(full paper is archived in the Miller Library)
Title: Optimal sampling design and spatial scales of variation in the abundance of three intertidal invertebrates
Student Author(s): Fu, Irene
Faculty Advisor(s): Watanabe, Jim
Location: Final Papers Biology 175H
Date: June 1995
Abstract: The spatial scales of variation of three intertidal invertebrates were determined using a nested sampling design and optimal quadrat size for each species. Sampling ws done at sites which were kilometers apart; subsites within sites, which were roughly 100 meters apart; transects within subsites, which were about 10 meters apart; and quadrats, which were on the scale of meters apart. An analysis of variance revealed that Lottia limatula is patchy on the spatial scale of tens of meters, while Serpulorbis squamigerus is patchy on the spatial scale of hundreds of meters, with considerable spatial variation within the patches themselves. For Littorina planaxis, there were no significant differences at any of three levels of nesting, indicating that the snail is fairly evenly distributed in the sites sampled. The index of departure from the Poisson distribution and the index of aggregation for S. squamigerus and L. planaxis indicate that both species tehnd to have clumped distributions, which agree with the natural histories of these organisms. The indices are more ambiguous for L. limatula, but the presence of a few high and many low count, as well as aspects from the natural history of this organism, indicate a clumped distribuiton. Determination of the spatial scales of variation for an organism to be studied permits the formation of a sampling design that maximizes accurarcy and precision while minimizing the total costs in terms of time, effort, and money.