The Natural Heritage of Ontario Rivers - Grand River Conservation ...

4 th Canadian River Heritage Conference Mike McMurtry, Wasyl Bakowsky & Gordon Wichert 

Guelph, Ontario June 6-9, 200 

The Natural Heritage of 

Proceedings 

Ontario’s Rivers 

The Natural Heritage of Ontario Rivers 

Mike McMurtry, Wasyl Bakowsky & Gordon 

Wichert 

Natural Heritage Information Centre, Ontario 

Ministry of Natural Resources 

Wednesday June 9, 2004 9:45-10:45 a.m. 

Mike McMurtry is the 

Natural Areas Ecologist 

at the Natural Heritage 

Information Centre 

(NHIC) in Peterborough. 

Mike works with a team 

of ecologists and other 

specialists to acquire, 

manage and analyze information on natural areas 

and natural heritage systems. 

Abstract 

Historically, rivers have been viewed in terms of the 

drinking water, recreation, fisheries, waste dispersal 

and transportation services they provide. Ontario 

rivers and associated riparian areas also provide a 

rich diversity of flora and fauna and ecological 

communities that are an essential part of our natural 

heritage. The Natural Heritage Information Centre in 

Peterborough maintains a central repository for 

natural heritage data in Ontario, including 

observations on rare species, vegetation communities 

and larger natural areas associated with rivers and 

riparian areas. This presentation will provide an 

overview of natural heritage information on rivers 

from the NHIC databases. Examples of rare species 

and communities throughout the province will be 

highlighted, from the Hudson Bay Lowlands to the 

Canadian Shield to the limestone-based systems of 

southern Ontario. Given the serious threats from 

invasive species, exploitation, altered hydrology, 

habitat destruction and pollution, it is important to 

continue to document the natural heritage of Ontario 

rivers. Classification systems for terrestrial and 

wetland communities are well developed but there is 

a need for an accepted classification system for the 

ecological communities of rivers and other aquatic 

systems. 

Historically, rivers have been viewed in 

terms of the drinking water, recreation, 

fisheries, waste dispersal and transportation 

services they provide. Henry David 

Thoreau, in A Week on the Concord and 

Merrimack Rivers (1983, first published in 

1849) recognized these values and was one 

of the first in North America to emphasize 

the importance of rivers for the diversity of 

plants and animals that they support: 

They are the natural highways of all nations, 

not only levelling the ground, and removing 

obstacles from the path of the traveller, … 

but conducting him through the most 

interesting scenery, the most populous 

portions of the globe, and where the animal 

and vegetable kingdoms attain their greatest 

perfection. 

Most of the scientific community still 

concentrates on the swimmable, drinkable, 

edible and navigable features of rivers, but 

there is increasing recognition of the 

biodiversity of river systems and the relation 

of biodiversity to overall ecosystem health. 

The Nature Conservancy recently reported 

on freshwater biodiversity using data from a 

network of natural heritage centres with 

startling results: organisms that depend on 

freshwater ecosystems are in a more 

imperilled condition than terrestrial species 

(Master et al. 1988). For example, 67 

percent of freshwater mussels in the United 

States are vulnerable to extinction or are 

already extinct; of the 303 fish species that 

make up the fish fauna in the United States, 

37 percent are at risk of extinction; 17 of 

these are already gone and most were lost in 

the twentieth century; 51 percent of U.S. 

crayfishes are imperilled or vulnerable; and 

40 percent of amphibians are imperilled or 

vulnerable. All of these taxonomic groups, 

which consist mostly or entirely of aquatic 

species, are proportionally more imperilled 

than the next most imperilled group, the 

flowering plants (Master et al. 1988). These 

figures also reflect the situation in Canada. 

The Ontario Natural Heritage Information 

Centre (NHIC), based in Peterborough, 

Ontario, is part of a hemisphere-wide 

network of conservation data centres called 

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NatureServe. Most Canadian provinces, as 

well as the Yukon Territories, now have 

such a centre. The NHIC acts as a central 

repository for natural heritage information 

and data in Ontario and makes this 

information available for conservation 

planning and action. The primary focus is on 

organisms and ecological communities that 

are rare or at risk. The NHIC also maintains 

a database on natural areas, including those 

recognized for their aquatic biodiversity. 

This paper will present a summary of the 

information available at the NHIC on the 

biodiversity of Ontario rivers and on areas 

where this biodiversity is concentrated. The 

emphasis will be on species that are 

provincially rare and/or tracked by the 

NHIC (because they may become rare). It 

will describe some examples of Ontario 

rivers with outstanding biodiversity and 

illustrate examples of species and plant 

communities associated with rivers. Some of 

these rivers are part of the Canadian 

Heritage River System and others are not. 

We will also describe new work to classify 

riverine ecosystems so that we can identify 

which ones are most important for 

conservation of flora and fauna. While there 

are fewer data on aquatic biodiversity 

compared to those for terrestrial, there is 

nevertheless a wealth of information to draw 

on. 

Distribution of Biota Associated with 

Rivers 

At the time of writing, the NHIC has records 

on 2265 element occurrences for plants and 

animals that are associated with rivers and 

an additional 200 element occurrences for 

plant communities (Figure 1). Not all of the 

species reported here are strictly aquatic; we 

have included those that occupy wetlands 

along rivers, streams and creeks as well. The 

reptiles and mammals included rely on 

riverine habitat for a critical portion of their 

habitat. An element occurrence is roughly 

equivalent to a population – it is the space 

where a single interbreeding occurrence is 

found. There can be many observations at 

different times in the NHIC database for a 

given element occurrence. An example of an 

element occurrence would be a patch of 

Meadow-beauty, Rhexia virginica, along a 

river shoreline, or a population of Redside 

Dace, Clinostomus elongatus, in a reach of 

the Rouge River. 

Most of these occurrences are in southern 

Ontario: this is both because the biodiversity 

is higher in southern rivers and because 

there has been more sampling activity in the 

south. Vascular plants are the best 

represented in the database, followed by 

odonates, fish, birds and molluscs (Table 1). 

Some insect groups known to be abundant in 

rivers are not represented at all: stoneflies 

(Plecoptera), mayflies (Ephemeroptera) and 

midges (Chironomidae), for example. This 

reflects where the NHIC expertise lies and 

what scientific disciplines have been 

involved in conservation. There may be data 

on rare mayflies in Ontario that would 

benefit our centre and our knowledge of 

aquatic biodiversity but they have not yet 

been discovered and incorporated. 

Most of these species are provincially rare 

(S-Ranked) and some are globally rare (G- 

Ranked). A high proportion of the nonvascular 

plants and molluscs are globally 

rare (Table 2). A high proportion of the 

species have been identified as being at risk 

either at the federal (Committee on the 

Status of Endangered Wildlife in Canada, 

COSEWIC) or provincial level (Committee 

on Species at Risk in Ontario, COSSARO). 

Almost all of the amphibians and reptiles 

tracked by the NHIC, and associated with 

riverine habitats, are designated as being at 

risk by COSEWIC and COSSARO. 

Examples include Queen Snake (Regina 

septemvittata), Spiny Softshell (Apalone 

spinifera) and Fowler’s Toad (Bufo fowleri). 

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Some of the species that are represented in 

the NHIC database are well-known species, 

such as Redside Dace, Bald Eagle 

(Haliaeetus leucocephalus), Lake Sturgeon 

(Acipenser fulvescens)and Wood Turtle 

(Clemmys insculpta)and others are lesser 

known, such as Emory’s Sedge (Carex 

emoryi), found in shoreline meadows along 

the Rainy, Sydenham, Thames and Grand 

rivers (Table 3). 

Rivers with Outstanding Biodiversity 

Three rivers stand head and shoulders above 

other rivers in our database in terms of the 

number of observations of rare species. 

They are the Grand, Thames (Figure 2) and 

Sydenham rivers. All of these rivers have a 

large drainage area and most of their extent 

is in Ecoregion 7E, or Carolinian Canada, a 

region known not only for its variety of 

species, but also for the number of species 

and spaces at risk. Recovery teams have 

been established for all of these rivers. 

The Grand River is aptly named; it has a 

huge watershed of over 7000 km² (Portt et 

al. 2003), the largest in southern Ontario, 

and encompasses many tributaries including 

the Speed, Eramosa, Nith and Conestogo 

rivers. Habitats for aquatic organisms are 

diverse. Headwaters with variable flow are 

underlain with clay and glacial till; middle 

reaches have both cool and coldwater 

habitats and numerous areas of groundwater 

discharge; and the lower reaches are highly 

productive with deep pools and extensive 

littoral zones. Over one-half of the 158 

freshwater fishes known to occur in Ontario 

have been documented in the Grand River 

watershed, including six species designated 

as Special Concern, Threatened or 

Endangered by COSEWIC (Portt et al. 

2003). It is justifiably a Canadian Heritage 

River. An example of an outstanding natural 

area associated with the Grand River is the 

Grand River Forests Area of Natural and 

Scientific Interest (ANSI) and its contiguous 

neighbour, the Spottiswood Lakes ANSI 

(Allen et al. 2000). The Grand River Forests 

ANSI includes seepage slope wetlands, 

upland mature hardwoods, riparian 

meadows, shallow water habitat, and even 

some tallgrass prairie. Twenty-two species 

of vascular plants found within the two 

ANSIs are considered provincially rare, and 

one sedge, Carex schweinitzii, is globally 

rare. The Threatened (COSEWIC and 

COSSARO) Queen Snake and Jefferson’s 

Salamander, Ambystoma jeffersonianum 

(COSEWIC) are both found within these 

ANSIs and the Grand River proper supports 

the Wavy-rayed Lampmussel, Lampsilis 

fasciola, a freshwater mussel designated as 

Endangered by COSEWIC (Allen et al. 

2000). 

Another jewel, in term of rare aquatic 

species, is the Sydenham River. Like the 

Grand, this river is located in the speciesrich 

Carolinian Zone, and supports the 

greatest diversity of freshwater mussels in 

all of Canada (Dextrase et al. 2002). Thirty 

four species of mussels and 80 species of 

fish have been documented here. Freshwater 

mussels in Ontario are under threat by the 

invasion of non-native species and water 

quality impairment such as siltation and 

over-enrichment with nutrients from runoff 

from farms and urban areas. The 

Endangered Rayed Bean, Villosa fabalis, 

(Figure 3) is found nowhere else in Canada 

and only in a few other locations in North 

America Dextrase et al. 2002). During 

fieldwork conducted in the summer of 2003 

in support of the Sydenham River Recovery 

Plan, Colin Jones, of the NHIC, and Peter 

Burke found a species of dragonfly new to 

Canada along the Sydenham River: it is 

called the Mocha Emerald, Somatochlora 

linearis (Figure 4). 

Some rivers are significant, not for the 

number of species they support, but because 

they provide a large proportion of the habitat 

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for one or a few species. The English and 

Winnipeg rivers, for example, have a 

disproportionately large number of Bald 

Eagle nesting locations compared to other 

rivers. The Ottawa River provides habitat 

for two species of fish that are under threat 

in Ontario: the Lake Sturgeon and River 

Redhorse, Moxostoma carinatum. Both of 

these species spawn in the rapids of large 

rivers. The Ottawa River near Fitzroy 

Provincial Park also has unique shoreline 

vegetation communities which can 

withstand annual ice scouring, periodic 

flooding and drought: Isoetes riparia, 

Helenium autumnale, Agalinus tenuifolia 

and Alisma gramineum are a few of the 

provincially rare species present (D.F. 

Brunton, pers. comm.). Many other rivers in 

Ontario are worthy of praise for the plants 

and animals they support; rivers frequently 

cited in the NHIC database include the St. 

Clair, Maitland, Ausauble, Humber, Rouge, 

Credit, and Canard in the south, and the 

Petawawa, Groundhog and Winisk further 

north. 

Riverine Processes That Shape Ecological 

Communities 

The energy associated with river systems 

creates a dynamic shoreline environment, 

particularly in areas where combinations of 

hydrology, topography and stream gradient 

are responsible for periodic flooding and 

associated flood-scour, or where rocks 

outcrop along major topographic breaks. 

Such areas are often further affected in 

winter by ice-push and ice-scour. As a 

consequence of this disturbance activity, 

active river shorelines create special habitats 

which often support rare flora and fauna. 

Some of the unique habitats associated with 

river shores include flood-scoured meadows, 

flood-scoured rocky shores, rapids, 

seepages, eroding banks, and canyons. 

Tallgrass prairie is a provincially rare 

vegetation type that can be associated with 

rivers; it occurs along the Ausable River and 

Grand River in the south, and the Rainy and 

English Rivers in north-western Ontario. 

Alvar vegetation occurs along the Ottawa 

River, where it is dependent on flood-scour 

and ice-push to maintain open conditions. 

In northern Ontario, many rivers have rocky 

rapids and canyons which support 

assemblages of arctic-alpine plant species. 

The Maitland River in southern Ontario also 

has relict arctic-alpine species. Additional 

information on the unique habitats and flora 

of northern rivers is available in the NHIC 

Winter 2004 Newsletter (Bakowsky 2004). 

Classification of Riverine Systems 

If we are to identify and protect the types of 

riverine systems that are associated with 

diverse communities of plants and animals, 

we have to understand the physical 

conditions that create the system and the 

type of watershed where they are located. 

Ideally this could be done with basic 

landscape data that are available for the 

whole province. The NHIC has been 

involved in work to create a classification 

system that will be useful in identifying 

riverscape units for conservation purposes. 

Rivers can be viewed as part of a continuum 

connecting drainage areas and upper 

tributaries with downstream receiving 

waters such as embayments, wetlands, and 

lakes. The form of river reaches is 

determined primarily by the upstream 

geomorphic regime as modified by climaterelated 

phenomena. The ecology of river 

reaches is strongly influenced by the 

upstream climatic regime and may be 

modified by the presence and movements of 

aquatic organisms including invertebrates, 

amphibians, birds, fishes and by physical 

phenomena, including seiches and upwelling 

events along the Great Lakes coast, for 

example. 

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Headwater areas and small rivers are 

strongly linked to the landscape by their 

high surface area to volume ratio. 

Headwater domains typically receive much 

allochthonous detritus (organic debris 

formed outside the river) where riparian 

vegetation exists. Resident communities 

usually include invertebrates that feed on 

coarse particulate organic matter (Vannote 

et al. 1980). Fish species in headwater areas 

generally prefer cold temperatures, feed on 

insects and deposit their eggs in the 

substrate. These areas exhibit low overall 

biodiversity and generally low in-stream 

plant diversity because little sunlight reaches 

the water. 

As stream size increases, a reduction in 

allochthonous inputs from terrestrial systems 

coincides with increased autochthonous 

primary production (production by plants 

within the river) and organic transport from 

upstream. Invertebrate communities are 

characterized by species that utilize coarse 

and fine particulate organic matter as well as 

those that scrape algae from attached 

surfaces (Vannote et al. 1980). Insect and 

fish-eating fish species dominate the middle 

reaches. In relatively undisturbed rivers, 

resident fish species in these larger sections 

prefer cool and warm water temperatures 

and prefer the stream margins or benthic 

habitats for feeding and breeding. 

Lower reaches are generally characterized 

by warm, daily stable water temperatures 

and slow currents. Surface-to-volume ratios 

are such that large lower reaches have 

relatively little interaction with the 

landscape on an ongoing basis. Landscape 

interactions are generally restricted to 

episodic flood events when the river waters 

spread across the floodplain. Most nutrients 

drift down from upstream and some come 

from autochthonous primary production. 

Invertebrates typically filter nutrients from 

transport or gather them from sediment 

(Vannote et al. 1980). In larger rivers, semipelagic 

(open water) systems with 

characteristic phytoplankton and 

zooplankton species persist with 

planktivorous fish, in addition to the 

carnivorous fish species from the middle 

reaches. 

Areas of high biodiversity persist where 

conditions support the feeding and 

reproduction of many species. Such locales 

coincide with populations of large, longlived, 

late-maturing benthic species that 

integrate ecosystem processes (Regier et al. 

1989). Examples of complex habitat such as 

accumulations of large woody debris, rocky 

rapids, large macrophyte beds, and dunes 

(bars) in sandy rivers, create the complex of 

ecosystem processes that support high levels 

of biodiversity. Centres of biodiversity and 

ecological communities cannot be related to 

physical processes of rivers in a linear and 

strongly predictive way, but some 

community-habitat regularities may be 

observed. For example, key headwater 

species require groundwater discharge to 

enhance spawning success. Groundwater 

discharge zones relate to areas with 

relatively permeable geology and mediumto-high 

stream gradient. 

River systems were classified along four 

dimensions: watershed position (and size), 

geological permeability, gradient, and water 

storage potential (Wichert et al. 2004). This 

classification should group river systems 

with similar processes such as potential 

groundwater recharge and discharge, water 

temperature, fluctuations in flow in response 

to snow-melt and heavy rain events, stream 

size and position, which can influence the 

type and source of nutrient inputs (Figure 1). 

The dimension captured by watershed 

position allows the identification of 

communities that typically persist at 

different points along the headwater to river 

mouth gradient. Classes relating to water 

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temperature and water flow dynamics allow 

identification of communities with 

contrasting temperature preferences. 

Characterizing flow dynamics allows 

distinction among groups of species that 

utilize the main channel, stream margins, 

and floodplains to complete life history 

cycles. This classification method takes into 

account the processes determining the rate 

of reproduction, predation, feeding, 

mortality and survival that will in tern affect 

community composition and success (Minns 

and Wichert, in review). Further analysis 

will reveal how the river system classes 

generated are associated with patterns of 

biodiversity. 

Summary 

We know that Ontario rivers provide us with 

many benefits, not the least of which is a 

rich heritage of plants, animals and their 

References 

habitat. There are, however, some obvious 

gaps in our knowledge that present 

opportunities for further exploration. For 

example, there are few data in the Natural 

Heritage Information Centre database on 

aquatic insects other than odonates. Data for 

even a well-known group such as the 

vascular plants is sparse in most riverine 

habitats, especially in northern Ontario. 

Given the serious threats from invasive 

species, exploitation, altered hydrology, 

habitat destruction and pollution, it is 

important to continue to document the 

natural heritage of Ontario rivers. The 

authors hope that this summary of 

information on rare and tracked species and 

communities in Ontario will stimulate more 

interest in the biodiversity of not only 

Canadian Heritage Rivers, but of all rivers in 

Ontario. 

Allen, G.M., D.A. Kirk, and M.D. Ross. 2000. A life science inventory and evaluation of the 

Grand River forests and Spottiswood Lakes: Areas of Natural and Scientific Interest (ANSI). 

Ontario Ministry of Natural Resources, Guelph District, Southcentral Region. OFER-2001. viii + 

75 p. + appendices + 2 folded maps. 

Bakowsky, W.D. 2004. Notes on the vegetation and flora of flooding river shores. Natural 

Heritage Information Centre Newsletter, Winter 2004. Vol. 9 (1): 5-8. 

Dextrase, A. , Metcalf-Smith, J. L., and S.K. Staton. 2002. recovery Strategy for species at risk 

in the Sydenham River: an ecosystem approach. Sydenham River Recovery Team. RENEW, 

Canadian Wildlife Service, Ottawa, Ontario. 93 p. 

Master, L.L., S.R. Flack, and B.A. Stein, eds. 1988. Rivers of life: critical watershed for 

protecting freshwater biodiversity. The Nature Conservancy, Arlington, Virginia. 71 p. 

Minns, C.K., and G.A. Wichert. A framework for defining fish habitat domains in freshwaters 

using lake ontario and its drainage as a case study. Journal of Great Lakes Research. In review. 

Oldham, M.J., W.D. Bakowsky,and D.A. Sutherland. 1995. Floristic quality assessment system 

for southern Ontario. Ontario Ministry of Natural Resources, Natural Heritage Information 

Centre, Peterborough. 69 p. 

Portt, C., G. Coker, and K. Barrett. 2003. Recovery strategy for fish species at risk in the Grand 

River, Ontario. Draft report for the Grand River Recovery Team. 80 p. 

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Regier, H.A., R.L. Welcomme, R.J. Steedman, and H.F. Henderson. 1989. Rehabilitation of 

degraded river ecosystems. Pages 86-97 in D.P. Dodge, editor. Proceedings of the International 

Large River Symposium. Canadian Special Publication of Fisheries and Aquatic Sciences 106. 

Thoreau, H.D. 1983. A week on the Concord and Merrimack Rivers. Princeton University Press, 

Princeton, New Jersey. 415 p. 

Vannote, R.L., G.W. Minshall, K.W. Cummins, J.R. Sedell, and C.E. Cushing. 1980. The river 

continuum concept. Canadian Journal of Fisheries and Aquatic Sciences 37:130-137. 

Wichert, G.A., J. MacKenzie, and P. Staples. 2004. Aquatic ecosystem classification for the 

Great Lakes basin. Ontario Ministry of Natural Resources. Peterborough, Ontario. (In review). 

Table 1 The number of river-associated element occurrences (EOs) from the Natural Heritage 

Information Centre occurring with certain taxonomic groups, vegetation communities, rarity 

ranks and at-risk categories. Element occurrences were considered associated with rivers if 

“river”, “stream” or “creek” was present in the location name or habitat description. For plants, 

only those with a wetness coefficient of -2 to -5 were included, i.e. plants of aquatic or wetland 

habitats (Oldham et al. 1995). GRANK=global rank, SRANK=subnational or provincial rank, 

COSEWIC=Committee on the Status of Endangered Wildlife in Canada, 

COSSARO=Committee on the Status of Species at Risk in Ontario. 

Group # EOs GRANK SRANK COSEWIC COSSARO 

Vascular Plants 713 38 708 114 23 

Non-Vascular Plants 70 52 67 1 None 

Amphibians 11 None 11 10 7 

Reptiles 126 18 126 96 95 

Birds 215 2 148 74 151 

Mammals 37 1 36 29 3 

Fish 594 69 451 378 256 

Molluscs 127 48 127 121 None 

Coleoptera 2 1 2 None None 

Lepidoptera 5 4 5 None None 

Odonata 365 31 357 None None 

Vegetation 

Community 

200 63 125 None None 

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Table 2. Number of species tracked by the Natural Heritage Information Centre and associated 

with rivers in Ontario. Species were considered associated with rivers if “river”, “stream” or 

“creek” was present in the location name or habitat description. For plants, only those with a 

wetness coefficient of -2 to -5 were included, i.e. plants of aquatic or wetland habitats (Oldham 

et al. 1995). GRANK=global rank of G1-G3G4, SRANK=subnational or provincial rank of S1- 

S3S4, COSEWIC=Committee on the Status of Endangered Wildlife in Canada, 

COSSARO=Committee on the Status of Species at Risk in Ontario. 

Group # Species G RANK S RANK COSEWIC COSSARO 

Vascular Plants 137 8 136 15 8 

Non-Vascular Plants 49 34 46 1 None 

Amphibians 4 None 4 3 2 

Reptiles 8 2 8 7 6 

Birds 24 2 22 7 9 

Mammals 11 1 10 5 2 

Fish 33 5 23 19 15 

Molluscs 11 4 11 7 None 

Coleoptera 2 1 2 None None 

Lepidoptera 3 2 3 None None 

Odonata 70 5 67 None None 

Table 3. Ten most-observed elements associated with rivers in the Natural Heritage Information 

Centre database. 

Species 

Number of EOs 

Redside Dace (Clinostomus elongatus) 140 

Emory’s Sedge (Carex emoryi 76 

Greenside Darter (Etheostoma blennioides) 65 

Greater Redhorse (Moxostoma valenciennesi) 60 

Green Dragon (Arisaema dracontium) 60 

Bald Eagle (Haliaeetus leucocephalus) 49 

Lake Sturgeon (Acipenser fulvescens) 46 

Silver Shiner (Notropis photogenis) 41 

Wood Turtle (Clemmys insculpta) 33 

Blanding’s Turtle (Emydoidea blandingii) 31 

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Figure 1. River-associated element occurrences in Ontario. Element occurrences were 

considered associated with rivers if “river”, “stream” or “creek” was present in the location name 

or habitat description. For plants, only those with a wetness coefficient of -2 to -5 were included, 

i.e. plants of aquatic or wetland habitats (Oldham et al. 1995). 

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Figure 2. Thames River viewed from Komoka Provincial 

Park. Photo by W.D. Bakowsky. 

Figure 3. Photograph of Rayed Bean, Villosa fabalis, from 

the Sydenham River, designated as Endangered in Canada. 

Photo by S.K. Staton. 

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Figure 4. A dragonfly new to Canada from the Sydenham River: 

Mocha Emerald, Somatochlora linearis. Photo by C.D. Jones. 

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Figure 5. Examples of classification of Ontario stream systems. Water flow was 

classified by watershed position, permeability, gradient, and water storage potential. 

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