An index of biotic integrity for macroinvertebrates and salamanders in primary headwater habitat streams in Ohio
Edward L. Moore, Jr., MS
Advisor: Robert Gates
The use of multimetric indices to assess aquatic communities is well established in Ohio. The fish Index of Biotic Integrity (IBI) and the Invertebrate Community Index are robust measures of aquatic community condition that have been used by the Ohio Environmental Agency (OEPA) for many years. These indices provide a definitive numeric assessment of the stream biotic communities to judge against established biocriteria in state water quality standards. However, neither of these assessment tools can be applied to the smallest headwater streams of watersheds. At the scale of the primary headwater habitat stream (PHWH) defined by OEPA as having shallow pools and a drainage area less than 2.56 km2, the ability to collect a quantitative sample using OEPA macroinvertebrate quantitative sampling methods was not successful. In addition, it was found that electrofishing methods to sample the fish community was not appropriate for primary headwater streams where fish are rare, or more often completely absent.
The Ohio EPA does not allow an assessment of attainment of stream quality unless a fish IBI score or an ICI is documented at that site. A qualitative narrative assessment of the macroinvertebrate community can be used to designate a stream use (e.g., coldwater habitat, warmwater habitat) but not an assessment of whether the stream community is attaining or meeting that designated use. Salamanders have been used by the Ohio EPA since 2002 to help determine PHWH stream classes (I, II, III) with the Class III PHWH having the highest quality biotic integrity and most ecologically sensitive taxa. Class III PHWH streams are dominated by cold water adapted macroinvertebrate taxa and by various salamander species, which ecologically replace the predatory functional role of fish.
There is no recognized assessment tool at present using either macroinvertebrates or salamanders to determine attainment of Clean Water Act goals for primary headwater streams in Ohio (<2.56 km2). The goal and objective of this study was to develop various indices of biotic integrity to be used as biomonitoring assessment tools for Class III primary headwater habitat streams. Macroinvertebrate assemblage data and salamander community data were investigated to score and evaluate whether known Class III PHWH streams were meeting performance standards as documented at least impacted PHWH watershed sites from this study.
PHWH sample sites were selected in central, north-central, and northeast Ohio that covered a range of human disturbance conditions (high quality reference sites to poor condition sites). Site and community quality differences developed a better understanding of the species-environment relationship that would define and establish responsiveness and suitability of possible metrics in the ICI development process. Quantitative sampling methods were compared (Surber, artificial leaf pack sample, and USEPA bucket sampling methods) for variability and suitability in sampling PHWH streams. The bucket sample method was selected as most appropriate for PHWH invertebrate stream sampling. Qualitative sampling of stream reach microhabitats (with presence/absence data) following OEPA protocols supplemented the quantitative samples. Direct gradient ordination (redundancy analysis - RDA) of the macroinvertebrate data and measured environmental variables was conducted to discern invertebrate taxa-environment relationships. Potential invertebrate metrics were included as passive species variables in the ordination so that they did not affect the position of the invertebrate taxa. Sensitive invertebrate taxa and metrics grouped around positively correlated environmental vectors in the RDA triplot, such as riparian width, forest cover, low embeddedness, maximum pool depth, and substrate quality. Reference sample sites were located in the positively correlated quadrants also with taxa nearby related to the respective sites and the positive environmental vectors. Facultative taxa were centered in the RDA analysis triplot near the moderate quality range of condition sites. Poor quality sites, tolerant invertebrate taxa, and negatively correlated environmental vectors, such as total suspended solids, percent silt and muck, and temperature, were grouped in negative quadrant of triplot. A distance matrix analysis (which measures the relatedness of data spatially) grouped possible invertebrate metrics into clusters based on their similarity. Invertebrate metrics for the PHWH Invertebrate Community Index (ICI) were selected from each cluster group after comparisons of utility (amount of information), redundancy, scope and the ability to reflect a wide range of conditions while distinguishing reference sites from disturbed sites. These comparisons were from statistical and empirical analyses of quantitative and qualitative sample data collected at Class III PHWH sample sites. The 14 selected invertebrate metrics were standardized by scoring continuously from 0 to 1 using a curvilinear equation developed from the relationship of the reference data and the range of condition sites. For each invertebrate metric, the minimum reference value scoring a metric score of 1 was determined along with the value where a 0 was scored. An invertebrate metric equation was developed for each metric with at least those points (or more) similar to the shape of the frequency distribution curve and then scaled to produce an ICI of 0 to 100. The developed PHWH ICI scored consistently and documented range of quality conditions among sample sites. All PHWH reference sites scored > 70% to 100%. Range of condition sites scored from < 10% to under 60%. Based on sample site scoring, the PHWH ICI biomonitoring criterion met PHWH Class III macroinvertebrate community performance expectations at scores > 70%. Associated narrative quality evaluations meeting Class III PHWH community performance expectations were designated as: 70% to < 80% (good); 80% to < 90% (very good); and > 90% (exceptional quality). PHWH ICI scores under 70% did not meet macroinvertebrate community quality expectations and were categorized as: 40% to < 70% (fair quality); 30% to < 40% (poor); and < 30% (very poor quality). These narrative quality categories were similar to OEPA narrative quality categories used in qualitative narrative assessments.
A Salamander Community Quality Index was developed from five different possible diversity indices of varying complexity with combined data from the 10 meter Visual Encounter Survey (VES) and incidental collections from the macroinvertebrate qualitative and quantitative sampling methods. The Visual Encounter Survey (VES) was determined to be the primary sampling method with supplemental incidental salamander collection data from the PHWH macroinvertebrate samples added to counts to get cumulative scores. Five stream-obligate salamander species were collected at 19 of 21 (90.5%) PHWH sample sites. Reference sites contained 3-5 salamander species at 7 of 10 sites. Positive common associations of species diversity were wide riparian corridors (range of 235-750 m), low percent silt and muck (range of 0-5%), and a mean forest cover of 56.4%. Conversely, low salamander diversity was influenced by increased percentages of cropland, silt and muck, and open canopy. Low riparian widths (0 and 2.25 meters) were measured at PHWH sites where no salamanders were collected. The Salamander Community Quality Index responded to environmental disturbances, and a wide range of quality was expressed between reference sites and the range of condition sites. The Salamander Community Quality Index (SCQI) was selected from five possible indices (index 4 with modifications) by comparisons and practical differences in scoring and data documentation for interpreting scoring. Index 4 had enough detail to document multiple year classes for site quality differentiation, yet index 4 was not so complex that it was not reproducible by herpetology non-experts. Sites that scored a Salamander Community Quality Index > 20 (7 of 21 sites) contained good salamander diversity and had good to exceptional quality associated habitat (HHEI scores of 62-96). The Salamander Community Quality Index biomonitoring criterion, based on sample site scoring, met PHWH Class III salamander community performance expectations at scores > 20 (of 50 possible points) or 40%.
Both the PHWH ICI Salamander Community Quality Index responded to environmental disturbances, and a wide range of quality was expressed between reference sites and the range of condition sites. A strong association was documented in a correlation analysis between the PHWH ICI and the Salamander CQI (r = 0.723; P < 0.010, 20 df). Consequently, the two Indices, the PHWH ICI and the Salamander Community Quality Index, were combined to form the Primary Headwater Community Quality Index (PHWH CQI). The use of both invertebrate and vertebrate response indicators to determine the biotic integrity of primary headwater streams is consistent with the OEPA approach for larger streams where both the fish IBI and macroinvertebrate ICI are utilized. The Primary Headwater Community Quality Index (consisting of the independent PHWH ICI and the Salamander CQI) can be applied to determine use attainment, preservation, mitigation, restorability, long-term land use development for watershed planning, and for establishing biocriteria for primary headwater streams wherever Class III type biological communities are documented to be present (with some localized limitations).