Determining and Using Reference Condition in Biological Assessments I
Presiding: T Whittier, Dynamac Corporation; B Hughes, Oregon State University
NB13D-01 INVITED 13:30h
Setting Expectations for the Ecological Condition of Streams:The Concept of Reference Condition
One step in evaluating the current ecological condition of streams involves estimating the expected condition (or biological composition) of the streams under study. The concept of a reference condition is increasingly used to describe the standard or benchmark against which current condition is compared. Many individual nations, and the European Union as a whole, have codified the concept of reference condition in legislation. However, the phrase "reference condition" has many meanings in a variety of contexts. Our primary purpose is to bring some consistency to the use of the term. We argue that "Reference Condition" should be reserved for referring to biotic integrity, defined in terms of the "naturalness" of the biota (structure, composition, function, diversity) and that naturalness implies the absence of significant human disturbance or alteration. To avoid the confusion that arises when alternative definitions of reference condition are used, we urge that these specific terms be used to refer to the concepts and methods used in individual bioassessments: Minimally Disturbed Condition; Historical Condition; Least Disturbed Condition; and Best Attainable Condition. We argue that each of these concepts can be narrowly defined, and each implies specific methods for estimating expectations.
NB13D-02 INVITED 13:45h
The Role of Reference Condition in Biological Assessment and Criteria: An EPA Guidance Document
The U.S. Environmental Protection Agency is preparing a document to provide States, Tribes, and other practitioners with guidelines on the reference condition concept and how to apply it in their water management programs, particularly for assessing the condition of aquatic resources. These guidelines are intended to broaden the implementation of biological monitoring and assessment, to increase the consistency among States and Tribes, and to improve the success of individual programs. Establishing and using the reference condition concept appropriately is critical to implementing biocriteria and tiered aquatic life uses to protect and restore water resource quality. This document will cover the following topics: a description of the concept of reference condition and related concepts (including minimally disturbed, least disturbed, and attainable conditions); methods for characterizing reference and related conditions; the role of water body classification to partition natural variability; setting thresholds to determine achievement of a target condition; and application of the concept in heavily modified regions (e.g., urban landscapes; agricultural regions) and waterbodies (reservoirs, regulated rivers). A section on frequently asked questions and answers is included. Throughout the document, examples are drawn from existing State and Tribal programs to illustrate specific applications that are consistent with the guidelines.
NB13D-03 INVITED 14:00h
The use of Reference Conditions in European Bioassessment and Restoration of Inland Waters.
The landscape of much of Europe has been altered for centuries, rendering the identification of pristine or even minimally disturbed ecosystems difficult in many regions. Recognising that aquatic resources are deteriorating at an alarming rate, the European Community recently agreed on a set of measures to retain and restore the integrity of inland waters. The European Water Framework Directive (WFD) is unique in many respects. For example, cognisant that present-day environmental problems require a more holistic approach to ecosystem management, the Directive has shifted focus from individual sites (lakes or river stretches) to viewing aquatic ecosystems more holistically and interconnected, thereby recognising that aquatic ecosystems are nested within and an integral part of the landscape. This view is clearly manifested in that catchment planning and management plans (aka River Basin Management Plans) are an intricate part of the WFD. This talk will review some of the advancements that have been made in European assessment of inland waters, with focus on: (i) the methods currently used to establish reference conditions, (ii) the challenging aspect of identifying reference conditions for a wide variety of ecosystem types, and (iii) the use of reference conditions for establishing restoration targets in a changing environment.
NB13D-04 INVITED 14:15h
Selecting Reference Condition Sites - An Approach for Biological Criteria and Watershed Assessment
This talk describes the Oregon Department of Environmental Quality's approach to selecting reference condition sites. The purpose of selecting reference condition sites is to establish an objective and systematic method for finding water bodies minimally disturbed by human activities for a given region. The approach consists of using geographic information systems (GIS) and site specific information to characterize human disturbance. Selected reference sites are then used to describe "reference condition" for a specific region for the purposes of stream and watershed assessment. Site selection involves three steps: 1.) Pre-screening, which involves selecting a region, identifying the primary natural gradients, and using GIS information and best professional judgment to identify watersheds with minimal human disturbance. 2.) Site visits which are used to record reach level human disturbance and together with delineated watershed geographic information is used to score a Human Disturbance Index (HDI). 3.) Site verification involves reviewing the disturbance information and sampling data. While reference site selection is not based on in-stream conditions, final verification includes an evaluation of the biological, physical habitat, and water quality data for outliers that might indicate unidentified problems. Verification is completed with the assignment of a "site classification" grade.
http://www.deq.state.or.us/lab/biomon/reports/WSA04-002.pdf
NB13D-05 INVITED 14:30h
A Multi-Scale Screening Process for Identification of Least-Disturbed Stream Sites: Finding the Best of What's Left
We developed a multi-stage screening approach for identifying least-disturbed perennial stream sites. The approach was applied and evaluated in the Northwestern Great Plains. A GIS-based coarse screen score was used to rank 125,000 nested 1st--5th order stream networks according to disturbance. Least-disturbed candidates were drawn from 35 predefined strata during subsequent screening stages. Approximately 680 catchments were fine screened using online digital orthophotos, 132 were subsequently reviewed by local resource managers, 77 inspected during aerial and ground reconnaissance steps, and 34 finally selected as least-disturbed candidates. The EPA's EMAP probability sites, with associated watershed-level land use and stream chemistry data, were used to evaluate screening effectiveness. Coarse and fine screen disturbance scores were calculated for the evaluation sites. These scores were then divided into thirds, representing `least', `moderate', and `most' disturbed sites. Least-disturbed sites, as defined by coarse screen scores had significantly less associated agriculture and lower total nitrogen, and somewhat lower ammonium levels than most-disturbed sites. Least-disturbed sites based on fine screen scores also had significantly less associated agriculture and lower ammonium, and somewhat lower total nitrogen levels. Based on these results, the multi-stage screening approach appears to be effective for identifying least-disturbed streams within predefined strata.
NB13D-06 INVITED 14:45h
Using Ecological Theory and Historic Surveys to Assess Water Quality When Reference Sites are Unavailable.
In large areas of southern Ontario, local reference or minimally impaired sites are no longer available largely as a result of extensive deforestation and agricultural practices over the past 1.5 centuries. For example in Essex County, less than 2 percent of the original forest cover is remaining and all streams have been "improved", i.e. deepened and channelized, to assist drainage. Published and unpublished historic benthic studies and surveys have been conducted by various researchers, e.g. Dr. F. Ide, and agencies, e.g Department of Lands and Forest, in Ontario since 1910 and thus may assist in establishing reference conditions in some areas. Meanwhile, using the principle of longitudinal zonation, benthic species can be associated with specific habitat reaches, e.g. creeks, streams, rivers, based on historic and current studies. Although we lack theory to predict specific composition of communities at a site, we can establish a "candidates list" for each habitat reach under reference conditions. When the candidate species are abundant within a habitat reach, water quality conditions approximate reference conditions. A reduction in the proportion of candidate species implies water quality impairment, whereas a lack of candidate species implies degraded water quality conditions.