Monitoring Benthic Algal Communities: A Comparison of Targeted and Coefficient Sampling Methods

다국어 초록 (Multilingual Abstract)

Choosing an appropriate sample unit is a fundamental decision in the design of ecological studies. While numerous
methods have been developed to estimate organism abundance, they differ in cost, accuracy and precision.
Using both field data and computer simulation modeling, we evaluated the costs and benefits associated with two
methods commonly used to sample benthic organisms in temperate kelp forests. One of these methods, the
Targeted Sampling method, relies on different sample units, each “targeted” for a specific species or group of
species while the other method relies on coefficients that represent ranges of bottom cover obtained from visual estimates
within standardized sample units. Both the field data and the computer simulations suggest that both methods
yield remarkably similar estimates of organism abundance and among-site variability, although the Coefficient
method slightly underestimates variability among sample units when abundances are low. In contrast, the two
methods differ considerably in the effort needed to sample these communities; the Targeted Sampling requires
more time and twice the personnel to complete. We conclude that the Coefficient Sampling method may be better
for environmental monitoring programs where changes in mean abundance are of central concern and resources are
limiting, but that the Targeted sampling methods may be better for ecological studies where quantitative relationships
among species and small-scale variability in abundance are of central concern.

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