degraded streams
2 views
Skip to first unread message
Fred Schueler
Jul 30, 2025, 8:55:45 AMJul 30
to Eastern Ontario Natural History listserve
Everyone,
Yesterday I was driving back from taking Aleta to the Dumoine DRAW art
camp, and stopped at two traditional sampling places on the Mississippi,
Pembroke & Blakeney, and at the Muskrat River at Hwy 17, and was
appalled by the degraded character of the streams: muddy bottoms, only a
few living Unionid mussels, no substantial populations of Zebra Mussels,
snails represented mostly by juveniles, and grotesque mats of clumpy
algae. I've appended a draft ms about the similar condition of the
Rideau at Andrewsville.
Some of these visits are the first after a lapse of years, and it looks
like our stream visits have been biased toward the relatively healthy
Kemptville Creek, so we wonder what others have seen in their streams.
fred.
------------------------------------------------------------
Frederick W. Schueler & Aleta Karstad
Fragile Inheritance Natural History - https://fragileinheritance.ca/
2024 annual letter: https://clt1233162.bmeurl.co/11E63979
6 St-Lawrence Street Bishops Mills, RR#2 Oxford Station, Ontario K0G 1T0
on the Smiths Falls Limestone Plain 44.87156° N 75.70095° W
------------------------------------------------------------
draft ms for the North Grenville Times:
At Andrewsville the Rideau Canal goes through the Upper Nicholson Lock,
while the river overflows a weir into a broad riffle of broken rocks and
limestone bedrock, and then under the historic Andrewsville bridge. Ever
since Zebra Mussels were found in Ontario in 1986, and then in the
Rideau in 1990, we’ve been surveying the native Unionid mussels here,
and also the shells of other molluscs found drifted in a ridge in an
eddy below an islet of hybrid Cattails.
André Martel and Jackie Madill from the Canadian Museum of Nature
surveyed the annual recruitment of Zebra Mussels, attached by their
byssus threads on the “upper doorsill” of the Upper Nicholsons lock
annually from 1993-2010, and again in 2015. The first juvenile Zebras
showed up in 1995, first exceeded 100/square metre in 2001, peaked at
6,205/m2 in 2005, were lower subsequently, and were 1,791/m2 at the last
survey in 2015.
Our first survey visit to Andrewsville was on 16 August 1995, when the
first few Zebra Mussels had been detected in the lock. The drifted shell
sample was dominated by the filter-feeding European Faucet Snail
(Bithynia tentaculata), with some of the introduced Banded Mystery
Snails, one native Brown Mystery Snail, and a few Common Stagnicola,
Larger Eastern Ramshorns, Three-keeled Valve Snails, Modest Gyraulus,
Ordinary Spire Snails, and Tadpole Snails. Five species of native
mussels were present as living individuals and fresh & old shells:
Elliptio complanata (Eastern Elliptio), Lampsilis cardium
(Pocket-Book), Pyganodon grandis (Common Floater), Lampsilis radiata
(Eastern Lamp-Mussel), and Lasmigona costata (Fluted Shell).
The same species were seen in 1997 & 1998, with the addition of
Fingernail Clams in the drift, and a few huge old Ligumia recta (Black
Sand-Shell) mussels, which we speculated may have been youngsters when
Colonel By was putting in the canal. In June of 1999 there was one
Zebra Mussel (Dreissena polymorpha), on one living native mussel, and 3
in September. These “few Zebras per visit” conditions continued in
2000, 2001, and 2002, but in 2003 for the first time, the Zebras were
“common,” with a few threaded onto most of the native mussel shells – 13
years after they were first seen in the Rideau system. Things were much
the same in 2004, but in 2005, the year of the maximum count on the
lock, while there weren’t a lot of dead native mussels the Zebras seemed
to be most abundant on dead shells “perhaps 4-5/shell average, but not
as many as an average of 1 on living Unionids.”
In 2006 all of the native mussels found, except for one Elliptio, were
dead, and the Zebras were abundant all over the riverbed. [[how zebs
kill unios]] In 2007 the bottom was “dark with a pavement of very living
Zebra Mussels… littered with dead Unionid shells, so densely piled at
the foot of the flat that the sample represents those I was able to pick
up without moving my feet, about a 60 cm radius. There were, among these
but not collected, 4 large living Elliptio , and one small Lamp-Mussel,
all with attached Dreissena.” The drift sample was about 65% small Zebra
shells, 25% Faucet Snails, and 5% Banded Mystery Snails, with a
scattering of Ramshorn Snails and Common Stagnicola.
On 9 July 2007 we saw a few invasive Rusty Crayfish crawling out from
under rocks as dusk fell; the banks were mostly crowded with Cathartic
Buckthorn and Tartarian Honeysuckle, and there were the dense islands of
Flowering Rush and Hybrid Cattail in the main channel, provoking the
idea that Parks Canada should redenominate the place "Aliensville" and
open a theme park.
Things continued like this in 2008, 2009, 2010 <<blog posts>> and 2015.
In 2016 the drift had a few Fingernail Clams and a few Faucet Snails –
all the rest was Zebra Mussels. An attempt to collect drift in 2020 was
thwarted by high flow in the river, perhaps due in part to
pandemic-reduced boat traffic through the locks.
On 16 July of this year I finally made a return visit to the site of
this dramatic faunal turnover, with our intern Luna Lopez-Andrews, and
her mother, math teacher & plant breeder, Telsing Andrews. The
traditional drift sampling site had a narrow 3 m ridge of Zebra Mussel
shells – no other species – at the edge of the current below the islet.
The native Unionidae shells, old, worn, and fragmentary, were still
fairly conspicuous on the rocky bottom. One living Elliptio, was found
with a crust of baby Zebras on it.
Elliptio – dark, compressed and fairly elongate, with a purple inner
shell – is the native species most able to coexist with Zebra Mussels,
perhaps because its ability to bury itself in the substrate to endure
harsh conditions allows it to suffocate attached Zebras. There are
places on the St Lawrence, South Nation, and Mississippi rivers where
Elliptio and other species are managing to survive in fair numbers among
reduced Zebra Mussel populations, but Andrewsville doesn’t seem to be
among them.
Yesterday I was driving back from taking Aleta to the Dumoine DRAW art
camp, and stopped at two traditional sampling places on the Mississippi,
Pembroke & Blakeney, and at the Muskrat River at Hwy 17, and was
appalled by the degraded character of the streams: muddy bottoms, only a
few living Unionid mussels, no substantial populations of Zebra Mussels,
snails represented mostly by juveniles, and grotesque mats of clumpy
algae. I've appended a draft ms about the similar condition of the
Rideau at Andrewsville.
Some of these visits are the first after a lapse of years, and it looks
like our stream visits have been biased toward the relatively healthy
Kemptville Creek, so we wonder what others have seen in their streams.
fred.
------------------------------------------------------------
Frederick W. Schueler & Aleta Karstad
Fragile Inheritance Natural History - https://fragileinheritance.ca/
2024 annual letter: https://clt1233162.bmeurl.co/11E63979
6 St-Lawrence Street Bishops Mills, RR#2 Oxford Station, Ontario K0G 1T0
on the Smiths Falls Limestone Plain 44.87156° N 75.70095° W
------------------------------------------------------------
draft ms for the North Grenville Times:
At Andrewsville the Rideau Canal goes through the Upper Nicholson Lock,
while the river overflows a weir into a broad riffle of broken rocks and
limestone bedrock, and then under the historic Andrewsville bridge. Ever
since Zebra Mussels were found in Ontario in 1986, and then in the
Rideau in 1990, we’ve been surveying the native Unionid mussels here,
and also the shells of other molluscs found drifted in a ridge in an
eddy below an islet of hybrid Cattails.
André Martel and Jackie Madill from the Canadian Museum of Nature
surveyed the annual recruitment of Zebra Mussels, attached by their
byssus threads on the “upper doorsill” of the Upper Nicholsons lock
annually from 1993-2010, and again in 2015. The first juvenile Zebras
showed up in 1995, first exceeded 100/square metre in 2001, peaked at
6,205/m2 in 2005, were lower subsequently, and were 1,791/m2 at the last
survey in 2015.
Our first survey visit to Andrewsville was on 16 August 1995, when the
first few Zebra Mussels had been detected in the lock. The drifted shell
sample was dominated by the filter-feeding European Faucet Snail
(Bithynia tentaculata), with some of the introduced Banded Mystery
Snails, one native Brown Mystery Snail, and a few Common Stagnicola,
Larger Eastern Ramshorns, Three-keeled Valve Snails, Modest Gyraulus,
Ordinary Spire Snails, and Tadpole Snails. Five species of native
mussels were present as living individuals and fresh & old shells:
Elliptio complanata (Eastern Elliptio), Lampsilis cardium
(Pocket-Book), Pyganodon grandis (Common Floater), Lampsilis radiata
(Eastern Lamp-Mussel), and Lasmigona costata (Fluted Shell).
The same species were seen in 1997 & 1998, with the addition of
Fingernail Clams in the drift, and a few huge old Ligumia recta (Black
Sand-Shell) mussels, which we speculated may have been youngsters when
Colonel By was putting in the canal. In June of 1999 there was one
Zebra Mussel (Dreissena polymorpha), on one living native mussel, and 3
in September. These “few Zebras per visit” conditions continued in
2000, 2001, and 2002, but in 2003 for the first time, the Zebras were
“common,” with a few threaded onto most of the native mussel shells – 13
years after they were first seen in the Rideau system. Things were much
the same in 2004, but in 2005, the year of the maximum count on the
lock, while there weren’t a lot of dead native mussels the Zebras seemed
to be most abundant on dead shells “perhaps 4-5/shell average, but not
as many as an average of 1 on living Unionids.”
In 2006 all of the native mussels found, except for one Elliptio, were
dead, and the Zebras were abundant all over the riverbed. [[how zebs
kill unios]] In 2007 the bottom was “dark with a pavement of very living
Zebra Mussels… littered with dead Unionid shells, so densely piled at
the foot of the flat that the sample represents those I was able to pick
up without moving my feet, about a 60 cm radius. There were, among these
but not collected, 4 large living Elliptio , and one small Lamp-Mussel,
all with attached Dreissena.” The drift sample was about 65% small Zebra
shells, 25% Faucet Snails, and 5% Banded Mystery Snails, with a
scattering of Ramshorn Snails and Common Stagnicola.
On 9 July 2007 we saw a few invasive Rusty Crayfish crawling out from
under rocks as dusk fell; the banks were mostly crowded with Cathartic
Buckthorn and Tartarian Honeysuckle, and there were the dense islands of
Flowering Rush and Hybrid Cattail in the main channel, provoking the
idea that Parks Canada should redenominate the place "Aliensville" and
open a theme park.
Things continued like this in 2008, 2009, 2010 <<blog posts>> and 2015.
In 2016 the drift had a few Fingernail Clams and a few Faucet Snails –
all the rest was Zebra Mussels. An attempt to collect drift in 2020 was
thwarted by high flow in the river, perhaps due in part to
pandemic-reduced boat traffic through the locks.
On 16 July of this year I finally made a return visit to the site of
this dramatic faunal turnover, with our intern Luna Lopez-Andrews, and
her mother, math teacher & plant breeder, Telsing Andrews. The
traditional drift sampling site had a narrow 3 m ridge of Zebra Mussel
shells – no other species – at the edge of the current below the islet.
The native Unionidae shells, old, worn, and fragmentary, were still
fairly conspicuous on the rocky bottom. One living Elliptio, was found
with a crust of baby Zebras on it.
Elliptio – dark, compressed and fairly elongate, with a purple inner
shell – is the native species most able to coexist with Zebra Mussels,
perhaps because its ability to bury itself in the substrate to endure
harsh conditions allows it to suffocate attached Zebras. There are
places on the St Lawrence, South Nation, and Mississippi rivers where
Elliptio and other species are managing to survive in fair numbers among
reduced Zebra Mussel populations, but Andrewsville doesn’t seem to be
among them.
Fred Schueler
Jul 31, 2025, 6:51:15 AMJul 31
to natur...@googlegroups.com
On 7/30/2025 8:55 AM, Fred Schueler wrote:
> it looks like our stream visits have been biased toward the relatively healthy Kemptville Creek
* and here's a visit to the creek, with invasive Crayfish and hybrid
> it looks like our stream visits have been biased toward the relatively healthy Kemptville Creek
Cattails, and regionally nonnative Walnuts, but generally vibrant
activity. The death of the Moss is taking out the carpet of growth from
last summer when the flow was much above average:
30 July 2025 -Canada: Ontario: Grenville County: Oxford-on-Rideau:
Oxford Mills Dam, Kemptville Creek. (100m ard dam), 44.96486° N
75.67863° W TIME: 1855-1907. AIR TEMP: 25°C, overcast, Beaufort gentle
breeze. HABITAT: brown-water creek at limestone flats below old milldam.
OBSERVER: Frederick W. Schueler. 2025/146/f, visit (event). natural
history, walk, checking out low water. Flow 0.075 cubic metres/second,
average 1.4 cubic metre/second from RVCA graph. slight flow over all
spillways. Just did the parkinglot and the E side without wading into
the water.
Rhus typhina (Staghorn Sumac) beside the lot sprouted up to 2 m height -
a 1.5 m Juglans nigra (Black Walnut) sapling at the edge of the Sumac
patch, and others on the "lawn" area - Typha (Cattail) above the dam
clearly Typha x glauca (Hybrid Cattail) with long dark heads and narrow
gaps - Eupatorium maculatum (Spotted Joe Pye Weed) > Eupatorium
perfoliatum (Boneset) below the dam - lots of the Joe Pye Weed swathed
in Cuscuta (Dodder) - scattered Lythrum salicaria (Purple Loosestrife)
in bloom, a few hammered by Galerucella biocontrol Beetles but most
imperforate - NO:Orconectes rusticus HYBRID:Orconectes propinquus
(Hybrid Crayfish) leavings around the dam or on shore - lots of dead
Fontinalis Moss dead exposed in a trangular 6 x 8 m patch on the middle
flat area - scattered Zizania (Wild Rice) plants in the Moss on the
flats, with spent heads as if seeds already shed - lots of little fish
zipping through the shallows and a scattering of dead 4 cm Centrachids
on the flats.
fred
Reply all
Reply to author
Forward
0 new messages