Tamotsu Shiroyama

Utilization of algal assays to assess the effects of municipal, industrial, and agricultural wastewater effluents upon phytoplankton production in the Snake River system

The most characteristic water quality problem of the Snake River Basin is the excessive aquatic growth and thick blooms of algae. The cause of these aquatic growths is related to the high concentrations of basic nutrients — nitrogen and phosphorus — in the Snake system. Industrial wastes, natural phosphate levels, irrigation return flows, municipal wastes, and the decay of aquatic biota all contribute to the nutrient balance which stimulates aquatic growths.Algal assays were conducted on waters of eighteen Snake River and tributary sites to: (1) determine if algal growth was consistent with results predicted from review of chemical analysis for orthophosphorus and total soluble inorganic N; (2) determine if algal yields were limited by P, N, or some other nutrient essential to algal growth; and (3) predict the effects of N or P additions on algal productivity.

Carbohydrate use and assimilation by litter and soil fungi assessed by carbon isotopes and BIOLOG® assays

Abstract Soil fungi are integral to decomposition in forests and other habitats, yet identifying probable functional roles of different taxa is problematic. Here, we compared carbohydrate assimilation patterns derived from stable isotope analyses on cultures with patterns of metabolic activity measured on Biolog ® SF-P plates for 12 taxa of soil- and litter-inhabiting saprotrophic fungi isolated from Douglas-fir ( Pseudotsuga menziesii ) ecosystems. To determine the relative assimilation of carbon from malt extract versus sucrose by 13 C stable isotope analyses, we cultured fungi with malt extract (consisting primarily of glucose and maltose) plus either C 3 - or C 4 -derived sucrose as carbon sources. Rhodotorula graminis and F. oxysporum assimilated the highest proportion of sucrose, a Mortierella isolate and an unidentified sterile isolate (FPC 341) assimilated the lowest proportion of sucrose, and remaining cultures assimilated similar and intermediate proportions of sucrose. On Biolog plates, low metabolic activity of Mortierella and FPC 341 on sucrose and R. graminis and F. oxysporum on maltose were qualitatively consistent with isotopic results. Assimilation of sucrose calculated isotopically was correlated with the ratio of sucrose: maltose activity calculated from Biolog assays ( r 2 =0.45, P =0.0145, n =12). Metabolic activity on Biolog plates for six other common soil carbohydrates were also determined: glucose, fructose, galactose, cellobiose, lactose, and glycogen. Metabolic activity was greatest overall on maltose and glucose and lowest on fructose. Two of the isolates ( Aspergillus flavus and F. oxysporum ) had higher metabolic activity on the glucose-containing disaccharide cellobiose than on glucose, strongly suggesting preferential uptake of cellobiose compared to glucose and suggesting the potential ability to use cellulose. The high metabolic activity of these cultures on galactose, a primary constituent of hemicellulose, also suggested cellulolytic capabilities. Our results indicated that stable isotope studies and Biolog assays may provide complementary information to characterize metabolic potential of fungi in forest litter and soil.

Bracken (Pteridium aquilinum L.) frond biomass and rhizosphere microbial community characteristics are correlated to edaphic factors

Bracken is a broadly distributed weedy fern common in disturbed habitats. Frond and rhizosphere soil samples were obtained from bracken growing in three clearcut locations in the Willamette National Forest in western Oregon. The highest frond biomass was correlated with soil having the highest total %N, lowest Fe content and oldest geological age. Based on analysis of variance of principal component scores for patterns of utilization of substrates on Biolog GN plates, metabolic profiles of rhizosphere microbial communities of bracken differed significantly between locations. Utilization of carbohydrates and phosphorylated compounds was positively correlated with organic matter (OM) and total N and negatively correlated with extractable Fe and Mn content of soil. Carboxylic acid utilization was positively correlated with pH and OM and negatively correlated with extractable Mn and P content of soils. Pseudomonas rDNA fingerprints of bracken rhizosphere samples suggested that the diversity of pseudomonads at the location with the most acidic (pH 5.5) soil (Burnside Road) differed from those at less acidic (pH 6.2 and 6.1) locations (Falls Creek and Toad Road). Mycorrhizal infection of bracken was lowest at Falls Creek, the location with the highest %N soil content. Our results suggest that bracken frond biomass and rhizosphere microbial community characteristics are correlated with local edaphic factors such as soil chemistry and geological age.

Plant reproduction is altered by simulated herbicide drift to constructed plant communities

Herbicide drift may have unintended impacts on native vegetation, adversely affecting individual species and plant communities. To determine the potential ecological effects of herbicide drift, small plant community plots were constructed using 9 perennial species found in different Willamette Valley (OR, USA) grassland habitats. Studies were conducted at 2 Oregon State University (Corvallis, OR, USA) farms in 2 separate years, with single and combined treatments of 0.01 to 0.2× field application rates (f.a.r.) of 1119 g ha-1 for glyphosate (active ingredient [a.i.] of 830 g ha-1 acid glyphosate) and 560 g ha-1 a.i. for dicamba. Plant responses were percentage of cover, number of reproductive structures, mature and immature seed production, and vegetative biomass. Herbicide effects differed with species, year, and, to a lesser extent, farm. Generally, 0.1 to 0.2× f.a.r. of the herbicides were required to affect reproduction in Camassia leichtlinii, Elymus glaucus, Eriophyllum lanatum, Festuca idahoensis, Iris tenax, and Prunella vulgaris. Eriophyllum lanatum also had a significant increase in percentage of immature seed dry weight with 0.01× f.a.r. of dicamba or the combination of glyphosate plus dicamba. Other species showed similar trends, but fewer significant responses. These studies indicated potential effects of low levels of herbicides on reproduction of native plants, and demonstrated a protocol whereby species growing in a constructed plant community can be evaluated for ecological responses. Environ Toxicol Chem 2017;36:2799-2813. Published 2017 SETAC. This article is a US government work and, as such, is in the public domain in the United States of America.

A rapid-test for screening biochar effects on seed germination

ABSTRACT We developed a rapid-test to screen for effects of biochar on seed germination and soils. Crop seeds were placed in containers and covered with 15 g of soil with 1% biochar by weight. Two agricultural soils from South Carolina USA were used. Eighteen biochars were produced from six primary feedstocks [pine chips (PC), poultry litter (PL), swine solids (SS), switchgrass (SG); and two blends of PC and PL, 50% PC/50% PL (55), and 80% PC/20% PL (82)]. Each feedstock was pyrolyzed at 350, 500 and 700°C. There were few biochar effects on seed germination. Shoot dry weight was increased for carrot, cucumber, lettuce, oat, and tomato; primarily with biochars containing PL. Soil pH, electrical conductivity and extractable phosphorus primarily increased with PL, SS, 55, and 82 treatments for both soil types and across species. This method can be an early indicator of biochar effects on seed germination and soil health.