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American water-willow (Justicia americana) recovery strategy: chapter 3

2. Population and distribution

2.1 Population and distribution objectives

The population and distribution objective is to maintain (and if possible increase) the current number of individuals to maintain the actual number of locations (10) and to prevent the decline in the quality of habitat.

2.2 Broad strategies and approaches to recovery

Recovery planning involves considering the threats and challenges associated with meeting the recovery objectives for the species. Recovery success requires close cooperation among the local participants who head the implementation of recovery actions.

Broad strategies and approaches for achieving the population and distribution objectives for American Water-willow are presented in Table 3. These priorities will be revisited in the action planning stage.

 

Table 3. Broad strategies and approaches for American Water-willow recovery
Approach Priority Threat / Concern Addressed Broad Strategy Outcome
1: Engage landowners and managers of sites that neighbour or harbour the American Water-willow populations in stewardship action and protection Medium Habitat loss Coordinate and encourage the actions of governments and NGOs with respect to population surveys, communications with landowners / land managers and protection activities.

A stewardship guideline and management practices is produced and stewardship measures (including briefings of landowners and land managers whose property includes or borders critical habitats) are implemented.

Encourage the gathering and transfer of Traditional Ecological Knowledge from Knowledge Holders to others.
2: Enhance current knowledge of the distribution and abundance of the American Water-willow populations throughout the species' current and historic range Medium Knowledge gap Revisit all sites of historical occurrence that continue to present potential for supporting this species. Inventories of sites of known historical occurrence that continue to present a potential for supporting this species.
2: Enhance current knowledge of the distribution and abundance of the American Water-willow populations throughout the species' current and historic range Medium Knowledge gap With the possible ephemeral nature of the species, seek opportunities to search for ‘new’ American Water-willow colonies in suitable habitats along the Ontario shorelines of the St. Lawrence River, the length of Niagara River, and on the Canadian site of Lake Erie. Identification of areas of suitable habitat where in-depth surveys can take place and inventories of all potential sites started.
3: Determine the biological requirements for the maintenance and growth of American Water-willow populations and document natural range of variability in population abundance Medium Knowledge gap Characterize the American Water-willow's habitat in Canada. Characterization of the American Water-willow's habitat in Canada.
3: Determine the biological requirements for the maintenance and growth of American Water-willow populations and document natural range of variability in population abundance Low Knowledge gap, Pollution Measure water quality parameters at current sites Acquisition of knowledge of the required physico-chemical characteristics of water for the maintenance and growth of American Water-willow populations.
3: Determine the biological requirements for the maintenance and growth of American Water-willow populations and document natural range of variability in population abundance Medium Knowledge gap (pop. dynamics) Identify the natural rhythm of fluctuation in American Water-willow populations with a view to determining whether the population is at risk or is simply experiencing normal variations. A completed report concerning population dynamics of American Water-willow populations.
3: Determine the biological requirements for the maintenance and growth of American Water-willow populations and document natural range of variability in population abundance Low Knowledge gap Assess if sexual reproduction is occurring by looking into insect pollination and seed dispersal. A completed study on the conditions required for pollination and dispersion.
4: Determine the pertinence and feasibility of increasing the number of individuals (augmentation) at actual sites, once knowledge about the ecology of this species has grown to the required levels and techniques of sowing and transplantation have become sufficiently refined; Medium Knowledge gap, Habitat loss Increase knowledge to determine if augmentation actions are appropriate. Informed knowledge base to determine if augmentations are appropriate.
4: Determine the pertinence and feasibility of increasing the number of individuals (augmentation) at actual sites, once knowledge about the ecology of this species has grown to the required levels and techniques of sowing and transplantation have become sufficiently refined; Medium Habitat loss Knowledge gap For sites recommended for augmentation, identify the specific conditions necessary to proceed with population restoration. As required, identification of conditions conducive to augment the number of individuals at specific populations.
4: Determine the pertinence and feasibility of increasing the number of individuals (augmentation) at actual sites, once knowledge about the ecology of this species has grown to the required levels and techniques of sowing and transplantation have become sufficiently refined; Medium Knowledge gap Develop effective transplantation or sowing technique. Development of an effective transplantation or sowing technique.
4: Determine the pertinence and feasibility of increasing the number of individuals (augmentation) at actual sites, once knowledge about the ecology of this species has grown to the required levels and techniques of sowing and transplantation have become sufficiently refined; Medium Habitat loss Augment, the American Water-willow plants in current sites in accordance with a rigorously controlled experimental set-up. Augment, where suitable and needed, the number of individual American Water-willow plants in actual sites.
5: Determine the degree of genetic diversity both within each population and between different American Water-willow populations. Low Knowledge gap Assess the relative extent of vegetative and sexual reproduction between Canada's two main populations. Acquisition of additional knowledge about the relative extent of vegetative and sexual reproduction among Canada's two main populations.
5: Determine the degree of genetic diversity both within each population and between different American Water-willow populations. Low Knowledge gap Perform genetic testing to determine the differences among, and within, the main Canadian populations. Perform genetic testing to determine the differences among Canadian populations, and the variability within populations.
6: Determine population viability Medium Knowledge gap Determine viability of American Water-willow populations in Canada. Determination of what is a viable population.
6: Determine population viability Medium Knowledge gap Establish population targets for each sites. Have a population abundance target established for each site.
7: Document threats more precisely Medium All threats, Knowledge gap Document more precisely the nature and extent of existing threats at known and recently discovered sites. A completed report describing the threats affecting known populations (new and old ones).
7: Document threats more precisely Medium All threats Initiate the implementation of site-specific actions to address the highest priority threats Reduce the impacts of most severe threats at each site.

2.3 Performance measures

  1. There will be at least 10 American Water-willow populations in 10 years.
  2. The number of individuals will have been maintained or increased.
  3. An increase in site protection through stewardship and other management initiatives will be noted by 2016: approach 1.
  4. At least 60 % of landowners neighbouring the colonies will have been made aware of this species by 2016: approach 1.

2.4 Critical habitat

Under SARA, critical habitat is defined as the habitat necessary for the survival or recovery of the listed species, and is meant to represent the habitat needed by the species to meet the stated population and distribution objectives. The critical habitat identified here is based on the best available information at this time.


2.4.1 Critical habitat identification

Critical habitat is identified for each of the 10 extant populations of American Water-willow. The critical habitat identified here is based on the best available information at this time, the quality of which varied from site to site. Consequently, slightly different methods were used to identify critical habitat at each site. For some sites, critical habitat has been identified comprehensively, with sufficient occupied and unoccupied suitable habitat included to allow for metapopulation dynamics to occur. For other sites, an occupancy-based approach was used, in which only the suitable habitat immediately around existing plants was identified as critical habitat.

In addition, for all but one site, the entire polygon (as depicted in the maps to follow) are critical habitat. For the site at Point Pelee National Park, critical habitat is only those parts within the defined area where specified biophysical attributes are found.

The biophysical attributes of the critical habitat for this species are defined as sheltered coves, shoals and shores of rivers, streams, ponds and lakes, where they form almost single-species colonies. The soil substrates used by American Water-willow varies from clay to sand to gravel and even rock. The species also tolerates considerable fluctuation in water levels and can even be found on non-submerged, though very wet soils adjacent to water bodies (adapted from Jolicœur and Couillard 2007).

Critical habitat does not include existing human infrastructures (sidewalks, wharves, bridges).

Details concerning the critical habitat identification for each of the 10 populations is as follows:

Leamington

The location of the critical habitat for the American Water-willow at the Leamington Municipal Marina, within the town of Leamington, is shown in Figure 3.

It is located within the rip-rap shoreline on the east side of the marina at the following approximate coordinates : southwest limit is at Latitude 82° 35' 47.45" W and Longitude 42° 1' 34.91" N. Northwest limit is at Latitude 82° 35' 47.37" W and Longitude 42° 1' 35.31" N. Northeast limit is at Latitude 82° 35' 46.83" W and Longitude 42° 1' 35.25" N. Southeast limit is at Latitude 82° 35' 46.92" W and Longitude 42° 1' 34.85" N.

The critical habitat includes an area of 5 m in all directions from the outside edge of the American Water-willow population which was approximately 2 m long by 1 m wide in 2009. Minimum critical habitat area is therefore 12 m long (parallel to the shoreline) by 11 m wide (perpendicular to the shoreline). The critical habitat includes the area underwater to a maximum depth of 1.1 m or 5 m downslope from the edge of the colony, whichever limit comes first.

Point Pelee National Park

Within Point Pelee National Park, critical habitat for the American Water-willow has been identified as the eastern sand/fine gravel high water mark along the shore of Pond Lake into the lake where the water reaches a depth of 1.1 m, within the area delineated by the bounding box as shown in Figure 4.

Monocultures of Common Reed within this area are excluded from critical habitat identification (American Water-willow cannot successfully compete against this species).

Pelee Island

Critical habitat is located along the southern point of Pelee Island, in Lake Erie, off South Shore road, 200 m west of a marina on a cobblestone shoreline as shown in Figure 5.

The critical habitat covers an area of 25 m2. The approximate coordinates for the two points on the shoreline are as follows : Northwest limit is at Longitude 82° 38' 34" W, and Latitude 41° 44' 32" N. Northeast limit is at 82° 38' 30" W, and Latitude 41° 44' 33" N.

Lyon's Creek

This area is occupied by an almost continuous stand of the American Water-willow. The critical habitat is a 5.5 km stretch of Lyon's Creek and covering 11.7 ha as shown in Figure 6.

Dufferin Island

Dufferin Island is located in a wetland adjacent to the Niagara river, below the Niagara river dam on the west side of the Niagara Parkway. The critical habitat is a 225 m2 area that is completely occupied by a dense patch of American Water-willow (Figure 7).

Grenadier Island

Grenadier Island is located in the Thousand Islands area. The critical habitat is a 170 m2 area located on the south shore of the island as shown in Figure 8. Coordinates for the southwestern limit is Longitude 75° 52' 59" W, and Latitude 44° 23' 44" N. and for the southeastern limit Longitude 75° 52' 59" W, and Latitude 44° 23' 44" N.

Hill Island

Hill Island is located in the Thousand Islands area in Ontario in the vicinity of St. Lawrence Island National Park in Ontario. Eight parcels of critical habitat are identified around the island as shown in Figure 9. For each parcel, critical habitat extends 15 m from the center point of known colonies, along the shoreline and out into the water to allow for population growth. Critical habitat does not extend on to land.

Ile Rock

Ile Rock is an island located in the Lachine rapids between Ile des Soeurs (Nuns' Island) and Ile aux Chèvres (Goat Island) in the St. Lawrence River south of Montreal. The island itself encompasses an area of 0.25 ha.

The critical habitat for the American Water-willow at Ile Rock consists of the shoreline area, extending 10 m away from the shore of the island, on the north and east side of the island as shown in Figure 10. This critical habitat occupies an approximate area of 970 m2.

Mille Îles River

This critical habitat is located in the Mille Iles River, between Terrebonne and Laval Island, north of Montreal in the vicinity of the Rapides du Moulin. This area covers 2.6 km2. The critical habitat starts from the west at the eastern point of Ile Saint-Jean (Beausoleil park, Terrebonne) at 150 m southwest of the dam on Ile des Moulins and extends 10 km eastward to end at Terrasse Mathieu street (Terrebonne) 500 m upstream from the highway 40 bridge as shown in Figure 11.

Rivière Godefroy

This critical habitat is located on lands that, for the most part, come within the boundaries of the Réserve écologique Léon-Provancher, a conservation reserve located just west of Bécancour and south of Trois-Rivières as shown in Figure 12.

The critical habitat covers a total area of 0.63 ha. It is located on either sides of the Rivière Godefroy in a stand of Silver Maple (Acer saccharinum). Rivière Godefroy is a small outlet of Lake St-Paul and a tributary of the St.Lawrence River.


Figure 3. Leamington critical habitat

Leamington Critical Habitat (see long description below).
Description of Figure 3

Figure 3 is a map showing the location of the critical habitat for the American Water-willow at the Leamington Municipal Marina, within the town of Leamington.

It is located within the rip-rap shoreline on the east side of the marina at the following approximate coordinates : southwest limit is at Latitude 82° 35' 47.45" W and Longitude 42° 1' 34.91" N. Northwest limit is at Latitude 82° 35' 47.37" W and Longitude 42° 1' 35.31" N. Northeast limit is at Latitude 82° 35' 46.83" W and Longitude 42° 1' 35.25" N. Southeast limit is at Latitude 82° 35' 46.92" W and Longitude 42° 1' 34.85" N.

 


Figure 4. Area within which critical habitat parcel #206_11 is found

Area within which critical habitat parcel #206_4 is found (see long description below).
Description of Figure 4

Figure 4 is a map showing critical habitat for the American Water-willow within Point Pelee National Park. The critical habitat has been identified as the eastern sand/fine gravel high water mark along the shore of Pond Lake into the lake where the water reaches a depth of 1.1 m.

 


Figure 5. Pelee Island critical habitat

Pelee Island critical habitat (see long description below).
Description of Figure 5

Figure 5 is a map showing critical habitat for the American water-willow located along the southern point of Pelee Island, in Lake Erie, off South Shore road, 200 m west of a marina on a cobblestone shoreline.

The critical habitat covers an area of 25 m2. The approximate coordinates for the two points on the shoreline are as follows : Northwest limit is at Longitude 82° 38' 34" W, and Latitude 41° 44' 32" N. Northeast limit is at 82° 38' 30" W, and Latitude 41° 44' 33" N.

 


Figure 6. Lyon's Creek critical habitat

Lyon's Creek critical habitat (see long description below).
Description of Figure 6

Figure 6 is a map showing the area is occupied by an almost continuous stand of the American Water-willow. The critical habitat is a 5.5 km stretch of Lyon's Creek and covering 11.7 ha.

 


Figure 7. Dufferin Island critical habitat

Dufferin Island critical habitat (see long description below).
Description of Figure 7

Figure 7 is a map showing Dufferin Island. It is located in a wetland adjacent to the Niagara river, below the Niagara river dam on the west side of the Niagara Parkway. The critical habitat is a 225 m2 area that is completely occupied by a dense patch of American Water-willow.

 


Figure 8. Grenadier Island critical habitat

Grenadier Island critical habitat (see long description below).
Description of Figure 8

Figure 8 is a map showing Grenadier Island. It is located in the Thousand Islands area. The critical habitat is a 170 m2 area located on the south shore of the island. Coordinates for the southwestern limit is Longitude 75° 52' 59" W, and Latitude 44° 23' 44" N. and for the southeastern limit Longitude 75° 52' 59" W, and Latitude 44° 23' 44" N.

 


Figure 9. Hill Island critical habitat

Hill Island critical habitat (see long description below).
Description of Figure 9

Figure 9 is a map showing Hill Island. It is located in the Thousand Islands area in Ontario in the vicinity of St. Lawrence Island National Park in Ontario. Eight parcels of critical habitat are identified around the island. For each parcel, critical habitat extends 15 m from the center point of known colonies, along the shoreline and out into the water to allow for population growth.

 


Figure 10. Île Rock critical habitat

Île Rock critical habitat (see long description below).
Description of Figure 10

Figure 10 is a map showing Île Rock. It is an island located in the Lachine rapids between Île des Soeurs (Nuns' Island) and Île aux Chèvres (Goat Island) in the St. Lawrence River south of Montreal. The island itself encompasses an area of 0.25 ha.

The critical habitat for the American Water-willow at Île Rock consists of the shoreline area, extending 10 m away from the shore of the island, on the north and east side of the island. This critical habitat occupies an approximate area of 970 m2.

 


Figure 11. Rivière des Mille Îles critical habitat

Rivière des Mille Iles critical habitat (see long description below).
Description of Figure 11

Figure 11 is a map showing critical habitat located in the Mille Îles River, between Terrebonne and Laval Island, north of Montreal in the vicinity of the Rapides du Moulin. This area covers 2.6 km2. The critical habitat starts from the west at the eastern point of Île Saint-Jean (Beausoleil park, Terrebonne) at 150 m southwest of the dam on Île des Moulins and extends 10 km eastward to end at Terrasse Mathieu street (Terrebonne) 500 m upstream from the highway 40 bridge.

 


Figure 12. Rivière Godefroy critical habitat

Rivière Godefroy critical habitat (see long description below).
Description of Figure 12

Figure 12 is a map showing critical habitat located on lands that, for the most part, come within the boundaries of the Réserve écologique Léon-Provancher, a conservation reserve located just west of Bécancour and south of Trois-Rivières.

The critical habitat covers a total area of 0.63 ha. It is located on either sides of the Rivière Godefroy in a stand of Silver Maple (Acer saccharinum). Rivière Godefroy is a small outlet of Lake St-Paul and a tributary of the St.Lawrence River.


2.4.2 Schedule of studies to identify critical habitat

A schedule of studies is not required at this time, as critical habitat is identified for all known populations.


2.4.3 Examples of activities likely to result in the destruction of critical habitat

Examples of activities likely to destroy critical habitat include infilling and/or dredging/removal of shoreline substrate where seeds and rhizomes can establish. Such activities may occur for the purpose of property expansion or other urban development and where they partially or completely modify (and destroy) existing shoreline substrate and plant habitat. Also, continuous human trampling, such as it is occurring at the Ile Rock shoreline by recreational watercraft users accessing the site, will likely create a modified shoreline structure; this is likely to occur if the current level of human use is maintained. Human-induced changes to water levels and dredging in areas near or at the site of colonies of American Water-willow will likely result in habitat loss. The deliberate introduction of invasive, alien plant species could also affect the availability of habitat for the species.

2.5 Statement on action plans

One or more action plans will be completed by January 2016.

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