Section 2. 
Research Approach 
Context for Research 
The common management goal for all aquatic ecosystems is to maintain ecological integrity by 
protecting aquatic systems against degradation of habitat, loss of ecosystem functions and 
services, and reduced biodiversity. To this end, environmental managers must be able to: 1) 
assess the condition of an aquatic resource and determine the degree of impairment, 2) diagnose 
the causes of impairment, 3) forecast the effects of changes in stressor levels, and 4) develop and 
implement remediation and maintenance strategies. The first step in this process is to assign a 
designated use for a water body and then to apply the available chemical and biological criteria 
necessary to protect the use. If a resource does not support the designated use, the cause of the 
impairment must be diagnosed. 
To accomplish these tasks, managers must be able to make proper assessments, know the 
appropriate reference conditions against which to compare their assessments, have the diagnostic 
tools necessary to ascertain causes, and understand specific aquatic systems well enough to 
forecast the effectiveness of potential remediation processes. While other ORD Laboratories and 
Centers will make important contributions to GPRA Goal 2, sub-objective 2.2.3, NHEERL will 
focus on conducting ecological effects research relative to steps 1-3 above. 
The focus on aquatic stressors such as habitat alteration, nutrients, suspended and bedded 
sediments, and toxic chemicals is consistent with recent scientific consensus, recognizing that 
these undeniably widespread concerns have the potential for tremendous impact on aquatic 
ecosystems (e.g.. National Research Council [NRC] 1993, Naiman et al. 1995, Vitousek et al. 
1997, EPA 1998, NOAA 1999, EPA 2000a). Because of these stressors, an aquatic resource 
often fails to meet its designated use. States and Tribes commonly report these stressors as part 
of their Section 303(d) lists under the CWA, thus requiring the development of total maximum 
daily loads (TMDLs). Therefore, managers need a decision support system to discern the 
probable causes of impairment and to identify remediation action that will restore and protect the 
resource. 
Research Process 
Effective management and protection of aquatic resources requires multiple research elements. 
The research process for developing these elements and the products of the research are shown in 
Figure 1. This process presents a generally linear research sequence, although some research 
elements will be conducted simultaneously. State and Tribal management agencies can protect 
the ecological integrity of aquatic ecosystems only through appropriate management action, but 
NHEERL can help by providing methods and tools for assessing conditions, diagnosing 
impairments, and forecasting changes. 
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