A Comparison of Nematode and Rotifer Frequency in BSC and Non-BSC Samples

1. A Comparison of Nematode and Rotifer Frequency in BSC and Non-BSC Samples Biological Soil Crusts are commonly found in semiarid and arid environments throughout the world. Areas in the United States include the Great Basin and Colorado Plateau. Crusts are also found in agricultural areas and native grasslands. Biological Soil Crusts typically consist of cyanobacteria, algae, micro fungi, lichens and bryophytes creating a surface crust of soil particles bound together by organic materials. The process of binding soil particles is due largely to the presence of filamentous cyanobacteria and green algae (Belnap, et al., 2001). These organisms swell when wetand migrate over the soil surface by extending their sheaths. After repeated moisture events, a network of empty sheath material is left on the surface which maintains soil structure after the organisms have dehydrated. In grasslands, nematodes (roundworm) and rotifers are also inhabitants of the soil. Byproducts from these organisms have been shown to strengthen and stabilize soil crusts (insert reference—IDK!!!!!!!). Nematodes are concentrated near their prey groups. Bacterial-feeders abound near roots where bacteria congregate; fungal-feeders are near fungal biomass; root-feeders are concentrated around roots of stressed or susceptible plants. Predatory nematodes are more likely to be abundant in soils with high numbers of nematodes (Bongers and Bongers, 1998). Because of their size, nematodes and rotifers tend to be more common in coarser-textured soils. Nematodes move in water films in large (>1/500 inch or 50 µm) pore spaces. Agricultural soils generally support less than 100 nematodes per gram of soil. Grasslands may contain between 50 and 500 nematodes per gram (Blair, 1996; Kuticova, 2003). INTRODUCTION PURPOSE Samples of soil were collected from the top 2.5 centimeters of randomly placed 0.5 meter transects at each study site. The samples were collected during field studies from October through March and sample sizes filled a 110 X 15 mm diameter petri dish. The samples were allowed to air dry in the lab. A 0.5 gram sample of BSC and a 0.5 gram sample of soil without BSC from each site were placed in separate 5 cm petri dishes. Five mL of distilled water was then added to each petri dish and the samples were placed under three fluorescent grow lamps for approximately 48 hours to reactivate the crust organisms. A concave microscope slide was filled with a soil/water mixture from the petri dish using a 1 mL transfer pipet. Under 40X magnification, the slide was scanned from left to right in the top, middle, and bottom portions of the concavity. This resulted in nine (three in each area) frequency counts. The organisms were able to move and some duplicated counts were possible. Two samples of the Outdoor Classroom were analyzed because initial data for this site was unusually high when compared to the other samples. Methods From the data collected there tended to be more rotifers than nematodes in most of the study sites. In the BSC there was just two rotifers and one in the soil from the Underwood site. Surprisingly there were twenty-four rotifers seen in the sample of BSC from the Outdoor Classroom and none in the soil. However, at Beaver Dunes there were more rotifers in the soil, six, than in the BSC, five. At Arkalon there were seven in the BSC and none in the soil. And at Meade St Park there were eight rotifers counted in the BSC and just one in the soil. The number of nematodes were not as extreme as the rotifers. Again the number of nematodes on the BSC generally tend to greater than in the soil. At Underwood there were four in the BSC and none in the soil. There was an equal amount of nematodes at the Outdoor Classroom which was one to one. Unexpectedly there were twice as many nematodes in the soil than the BSC at Beaver Dunes, four and two. For Arkalon there was just one nematode found in the BSC and none in the soil. And lastly for Meade St Park there was four nematodes found in the BSC and one in the soil. RESULTS The purpose of this study was to determine the frequency of nematodes and rotifers in the top 10 mm of soil samples taken from five study sites in Seward County, Kansas and Beaver County, Oklahoma. The study sites are found in the northeast quarter of Major Land Resource Area 77A. Comparisons were made between samples containing soil crusts and samples without soil crust. Previous studies in our lab have documented typical BSC organisms in the northeast quarter of MRLA 77E, but the presence or frequency of nematodes and rotifers have not been reported. There was one limitation that came into effect during this study. This limitation would be that there was only one frequency count per site. Therefore we were not able to collect the best amount of data to conduct this study at maximum capacity. From the data collected there seems to be a general trend throughout most of the study sites. That trend would be that there were more rotifers and nematodes in the BSC rather than in the soil. I would gather that the reason to this would be that there is more nutrients in the BSC than in the soil for this organisms to grow and live. REFERENCES Belnap, J., J.H. Kaltenecker, R. Rosentreter, J. Williams, S. Leonard, and D. Eldridge. 2001. Biological soil crusts: ecology and management. technical reference report BLM/ID/ST-01/001+1730. USDI - BLM/USGS, Denver. Blair, J. M. et al. 1996. Soil invertebrates as indicators of soil quality. In Methods for Assessing Soil Quality, SSSA Special Publication 49, pp. 273-291. Bongers, T., and Bongers, M. 1998. Functional diversity of nematodes. Appl. Soil Ecol. 10:239-251. Kutikova, L. A. 2003. Bdelloid Rotifers (Rotifera, Bdelloidea) as a Component of Soil and Land Biocenoses. Biology Bulletin. May2003. 30(3). The purpose of this study was to determine the frequency of nematodes and rotifers in the top 10 mm of soil samples taken from five study sites in Seward County, Kansas and Beaver County, Oklahoma. The study sites are found in the northeast quarter of Major Land Resource Area 77A. Comparisons were made between samples containing soil crusts and samples without soil crust. Previous studies in our lab have documented typical BSC organisms in the northeast quarter of MRLA 77E, but the presence or frequency of nematodes and rotifers have not been reported. Megan Campbell Credit: Elaine R. Ingham.