The Society of Protozoologists - 53rd annual meeting - June 24-28, 2000 -(Abstracts 1-44)

摘要

A Preliminary Report on Soil Ciliate Biodiversity and Spatial Heterogeneity from a Highly Stratified Sampling Grid. D. ACOSTA and D.H. LYNN, Department of Zoology, University of Guelph, Guelph, Ontario, Canada. Diversity and abundance of soil ciliates have been positively correlated with soil nutrient cycles and primary productivity. However, previous samplings of soil habitats that lead to this 6onclusion often have not considered the spatial correlations between soil ciliate populations. Without considering spatial distribution, one must be cautious to link diversity with ecosystem processes. Our approach was to first explore sampling techniques to estimate diversity using the flooded-Petri dish method. Live counts done on fresh samples were significantly more diverse than replicate 10-week stored samples (paired t-test, t = 5.33, p = 0.001, n = 10). Petri dishes were divided into four quadrants from which water samples were removed; three Chi-square tests showed a significant difference among quadrants (p > 0.01, n = 3). Following wetting of the soil, live counts were performed at days 2, 4, 7, 14, 18 and 22, and species accumulation curves were plotted for three samples. Ciliate diversity plateaued by day 7; thus, a confident estimate of diversity can be obtained by sampling on days 2, 4 and 7. Diversities were compared between live counts and counts obtained after filter-protargol staining. Stained samples were significantly more diverse than samples from live counts (paired t-test, t = 3.09, p = 0.008, n = 13). A geostatistical program was used to determine the level of spatial dependance and heterogeneity in ciliate diversity through semivariograms derived from two highly stratified 2 X 4 m grids in the west end of Puerto Rico. Both plots revealed a high degree of spatial heterogeneity with spatial dependance (i.e., samples being similar to each other) up to 8 m and 3 m in the serpentine and limestone substrates, respectively. This accords with the degree of vegetation and topographical heterogeneity. There were scattered hot spots in biodiversity, suggesting the need for a directed and standarized sampling design. Perhaps everything is not everywhere, and perhaps the results from random sampling obscure significant interactions, making previous generalizations about ecosystem stability and ciliate diversity in temperate and tropical systems hard to interpret.