Spatial scales and probability based sampling in determining levels of benthic community degradation in the Chesapeake Bay.

摘要: The extent of degradation benthic communities the Chesapeake Bay was determined by applying a previously developed index biotic integrity at three spatial scales. Allocation sampling probability-based allowing areal estimates with known confidence intervals. scales were: (1) tidal Bay; (2) Elizabeth River watershed; and (3) two small creeks within Southern Branch that are part sediment contaminant remediation effort. areas covered varied from 10−1 to 104 km2 all were sampled in 1999. divided into ten strata, five strata each single stratum. determination number size based upon consideration both managerially useful units for restoration limitations funding. Within stratum 25 random locations community condition. In 1999 percent benthos poor condition entire 47% 20% mouth 72% Potomac River. estimated area 64% 52–92%. Both had 76% These kinds allow environmental managers better direct efforts evaluate progress towards restoration. Patterns smaller may not be correctly inferred larger Comparisons patterns across scales, between combinations must cautiously interpreted.