FINAL ENVIRONMENTAL CONDITIONS DOWNSTREAM OF SLAB CREEK DAM WITH REGARD TO THE ECOLOGY OF THE ALGA DIDYMOSPHENIA GEMINATA AND ITS IMPACT ON BENTHIC MACROINVERTEBRATES AND FISH PREPARED BY: AECOM SACRAMENTO, CALIFORNIA PREPARED FOR: SACRAMENTO MUNICIPAL UTILITY DISTRICT SACRAMENTO, CALIFORNIA December 12, 2012 This page left blank intentionally. FINAL ENVIRONMENTAL CONDITIONS DOWNSTREAM OF SLAB CREEK DAM WITH REGARD TO THE ECOLOGY OF THE ALGA DIDYMOSPHENIA GEMINATA AND ITS IMPACT ON BENTHIC MACROINVERTEBRATES AND FISH PREPARED BY: AECOM SACRAMENTO, CALIFORNIA PREPARED FOR: SACRAMENTO MUNICIPAL UTILITY DISTRICT SACRAMENTO, CALIFORNIA December 12, 2012 This page left blank intentionally. TABLE OF CONTENTS Section & Description Page 1.0 Ecology of Didymosphenia geminata ......................................... 1-1 1.1 Introduction ..................................................................................................... 1-1 1.2 Environmental Factors Associated with D. geminata ...................................... 1-5 1.2.1 Physical Factors ........................................................................................ 1-5 1.2.1.1 Catchment Characteristics ............................................................ 1-5 1.2.1.2 Streamflow and Water Velocity ..................................................... 1-7 1.2.1.3 Water Temperature ....................................................................... 1-8 1.2.1.4 Light............................................................................................... 1-8 1.2.1.5 Conductivity ................................................................................... 1-9 1.2.1.6 Substrate ....................................................................................... 1-9 1.2.2 Chemical Factors ..................................................................................... 1-10 1.2.2.1 pH ................................................................................................ 1-10 1.2.2.2 Oxygen ........................................................................................ 1-10 1.2.2.3 Chloride ....................................................................................... 1-10 1.2.2.4 Sulfur ........................................................................................... 1-11 1.2.2.5 Calcium ....................................................................................... 1-11 1.2.2.6 Phosphorus ................................................................................. 1-12 1.2.2.7 Nitrogen ....................................................................................... 1-16 1.2.2.8 Iron .............................................................................................. 1-17 1.2.2.9 Sodium ........................................................................................ 1-17 1.2.2.10 Potassium .................................................................................... 1-18 1.2.2.11 Magnesium .................................................................................. 1-18 1.2.2.12 Bicarbonate ................................................................................. 1-18 1.3 Summary and Discussion of D. geminata Ecology with Regard to Environmental Conditions Downstream of Slab Creek Dam ......................... 1-19 2.0 Ecological Effects of Didymosphenia geminata ......................... 2-1 2.1 Effects of D. geminata on Benthic Macroinvertebrates ................................... 2-1 2.2 Composition of the Benthic Macroinvertebrate Community Downstream of Slab Creek Dam and the Potential Effects of D. geminata ............................. 2-6 2.3 Effects of D. geminata on Fish ...................................................................... 2-13 2.4 Composition of the Fish Community Downstream of Slab Creek Dam and the Potential Effects of D. geminata .............................................................. 2-17 2.5 Proposed Changes to the Minimum Flow and the Effect on D. geminata ..... 2-18 3.0 References Cited .......................................................................... 3-1 Ecology of Didymosphenia geminata Table of Contents December 12, 2012 Page i LIST OF TABLES Table No. & Description Page Table 1. D. geminata Tolerances Report from the Literature Compared to Conditions Downstream of Slab Creek Dam ........................................ 1-22 Table 2. Taxonomic List of Benthic Macroinvertebrates Sampled in the South Fork American River between Slab Creek Dam and the White Rock Tunnel Adit. ............................................................................................ 2-7 Table 3. Taxonomic Numerical Abundance and (Percent Abundance) by Invertebrate Order. .............................................................................. 2-12 LIST OF FIGURES Figure No. & Description Figure 1. Scanning electron micrograph of the silica cell wall of D. geminata. The raphe is composed of the two slits that run along the apical axis of the cell. At the base of the cell is the porefield, through which the stalk is secreted. Scale bar equal to 50 microns (μm). Image by Sarah Spaulding, U.S. Geological Survey. ............................................ 1-1 Figure 2. Scanning electron micrograph of D. geminata cells and their mucopolysaccharide stalks. The stalks produced within the cell are many times the length of the cell itself. Note the smaller diatoms growing attached to the stalks. Scale bar equal to 100 μm. Image by Sarah Kiemle, Michigan Technological University. ................................ 1-2 Figure 3. Nuisance bloom of D. geminata mats in New Zealand. ......................... 1-2 Figure 4. Worldwide distribution records for D. geminata. Figure from Whitton et al. (2009) ............................................................................................ 1-3 Figure 5. Confirmed presence and absence records of D. geminata in the United States (Spaulding and Elwell 2007). Map by Sarah Spaulding, U.S. Geological Survey. 1-4 Figure 6. (A) Photographs of D. geminata mat in Rapid Creek showing photosynthetically active aerobic surface. Note that oxygen bubbles produced by photosynthesis and trapped within the mat is visible. (B) The underside of the mat revealing black material indicative of reducing conditions and deposition of iron monosulfides (FeS). (C) Illustration of a conceptual biogeochemical process—the Fe‐P‐S couple—by which sequestered P is solubilized. Figure from Sundareshwar et al. (2011). ................................................................. 1-15 LIST OF APPENDICES Appendix & Description A Partial List of Locations in the Sierra Nevada, California-Nevada Reported to Support Didymosphenia geminata B Periphyton Downstream of Slab Creek Dam Ecology of Didymosphenia geminata Table of Contents December 12, 2012 Page ii 1.0 ECOLOGY OF DIDYMOSPHENIA GEMINATA 1.1 Introduction Didymosphenia geminata (Lyngbya) M. Schmidt 1899 (Bacillariophyceae: Cymbellaceae) (D. geminata) is a relatively large freshwater benthic colonial diatom (a type of single-celled green alga) that occurs on long branching stalks (Kociolek and Spaulding 2003). Diatoms are unique for their silica (SiO2) cell walls, which are often well preserved in sediments, thus making diatoms useful in environmental applications such as paleolimnological reconstructions, and as indicators of water quality (Smol 1990; Smol and Stoermer 1998). Cells of D. geminata (Figure 1) possess a raphe.1 Through the raphe, the living diatom secretes mucilage, with which it may attach to a substrate or move by gliding over the substrate. The cells also possess an apical porefield, through which a mucopolysaccharide stalk is secreted (Figure 2). The stalk, which typically can reach several centimeters in length, may attach to rocks, plants, or any other submerged substrate. When the diatom cell divides through vegetative reproduction, the stalk also divides. Under appropriate environmental conditions, small colonies of D. geminata can grow into a dense wooly mass (mats) of branching stalks to create nuisance blooms with potential consequences on both economics (Deloitte 2011) and the environment (Larned et al. 2007). It is not the diatom cell itself that is responsible for the potential impacts of D. geminata blooms, Figure 1. Scanning electron micrograph of the but the massive production of silica cell wall of D. geminata. The raphe is extracellular stalks (Larned et al. 2006; composed of the two slits that run along the apical axis of the cell. At the base of the cell is Figure 3). the porefield, through which the stalk is secreted. Scale bar equal to 50 microns (μm). Of the 11 or so Didymosphenia species Image by Sarah Spaulding, U.S. Geological reported by taxonomists worldwide, only Survey. D. geminata occurs in western North America (Kociolek and Spaulding 2003; Whitton et al. 2009). It is considered a native species in northern North America, but whether it is native to much of the western United States and California is unresolved. 1 The raphe is a long slit along the long axis of pennate (i.e., bilaterally symmetric) diatoms through which the diatom secretes mucilage. Ecology of Didymosphenia geminata Ecology of Didymosphenia geminata December 12, 2012 Page 1-1 Figure 2. Scanning electron micrograph of D. geminata cells and their mucopolysaccharide stalks. The stalks produced within the cell are many times the length of the cell itself. Note the smaller diatoms growing attached to the stalks. Scale bar