Detecting the ecological effects of environmental impacts: A case study of kelp forest invertebrates
- Ecometrics, Carlsbad, CA (United States) Univ. of Southern California, Los Angeles, CA (United States)
- James Madison Univ., Harrisonburg, VA (United States) Univ. of Southern California, Los Angeles, CA (United States)
- Science Explorations, Carlsbad, CA (United States) Univ. of Southern California, Los Angeles, CA (United States)
- Univ. of California, Santa Barbara, CA (United States)
Detecting the environmental impacts of human activities on natural communities is a central problem in applied ecology. One must separate human perturbations, usually unique events, from considerable natural temporal variability in most populations. These problems can be successfully addressed with the Before-After/Control-Impact (BACI) sampling design, in which Impact and Control sites are sampled contemporaneously and repeatedly in periods Before and After the human perturbation. In this case, the ecological effects of the cooling water discharge from a coastal nuclear power plant in southern California was examined. The results suggest some general lessons applicable in many ecological contexts. In systems where plants and animals are long-lived and recruit sporadically, the rates of change in density are often so low that sampling more than a few times per year will introduce serial correlations in the data. As a result, for studies of few years duration, few samples will be taken. A small sample size means that the tests of the underlying assumptions underlying, e.g., independence and additivity, will have low power. This injects uncertainty into the conclusions. Small sample size also means detecting any but very large effects will be low. In our study, sampling periods of 2-3 yr both Before and After the impact were not long enough to detect a halving or doubling of populations. We concluded that there were significant environmental impacts because: (1) the effect size was generally very large ([approx] -75%); (2) there was a consistent pattern among species; (3) there were two Impact sites, and effects were larger at the site nearest the discharge; (4) the observed effects accorded with physical changes that could be linked with the source of impact; and (5) a number of alternative mechanisms, unrelated to the source of impact, were examined and rejected. 37 figs., 6 figs., 10 tabs.
- OSTI ID:
- 5604888
- Journal Information:
- Ecological Applications; (United States), Vol. 3:2; ISSN 1051-0761
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
COASTAL REGIONS
AQUATIC ECOSYSTEMS
INVERTEBRATES
GROWTH
SPECIES DIVERSITY
REACTOR COOLING SYSTEMS
THERMAL EFFLUENTS
BIOLOGICAL EFFECTS
NUCLEAR POWER PLANTS
TURBIDITY
ANIMALS
COOLING SYSTEMS
ECOSYSTEMS
ENERGY SYSTEMS
NUCLEAR FACILITIES
POWER PLANTS
REACTOR COMPONENTS
THERMAL POWER PLANTS
560200* - Thermal Effects
540340 - Environment
Aquatic- Thermal Effluents Monitoring & Transport- (1990-)