![[Cambarus bartonii]](cbartonii.jpg)
Cambarus bartonii
Common Crayfish
DESCRIPTION
The Appalachian Brook
Crayfish is also known as Ecrevisse du Nord.
It is a medium to small crayfish with
generally smooth appearance, small eyes set
into the carapace and smooth chela with
fingers curved inwards. It is distinguished
from the similar species the Robust Crayfish
by a shorter rostrum and single row of
tubercules on inner border of palm of
chelipeds. Colouring is characteristically
orange-brown but can also be blueish-green.
Blue morphs of this species have been
recorded in Ontario (Crocker and Barr, 1968;
Hamr, unpublished data).
HABITAT
Found in streams, rivers and lakes. The Appalachian Brook Crayfish is most common in
fast flowing, rocky areas which remain cool and well oxygenated in the summer. It is
therefore often associated with rapids and waterfalls.
DISTRBUTION
Canada/Ontario
This
species is found in New Brunswick, Quebec
and Ontario. In Ontario, where its
distribution has been well documented, it
is found from the Moose River
drainage in the north,
westward to the eastern
shore of Lake Superior,
south to the western
end of Lake Ontario and
east to the Ottawa-St.
Lawrence River drainages
(Crocker and Barr, 1968; Berrill
1978; Hamr 1983; David et al.,
1994, Guiasu et al., 1996; David
et al., 1997;). In Quebec its
distribution remains largely
undocumented but it occurs in both
the St. Lawrence River and Ottawa River
drainages. To date it has been collected
from the Ottawa region south to Montreal
and eastward, on both north and south
shores of the St. Lawrence River to the
Madawaska drainage on the New Brunswick
border (Bousfield, 1969; Burgess and Bider,
1980; Schueler, 1985; Dube (unpublished
records); Hamr (unpublished records). The
species is also found in the Laurentides
region north of the St. Lawrence River
(Dube, unpublished records) and it is very
likely to range as far north as James Bay. In
New Brunswick, Cambarus bartonii is found in the Saint John, the
Restigouche and in the Miramichi
drainages. No crayfishes have been
observed in any of the Northumberland
Strait or in east Bay of Fundy rivers
(Schueler, 1985; Hooper pers. comm.).
North America Ð This species is widely
distributed along the eastern part of
North America and has been
recorded from New Brunswick,
Quebec, Ontario, Maine,
Massachusetts, Rhode Island,
Vermont, New York, New Jersey,
Connecticut, Pennsylvania, Maryland,
District of Columbia, Delaware,
Virginia, West Virginia, Kentucky,
Tennessee, North Carolina, South
Carolina, Georgia and Alabama.
ECOLOGY
This species is
most common in fast flowing, rocky areas
which remain cool and well oxygenated in
the summer(Crocker and Barr, 1968; Bousfield,
1969; Berrill, 1978; Hamr and Berrill, 1985;
Guiasu et al., 1996). Shelters usually consist
of excavations in gravel and sand under
larger rocks (Crocker and Barr, 1968; Hamr,
1983). The species shows a remarkable ability
to penetrate deep into the substrate.
Excavations can go as deep as 1 m
throughout several layers of rock and gravel
(Hamr, 1983). On the Canadian Shield in
Ontario, this species has been found in deep,
high elevation lakes spanning abroad range
of pH values (5.0->7.0)(David et al., 1994).
In Canada, this species has been found
together with Robust Crayfish, Northern
Clearwater Crayfish, Virile Crayfish, Obscure
Crayfish, Papershell Crayfish and Rusty
Crayfish (Berrill, 1978; Hamr, 1983; David et al.,
1997). In laboratory studies Cambarus bartonii was found to be clearly more
aggressive than Virile Crayfish and Northern
Clearwater Crayfish but less aggressive than
Robust Crayfish (Guiasu and Dunham, 1997).
LIFE HISTORY
In Ontario, reproduction
appears to take place from spring to fall.
Mature females show strong glair gland
development from April to August.
Copulation has been observed in October in
the wild and late April to early June in
captivity. Females with eggs are found from
June to August and with young from July to
September. Eggs and young are therefore
carried into autumn and there is evidence
that some females may over winter with
attached eggs or young and release them
(and then moult) the following summer
(MacManus, 1960b; Hamr, 1983). Hatching
occurs between July and August and the
young undergo two moults in their
metamorphosis, spending about 15 days
attached to their mothers. Free-living young
measuring about 5 mm (0.195 in.) CPL are
first found in August (Hamr, and Berrill, 1985).
Moulting in immature crayfishes take place
form May to early October and maturity is
reached at about 2 years of age. Adult males
moult in July and September. Moulting into
both Form I and Form II at the same time of
year has been observed (Hamr and Berrill,
1985). Mature females moult once following
the reproductive season but the timing of
moult is variable (September or the
following June-July) depending on local
conditions. The average life-span appears to
be 3 years old and the maximum life-span is
4 years. The maximum recorded size is 39
mm (1.52 in.) CPL from a male collected in
Rawdon, Quebec. Sexual dimorphism with
respect to chela length between sexes and
Form I and From II males is present but not
as pronounced as in the Orconectid
crayfishes (Hamr and Berrill, 1985).
CONSERVATION STATUSAlthough this
species remains fairly common in certain
parts of Ontario, many recent collections
come primarily from within protected areas
inside provincial parks and conservation
areas where riparian vegetation surrounding
streams is well preserved and the level of
water pollution and human interference is
generally lower than elsewhere (Barr, 1996).
Similarly, populations of this species have
been found in waters infested with the
introduced Rusty Crayfish (e.g. Otonabee
River, Ontario). A major environmental
pressure is the gradual acidification of lakes
and streams due to acid rain, particularly in
southeastern Ontario (DiStefano et al., 1991).
Although mature Cambarus bartonii appear to be somewhat acid
tolerant, it has been demonstrated that
juvenile and moulting crayfishes may be
more vulnerable to the acidification process
than larger, intermoult individuals (Berrill et
al., 1985; DiStefano et al., 1991). A study of
crayfishes in lakes of the Canadian
(Precambrian) Shield in Ontario found
significant decreases in the Cambarus bartonii populations. It was suggested
that these declines may be linked to low pH
and high aluminum concentrations (David et
al., 1997). Studies of this species in the
Sudbury area where emissions of heavy
metals remain high, showed that although
metals were accumulated the species
appeared to tolerant of copper, cadmium
and nickel (Bagatto and Alikhan, 1987; Zia
and Alikhan, 1989).
The closely related Robust Crayfish has
been shown to be clearly dominant in
aggressive interactions with Cambarus bartonii and the
distribution of the two is largely non-
overlapping. Given the apparent range
expansion of Robust Crayfish in Ontario
and Quebec during the past 30 years it
appears that this species has the potential
to competitively exclude Cambarus bartonii if the two species are
competing for limited resources (Guiasu and
Dunham, 1997). In conclusion, this species
has a fairly extensive distribution with
apparently many "safe" northern
populations and should therefore be
considered to have a "Currently Stable"
status in Canada (Hamr, 1998).
(Used by permission: text by Premek Hamr, modified from "Baitfish of North America"2007
painting by Aleta Karstad)
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