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The Problem
There is a great need for leading indicators of disturbance to biological communities. Generally, by the time demographic or pathologic evidence of community disturbance surfaces, remediation and recovery are either impractical, impossible or cost prohibitive. In general, the standard (EPA) bioindicators are artificial indicators not directly related to real, in situ situations; and chemical and other non-biological indicators are even farther removed from the systems they propose to monitor. Karr’s Index of Biotic Integrity is a step in the right direction, but needs to be compared with other approaches both to validate its sensitivity, consistency and biological relevance and for the purposes of comparing and testing the sensitivity, consistency and biological relevance of other measures. There are now a number of alternative measures, some modifications of old concepts (indicator species), some modifications or improvements on ideas that propose to integrate community function and structure (ecofunction groups and ecological metrics), and some relatively new measures (developmental instability). Objectives The 5-year research goals of the Fisheries and Aquatic Resources Program addressed are to: understand relationships between and among species habitats; provide science for restoring and maintaining declining species and their required habitat; and investigate aquatic species diversity. The subtask will test the efficacy, effectiveness and sensitivity of a variety of "ecological guilds" as indicators of environmental quality and stress on both plant and animal populations at Fort Benning, Georgia. Anthropogenic stress in the present study comes from disturbance by vehicles, particularly tanks used in army training, and from proscribed burning of undergrowth. The whole study, partially funded through the US Army, involves testing of water and soil quality, physical and biotic indicators of stress at both the population and community level. Stress measures include disturbed status of indicator species and ecofunctional groups, measures of water stress and photosynthetic efficiency in plants, measures of microbial function, nutrient fluxes, standard EPA test protocols, the Index of Biotic Integrity and developmental instability. Work covers aquatic, riparian and upland systems. The role of the BRD in this subtask is to aid in data collection for all sites, to help in analysis of developmental instability, and to model stress responses at the landscape scale.Methodology Developmental instability is measured in terms of deviations from symmetry in normally summetric traits. In particular, past work has involved measures of bilateral asymmetry. Work by several of the PI's on this subtask (Emlen (BRD), Freeman (Wayne State Univ.), Graham (Berry College), however, has demonstrated the feasibility, and in many cases the superiority, of using measures of other sorts of symmetry...spiral, radial, translational and spatial (fractal measures). In this work, we are collecting morphometric data from fish, aquatic invertebrates and aquatic plants, and utilizing all pertinent measures with the goal of comparing the sensitivity and consistency of these measures with others (listed above). Approaches to the modeling of the impacts of stress on stress measures and fitness of individual populations must await review of the nature of the data, including measures of physical landscape effects of disturbance. Modeling of the impacts of stress, as indicated by the various measures, on whole community structure and function can follow standard multivariate approaches, simple ecological model approaches, or the new methodology of Interaction Assessment (INTASS). We are collaborating with two other large scale projects, also being carried out at Ft. Benning (A group from Univ. Florida working on soils and hydrology; an Oak Ridge Nat'l. Lab. Group working on ecosystem health and indicators of ecological change) in terms of sharing data, expertise and ideas. Highlights and Key Findings 10/1/2001 - A major effort went into cooperative field work with Dr. D.C. Freeman in the springs of both 2000 and 2001. Several papers, dealing with correlations among developmental instability (DI) measures, consistency with which different measures reflect levels of disturbance, sensitivity of the various measures, and the degree to which DI measures correlate with evidence of disturbance based on growth ring patterns, photosynthetic efficiency, transpiration and stomatal conductance are in
4/1/2002 - The new approach for assessing community response, based on fractal analysis of transect data collected at multiple spatial scales ihdicates that proscribed burning strains ecosystem structural integrity in the same year, but … probably via enhanced nutrient values … enhances integrity in the following year. Repeated stresses, such as those imposed by Army activities, shift the system into new homeostatic states with a correspondingly new structural order. Consequently, such "stresses" constitute a new physical environmental milieu and so cease to be stressors. Army activities have, in fact, altered ecosystem structure, and no longer manifest themselves as strains on structural integrity. These results, rather reassuringly, correlate well with what we find with developmental instability. Where Are We Headed In 2003 Three papers, two dealing with the transect analysis outlined above and one dealing with the application of INTASS to dwarf sumac, Rhus copallinum, will be ready to submit by the end of Feb., 2003. Spring field season will emphasize trransect and possibly INTASS and developmental instability work over a much larger number of sites (60) to further test the efficacy of the array of stress indicators. Project Contact John Emlen Email: john_emlen@usgs.gov Publications |
