Stream Salamanders as Indicators of Stream Quality in Maryland

1. www.esm.versar.com • 1. Identifying Reference and Degraded Sites • Reference sites must meet all of the following criteria: • - F-IBI or B-IBI ≥ 4 (scale of 1 to 5) • - Forest land use ≥ 75% • - Riparian buffer width ≥ 50 m • - Stream shading ≥ 50% • - Aesthetic rating ≥ 10 (scale of 0 to 20) • Degraded sites must have B-IBI < 3 or F-IBI < 4 and any of the following: • - Forest land use ≤ 10% • - Riparian buffer width ≤ 15 m • - Stream shading ≤ 40% • - Aesthetic rating ≤ 5 (scale of 0 to 20) • After the thresholds for designating sites as reference and degraded were applied, sites not meeting either threshold were classified as intermediate. Fish Index of Biotic Integrity (F-IBI) is Not Rated for the Smallest Streams • Study Question • Can streamside salamanders effectively discriminate ecological condition in small streams across ecological regions and gradients of human disturbance? • Study Approach • Piggyback on MBSS sites in Highlands and Piedmont during summer of 2001 • Apply proven transect and quadrat sampling methods Authors Mark Southerland1 Robin Jung2 David Baxter1 Isaac Chellman2 Ginny Mercurio1 Jon Vølstad1 • 3. Testing Salamander Metrics • We tested 11 candidate salamander metrics to see if values were significantly different between reference and degraded sites: • Measures of Species Richness and Composition: number of species, numbers of D. fuscus, D. ochrophaeus, E. bislineata, and G. p. porphyriticus • Measures of Salamander Abundance: number of all salamanders • Measures of Species Tolerance: number and percentage of intolerant salamanders (defined as all species except E. bislineata) • Measures of Reproductive Function: number of adults, number and percentage of larvae • Metric values received a discrete score (i.e., 0, 5, 10) based on comparison to the 10th and 50th percentile of reference. “Reverse” metrics are scaled so that higher values receive lower scores. 1Versar, Inc. 9200 Rumsey Road Columbia, MD 21045 410-964-9200 southerlandmar@versar.com 2 USGS Patuxent Wildlife Research Center 12100 Beech Forest Road Laurel, MD 20708 Stream Salamanders as Indicators of Stream Quality in Maryland • 4. Creating the Index • Stream Salamander Index of Biotic Integrity (SS-IBI) = • Sum of Normalized Metric ScoresDivided by the Number of Metrics (4) • Number of Species • Number of Salamanders • Percentage of Adults • Percentage of Intolerants • Scores are assigned on a 0-10 scale, with a score of <5 the threshold for degradation. • Distribution of Non-Coastal Plain SS-IBI scores for 76 stream sites separated into reference, intermediate, and degraded classes based on non-salamander criteria. Boxes describe the 75th, 50th, and 25th percentiles with dotted lines denoting means. Whiskers describe 90th and 10th percentiles with dots denoting values outside the range. • Multivariable Analyses of Important Factors • Land use – Percent forest (+), percent impervious surface (-), percent urban (-) • Physical Habitat – shading (+), gravel (-), riffle extent (+), riparian buffer width (+), aesthetic rating (+), total rocks (+), maximum depth (+), average thalweg depth (-) • Water Quality – ANC (-), DOC (+) • Biology – B-IBI (+), predator fish abundance (-) Introduction Biological indicators are critical to the protection of small, headwater streams and the ecological values they provide. Maryland and other state monitoring programs have determined that fish indicators are ineffective in small streams, where stream salamanders may replace fish as top predators. Because of their life history, physiology, abundance, and ubiquity, stream salamanders are likely representative of biological integrity in these streams. The goal of this study was to determine whether stream salamanders are effective indicators of ecological conditions across biogeographic regions and gradients of human disturbance. Stream Salamander Sampling Sites Distribution of stream salamander sampling sites in the Non-Coastal Plain of Maryland. Each site was also sampled for water chemistry, physical habitat, and other biological variables using MBSS methods. • Steps in Indicator Development • Identify Reference and Degraded Sites • Partition Natural Variability • Test Salamander Metrics • Create the Index Salamanders are Sensitive to Human Disturbance Stream Salamanders in Maryland Northern Two-lined salamander Long-tailed salamander Eurycea bislineata Eurycea l. longicauda Allegheny Mountain dusky salamander Northern dusky salamander Desmognathus ochrophaeus Desmognathus fuscus Seal salamander Desmognathus monticola Northern spring salamander Gyrinophilus p. porphyriticus Eastern mud salamander Red salamander Pseudotriton montanus Pseudotriton ruber • MBSS Provides Stressor Information at Each Site • Samples 1,500 stream sites in each 5-year round • Uses probability-based design stratified on watershed and stream order • Measures water chemistry, physical habitat, and biological communities • Developed reference-based indicators of integrity for fish, benthic invertebrates, and physical habitat • Index Performance • Percentage of sites correctly classified by the SS-IBI: • Highland SS-IBI • 85% reference, 100% degraded, 88% combined • Piedmont SS-IBI • 100% reference, 75% degraded, 87% combined • Non-Coastal Plain SS-IBI • 88% reference, 93% degraded, 90% combined Index Validation Partial validation of these indices was obtained when a test of the number of salamander species metric produced an 82% correct classification of 618 MBSS sites surveyed in MBSS Round One. Salamander abundances were not recorded at these sites so the other metrics could not be calculated. • Summary • Small streams contribute to water quality and biodiversity but have been historically overlooked • Stream salamanders are effective indicators of health in small streams • Stream salamander searches require a 10% increase in sampling effort of MBSS • SS-IBI provides a vertebrate indicator in streams too small for fish 2. Partitioning Natural Variability Stream salamander communities differ slightly among the four physiographic regions west of the Coastal Plain in Maryland. Distribution maps show that D. monticola and D. ochrophaeus are not found in the Blue Ridge or Piedmont of Maryland, while P. montanus is not found in the Appalachia Plateau, Valley & Ridge, or Blue Ridge regions. The other five stream salamander species occur in all four regions. Because of these species distribution differences, indicator development was conducted separately for the Highlands and Piedmont as well as for all sites combined (i.e., Non-Coastal Plain Maryland). Acknowledgements We would like to thank the stream salamander field crew that in addition to DPB and ICC included Jeff Tomlinson and Ed Schwartzman. We thank Ron Klauda and Paul Kazyak of the MBSS and Erica Shingara of the City of Gaithersburg for permission to use the non-salamander data collected at the sites, and J. Andrew Royle, Jodi Dew, and Allison Brindley for statistical and analytical support. We give special thanks to MBSS crew leaders, Tony Prochaska and Matt Kline, for welcoming our salamander crew during their sampling. The funding for this research was provided by the U.S. Geological Survey Amphibian Research and Monitoring Initiative (ARMI) in the Northeast region. • Stream Salamander Data • Collected 1,584 stream salamanders • Mean of 21 salamanders and 2 species per site • 37% adults; 63% larvae • Eurycea bislineata at 88% of stream sites; comprised 75% of all salamanders collected • Salamander detection probabilities ranged from 0.71 to 0.85 • Stream Salamander Indicator Study Components • Sampled 76 streams with transects and quadrats at MBSS sites • Removal samples on transects to determine salamander detection probabilities • Multivariate analysis of 52 water quality, physical habitat, land use and biology variables to identify factors affecting salamander distribution and abundance • Reference-based indicator development