Paul J. Anders

Effects of Sediment Cover on Survival and Development of White Sturgeon Embryos

Abstract A simple, inexpensive apparatus (embryo incubation unit (EIU)) was developed and used to assess the relationship between sediment cover (Kootenai River sediments, 97% by weight in the 0.83-mm- to 1.0-mm-diameter range) and survival of white sturgeon Acipenser transmontanus embryos in the laboratory. An apparatus-testing trial assessed the effects of two sediment depths (5 and 20 mm), three EIU ventilation hole sizes (4.8, 6.8, and 9.5 mm) providing three levels of intrasediment flow, and EIU location (upstream or downstream in laboratory troughs) on embryo survival at two above-substrate flow velocities (0.05 and 0.15 m/s). A second trial assessed the effects of sediment cover duration (5-mm sediment cover for 4, 7, 9, 11, or 14 d, with a ventilation hole size of 9.5 mm and a flow velocity of 0.17 m/s) on mean embryo survival and larval length and weight. In the apparatus-testing trial, embryo survival was reduced (P < 0.0001) to 0–5% under sediment covers of either 5 or 20 mm in both the higher-...

Effects of nutrient replacement on benthic macroinvertebrates in an ultraoligotrophic reach of the Kootenai River, 2003–2010

Abstract: Large impoundments remove substantial amounts of sediment and nutrients from rivers and often limit production by downstream primary producers and secondary consumers. Nutrient levels and macroinvertebrate and fish abundance in the lower Kootenai River (7th order, mean annual discharge = 454 m3/s) in Idaho and Montana declined dramatically after Libby Dam was built in 1972. A subsequent study implicated ultraoligotrophic conditions (total dissolved P [TDP] ≤ 2 µg/L TDP) as a principal causative agent and prompted an on-going experimental nutrient-addition program for the Kootenai River downstream from Libby Dam, with dosing at the Idaho—Montana border. Pre-treatment monitoring began in 2003 and liquid ammonium polyphosphate fertilizer (10-34-0) was added each year during the growing season from 2006 through 2010 with a target TDP concentration of 3 µg/L and TN:TP near 20:1. We studied benthic macroinvertebrate responses to the experimental addition and hypothesized moderate increases in invertebrate richness, abundance, and biomass with little change in assemblage structure. We used a before—after control—impact BACI design with macroinvertebrate samples collected pre- and post-treatment from July to early November 2003–2010 from fertilized and unfertilized reaches. After treatment, mean modified (Oligochaeta and Chironomidae subtaxa excluded) total abundance increased 72%, mean total abundance increased 69%, and mean biomass increased 48%. Abundance of Ephemeroptera, the principal insect order in the study area increased 66%. Filter-feeder abundance also increased, indicating increased suspended organic matter in addition to the attached forms consumed by other benthic macroinvertebrates. The first 5 y of experimental treatment resulted in increased food resources for resident native fishes with no major alteration of macroinvertebrate community structure or trophic pathways.

Performance and Macronutrient Composition of Age-0 Burbot Fed Four Diet Treatments

Abstract As there are few larval-diet rearing methods for burbot Lota lota, it is important to develop these methods for ongoing conservation and future commercial aquaculture efforts. The performance and macronutrient composition of age-0 burbot were compared after fish were fed four different diets for 8 weeks. Diets included three commercial larval-rearing diets and Daphnia magna. Performance metrics involved mean length and weight, survival, and cannibalism. The macronutrient composition (dry matter) of fish and diets was measured as the percentages of moisture, lipid, protein, and ash, along with energy content. Significant differences in mean length and weight occurred, although survival and cannibalism were not different among treatments at the end of the experiment. Mean weight and length were significantly higher with diets 1 and 2. Fish fed diet 2 had the greatest mean survival (32%), followed by those fed the D. magna diet (30%), diet 3 (27%), and diet 1 (25%). Fish fed diet 1 experienced the g...

Water quality, chlorophyll, and periphyton responses to nutrient addition in the Kootenai River, Idaho

Abstract: During the past century, the Kootenai River, Idaho (USA), has experienced cultural oligotrophication following extensive levee construction, channelization, wetland drainage, and impoundment. A multiyear, whole-river nutrient-addition experiment was undertaken to mitigate these effects. The river was dosed with liquid agricultural-grade ammonium polyphosphate fertilizer (10-34-0) from June through September 2006–2010 to achieve an in-river total dissolved P (TDP) concentration of 3.0 µg/L. A fine-scale monitoring program included 8 sites over a 20-km reach (2 upstream control sites, one injection site, and 5 downstream treatment sites). Nutrient addition did not significantly increase N and P concentrations in the water column, but it significandy increased chlorophyll accrual rates and densities of edible green algae and diatoms. Nutrient addition significantly reduced NO3_+NO2_ concentrations, atomic TN:TP ratios, and densities of inedible cyanophytes. Mean NO3_ +NO2_ values decreased along a downstream gradient below the nutrient-addition site, whereas chlorophyll accrual rate typically peaked immediately downstream from the nutrient addition site then decreased progressively down-stream. Our study showed that nutrient addition is a useful river restoration technique for the Kootenai River.

Evaluating Microsatellite Markers for Parentage-Based Tagging of Hatchery Burbot

Abstract Concerned stakeholders in various nations are investigating stock enhancement with hatchery supplementation as one of several strategies to restore imperiled burbot (Lota lota L.) populations. In other intensively studied species, the use of genetic markers for parentage-based tagging (PBT) has become an important tool for evaluating the ecology of hatchery-wild fish interactions. Our objective was to determine if microsatellites previously developed for studies of burbot phylogeography could be multiplexed for effective PBT. A total of 14 microsatellite loci were multiplexed in four panels and tested for PBT efficacy in a hatchery population of burbot. An exclusion-based test involving 123 anonymous offspring and 51 known parent-pairs resulted in 97% of the progeny assigning to the correct parents. Due to modest genetic diversity in the broodstock population, a high false-assignment rate (19%) was observed when parental cross information was excluded from parentage analyses. While the existing set of burbot microsatellites can be multiplexed into effective panels for PBT, we recommend the development of additional microsatellite or single nucleotide polymorphism markers to improve exclusionary power.

Long-Term Seasonal Trends in the Prey Community of Delta Smelt (Hypomesus transpacificus) Within the Sacramento-San Joaquin Delta, California

Abiotic factors and species introductions can alter food web timing, disrupt life cycles, and change life history expressions and the temporal scale of population dynamics in zooplankton communities. We examined physical, trophic, and zooplankton community dynamics in the San Francisco Estuary, California, a highly altered Mediterranean climate waterway, across a 43-year dataset (1972–2014). Before invasion by the suspension-feeding overbite clam (Potamocorbula amurensis) in the mid-1980s, the estuary demonstrated monomictic thermal mixing in which winter turbidity and cool temperatures contributed to seasonally low productivity, followed by a late-spring-summer clearing phase with warm water and peak phytoplankton blooms that continued into early winter. Following the clam invasion, we observed a shift in peak phytoplankton bloom timing, with peak productivity now occurring in May compared to June prior to the invasion. Peak abundance of several zooplankton taxa (Eurytemora affinis, Pseudodiaptomus, other calanoids, and non-copepods) also shifted to earlier in the season. We present the first evidence of a shift in the timing of peak abundance for zooplankton species that are key prey items of delta smelt (Hypomesus transpacificus), a federally threatened pelagic fish species. These timing shifts may have exacerbated well-documented food limitations of delta smelt due to declines in primary productivity since the invasion of the overbite clam. Future conservation efforts in the estuary should consider measures designed to restore the timing and magnitude of pre-invasion phytoplankton blooms.

Note on Occurrence of Mymaromella pala Huber and Gibson (Hymenoptera: Mymarommatidae) in Montana: A New State Record

ABSTRACT. The parasitic wasp Mymaromella pala Huber and Gibson (Hymenoptera: Mymarommatidae) was collected at 4 sites within a canyon reach of the Kootenai River in Lincoln County, Montana. This minute species has only recently been described, but it appears to have a large distribution throughout the United States and to be associated with upland and riparian forests.

Oreoleptis torrenticola Zloty, Sinclair and Pritchard (Diptera: Tabanomorpha) Discovered in a Fourth-Order Stream of the Cascade Mountains of Eastern Washington

ABSTRACT. The recently described Oreoleptis torrenticola Zloty, Sinclair and Pritchard (Diptera: Tabanomorpha), belonging to the monotypic family Oreoleptidae, was previously described from the Northern Rocky Mountains of the USA and Canada. However, as part of a broad, multidisciplinary study by the Yakama Nation, 30 larvae of O. torrenticola were collected at multiple sites within the Twisp River of the Cascade Mountains in Okanogan County, Washington, 2008–2010. This finding represents a substantial range extension for the species.