David W. Ostendorf | Search USGS

USGS2005

Efficacy of a benthic trawl for sampling small-bodied fishes in large river systems

We conducted a study from 1998 to 2001 to determine the efficacy of a benthic trawl designed to increase species detection and reduce the incidence of zero catches of small-bodied fishes. We modified a standard two-seam slingshot balloon trawl by covering the entire trawl with a small-mesh cover. After completing 281 hauls with the modified (Missouri) trawl, we discovered that most fish passed through the body of the standard trawl and were captured in the cover. Logistic regression indicated no noticeable effect of the cover on the catch entering the standard portion of the modified trawl. However, some fishes (e.g., larval sturgeons Scaphirhynchus spp. and pallid sturgeon S. albus) were exclusively captured in the small-mesh cover, while the catch of small-bodied adult fish (e.g., chubs Macrhybopsis spp.) was significantly improved by use of the small-mesh cover design. The Missouri trawl significantly increased the number and species of small-bodied fishes captured over previously used designs and is a useful method for sampling the benthic fish community in moderate- to large-size river systems.

North American Journal of Fisheries Management↗

USGS2005

Geobacter bemidjiensis sp. nov. and Geobacter psychrophilus sp. nov., two novel Fe(III)-reducing subsurface isolates

Fe(III)-reducing isolates were recovered from two aquifers in which Fe(III) reduction is known to be important. Strain Bem T was enriched from subsurface sediments collected in Bemidji, MN, USA, near a site where Fe(III) reduction is important in aromatic hydrocarbon degradation. Strains P11, P35 T and P39 were isolated from the groundwater of an aquifer in Plymouth, MA, USA, in which Fe(III) reduction is important because of long-term inputs of acetate as a highway de-icing agent to the subsurface. All four isolates were Gram-negative, slightly curved rods that grew best in freshwater media. Strains P11, P35 T and P39 exhibited motility via means of monotrichous flagella. Analysis of the 16S rRNA and nifD genes indicated that all four strains are δ -proteobacteria and members of the Geobacter cluster of the Geobacteraceae . Differences in phenotypic and phylogenetic characteristics indicated that the four isolates represent two novel species within the genus Geobacter . All of the isolates coupled the oxidation of acetate to the reduction of Fe(III) [iron(III) citrate, amorphous iron(III) oxide, iron(III) pyrophosphate and iron(III) nitrilotriacetate]. All four strains utilized ethanol, lactate, malate, pyruvate and succinate as electron donors and malate and fumarate as electron acceptors. Strain Bem T grew fastest at 30 °C, whereas strains P11, P35 T and P39 grew equally well at 17, 22 and 30 °C. In addition, strains P11, P35 T and P39 were capable of growth at 4 °C. The names Geobacter bemidjiensis sp. nov. (type strain Bem T =ATCC BAA-1014 T =DSM 16622 T =JCM 12645 T ) and Geobacter psychrophilus sp. nov. (strains P11, P35 T and P39; type strain P35 T =ATCC BAA-1013 T =DSM 16674 T =JCM 12644 T ) are proposed.

International Journal of Systematic and Evolutiona↗