Gulf of St. Lawrence aster COSEWIC assessment and status report: chapter 13

Technical summary

Symphyotrichum laurentianum
Gulf of St. Lawrence Aster

Aster du Saint-Laurent

Range of Occurrence in Canada: Gulf of St. Lawrence, Quebec (Magdalen Islands [MI]), Prince Edward Island (PEI), New Brunswick (NB)


Extent and area information

Extent of occurrence (EO) (km 2 ).
(Based on GIS calculation of a polygon in which all points at outer limits of range are included.)
perhaps ~2000
Specify trend in EO.
Stable
Are there extreme fluctuations in EO?
No
Area of occupancy (AO) (km 2 ).
<5
Specify trend in AO.
(Declines noted in NB and PEI may not be long term trends but may possibly reflect periodic fluctuations due to such significant impacts as major storm events.)
Stable overall in Magdalen Is. but with recent declines in some populations;
Possibly declining in PEI Fluctuating, possibly declining in NB
Are there extreme fluctuations in AO?
Yes due to storm events and natural fluctuations in population size of this annual species
Number of known or inferred current locations.
28 extant (33 total, of which 4 are historical and 1 not seen since 1986).
Specify trend in #.
Possibly stable but varies with fluctuations in populations due particularly to storm events
Are there extreme fluctuations in number of locations?
No
Specify trend in area, extent or quality of habitat.
(Area of occurrence fluctuates depending on such impacts as major storm events; recent declines noted may reflect temporary changes but this is uncertain.)
Possibly declining in PEI for 2 years.  Stable, overall, in MI;


Population information

Generation time (average age of parents in the population).
1 year
Number of mature individuals.
12 000 000 (MI), 1 000-2 000 (NB), ~40 000 (PEI)
Total: ~12 000 000
Total population trend:
Stable overall due to the large numbers in MI (fluctuating, and with recent declines in some populations in MI, possibly declining in NB and in PEI)
% decline over the last/next 10 years or 3 generations.
Not Applicable
Are there extreme fluctuations in number of mature individuals?
Yes
Is the total population severely fragmented?
Yes No
Specify trend in number of populations.
Stable overall (fluctuating, in MI, possibly declining in NB and in PEI).
Are there extreme fluctuations in number of populations?
No but some fluctuations occur
List populations with number of mature individuals in each:


Threats (actual or imminent threats to populations or habitats)

  • all-terrain vehicles (ATVs) in its habitat (dune slacks); filling of the habitat for construction or development work
  • covering of populations with sand during storm events
  • high water levels


Rescue effect (immigration from an outside source)

Status of outside population(s)?
USA: None
Is immigration known or possible?
Not Applicable
Would immigrants be adapted to survive in Canada?
Not Applicable
Is there sufficient habitat for immigrants in Canada?
Not Applicable
Is rescue from outside populations likely?
No (Endemic)


Quantitative Analysis

Not Applicable


Other status

Committee on the Status of Endangered Wildlife in Canada (COSEWIC): Special Concern (1989)
Quebec: Menacée
New Brunswick: Endangered
Prince Edward Island: rare but not officially listed


Status and reasons for designation

Status: Threatened
Alpha-numeric code: D2


Reasons for Designation: An annual halophyte of maritime littoral habitats endemic to the Gulf of St. Lawrence. It is found at nearly 30 extant sites with some very large populations, especially on the Magdalen Islands, but has a very small total area of occupancy of much less than five square kilometres. Many of the populations are subject to natural fluctuations in size and at times suffer important losses due to severe storm events. On-going impacts also exist from human recreational activities and losses of habitat due to development activities.


Applicability of criteria

Criterion A (Declining Total Population): Not Applicable. Declines in NB and PE are relatively small in relation to huge population size in Magdalen Islands; some new populations have also been found in NB and the Magdalen Islands due to increased search effort and the recent losses of populations due to storm events are too recent to recognize as being permanently extirpated since the seeds of the species have a longevity of as much as 10 years.

Criterion B (Small Distribution, and Decline or Fluctuation): Not Applicable. Although possessing small EO and AO there is uncertainty as to whether the populations are severely fragmented due to the plants manner of seed dispersal and the uncertainty, over the long term, of the impact of fluctuating population sizes and the impact of storm events.

Criterion C (Small Total Population Size and Decline): Not Applicable. Total minimum population is too large.

Criterion D (Very Small Population or Restricted Distribution): Threatened under D2 with an area of occupancy <5 km2.

Criterion E (Quantitative Analysis): Not Applicable.

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