BRASSILS CREEK SURVEY
FOR CRAYFISH




Crayfish Crawl

 8 - 10 August 2008

 Brassils Creek, east of Dwyer Hill Road,
Burrits Rapids,
Ottawa-Carleton Region,
Ontario


[young Orconectes rusticus]
A crayfish identification and stream survey workshop for
Ontario Nature's "Volunteer for Nature"program


 assisted by the Bishops Mills Natural History Centre






Contact Bishops Mills Natural History Centre
by phone at (613)258-3107
or e-mail bckcdb@istar.ca


crayfishontario.ca


Pinicola home


Bishops Mills
Natural History
Centre


BMNHC outings

[orientation]

Following Brassils Creek on the map

Having had our introduction to crayfish life history and ecology last night at Rideau River Provincial Park, the group was keen to find Brassils Creek and get into some crayfish habitat. We chose the second bridge north of Burritts Rapids, as two years ago Fred and I, with the Ottawa Stewardship Rangers, had made a big harvest of Orconectes rusticus, the invasive Rusty Crayfish, which is in the Rideau River and this section of Brassils Creek.


[beetled Loosestrife]

Purple Loosestrife suffers beetle damage

The Galerucella beetles, introduced from Europe to suppress the invasiveness of the Purple Loosestrife (as they do in their homeland) are doing a good job here.


[paden bridge group]

starting on the upstream side

With nets and buckets, we began around 10:00. Crayfish enthusiasts of all ages began the work of dipping and catching, reporting everything they saw.


[crayfish catchers]

Spreading out, making discoveries

The water levels have been high all summer due to persistent rain, and the current is fairly strong, challenging the footing of the younger members of the expedition.


[beaver dropping]

Beaver dropppings on the creek bottom

About 15 cm long, it looked like a row of fine pale sawdust. We had already found Beaver workings farther downstream, a brief knee-high berm of roots and mud between two channels through the flooded Dogwood.


[male Rusty Crayfish fighting]

Rusties in male combat

We wondered whether these were mating, but when we caught them, we found them both to be males, so this was definitely a battle, with the victor on top, holding the "wrists" of the loser.


[measuring Rusty Crayfish]

measuring Rusty Crayfish

The youngest, who was shy of crayfish pincers last night in the park, soon lost her fear, proudly handling them with grace and dexterity, presenting them to be measured.


[Paden Road Rusty Crayfish]

waiting to be measured and released

Crayfish coloration varies from population to population within species. We were impressed by the blue-green sheen on the heads of some of the Rusties here.


[female Orconectes virilis]

first Orconectes virilis found here

Orconectes virilis is the native species all along Brassils Creek, but they have been displaced by Orconectes rusticus here. Why they are limited to this stretch is still a mystery, but we suspect that the natives are better than the Rusties at surviving summer drought in shallower sections of the creek. Looks like O. virilis is nicely patterned here. The one I painted in the Crayfish Identification Guide is plain and unpatterned.


[Flood Road upstream]

upstream at the Flood Road bridge

After lunch we moved along Dwyer Hill Road to the next bridge accessible by road, just a little piece east on Flood Road.


[Orconectes virilis]

large female O. virilis from the deep

Fred and Cody discovered a large hole in the bed of the creek, off to one side of the main current, covered with a blanket of sunburned Coontail, mixed with a fine strap-leaved Pondweed. Cody stepped off the edge into it and was nearly submerged. Fred put his big aluminum frame dipnet underneath the vegetation and came up with this impressive female crayfish and a few large snails, Helisoma trivolvis.


[Damselfly]

male Damselfly

While everyone else weilded nets, I hunted by camera, and captured the image of a shy Damselfly. I had no success in approaching them, but as I stood still in the channel that flows past the west side of the island, one came and alighted right beside me.


[Flood Road bridge]

under the Flood Road bridge

On the top of the east end of the bridge, attached to the chain-link gabion filled with crushed rock, we found the freshly shed skin of a large Garter Snake, whose owner was still resting, coiled among the rocks.


[downstream from Flood Road bridge]

downstream survey

[pail of macroinvertebrates]

a healthy diversity of macroinvertebrates

We found flat, gill-sided Stonefly nymphs, indicators of a clean, healthy stream. There were big-headed Dragonfly nymphs too, and Caddis flies, with and without their protective casings of sticks and stones. A diversity of tiny fish were not identified.


[Cranefly larva]

wonderful Cranefly larva

A strange legless larva with a many-tubed tail end will grow up to be a delicate, long-legged Crane Fly.


[Leech with young?]

leech with its offspring?

We found a flat, ribbon-like leech with a single row of small yellow spots along the centre of its dark brown back, and a vivid orange underside. Another, larger leech was rounder in profile, and was being climbed all over by a much smaller leech with white dots. Fred says that some leeches carry their young about with them.


[emptying boots]

our intrepid leader empties her boots

Time to drive to the next bridge.


[Brassils Creek at Dwyer Hill Rd]

Brassils Creek at Dwyer Hill Road

Looking upstream into the wetland. The bottom was determined to be mucky and about chest deep on our bold assistant Cody. A few Green Frogs were seen on the south side as we sat on the flat cement ledge of the bridge. Two of them sat facing each other, on lily pads half a metre apart. We at first thought that they may be Mink Frogs.


[ditch at Dwyer Hill Rd]

finding crayfish in the ditch

This is where Orconectes virilis were found. The ditch is shallow enough to sweep the bottom with nets.


[Bull Frog]

Bull Frog with an attitude

This individual swam briskly across to observe us, changing his vantage point several times in a brusque, officious manner, totally fearless! After I took my photo, it finally took up a position directly below our dangling legs, and looked up as Dierdre looked down at it with her camera.