The Canadian Field-Naturalist First records of two freshwater mussel Species at Risk, Mapleleaf (Quadrula quadrula) and Lilliput (Toxolasma parvum), in the Canard River, Ontario, with implications for freshwater mussel recovery in the Detroit River Todd J. Morris1, *, Margaret N. Sheldon1, and Kelly A. McNichols-O’Rourke1 1Great Lakes Laboratory for Fisheries and Aquatic Sciences, Fisheries and Oceans Canada, 867 Lakeshore Road, Burlington, Ontario L7S 1A1 Canada *Corresponding author: [email protected] Morris, T.J., M.N. Sheldon, and K.A. McNichols-O’Rourke. 2020. First records of two freshwater mussel Species at Risk, Mapleleaf (Quadrula quadrula) and Lilliput (Toxolasma parvum), in the Canard River, Ontario, with implications for freshwater mussel recovery in the Detroit River. Canadian Field-Naturalist 134(2): 179–188. https://doi.org/10. 22621/v134i2.2549 Abstract Freshwater mussels of the family Unionidae are among the world’s most imperilled animals. A third of Canadian species have been assessed by the Committee on the Status of Endangered Wildlife in Canada as Extirpated, Endangered, Threatened, or Special Concern, with losses attributed to natural system modifications such as damming, pollution, exploitation for buttons and pearls, urbanization, and the introduction and subsequent effects of aquatic invasive species. In the Great Lakes basin, the introduction of dreissenid mussels in the 1980s caused catastrophic declines, with remnant populations restricted to lotic riverine habitats. In southwestern Ontario, the Canard River is the largest remaining direct tributary of the Detroit River that could provide a source of mussels to aid natural recovery. In 2019, nine sites in the Canard River were sampled using a timed- search approach (4.5 person-hours/site) with a combination of tactile searching by hand and mussel scoops (7-mm mesh) or underwater viewers. The search yielded 362 individuals of eight species, including two Species at Risk, Mapleleaf (Quadrula quadrula) and Lilliput (Toxolasma parvum), which had never been previously recorded in the Canard River. Key words: Bivalve; Unionidae; Great Lakes; Zebra Mussel; Dreissena polymorpha; Quagga Mussel; Dreissena rostriformis bugensis; Asian Clam; Corbicula fluminea Introduction Endangered Wildlife in Canada (COSEWIC). Freshwater bivalves have undergone large-scale Global declines have been attributed to a variety of global declines and are now among the most imper- causes including natural system modifications, such illed taxa in the world with ~40% of species consid- as damming, pollution, exploitation for buttons and ered at risk (Lopes-Lima et al. 2018). Within this pearls, urbanization, and the introduction and subse- group, the freshwater mussels of the order Unionida quent effects of aquatic invasive species (COSEWIC and family Unionidae are the most at risk. Lopes- 2016; Lopes-Lima et al. 2018). Although all of these Lima et al. (2018) report that 45% of the more than have contributed to the decline of Canadian freshwa- 800 species of Unionida have undergone assessment ter mussels, the arrival and establishment of dreisse- by the International Union for Conservation of Nature nid mussels (Zebra Mussel [Dreissena polymorpha] and are considered Near-Threatened, Threatened, or and Quagga Mussel [Dreissena rostriformis bugen- Extinct while at least two-thirds of the ~300 North sis]) in the Great Lakes basin in the mid-1980s proved American members of the family Unionidae are con- particularly catastrophic (Mackie 1991; Ricciardi et sidered at risk (Williams et al. 1993; Lopes-Lima et al. 1998). In little more than a decade after their ar- al. 2018). In Canada, 46% of Unionida are consid- rival, dreissenids had contributed to the near to- ered vulnerable to extirpated (CESCC 2016) and 19 tal extirpation of freshwater unionid mussels from species (35%) of Unionidae have already been as- Lake St. Clair (Nalepa et al. 1996), the Detroit River sessed as Extirpated, Endangered, Threatened, or (Schloesser et al. 1998, 2006), and the western basin Special Concern by the Committee on the Status of of Lake Erie (Schloesser and Nalepa 1994). 179 © Fisheries and Oceans Canada 2020. This work is freely available under the Creative Commons Attribution 4.0 International license (CC BY 4.0). 180 The Canadian Field-Naturalist Vol. 134 As the planktonic veliger larvae of dreissenid Methods mussels are not well adapted to establishment in lotic The Canard River, located in southwestern On- systems, it was recognized early that upstream riv- ta rio on the Essex Clay Plain, is a small low-gradi- erine habitats would represent important refuges for ent river draining an area of 347 km2. Land use in Ontario mussels (Clarke 1992). Two major river sys- Essex County, including the Canard River watershed, tems (Sydenham and Thames Rivers) and several is primarily agricultural (80–85%); only 4.5% of the smaller ones (Belle, Puce, and Ruscom Rivers for watershed is forested and <1% is considered wet- Lake St. Clair; Canard River for the Detroit River; land (Essex Region Conservation Authority 2015). Big Creek and Clear Creek in the western basin of Riparian forest is sparse in the Canard River water- Lake Erie) provide Canadian refuges for freshwa- shed with only 7.9% of riverbanks forested. Natural ter mussels of Lake St. Clair, the Detroit River, and flow patterns in the system have been heavily altered the western basin of Lake Erie. The Sydenham and in some areas through realignment by artificial means Thames Rivers represent Canada’s most speciose to support agriculture, and provincial guidelines for rivers, with historical complements of 35 species in nitrates, nitrites, ammonia, total phosphorus, and sus- each system and relatively intact assemblages of 34 pended solids are regularly exceeded (Essex Region and 32 species remaining in each system, respectively Conservation Authority 2015). (McNichols-O’Rourke et al. 2012). The smaller tribu- On 15 July 2019, visual reconnaissance of the taries of the southern shore (Belle, Puce, and Ruscom watershed was conducted to determine which sites would be sampled between 16 and 18 July 2019. Sites Rivers) have comparably smaller and less speciose were evaluated based on location in the watershed assemblages (4–8 species; McNichols-O’Rourke et al. (coverage and proximity to other sites), access, water 2012; Fisheries and Oceans Canada unpubl. data); depth, turbidity, substrate type, and any evidence of however, these five systems all represent potential the presence of mussels (e.g., shells or middens). The sources of recolonizers for the Lake St. Clair system. three sites surveyed by Morris and Di Maio (1998– In contrast to the multiple rivers of the Lake St. 1999) in 1993 were revisited during this reconnais- Clair drainage, the Canard River represents the one sance trip. In total, nine sites were selected for a full river system in Canada that drains directly into the survey based on the parameters outlined above: two Detroit River. Morris and Di Maio (1998–1999) pro- represented the historical sites of Morris and Di Maio vided the only available information on the Canard (1998–1999) and seven were new. These sites were River mollusc fauna when they surveyed three sites arranged such that seven, including both historical on the river in 1993, collecting only 15 individuals sites, were located in the main branch of the Canard of five species. Despite the low species richness and River and two were located in the south branch (Table abundance, the direct outflow of the Canard River 1; Figure 1). into the Detroit River makes it a potentially important Physical data were collected at each site us- source of natural recolonizers of the Detroit River if ing a range of equipment. Air temperature (Hanna recovery is likely to occur. The study described here HI98311 DiST 5 EC/TDS/Temperature Tester; ITM was designed to assess the current status and distri- Instruments Inc., Newmarket, Ontario, Canada), bution of the freshwater mussel assemblage of the wind speed (Kestrel 2000 Pocket Wind Meter; ITM Canard River with the goal of understanding the po- Instruments Inc., Newmarket, Ontario, Canada), and tential for this assemblage to contribute to future nat- weather by visual observation were recorded from the ural recolonization of the Detroit River. side of the river before the survey began. Additional Table 1. Sites, in upstream to downstream order, and dates of surveys by Fisheries and Oceans Canada in 2019. Site code Drainage Water body Latitude, °N Longitude, °W Survey date CRD-CRD-01 Lake Erie Canard River (main branch) 42.12329 82.84820 18 July CRD-CRD-09 Lake Erie Canard River (main branch) 42.13216 82.87779 17 July CRD-CRD-08 Lake Erie Canard River (main branch) 42.14094 83.00359 17 July CRD-CRD-02 Lake Erie Canard River (main branch) 42.15915 83.01888 18 July CRD-CRD-06 Lake Erie Canard River (main branch) 42.17483 83.03442 16 July CRD-CRD-05 Lake Erie Canard River (main branch) 42.18673 83.07065 16 July CRD-CRD-10 Lake Erie Canard River (south branch) 42.14268 83.06861 18 July CRD-CRD-07 Lake Erie Canard River (south branch) 42.16492 83.07537 17 July CRD-CRD-04 Lake Erie Canard River (main branch) 42.16947 83.09765 16 July 2020 Morris et al.: Freshwater mussels of the Canard River 181 Figure 1. Location of nine sites surveyed in the Canard River by Fisheries and Oceans Canada in 2019. parameters were collected from the river: water clar- Surveys were conducted in wadable habitats (max- ity (60-cm turbidity tube; Hoskin Scientific Ltd., Oak- imum depth searched = 1.56 m) following the timed- ville, Ontario, Canada), water velocity (OTT MF Pro search methods of Metcalfe-Smith et al. (2000), Flow Meter; OTT HydroMet, Loveland, Colo ra do, whereby each site was surveyed for 4.5 person-hours USA), and water chemistry, including water tem- (p-h) by a four- or five-person crew using a combina- perature, conductivity, total dissolved solids, optical tion of mussel viewers, mussel scoops (7-mm mesh; dissolved oxygen, pH, and turbidity (EXO hand held Wright et al.