Gulf of St. Lawrence aster COSEWIC assessment and status report: chapter 6

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Distribution

• Global range
• Canadian range

Global range

Gulf of St. Lawrence Aster is an endemic species of the Gulf of St. Lawrence region. It is found only in Quebec, New Brunswick and Prince Edward Island (PEI) (Houle and Haber, 1990; Gilbert et al., 1999). Its global distribution is therefore extremely limited (Figure 2). It colonizes sites of brackish sands in the Magdalen Islands, in Prince Edward Island and in New Brunswick. The localities are all within regions of comparable warmth and low elevations.

Figure 2. Canadian distribution of Gulf of St. Lawrence Aster

Canadian range

Distribution in Quebec

The distribution of Gulf of St. Lawrence Aster in the Magdalen Islands (MI), the only location where the species grows in Quebec, has been described in detail by Gagnon (1996), Gagnon et al. (1995a, 1995b) and Houle et al. (2002). During these surveys, all the sites mentioned in Houle and Haber (1990) were located again and three new sites (Localities 6, 14 and 16, Figure 3) were discovered. Certain occurrences recognized in the report by Gilbert et al. (1999), populations of which are segmented, were subdivided into two or three separate occurrences by Houle et al. (2002). In this report, we recognize these new subdivisions as separate occurrences.

Figure 3. Distribution of Gulf of St. Lawrence Aster in the Magdalen Islands

Occurrences of Symphyotrichum laurentianum in the Magdalen Islands.

The Magdalen Islands currently have 16 separate occurrences of Gulf of St. Lawrence Aster, including one dating from 1912 (Fernald, 1914), which has never been found again. The Havre aux Basques lagoon has three large populations, while others contain only a limited number of individuals. The total population of this species in the Magdalen Islands was estimated, in 2002, at more than 12 million individuals distributed over slightly less than 10 ha. A summary of the information gathered at each Quebec locality is provided in Table 1.

Distribution in New Brunswick.

Recent survey efforts have located four new occurrences in New Brunswick since 1999. For the original COSEWIC status report, Houle (1988b) surveyed two sites in New Brunswick, on Miscou Island (lighthouse) and near Tracadie (Val-Comeau). Gulf of St. Lawrence Aster populations are now known in four areas. One on Miscou Island (Malbaie south), discovered in 2002 (Sabine Dietz, Piper Project, pers. comm.), another near Tracadie (Val-Comeau), a third in Kouchibouguac National Park (two occurrences) and one at Bouctouche Dune (Godbout, 2000). There are therefore a total of seven occurrences (Figure 4), one of which is almost certainly historical in Kouchibouguac Park (St. Louis wharf). This locality, from which a specimen was collected in 1979 and identified as A. brachyactis by Munro (Hinds, 1983), was not found by Houle (1988b). The specimen itself is now untraceable in the herbaria consulted (DAO, GH, NBM and UNB). A reconnaissance survey conducted in 1999 (Dietz and Chiasson, 2001) also failed to find any population at this locality. A summary of the information gathered at each New Brunswick locality is provided in Table 2. Additional fieldwork at sites 2 and 7 conducted in 2003 after the completion of this report are included in the report (M. Toner, pers. comm.).

Figure 4. Distribution of Gulf of St. Lawrence Aster in New Brunswick

Malbaie south (upper right insert)

Distribution in Prince Edward Island

There are currently 10 known occurrences of Gulf of St. Lawrence Aster in Prince Edward Island, two of which are historical (Figure 5). Guignion et al. (1995) located six sites solely within Prince Edward Island National Park. One of these, East Marsh, has since been subdivided into two separate occurrences, East Marsh A and B (Denyse Lajeunesse, PEI National Park, pers. comm.). The type locality of Brackley Point has disappeared following development work carried out in the park. However, large populations have been observed elsewhere in the park, the largest at Blooming Point, namely occurrences 4, 5, 6 and 7 (Western Wetland, Dune Slack and East Marsh A and B). Elsewhere in Prince Edward Island, a population was located at Tignish, Prince County, on the northern tip of the island (Houle 1988b), but not seen again subsequently in 2001 or in 2002 (Sean Blaney, Atlantic Data Center, pers. comm.). All that remains of the Grand Tracadie site in Queens County is a single specimen collected by Fernald, Long and St. John in 1912 (GH!, in Houle, 1988b). During a brief visit in the 1984-86 period, Houle did not find any Gulf of St. Lawrence Aster there. A summary of the information gathered at each PEI locality is provided in Table 3.

Figure 5. Distribution of Gulf of St. Lawrence Aster in Prince Edward Island

Occurrences of Symphyotrichum laurentianum in Prince Edward Island.

PEINP: Data collected by the staff of the Prince Edward Island National Park (Denyse Lajeunesse, pers. comm., November 15, 2002)
UPEI: Data of Dr. C.R. Lacroix, from the University of Prince Edward Island (D. Lajeunesse, pers. comm.)
Ben Hoteling: instructor at Holland College; observations by him and his students (D. Lajeunesse, pers. comm.)
INT: Island Nature Trust, Prince Edward Island; pers. comm. of Kate MacQuarrie, November 12, 2002.