An Evaluation of the U.S. Navy's Extremely Low Frequency Submarine Communications Ecological Monitoring Program (1997) / Chapter Skim
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4: Common Issues
4: Common Issues
Pages 111-137
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From page 111... ...
Overall conclusions and recommendations concerning the common issues are presented in Chapter 5. USE OF EXPOSURE DATA BY ECOLOGICAL MONITORING TEAMS All ecological monitoring teams made use of the division between treatment and control sites.
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From page 112... ...
soil depth but never used it. Extensive measurements of the electric field in the earth were made at the Martel's Lake site (overhead antenna treatment site for upland-flora and litter decomposition and microflora studies)
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1993) , the indicator was based on "average exposure to magnetic flux density during that particular growing season." It does not appear that the actual measure used in the study is consistent with this definition.
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They reported that the indicator of dose was defined as "average exposure to magnetic flux density during that particular growing season." The indicator actually used was based on spot measurements while at least one antenna was on. The authors did not provide a clear rationale for the indicator of dose that they used.
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It is not clear why values In the table were used, inasmuch as those reported here were more common during growing season. why they used particular values of magnetic field rather than others when more than one was reported during a given year.
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STUDY-SITE SELECTION The original request for proposals (RFP) for research regarding the effects of ELF EMFs on biologic systems emphasized selection of study sites so that appropriate levels of ELF EMFs existed at control sites versus treatment sites.
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From page 117... ...
In the aquatic study, the researchers sought an upstream control site but could not find one, because none that was of the same stream order and physical attributes as the treatment site existed. in general, so many conditions had to be met for site selection that perfect matches were impossible.
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From page 118... ...
The effects of the antenna on response variables are therefore confounded with the background effects of the different soils, climate, etc., on each site, and the two cannot easily be separated. This problem arises in the litter decomposition and microflora studies, the aquatic ecosystem studies, the upland-flora studies, and others.
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From page 119... ...
That type of pretreatment survey was performed only for the upland-flora studies. In contrast, the litter decomposition studies are seriously compromised because there were large differences in decay rates between sites before the antennas were in operation.
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The lack of quantification of statistical bias is exacerbated by the pseudoreplication or even lack of replication in many of the experiments. SPECIES SELECTION The Navy's original plan for an ecological monitoring program recommended that species (or related species)
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, O The ability to measure response variables determined the choice of some species. For example, in the wetlands study, several species were dropped when it became clear that stomata!
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The study of bird populations also relied on a weak test: the treatment site was far from the antenna and had very low exposure levels. The second priority of the original RFP included studies of soil microbiology and ecology, plant ecology, and insect populations and behavior.
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First, some researchers chose response variables that they argued were unlikely to be affected by factors other than ELF EMFs. For example, leaf foraging by bees, rather than flower foraging, was studied because flowers varied among sites.
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Embryo development in birds had a 4-day window when exposures could be effective, but antenna operation times were not considered. In the wetlands study, the individual measurements of stomata!
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WEAKNESS IN THE GENERAL RESEARCH DESIGN FOR RESPONSE VARIABEES One weakness of the research design for examining responses was the lack of emphasis on understanding possible mechanisms and using mechanistic models. Some researchers did justifier their response variables on the basis of known possible mechanisms.
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STATISTICAL POWER The power of a statistical design reflects the likelihood that an experiment will be able to detect the presence or absence of a treatment effect. The importance of adequate power is simple: a study with low statistical power will not be able to accept or reject the null hypothesis with sufficient confidence.
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From page 127... ...
, and the magnitude of effect that will be assumed to result from the experimental intervention. For example, consider the following hypothetical scenario chosen for its relevance to the ELF ecological monitoring program: · The goal is to compare 20 pairs of nesting birds in a control plot with 20 pairs of birds at one of the treatment sites.
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Tt provides us with some reasonable bounds on the uncertainty. An alternative experimental design with a power of 0.3 or less (like those reported in a number of experiments in the ELF ecological monitoring program)
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However, reviewer concerns regarding low statistical power and lack of data archiving were not addressed. Every year, TTTR]
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Those considerations have given rise to socalled double blind experimental protocols, in which neither the subject nor the experimenter has knowledge that will allow such potential bias.) In several studies of the Navy's ecological monitoring program, modest but significant differences were observed between data collected at treatment sites and data from control sites.
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Therefore, the issue is not whether significant results emerged from time to time, but whether the number of such events was larger then expected. That issue was not examined systematically as part of the ecological monitoring program.
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LACK OF INTEGRATION AMONG STUDIES AND SYNTHESIS OF INFORMATION As noted in Chapter I, the original RFP for studies of the effects of ELF EMFs on biologic systems in the region of the ELF communications system antennas was developed by ITTRT on the basis of a monitoring program outline from the Navy, previous research, information from state agencies and the U.S. Forest Service, and comments on the Navy's draft environmental-impact statement.
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From page 134... ...
Instead, possible responses were considered as isolated events, that is, outside an ecosystem or integrated context. Such a perspective might have caused the managers of the ecological monitoring program to establish study site selection requirements based only on exposure levels and research impacts on limited populations of sensitive species.
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DATA ARCHIVING The final and annual reports do not contain information on archiving of data generated by the Navy's ecological monitoring program. To understand the current state of data archiving, the committee spoke with several researchers directly.
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Apparently, the recommendation was not followed, and documented archiving of data was not undertaken. The Navy ELF ecological monitoring program supported 11 {ong-term studies.
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or later for formatting, documenting, or reporting the data. After millions of dollars had been spent on a monitoring program that could be used for further understanding of the monitored ecosystems, the resulting information appears not to be readily available; if available, it is not in a uniform, user friendly format; and there is no common location to which an outsider can address requests for information.
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