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Synergistic Effects of Climate Change, Wildfire, and Severe Water Quality Degradation on the Aquatic Ecosystems and Ichthyofauna of the Middle Rio Grande.

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Presentation on theme: "Synergistic Effects of Climate Change, Wildfire, and Severe Water Quality Degradation on the Aquatic Ecosystems and Ichthyofauna of the Middle Rio Grande."— Presentation transcript:

1 Synergistic Effects of Climate Change, Wildfire, and Severe Water Quality Degradation on the Aquatic Ecosystems and Ichthyofauna of the Middle Rio Grande Reale, J.K. 1,3, Candelaria-Ley, R. 1, Dudley, R.K. 4,5, Reale, C.S. 2,3, Van Horn, D.J. 1, Dahm, C.N. 1 University of New Mexico, Department of Biology; 2 University of New Mexico, Department of Earth and Planetary Sciences; 3 U.S. Army Corps of Engineers, Albuquerque District; 4 American Southwest Ichthyological Researchers; 5 University of New Mexico, Museum of Southwestern Biology, Division of Fishes. Since the 1900’s, wildfire frequency and severity in the southwestern U.S. has increased despite human suppression efforts 1. Watershed impacts, including accelerated flooding and erosion, are common after high intensity crown fires. Accelerated riverine sedimentation following wildfires, can negatively impact water quality and aquatic ecological health. Impacts may include increased sediment oxygen demand resulting in dissolved oxygen sags and fish kills. In 2011, the Las Conchas Fire burned ~ 635 km 2 in central New Mexico. Subsequent monsoonal precipitation events occurring within the burnt watershed resulted in altered downstream water quality and documented fish kills. The focus of this poster is the Middle Rio Grande (MRG), Angostura reach. Here we are reporting on continuous water quality, Next Generation Weather Radar (NEXRAD), and monthly fish monitoring with the following questions in mind: What is the interannual variability in water quality parameters and discharge of the MRG during the monsoon season? How do monsoonal precipitation events alter water quality of the Middle Rio Grande, especially those that occurred within the burn scar of the Las Conchas Fire? What is the location and quantity of monsoonal precipitation in relation to the burn scar? How did the Las Conchas fire impact the fish community of the Angostura Reach? Background: Study Area, Burn Severity, and Monitoring Locations Results: Continuous MonitoringIntroduction Results: Geospatial Precipitation Analysis Results: Ichthyofauna Monitoring (Angostura Reach) Pre-Las Conchas Fire: changes in discharge did not cause a hypoxic (< 2mg/L) environment. Post-Las Conchas Fire: Multiple hypoxic periods were observed after a change in discharge. New Mexico water quality criteria for marginal warmwater aquatic life, which includes the the MRG (Dissolved Oxygen > 5 mg/L, pH range of 6.6 to 9.0, and maximum temperature 32.2°C ) 2. Relevant toxicity values( H. amarus: LC 50(larvae) = 0.7 mg/L DO; threshold for acute adult mortality, change in ventilation rates, lack of feeding activity, increased respiration, changes in metabolism, altered behavior leading to increased predation = 4.4 mg/L) 3 Notes: Discharge Location: Rio Grande at San Felipe (USGS ); Maximum detection limit of turbidity = 1,000 NTU. Using ArcGIS, daily precipitation for each of the five HUC sub-regions and the Las Conchas burn scar was generated using NOAA Next Generation Weather Radar data. This hyetograph corresponds to change in discharge, which in turn altered water quality of the MRG. Due to the high burn severity of the Las Conchas fire, precipitation events resulted in spikes in discharge, which altered water quality of the Middle Rio Grande during August, Current and Future Work The continuous water quality monitoring network was expanded to included three locations upstream of Cochiti Dam to capture events as they propagate through the system (Summer 2012). Continuous dissolved nitrate and phosphate analyzers were added to the Bernalillo station (Summer 2012). Additional water quality and geospatial precipitation analysis during the monsoon periods prior to and post- fire on the Rio Grande and Chama River. Collaboration with others at the Valles Caldera National Preserve who are collecting continuous data on the East Fork of the Rio Jemez. Calculate stream metabolism values during the monsoon season during the period of interest. Acknowledgements Numerous people have been involved in this research. We especially thank ASIR staff, Deirdre Kann (NOAA NWS), John Craig (UNM lab manager), Michael Porter (USACE) and Betsy Shafer (UNM Water Resources) for their assistance. We would also like to thank NMEPSCoR, USACE-Albuquerque District, the Middle Rio Grande Endangered Species Collaborative Program and the Sevilleta LTER for funding to collect and analyze these datasets. Monthly sampling by ASIR used (3.1 x 1.8 m small mesh, ca. 5 mm) seine to sample discrete mesohabitats. Effort was normalized using seine haul area. The focus of this analysis was small bodied fishes in the family Cyprinidae and Poeciliidae. No significant downward trends in lnCPUE were identified pre and post fire. The precipitous drop in Rio Grande silvery minnow ( H. amarus) is likely due to non-fire related stressors such as poor spring runoff and low summer flows. Pairwise Kruskal-Wallis and Wilcoxon sign-rank test were preformed, comparing yearly population rank between years. Conclusions Precipitation events during the monsoon period of 2011 had a greater effect on water quality of the MRG than years prior to the Las Conchas fire. A geospatial analysis of precipitation (using NEXRAD data and ArcGIS) is an effective tool to determine the location and quantity of monsoonal precipitation events. Small bodied native (Cyprinidae) and non-native (G. affinis) fishes of the MRG appear to be adapted to withstand episodic deleterious water quality events (high turbidity and low dissolved oxygen) during the monsoonal period after a high intensity forest fire in the upper watershed. References 1.Allen, C.D Fire and vegetation history of the Jemez Mountains. 5 p NMAC 3. U.S. Fish and Wildlife Service Biological opinion on the Albuquerque MS4 stormwater permit. 88p


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