At-risk Freshwater Mussel Survey of Bogue Chitto National Wildlife Refuge PROJECT ID: FWS/R4/NWRS/DSRM/Inventory-Monitoring Branch Principal Investigators: Daniel Breaux Refuge Manager Bogue Chitto NWR Southeast Louisiana Refuge Complex 61389 Hwy 434 Lacombe, LA 70445 Office Phone: 985-882-2030 Fax Phone: 985-882-9133 [email protected] Gary Vitrano Louisiana Department of Wildlife and Fisheries Inland Fisheries Biologist Manager - District VIII 61384 Fish Hatchery Road P.O. Box 1190 Lacombe, LA 70445 Office: 985-882-0027 Fax: 985-8820-0029 [email protected] FINAL REPORT ABSTRACT Timed, qualitative searches were performed at established sample sites within the boundaries of the Bogue Chitto National Wildlife Refuge (BCNWR), and waterways adjacent to the refuge within the Pearl River watershed, to determine freshwater mussel assemblage structure, species richness, relative abundance, diversity, and to document species of greatest conservation need. Twenty-three sample sites within the refuge were surveyed, plus an additional twenty-seven sites on adjacent water ways and tributaries. A total of 10,086 individual mussels were collected with an estimated species richness of 29, a Shannon-Wiener Diversity H’ Index of 2.35 and a catch- per-unit-effort (CPUE) of 201.72 mussels per 90-minute sample. Cyclonaias refulgens was the most common species, representing 24% by total number, while Megalonaias nervosa, Lasmigona complanata, and Villosa vibex were the least abundant species. Within the boundaries of the refuge, 6,526 individual mussels were collected, with an estimated species richness of 27, a Shannon-Wiener Diversity H’ Index of 2.239 and a CPUE of 283.74 mussels per 90-minute sample. Quadrula nobilis was the most common species, representing 24% by total number, while Obovaria unicolor, Utterbackia imbecillis, and Villosa vibex were the least abundant species. Potamilus inflatus, federally listed as Threatened, was not found in the sampled areas of this project. INTRODUCTION Freshwater mussels are the most endangered freshwater organisms in North America, with three quarters of the species in the United States considered species of concern (Strayer, 2008). Mussels are particularly susceptible to habitat disturbances and disruption of host fish dispersal. Inventories of mussel populations, relative abundances and species composition are important for future conservation efforts. The primary focus of the project is to provide a baseline comprehensive survey of freshwater mussels on the Bogue Chitto National Wildlife Refuge (BCNWR), and to describe species assemblages across the refuge’s major waterways and many of the smaller tributary streams and sloughs. In addition to waters in the BCNWR, mussel communities were sampled in adjacent tributaries and other waters of the basin, resulting in a comprehensive survey of the waters of the Bogue Chitto and Lower Pearl River of Louisiana. PROJECT OBJECTIVES Objective 1 – Conduct twenty-three qualitative samples (timed searches) on sites located within the boundaries of the BCNWR in Louisiana. These surveys were distributed across sites within the Bogue Chitto River, Holmes Bayou, Wilson Slough, the West Pearl River and the Pearl River proper, along with adjacent backwater sloughs and remnant river channels. This distribution of sample sites contains a representative cross section of aquatic habitats within the BCNWR. In addition to the BCNWR sites, 27 locations on waterways and tributaries across the Pearl River Watershed adjacent to the refuge were sampled. Objective 2 – Document the presence or absence of endangered federally listed mussel species or species of concern, and other freshwater mussel species that may occur in these waterways, and determine an estimate of relative abundance and relative composition. Objective 3 – Provide a report that describes estimated species richness, relative abundance, relative composition, diversity and abiotic variables, to be used to create future management plans for protection or improvement of habitat to encourage conservation for mussels found within the BCNWR along with GIS locations and maps of assemblage results. METHODS Study Areas / Sample Site Established in 1980, BCNWR is located within the Pearl River watershed. The 36,502-acre refuge is bisected by the West Pearl River, the Bogue Chitto River, and Holmes Bayou. The refuge is bounded by the Pearl River, East Pearl River, and the Pearl River Navigation Canal. The Mississippi Old River Wildlife Management Area (15,400 acres) and the State of Louisiana's Pearl River Wildlife Management Area (35,031) are adjacent to the refuge, forming an 87,000-acre block of protected forested wetlands and adjacent uplands within the Pearl River Basin. In addition to these protected areas, the Pearl River extends 61 river miles north of the refuge in Louisiana, and the Bogue Chitto River continues 56 miles to the northwest in Louisiana. Impediments to the passage of aquatic organisms within the watershed include the diversion at Walkiah Bluff, the low water sill on the Bogue Chitto River, and the low water sill on the Pearl River at Pools Bluff. Fifty sites were sampled across the watershed to achieve the project objectives (Table 1, Appendix I Maps 1-10). Within BCNWR The BCNWR can be further delineated into 5 sectors: 1. Upper West Pearl / Wilson Sough (Table 1, Appendix I Map 3). a. Sites: 12, 13, 14, 16, 17, 18 ,19, 20, 23, and 24 2. East Pearl River - south of the Walkiah Diversion / Holmes Bayou (Table 1, Appendix I Map 4). a. Sites: 15, 21 and 22 3. Upper Pearl River - north of the Walkiah Diversion (Table 1, Appendix I Map 5). a. Sites: 25, 26, 27 and 28 4. Bogue Chitto - below the sill (Table 1, Appendix I Map 6). a. Sites: 38 and 39 5. Lower West Pearl River - south of the confluence at Holmes Bayou (Table 1, Appendix I Map 7). a. Sites: 8, 9, 10 and 11 Pearl River Watershed within Louisiana, outside BCNWR Sample sites beyond the boundaries of the BCNWR were selected in an attempt to quantify the presence or absence of the threatened and endangered Potamilus inflatus and delineate differences in community structure at impediment points for river fish passage. Areas outside the BCNWR can be delineated further into distinct habitat sectors which include: 1. Bogue Chitto - north of the sill (Table 1, Appendix I Map 8). a. Sites: 40, 41, 42, 43, 44, 45, 46, 47, 48, 49 and 50 2. Pearl River - north of the sill (Table 1, Appendix I Map 9). a. Sites: 29, 30, 31, 32, 33, 34, 35, 36 and 37 3. Lower West Pearl River - south of the confluence at Holmes Bayou (Table 1, Appendix I Map 10). a. Sites: 1, 2, 3, 4, 5, 6 and 7 Table 1. BCNWR freshwater mussel sample stations and associated GPS coordinates (decimal degree) sampled in the summer of 2018. Site LDEQ sub- Number Site Reference basin BCNWR Latitude Longitude 1 5554-1 90202 30.29347 -89.69859 2 5555-2 90202 30.30693 -89.70453 3 5556-3 90202 30.31670 -89.69516 4 5557-4 90202 30.32215 -89.69537 5 5558-5 90202 30.33400 -89.70845 6 5559-6 90202 30.36252 -89.71880 7 5519-7 90202 30.36532 -89.72173 8 5560-8 90202 30.40430 -89.74327 9 5517-9 90202 30.42953 -89.73873 10 5561-10 90202 30.44280 -89.74966 11 5562-11 90202 X 30.45227 -89.75474 12 5534-12 90201 X 30.46527 -89.77250 13 5563-13 90201 X 30.46875 -89.77893 14 5516-14 90201 X 30.47531 -89.78063 15 5564-15 90106 X 30.49549 -89.75723 16 5565-16 90201 X 30.50227 -89.80411 17 5533-17 90201 30.50621 -89.80044 18 5566-18 90201 X 30.51600 -89.79739 19 5520-19 90201 X 30.51792 -89.80422 20 5567-20 90201 X 30.52454 -89.80506 21 5568-21 90106 X 30.53687 -89.77347 22 5569-22 90106 X 30.54716 -89.79994 23 5532-23 90201 X 30.54731 -89.82764 24 5570-24 90201 X 30.55209 -89.83430 25 5521-25 90107 X 30.60367 -89.82175 26 5571-26 90107 X 30.60630 -89.82022 27 5572-27 90107 X 30.62497 -89.82203 28 5573-28 90107 X 30.65430 -89.83021 29 5522-29 90101 30.72484 -89.83945 30 5574-30 90101 30.80422 -89.81394 31 5575-31 90101 30.80842 -89.80214 32 5576-32 90101 30.81033 -89.78843 33 5577-33 90101 30.82075 -89.78177 34 5578-34 90101 30.85129 -89.79042 35 5579-35 90101 30.88629 -89.77388 36 5580-36 90101 30.96217 -89.73891 37 5581-37 90101 30.99261 -89.72809 38 5548-38 90203 X 30.59772 -89.84586 39 5547-39 90203 30.61117 -89.85210 40 5524-40 90501 30.62213 -89.87791 41 5582-41 90501 30.62854 -89.90935 42 5583-42 90501 30.63882 -89.96250 43 5584-43 90501 30.66528 -89.99035 44 5585-44 90501 30.66153 -89.99719 45 5586-45 90501 30.67353 -90.01984 46 5587-46 90501 30.69823 -90.06481 47 5588-47 90501 30.73129 -90.10610 48 5589-48 90501 30.74787 -90.12136 49 5590-49 90501 30.76084 -90.13691 50 5591-50 90501 30.94955 -90.20414 Sampling Protocol Sampling adhered to the qualitative protocol (timed searches) established by Louisiana Department of Wildlife and Fisheries (LDWF) and Louisiana State University (LSU), and concentrated on primary mussel habitat parameters. Qualitative surveys produce a more complete species list, especially when determining the presence of a rare species (Strayer et al. 2003). Timed qualitative searches were performed at each established sample site. Biologists located mussels by tactile search along the littoral zones (<1 m depth), retrieving both living mussels and shell.