The land resources of the Department of Defense are essential for military training and testing activities and as important habitat for more than 300 federally protected plant and animal species. There is increasing concern that training and testing activities could be compromised by land-use restrictions designed to protect threatened, endangered, and at-risk species (TER-S) and their habitat. At present, land-use decisions often must be made in situations in which limited information is available on the TER-S of concern and the relationship between military activities and potential impacts on TER-S is poorly understood. Conventional population- or community-level surveys are the methods most commonly used to evaluate TER-S. These techniques, however, can be expensive, time-consuming, and relatively insensitive to environmental stressors with long response times. Measurements also may provide only weak causal links between military activities and apparent effects. Improved, sensitive, and cost-effective methods are therefore needed to objectively monitor and evaluate the potential effects of military activities on TER-S.
The main objectives of this project were to develop and apply an integrated multivariate bio-indicator approach for assessing effects of military activities and other environmental factors on TER-S and to serve as an operational framework for resource managers at military sites to evaluate the fitness of TER-S populations. This would be measured by a suite of sensitive and rapidly-responding physiological indicators related to reproductive and population-level fitness.
Field investigations were conducted at Eglin Air Force Base (AFB), Florida and at Camp Shelby Training Site, Mississippi on representative terrestrial TER-S from two major vertebrate groups, the gopher frog (Rana capito) at Eglin AFB and the gopher tortoise (Gopherus polyphemus) at Camp Shelby. A suite of biomolecular, biochemical, physiological, histopathological, and immunological responses were measured for both species to determine if these sensitive and early-warning bioindicators could be used to reliably predict effects of military activities on ecologically relevant responses such as reproductive integrity and population status. At Camp Shelby, a two-factor randomized design was used to test for the effects of habitat disturbance on the health of the gopher tortoise. The effects of explosive residuals such as TNT and RDX on the health of the gopher frog were assessed at Eglin AFB.
Both level of military activity and habitat quality were influential factors in dictating the magnitude and nature of health responses in gopher tortoises at Camp Shelby, with habitat apparently having the greater (relative) effect. The fitness of tortoise populations is primarily related to habitat quality because habitat quality influences population size and population size is directly related to genetic fitness and therefore to overall health of tortoises. A multivariate discriminant analysis revealed that a reduced set (7 to 8) of bioindicators from a total set of about 40 measured variables effectively predicted tortoise health. Using multiple response variables at different levels of biological organization is necessary in helping to understand causal relationships between environmental factors, organism response, and the biological relevance of such responses.
Results provided by this study suggest that some effective environmental management options are available for mitigating or minimizing effects due to military activities on TER-S such as the gopher tortoise. Identification of those specific actions and environmental variables responsible for injury to TER-S should reduce the uncertainty of environmental management and regulatory decisions resulting in an increased ability to predict the consequences of specific actions or activities on military ranges. This ability has been aided by the bio-assessment tool developed during this project, which enables natural resource managers at military facilities to quickly and cost-effectively determine if certain activities are compromising the health or status of terrestrial TER-S.