Unionid mussels of Eastern Ontario
this will provide both a list of species known from eastern Ontario (a vaguely defined region, more-or-less bounded by the Petawawa and Moira river drainages), and thoughts on their systematic status, ecology, and conservation status. Right now it's under construction – you'll know a species has been done when its name is a link rather than just text.
Actinonaias ligamentina
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Alasmidonta marginata
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Alasmidonta undulata
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Anodonta implicata
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Anodontoides ferussacianus
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Elliptio
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Elliptio complanata
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Elliptio dilatata
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Elliptio cf crassidens
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Lampsilis
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Lampsilis cariosa
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Lampsilis cf fasciola
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Lampsilis radiata
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Lampsilis radiata cf radiata
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Lampsilis radiata cf siliquoidea
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Lampsilis ventricosa/ovata/cardium
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Lasmigona compressa
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Lasmigona costata
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Leptodea fragilis
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Leptodea ochracea
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Ligumia nasuta
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Ligumia recta
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Obovaria olivaria
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Potamilus alatus
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Pyganodon spp.
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Pyganodon grandis
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Strophitus undulatus
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Utterbackia imbecillis
Study Unionoid
mussels!
our
subtly beautiful largest invertebrate animals
Ligumia
nasuta from Lyn Creek, Lyn, Ontario
Before
European settlement, our long-lived native Unionoid Mussels were the
dominant filter-feeding organisms in North American rivers and lakes,
often covering the bottoms at densities of hundreds per square metre,
and with astonishing numbers of species in a single bed. Their
filtering kept the water clear, and the digging action of their feet
kept the sediments oxygenated. They have long been declining, due to
harvesting for shells and pearls, sedimentation, and pollution.
Introduced European Zebra Mussels are eliminating entire species and
faunas by smothering, displacement, and starvation. It behooves
naturalists to get to work before these subtly lovely bivalves, our
largest invertebrate animals, are gone from many places where we
wouldn't have even known that they occurred. Unionids depend on fish
to disperse their larvae, and live for many decades, so adults may
persist long after reproduction has ceased. Shells may be found long
after the last animals at a site have died.
Because of their constant filtering, Unionids are the heavy-duty
in-stream providers of "water quality," and unlike fish, they can't get
out of the way and then quickly swim back to recolonize a site. Stream
projects should avoid disturbing the sreambed where they're abundant,
since the mussels take 10 years or so to mature, and mature individuals
can keep providing improved water quality for decades.
There's
no better way to spend a summer than wading or canoeing creeks,
rivers, and lakes to document hidden nodes of unionoid abundance.
It's different from looking for frogs or birds, because there's
nothing like a random transect through an area. You have to go to
very specific sites, and each stretch of stream or lakeshore may
have a different mix of species, depending on substrate, water
flow and hardness, phytoplankton, movements of host fish, and
bottom disturbance or interruptions of flow over the past few
decades.
To become the local unioniod expert, search shores
and bottoms of streams, and shores and shallows of lakes,
concentrating on clear-water habitats and on riffles, and
especially on streams right below dams and lake outlets, where
phytoplanktonic food that grows in still water flows by
filter-feeders like a perpetual buffet. Some species are wedged
into the mucky banks of streams. Muskrats accumulate shell piles
beside stumps and rocks on the bank, which you'll find easily once
you begin to think like a Muskrat. Otters scatter shells, and
Beavers cover big areas of the bottom with shells. Flood waters
concentrate shells at the foot of bars, or in eddies. It's
important to examine lots of animals and collect lots of shells,
because many species are superficially hard to tell apart. But
they're no harder than fall Warblers or Damselflies. And since you
can collect dead shells without harming the populations, it's
possible to gather material documentation of the occurrence of
species, and their variation.
We've prepared a datasheet
that observers can use to describe the circumstance in which they
find shells. Print this datasheet on good (bond) paper in
waterproof ink, gather a common plastic grocery bagfull of shells
from each site where you notice them, fill out the sheet, and send
them to us. We'll identify the shells, catalogue them into the
BMNHC collection, and send an account of the sample to you, along
with identified shells that will help you learn the species in
your river or watershed. you
can download the datasheet here
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