Mapleleaf mussel (Quadrula quadrula) COSEWIC assessment and status report: chapter 4

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Distribution

Global range

Quadrula quadrula is distributed throughout the Ohio-Mississippi River drainages extending southeast to Louisiana, southwest to eastern Texas and northwest to Minnesota (Clarke 1981; Parmalee and Bogan 1998). It is present in the Red River drainage in North Dakota, Minnesota and Manitoba (Clarke 1981; Cvancara 1983). In the Great Lakes drainage it has been recorded from the Lake Erie and Lake St. Clair drainages. In the United States Q . quadrula has been reported from the states of Alabama, Arkansas, Iowa, Illinois, Kansas, Kentucky, Louisiana, Michigan, Minnesota, Missouri, Mississippi, North Dakota, Nebraska, New York, Ohio, Oklahoma, Pennsylvania, South Dakota, Tennessee, Texas, Wisconsin and West Virginia (Parmalee and Bogan 1998; NatureServe. accessed 26 November 2004).

Canadian range

In Canada, Quadrula quadrula has been reported only from Manitoba and Ontario (Figure 4). In Manitoba Q . quadrula has been recorded from the Assiniboine River, Bloodvein River, Red River and the Roseau River. In Ontario Q . quadrula has been reported from Lake St. Clair and western Lake Erie and tributaries including the Sydenham, Ausable, Grand, Thames Rivers and others.

Distribution of Quadrula quadrulain Ontario

The National Water Research Institute’s Lower Great Lakes Unionid Database was used to identify occurrence records for Quadrula quadrula in Ontario. The database is continually updated with the results of new surveys by Janice Metcalfe-Smith and her team as well as surveys elsewhere in Ontario by other organizations such as the Department of Fisheries & Oceans’ Great Lakes Laboratory for Fisheries and Aquatic Sciences and the Eastern Ontario Biodiversity Museum. At the time of writing the database consisted of approximately 8,200 records for 40 species collected from nearly 2,500 sites throughout the Lake Ontario, Lake Erie, Lake St. Clair and lower Lake Huron drainage basins since 1860. For a detailed description of the database and its historical data sources, see Metcalfe-Smith et al. (1998a).

Quadrula quadrula was historically collected from the Detroit, Sydenham, Thames, Grand, Welland and Niagara Rivers as well as Lake Erie and Lake St. Clair. The earliest known records of the species in each of these waterbodies was as follows: between the 1880s and 1930s by various surveyors for the Detroit River (Schloesser et al. submitted), 1963 by H.D. Athearn for the Sydenham River near Shetland, 1894 by J. Macoun for the Thames River near Chatham, 1885 by J. Macoun for the Grand River near Cayuga, 1983 by D.J. Berg for the Welland River in Welland, 1934 by J.P. Oughton for the Niagara River, 1894 by J. Macoun for Lake Erie at Rondeau Bay, and 1965 by C.B. Stein for Lake St. Clair near the mouth of the Thames River. Figure 5 shows the historical distribution of Q. quadrula in Ontario based on 78 records collected between 1885 and 1994. The current distribution of the species is shown in Figure 6 and is based on 57 records (live animals and shells) collected between 1995 and 2005. Live specimens were most recently collected from the Lower Thames River in September 2005.

Populations of Quadrula quadrula and other species of freshwater mussels in the Canadian and U.S. waters of the lower Great Lakes and connecting channels have been almost entirely lost due to the impacts of dreissenid mussels (Dreissena polymorpha and D. bugensis). Small isolated populations can still be found in some nearshore areas where densities of dreissenids have remained low (e.g. Nichols and Wilcox 1997; Zanatta et al. 2002). In the Detroit River, less than 10% of the unionid population and only 13 of 24 species present prior to the dreissenid invasion survived to 1994 (Schloesser et al.1998). Only 5 live mussels were found during follow-up surveys at several sites in 1998 (Schloesser et al. submitted) and none were Q. quadrula. Nalepa et al. (1996) surveyed 29 sites in the offshore waters of Lake St. Clair in 1986, 1990, 1992 and 1994. Quadrula quadrula was found alive at one site in U.S. waters in both 1986 and 1990 but not during later surveys. Gillis and Mackie (1994) surveyed an area off the mouth of the Puce River on the southwestern shore of Lake St. Clair between 1990 and 1992. The number of species found declined from 11 in 1990 to 4 in 1991 and no live mussels were found in 1992. They did not find any Q. quadrula during their surveys. Zanatta et al. (2002) surveyed 95 sites in nearshore areas around Lake St. Clair between 1999 and 2001 and found one Q. quadrulaat a site near the mouth of the Thames River in 1999. Metcalfe-Smith et al. (2004) surveyed 28 sites in Canadian and U.S. waters of the Lake St. Clair delta in 2003 and did not find any live Q. quadrula . Quadrula quadrula was reported from Rondeau Bay on the north shore of Lake Erie in 1894 and 1961, but only old weathered shells were found during a survey in 2001 (D.T. Zanatta, unpublished data). There are records for Q. quadrula from Pelee Island in 1962, 1978 and 1985 and shells were collected in 1992. Although there have been no further surveys around Pelee Island, 19 sites around the nearby Bass Islands (U.S. waters) were surveyed in 1998 and no live unionids were found (Ecological Specialists 1999). One site on South Bass Island had supported 27 live species of mussels in 1960. There are two historical records for Q. quadrula from the Niagara River. Thirteen sites were surveyed in 2001 for the New York Power Authority. Old shells of 16 species were found and one site had living animals of 3 species; unfortunately, the consultant who did the survey was unable to disclose the names of the species found alive (K. Schneider, Stuyvesant Falls, NY, pers. comm., November 2002). There are no recent data available for the Welland River.

According to Metcalfe-Smith et al. (2003), Quadrula quadrula has been encountered more frequently in the Sydenham River during recent surveys than in the past. It was found at 56% of 16 sites surveyed in 1997-1999 vs. 30% of 23 sites surveyed in the same reaches between 1929 and 1991. Intensive survey work on the Sydenham River has continued and by the end of 2004 a total of 18 sites had been sampled semi-quantitatively and 15 sites quantitatively (13 sites were sampled using both techniques). New data have extended the known range of Q. quadrula further downstream in the east branch of the river, but the range of this species may have contracted in the north branch (Metcalfe-Smith and Zanatta 2003; Metcalfe-Smith et al., unpublished data).

There are only scattered historical records available for mussels in the Thames River. However, Quadrula quadrulawas reported from several locations in the middle and lower reaches in 1894, 1934, 1963, 1973, 1985 and 1991-92. The river has been extensively surveyed in recent years. Morris (1996) surveyed 30 sites in 1994, focusing on the smaller tributaries, and found Q. quadrula at one site on McGregor Creek in Chatham. Metcalfe-Smith et al. (1998b, 1999) surveyed 16 sites, mainly on the main stem, in 1997-98 and observed the species at 7 sites in the lower part of the watershed. Morris surveyed 25 sites in the Upper Thames River above Delaware in 2004 and did not find Q. quadrula at any site (T.J. Morris, Department of Fisheries and Oceans, Burlington, ON, unpublished data). In 2005, Morris returned to the lower Thames River and found Q. quadrula at 10 sites. Although his data do not extend the range in the Thames they do fill some previous gaps in coverage and show that most of the lower Thames is occupied by the Mapleleaf. The available data do not indicate any change over time in the distribution of Q. quadrula in the Thames River.

The Grand River is one of the best studied watersheds for mussels in Ontario, with nearly 1,000 records available from 1885-2004. Collections have been made in nearly every decade. Major surveys were conducted in 1970-72 (68 sites, Kidd 1973) and in 1995 and 1997-98 (94 sites, Metcalfe-Smith et al. 2000a). There have been no changes over time in the distribution of Quadrula quadrula in the Grand River; it has always occurred in the lower 50 km of the river between Caledonia and Port Maitland.

Detweiler (1918) surveyed the Ausable River in 1916 primarily for thick-shelled species that could be used in the pearl button industry. There are also records from 1929 and 1950 for a site near Hungry Hollow in the lower portion of the watershed and Morris and Di Maio (1998-1999) surveyed 6 sites on the river in 1993-94. Quadrula quadrula was not among the 14 species found during these surveys. Metcalfe-Smith et al. (unpublished data) surveyed 25 sites throughout the river from 1998-2004 and found 23 species of mussels alive including Quadrula quadrula, which was restricted to 4 sites in a short stretch of the lower main stem of the river. It is unlikely that Q. quadrula ever occurred in the lower Lake Huron drainage north of the Ausable River. It was not among 7 species found by Morris and Di Maio (1998-1999) during surveys of 6 sites on the Saugeen River in 1993-94 nor was it among 11 species found by Metcalfe-Smith et al. (unpublished data) during surveys of 21 sites on the Maitland River in 1998-2004.

Overall, Quadrula quadrula has been lost from approximately 49% of its former range (in terms of extent of occurrence) in Ontario, with virtually all of this loss occurring in the Great Lakes and connecting channels. The current extent of occurrence (EO) is approximately 12,500 km² as compared with 24,500 km² historically. The current area of occupancy (AO) is approximately 35.2 km² (Table 2).

Distribution of Quadrula quadrula in Manitoba

There are few historical records for Quadrula quadrulain Manitoba. Clarke (1973) summarized the history of malacological research in the Canadian Interior Basin as well as results from investigations into mollusc distributions undertaken from 1959-1969. During this time, surveys within Manitoba were conducted for 7 years. A total of 103 stations were examined and approximately 15,310 specimens representing 13 species were collected. Sampling methods included visual search in clear water, using a glass-bottomed viewing box, and feeling by hand. This indicates collecting was done close to shore in water that would not exceed waist deep (approximately 1 m). Pip (pers. comm., 2000), from 1961 to present, was investigating freshwater molluscs in Manitoba and recorded the presence of freshwater mussels at a variety of sites along the Assiniboine River, tributaries of the Red River and Lake Winnipeg. These 2 sources, with the contribution of a single study by Scaife and Janusz (1992), provide the bulk of information for the historical distribution of Quadrula quadrula in Manitoba.

Results summarized by Clarke (1973) indicate that, within the Hudson Bay drainage, Quadrula quadrula was distributed within the Red River and lower reaches of larger tributaries of the Red River such as the Assiniboine and Roseau rivers in Manitoba (Figure 7), Red Lake River in Minnesota and the Pembina and Sheyenne rivers in North Dakota. Within the boundaries of Manitoba, Clarke (1973) records Q. quadrula from the Red River at St. Jean Baptiste and Aubigny and reports additional historical records from the Red River at Fort Garry, Winnipeg and Emerson. Quadrula quadrula was also collected from the Assiniboine River in and near Winnipeg and from the Roseau River near Tolstoi. Data recorded by Pip (pers. comm.) extend the distribution to the length of the Assiniboine River from Lake of the Prairies to Winnipeg and from sites on the Shell, Rat, Morris, Seine and LaSalle Rivers and from Lake Winnipeg. With the exception of the lower Assiniboine near Winnipeg, these are locations from which Q. quadrula has not previously, or subsequently, been observed (Clarke 1973, Watson et al.1998, Carney 2003a, unpublished data), The study reported by Scaife and Janusz (1992) in the Assiniboine River near Winnipeg, recorded Q. quadrula well within the distribution established by both Clarke (1973) and Pip (pers. comm.). Taken in concert, it seems reasonable to conclude that the historical distribution of this species was limited to the Red River and the lower reaches of its tributaries, the Assiniboine River, and Lake Winnipeg.

Recent investigations into the freshwater mussel fauna of Manitoba indicate a decline in the distribution of Quadrulaquadrula. Watson et al. (1998) and Carney (2003) report Q. quadrula from the lower Assiniboine River, in the stretch below the Portage Diversion, a large water control dam located at Portage la Prairie that diverts water from the Assiniboine River north to Lake Manitoba. Watson et al. (1998) surveyed 18 sites on 157 km of the Assiniboine River between Portage la Prairie and Winnipeg and recovered Q. quadrula from 4 sites. Watson et al. (1998) searched an additional 167 sites on 15 rivers draining into the Assiniboine River and encountered no evidence of Q. quadrula at any of these sites. Carney (2003, 2004a, b) surveyed 67 sites on 10 rivers and recovered live Q . quadrula from only some sites on the lower Assiniboine River. In addition, Carney (2003) collected a single, small individual approximately 50 km upstream of the Portage Diversion. This represents the only recent documented case of Q . quadrula upstream of the Portage Diversion. Extensive subsequent surveys from the Portage Diversion upstream to the Shellmouth Reservoir have not encountered any other individuals of this species (Carney unpublished data). In 1992 live Q . quadrula were recovered from the Roseau River (Carney, unpublished data), but not in the surveys conducted in 2003-2004. Carney (2004a) encountered no live Q . quadrula from the same sites along the Red River investigated by Clarke (1973) although there was ample evidence of fresh-dead individuals stranded due to low water levels in 2003. In 2004 Carney and Watkins (unpublished data) investigated sites along the Red River south of Winnipeg, including those reported by Clarke (1973), and found no live Q. quadrula. They did find half a dozen highly weathered empty valves. Recent surveys by Pip (pers. comm.) throughout Lake Winnipeg have found no evidence of Q . quadrula.

These data collectively indicate that the present distribution of Quadrula quadrula is limited to confirmed populations scattered throughout the lower Assiniboine River. Populations in the Assiniboine appear to occur as assemblages of a few widely separated individuals separated by long stretches of river bottom composed of drifting sand that is completely unsuitable habitat. It is likely that populations persist in the Red River based on the historical record, river size and current lack of extensive search effort. It is unknown if populations persist in the Roseau. Recent investigations have not recovered evidence of this species in this river at sites where it has been reported. However, the limited amount of search effort on this river, and low mussel densities cannot preclude the presence of Q . quadrula in the Roseau River.

The current distribution has declined by comparison to that recorded historically (Clarke 1973; Pip pers. comm.). The current extent of occurrence is approximately 11,500 km². The current area of occupancy is estimated to be 29.14 km² (Table 3). This should be considered an upper boundary because it assumes there are still populations in the Roseau and that the single individual collected above the Portage Diversion was not vagrant, and that the Red River still harbours populations.