Comparing fixed-point and probabilistic sampling designs for monitoring the marine ecosystem near McMurdo Station, Ross Sea, Antarctica

摘要

AbstractFixed-point and probabilistic sampling designs were compared to investigate which design best detected known contamination gradients in the marine ecosystem adjacent to McMurdo Station, Antarctica. The fixed-point sampling design included transects along historical contamination and physical disturbance gradients. The probabilistic sampling design used randomly selected hexagons spaced at 50?m intervals. In both designs, 15 stations were sampled over a small area (~1?km2) that extended from Winter Quarters Bay to Cape Armitage. Sediment quality triad components (sediment chemical contaminants, sediment toxicity, and a benthic index of biotic integrity) were measured to indicate chemical, toxicological, and biological effects. There were higher correlations between sediment quality triad components for the fixed-point sampling design than for the probabilistic design. The fixed-point design was better at detecting the intensity of alteration because disturbance of the marine ecosystem at McMurdo Station is localized within a small area. Based on these results, a limited fixed-point design with nine stations detected no significant change in macrofaunal community structure over a four year period from 2000–2004. However, the macrofaunal assemblages present in the contaminated portions of Winter Quarters Bay are indicative of a disturbed benthic community that has been subject to organic enrichment and toxic chemical exposure.