SOUTHERN COASTAL SANTA BARBARA STREAMS AND ESTUARIES BIOASSESSMENT PROGRAM 2014 REPORT AND UPDATED INDEX OF BIOLOGICAL INTEGRITY Prepared for: City of Santa Barbara, Creeks Division County of Santa Barbara, Project Clean Water Prepared By: www.ecologyconsultantsinc.com Ecology Consultants, Inc. Executive Summary Introduction This report summarizes the results of the 2014 Southern Coastal Santa Barbara Streams and Estuaries Bioassessment Program, an effort funded by the City of Santa Barbara and County of Santa Barbara. This is the 15th year of the Program, which began in 2000. Ecology Consultants, Inc. (Ecology) prepared this report, and serves as the City and County’s consultant for the Program. The purpose of the Program is to assess and monitor the “biological integrity” of study streams and estuaries as they respond through time to natural and human influences. The Program involves annual collection and analyses of benthic macroinvertebrate (BMI) samples and other pertinent physiochemical and biological data at study streams using U.S. Environmental Protection Agency (USEPA) endorsed rapid bioassessment methodology. BMI samples are analyzed in the laboratory to determine BMI abundance, composition, and diversity. Scores and classifications of biological integrity are determined for study streams using the BMI based Index of Biological Integrity (IBI) constructed by Ecology. The IBI was initially built in 2004, updated in 2009, and has been updated again this year. The IBI yields a numeric score and classifies the biological integrity of a given stream as Very Poor, Poor, Fair, Good, or Excellent based on the contents of the BMI sample collected from the stream. Several “core metrics” are calculated and used to determine the IBI score. Each core metric is highly sensitive to human disturbance as determined through rigorous statistical analyses of data from local streams. Collectively, the core metrics represent different aspects of BMI community structure including diversity, composition, and trophic group representation. By condensing complex biological data into an easily understood score and classification of biological integrity, the IBI serves as an effective tool for the City and County in monitoring the condition of local streams, and evaluating the benefits or consequences of watershed management actions. In 2011 the Program was expanded to include the study of local estuaries. Estuaries are open water bodies where a freshwater stream meets and mixes with saltwater from the ocean, creating brackish water conditions with salinities that change depending on varying seasonal inputs from the stream and ocean. USEPA endorsed rapid bioassessment methods for estuaries were used to collect BMI samples and other pertinent physiochemical and biological data. Over the past four years, a relatively limited data set has been compiled for local estuaries. Study sites have included the range available along a disturbance gradient, from “reference” sites that are fairly intact in form with little urbanization in their watersheds to “highly disturbed” sites that have been substantially altered in form and drain highly urbanized watersheds. Intermediate “moderately disturbed” sites have also been surveyed. A major goal in studying local estuaries is to identify several reliable BMI indicator metrics that show significant differences trends along a disturbance gradient. Such indicator BMI metrics will be the foundation in developing a reliable IBI for local estuaries. Study Area The study area encompasses approximately 80 km of the southern Santa Barbara County coast from the Rincon Creek watershed at the Santa Barbara/Ventura County line west to Jalama Creek just north of Point Conception. There are approximately 50 1st to 5th order coastal Southern Coastal Santa Barbara Streams and Estuaries Bioassessment Program Page 2 2014 Report and Updated Index of Biological Integrity Ecology Consultants, Inc. streams along this stretch of coast, all of which drain the southern face of the Santa Ynez Mountains. 49 different stream study reaches in 20 watersheds have been surveyed on one or more occasions from during the 15 years of the Program, while 10 different estuaries have been studied once or more over the last 4 years. Results Over the past 15 years, the Program has provided a wealth of information regarding the physiochemical habitat conditions and biota (particularly the BMI community) present in local streams. The influences of natural physiochemical and climatic variability and human development on local stream communities have been extensively examined. The following statements can be made based on the research completed thus far: • The updated IBI is highly effective as an indicator of biological integrity, with highly significant relationships with indicies of human disturbance. The IBI has properly differentiated between reference (REF), moderately disturbed (MOD DIST), and highly disturbed (HIGH DIST) study reach groups at a significant level for each year of the Program. • Negative impacts of human land use on local stream communities (particularly BMIs) have been documented with highly significant statistical test results. Degradation of stream communities (e.g., lower IBI scores and loss of sensitive species), as well as physiochemical habitat conditions, has increased linearly with increased watershed development. Urban development has been shown to have greater impacts on stream communities than has agricultural development. • Major episodic disturbances including extreme stream flows, drought conditions, and wildfires have been definitively shown to negatively impact stream communities, as evidenced by lower IBI scores and loss or significant reduction of sensitive BMI and vertebrate taxa following such events. Local stream BMI communities have proven to be resilient, typically showing dramatic recovery from extreme episodic disturbances in a year or two. However, some of the more sensitive species (e.g., rainbow trout) have yet to return to streams impacted by recent wildfires, and may require many years to recover. • Stream habitat restoration sites M2 and AB5 have shown improved habitat conditions, but significant improvements in the BMI community have not occurred thus far at these sites. Channel and riparian restoration at these sites did not address larger scale impairments in hydrology, geomorphology, water quality, habitat continuity and connectivity that have resulted from alteration of their respective watersheds. Much of this watershed-scale impairment cannot be undone from a practical sense. Whether or not current and future restoration efforts will improve the BMI community at M2 and AB5 can only be evaluated via continued monitoring through time. The Program effort to study local estuaries is still relatively new. Based on the limited data set available, the following can be stated thus far: • Seven BMI metrics appear to have promise as indicators of biological integrity for salinities between 0-30 ppt, with significantly different mean abundances between reference and highly disturbed sites. Some or all of these BMI metrics may be suitable Southern Coastal Santa Barbara Streams and Estuaries Bioassessment Program Page 3 2014 Report and Updated Index of Biological Integrity Ecology Consultants, Inc. for use as core metrics in an estuarine IBI that could be developed in the future. % sensitive BMIs and % tolerant BMIs thus far have the greatest potential, both of which have been significantly different between reference and highly disturbed estuaries in each year of study despite wide physiochemical variability from year to year caused by variable rainfall and freshwater inputs. • While salinity certainly has major influences on the composition of the BMI community in local estuaries (i.e., the specific taxa present), thus far it has had no significant effects on any of the potential core BMI metrics within the range of 0-30 ppt. More replication and diversification of reference estuaries having greater physiochemical variability will be needed to gain more confidence in our ability to understand the influences of salinity and other physiochemical parameters on potential indicator BMI metrics. Understanding natural physiochemical influences will be a key step in evaluating the suitability of potential core BMI metrics for inclusion in a future estuarine IBI. • Four of the estuaries surveyed this past year had bottom salinities of greater than 30 ppt. This was the first time that salinities of this level were present in study estuaries. The four high salinity estuaries surveyed include one moderately disturbed and three highly disturbed sites. The four estuaries having salinity of greater than 30 ppt had different BMI composition by disturbance group compared to all the other estuaries. Salinity may become the dominant determining factor of BMI composition where it exceeds 30 ppt. More study of high salinity estuaries, and reference sites in particular, will be needed to further explore this. • Developing a reliable IBI for local estuaries is a major goal of this Program. Accomplishing this will require a greater understanding of relationships between potential core BMI metrics, human disturbance, and the effects of natural physiochemical variables. Based on the progress made thus far, it is hoped this goal will be attained through another two or three years of study. Southern Coastal Santa Barbara Streams and Estuaries Bioassessment Program Page 4 2014 Report and Updated Index of Biological Integrity