Version 1.5 Native Unionoida Surveys, Distribution, and Metapopulation Dynamics in the Jordan River-Utah Lake Drainage, UT Report To: Wasatch Front Water Quality Council Salt Lake City, UT By: David C. Richards, Ph.D. OreoHelix Consulting Vineyard, UT 84058 email: [email protected] phone: 406.580.7816 May 26, 2017 Native Unionoida Surveys and Metapopulation Dynamics Jordan River-Utah Lake Drainage 1 One of the few remaining live adult Anodonta found lying on the surface of what was mostly comprised of thousands of invasive Asian clams, Corbicula, in Currant Creek, a former tributary to Utah Lake, August 2016. Summary North America supports the richest diversity of freshwater mollusks on the planet. Although the western USA is relatively mollusk depauperate, the one exception is the historically rich molluskan fauna of the Bonneville Basin area, including waters that enter terminal Great Salt Lake and in particular those waters in the Jordan River-Utah Lake drainage. These mollusk taxa serve vital ecosystem functions and are truly a Utah natural heritage. Unfortunately, freshwater mollusks are also the most imperiled animal groups in the world, including those found in UT. The distribution, status, and ecologies of Utah’s freshwater mussels are poorly known, despite this unique and irreplaceable natural heritage and their protection under the Clean Water Act. Very few mussel specific surveys have been conducted in UT which requires specialized training, survey methods, and identification. We conducted the most extensive and intensive survey of native mussels in the Jordan River-Utah Lake drainage to date from 2014 to 2016 using a combination of reconnaissance and qualitative mussel survey methods. We also developed probability of detection estimates to illustrate how critically low Anodonta densities are in the drainage and determined that even if our search efficiencies were theoretically atrocious, our methods were more than adequate to meet 90% probability of detections. Our findings are very disappointing. Out of the dozens of stream and shoreline kilometers surveyed, only two very small, highly-fragmented, and isolated populations of only one mussel species, Anodonta sp. were encountered. Reasons for the demise of native mussel in the drainage are numerous and entirely due to human activities including: sedimentation; intensive and extensive urbanization; industrialization; agriculture impacts (including dewatering and channelization); water quality impairment; invasive species particularly Asian clams, New Zealand mudsnails, and carp; loss of and extremely low densities of native fish hosts for glochidia larvae attachment; loss and fragmentation of suitable and occupied habitat; metapopulation and isolated population dynamics (demographic and environmental stochasticity); and absence of a monitoring program. These combined Native Unionoida Surveys and Metapopulation Dynamics Jordan River-Utah Lake Drainage 2 impacts have reduced or completely eliminated dispersal between populations and have negatively affected population abundance and viability, which resulted in loss of genetic diversity, and subsequently have multiplicatively resulted in extremely high extinction risk in the drainage. We do not expect native mussels in the Jordan River-Utah Lake drainage to persist into the near future without adequate protection, improved habitat, and a comprehensive reintroduction program. Native Unionoida Surveys and Metapopulation Dynamics Jordan River-Utah Lake Drainage 3 TABLE OF CONTENTS Introduction ................................................................................................................................................................................ 15 Native Freshwater Mollusks ............................................................................................................................................ 15 Justification ................................................................................................................................................................................ 17 Unionid Mussels ...................................................................................................................................................................... 18 Native Mussel Taxa Historically Found in the Jordan River-Utah Lake Drainage ............................................ 19 Anodonta californiensis Lea 1852/Anodonta nuttalliana (Lea, 1838) ............................................................... 20 Margaritifera falcata Gould 1850 ................................................................................................................................. 25 Utterbackia imbecillis (Say, 1829) ................................................................................................................................ 29 Jordan River-Utah Lake Drainage .................................................................................................................................... 30 Native Mussel Surveys 2014-2015 ..................................................................................................................................... 34 Survey methods .................................................................................................................................................................... 34 Probability of Detections, Search Efficiencies as Related to Density Estimates ........................................... 35 Jordan River .......................................................................................................................................................................... 36 Methods and Results ................................................................................................................................................... 36 Other mollusk taxa as indicators of suitable native mussel habitat in the Jordan River .............. 40 Mill Creek .............................................................................................................................................................................. 44 Mill Creek Methods ...................................................................................................................................................... 45 Mill Creek Survey Locations .................................................................................................................................... 46 Mill Creek Results ........................................................................................................................................................ 48 Closest Known Extant Population of Margaritifera falcata to Jordan River-Utah Lake drainage .............................................................................................................................................................................................. 50 Status of Native Unionids in Other Tributaries to the Jordan River ............................................................ 50 Mill Creek Upstream of Surveys ............................................................................................................................ 50 Mill Creek Upstream of USFS Boundary ............................................................................................................. 51 M. falcata Extirpated from Big Cottonwood Creek ........................................................................................ 51 City Creek .............................................................................................................................................................................. 53 Native Unionoida Surveys and Metapopulation Dynamics Jordan River-Utah Lake Drainage 4 Red Butte Creek ................................................................................................................................................................... 53 Bingham Creek .................................................................................................................................................................... 53 Utah Lake and Tributaries ................................................................................................................................................ 53 Beer Creek ............................................................................................................................................................................. 54 Southern Utah Lake Shoreline and Spanish Fork River ........................................................................................ 57 Hobble Creek ........................................................................................................................................................................ 57 Mill Race Creek ................................................................................................................................................................... 59 Spring Creek ......................................................................................................................................................................... 61 American Fork River ......................................................................................................................................................... 65 Burraston Ponds and Currant Creek ............................................................................................................................