured all species more frequently at night or twilight (n = 296) than during the day (n = 83...

Recolonization by warmwater fishes and crayfishes after severe drought in upper coastal plain hill streams

Abstract Extreme hydrologic disturbance, such as a supraseasonal drought, can dramatically influence aquatic communities. Documentation of the responses of aquatic communities after such disturbances provides insight into the timing, order, and mechanisms of recolonization. Postdisturbance recolonization of streams depends on many factors, including the region and characteristics of the disturbance relative to the disturbance regime. A supraseasonal drought that ended in the fall of 2000 resulted in the desiccation of numerous small streams or stream segments in northern Mississippi that were normally perennial. We repeatedly sampled fish and crayfish during predrought and postdrought periods in seven stream reaches that dried and five that remained flowing during the drought. From immediately after the drought until early summer of 2001, postdrought fish and crayfish assemblages differed from predrought assemblages in dry sites but not in flowing sites. The initially slow recolonization rates increased c...

Freshwater Sculpins: Phylogenetics to Ecology

Abstract Freshwater sculpins (Cottidae) are a diverse and ecologically important component of cool- and coldwater ecosystems throughout the northern hemisphere. More than 60 sculpin species occur in a variety of habitats, and sculpin distributions range from highly localized to widespread. Despite the frequently high biomass of sculpins and their numerous ecosystem functions, the traditional fisheries management emphasis on sport fishes has led to a general neglect of small-bodied, nongame fishes, such as sculpins, in both research and management. Ironically, in many coldwater ecosystems, salmonids are used as umbrella species to conserve and protect all aquatic vertebrates; however, many management and conservation goals may be better met by focusing on sculpins. This module arose from a symposium entitled “Ecology and Phylogeny of Freshwater and Diadromous Sculpin,” which was held at the 2005 annual meeting of the American Fisheries Society in Anchorage, Alaska, and which brought together researchers st...

Direct and indirect effects of channel catfish (Ictalurus punctatus) on native crayfishes (Cambaridae) in experimental tanks

ABSTRACT 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.

Basin Visual Estimation Technique (BVET) and Representative Reach Approaches to Wadeable Stream Surveys

Abstract Basin Visual Estimation Techniques (BVET) are used to estimate abundance for fish populations in small streams. With BVET, independent samples are drawn from natural habitat units in the stream rather than sampling “representative reaches.” This sampling protocol provides an alternative to traditional reach-level surveys, which are criticized for their lack of accuracy in estimating abundance at larger scales. BVET methodologies have been adopted and used by numerous government agencies for monitoring stream biota. Many of the assumptions of BVET methods, however, cannot be met in streams where they are being implemented because of unsuitable conditions for BVET surveys. Lack of bed control structures, variability in flow regimes, and lack of consistency among observers create difficulties in assessing habitat using BVET methods. BVET methods also are used to assess assemblage structure in streams although that was not the application for which they were originally designed. Representative reach ...

Potential Roles of Fish, Birds, and Water in Swamp Privet (Forestiera acuminata) Seed Dispersal

Abstract Forestiera acuminata (swamp privet) is a common wetland shrub/small tree native to the southeastern United States. We examined several possible dispersal avenues for the plant. We tested germination of seeds exposed to various treatments, including passage through Ictalurus punctatus (Channel Catfish) guts, and conducted other tests and observations to infer seed-dispersal pathways. Channel Catfish consumed swamp privet drupes and defecated viable seeds, confirming that they are seed dispersers. Bombycilla cedrorum (Cedar Waxwings) ate the carbohydrate-rich drupes, and we predict that they disperse the seeds. We also inferred passive seed dispersal by water. Diverse dispersal pathways may allow for effective seed dispersal under a wide range of environmental conditions. Growing in wetlands and riparian areas, the plant experiences extreme annual variation in hydrologic conditions, which should influence the importance of the various dispersal pathways among years.

SYSTEMATICS AND BIOGEOGRAPHY OF ORCONECTES, SUBGENUS TRISELLESCENS, IN THE SOUTHEASTERN UNITED STATES, A TEST OF MORPHOLOGY-BASED CLASSIFICATION

Diagnosable taxonomic units are fundamental to conservation biology and management of resources and the need for sound science in both fields is more pressing for aquatic ecosystems. Within freshwater crayfishes, the North American genus Orconectes is one of the most diverse in the World. Accurate assessments of species level relationships and species boundaries within the genus have historically been hampered by a low number of variable morphological characters and inadequate sampling from across the ranges of many taxa. We examine a diverse group of southeastern United States stream dwelling Orconectes in the subgenus Trisellescens using 16S, COI mtDNA, and morphology to resolve uncertainties in species boundaries. Our results suggest that strong divergences exist between taxa found above and below the Fall Line in parts of the southeastern United States and the taxonomy for taxa found in that region should remain unchanged. However, using both molecular and morphological datasets we are unable to determine species limits for some taxa found on and below the Fall Line. Analysis of DNA data suggests that historical and ongoing genetic events such as gene introgression may contribute to these uncertainties. For taxa found on and below the Fall Line, we suggest tentative, taxonomic assignments. Finally, we argue for increased sampling of independent molecular datasets and increased sample sizes for all cambarid crayfish biogeographic studies.

Threatened fishes of the world: Alosa alabamae (Jordan and Evermann, 1896) (Clupeidae)

Common names: Alabama shad, Gulf shad. Conservation status: US National Marine Fisheries Service Species of Concern, AFS: Vulnerable; IUCN: Endangered. Identification: Upper jaw median notch, protruding lower jaw, one row tongue teeth, 41–48 rakers on lower anterior gill arch; no dorsal filament. Silver with black spots on lower jaw; greenish-blue dorsally. Females 36–46 cm, males 9–42 cm SL. Distribution: Euryhaline, anadromous, schooling; spawns in medium to large rivers from the Mississippi River drainage to the Suwannee River, Florida (Mettee and O’Neil 2003); extirpated from at least 8 of the 14 native states (Mettee and O’Neil 2003). Abundance: Once commerically harvested, now rare (Mettee and O’Neil 2003); largest remaining population occurs in the Apalachicola River, Florida (Barkuloo et al. 1993). Habitat and ecology: Juveniles are found in rivers for their first 6–8 months, eat fishes and invertebrates. Diurnally, small juveniles use sandbars, then switch to open channels and steep bank habitat; they select cooler temperatures (Mickle 2006). Little is known of their ecology in marine environments. Juveniles enter the Gulf of Mexico from late summer to early winter. Spawning starts primarily at age 2 and live 6 years (Mettee and O’Neil 2003). Reproduction: Broadcast spawn spring/early summer at 18–238C over coarse sand and gravel in moderate currents; no foraging during spawning (Mills 1972). Arrival time varies by sex and age (Mette and O’Neil 2003), return to sea after spawning (Barkuloo et al. 1993). Some homing and genetic differences among drainages (Bowen 2005). Threats: Dams block spawning access and alter hydrology and substrates (Adams et al. 2000; Mettee and O’Neil 2003); poor water quality, siltation, altered habitat and thermal regimes, dredging, and perhaps bycatch in marine fisheries. Conservation recommendations: Implement effective fish passage; restore hydrologic regimes. Research into the marine phase including migrations, feeding and bycatch; and spawning, rearing, and other habitat needs. Remarks: Allopatric species pair with A. sapidissima. D. W. Meadows (&) Office of Protected Resources F/PR3, National Marine Fisheries Service, 1315 East West Highway, Silver Spring, MD 20910, USA e-mail: Dwayne.Meadows@noaa.gov

Summer Stream Temperatures Influence Sculpin Distributions and Spatial Partitioning in the Upper Clark Fork River Basin, Montana

The upper Clark Fork River basin of western Montana supports a poorly understood sculpin (Uranidea spp.) fauna that has perplexed ichthyologists and fish ecologists since the late 1800s. During our study, the basin contained three sculpin taxa whose taxonomy was under revision. All three taxa were formerly referred to the genus Cottus but are now treated as Uranidea. Our goal was to improve understanding of the distribution and ecology of two of the taxa. From 2006 to 2009, we sampled 144 reaches in 31 streams and rivers to determine distributions of each taxa across the study area and within streams. We collected habitat data in 2007 and stream temperature data from 2006–2009 to identify correlates of sculpin distributions. In streams where both taxa occurred, Rocky Mountain Sculpin Uranidea sp. cf. bairdii were downstream and Columbia Slimy Sculpin U. sp. cf. cognata were upstream with a syntopic zone in between. Summer stream temperatures strongly influenced sculpin distributions, with mean August 2007 water temperatures increasing in order of reaches characterized as: Columbia Slimy Sculpin-dominated, syntopic, Rocky Mountain Sculpin-dominated, and no sculpin. Columbia Slimy Sculpin occurred in cold tributaries of the Blackfoot, Clark Fork, and Bitterroot rivers and in two coldwater refugia in the mainstem Bitterroot River. In contrast, Rocky Mountain Sculpin occupied warmer downstream segments of many Blackfoot and Clark Fork river tributaries as well as some mainstem reaches of both rivers but were absent from the Bitterroot River drainage. Persistence of the taxa will likely depend, both directly and indirectly, on future water temperatures, and thus, sculpins are appropriate targets for researching and monitoring biological changes resulting from climate change.

Diet of Juvenile Alabama Shad (Alosa alabamae) in Two Northern Gulf of Mexico Drainages

Abstract Understanding food-web ecology is valuable to conservation by linking interactions of multiple species together and illustrating the functionality of trophic exchange. Alosa alabamae (Alabama Shad), an anadromous species, reproduces in northern Gulf of Mexico drainages from February through May, and for this study, the Pascagoula and Apalachicola rivers were chosen to sample juvenile Alabama Shad. The age-0 fish mature within these rivers and have the potential to impact the food web of the systems in which maturation occurs. The focus was to determine if diet changes as Alabama Shad mature, and to identify diet differences between drainages. Diets of Alabama Shad <50 mm standard length (SL) consisted primarily of a dark, almost black material labeled as unidentifiable organics, while larger Alabama Shad, >50 mm SL, fed almost exclusively on insects. Many groups of aquatic and terrestrial insects were found in the stomachs of this species. Alabama Shad diets also differed among drainages, with the Apalachicola River being dominated by terrestrial insects, and the Pascagoula River having both terrestrial and aquatic insects. Diet and trophic placement of Alabama Shad may allow managers to understand the importance of this fish within its natal rivers.