Large lakes like Lake Ontario seem mysterious because they are so
deep that it seems impossible to imagine what is happening below
the surface. More easily seen is the shoreline that is important
habitat for many plant and animal species. It is largely because
people have come to realise the value of shoreline habitats for
wildlife that the restoration of much of the Great Lakes has occurred.
In some areas the shore is rocky and there is little sediment to
support plant roots, but in many areas there is a gradually sloping
shoreline. In these shallow areas plants are able to grow roots
down into the lake sediment, stabilising the shoreline and forming
coastal marshes. Plants that do this effectively are cattails (Typha
spp.) and bulrushes (Scirpus spp.). This is the most
productive zone of the lake, where fish spawn and birds nest.
Grebes feeding young. Photo by Barry Cherriere.
ducks and geese in particular take advantage of shoreline habitat,
foraging at the lake edge. Some even nest nearby. In the restored
areas of Hamilton Harbour you can find terns (e.g. Sterna caspia,
the Caspian Tern), gulls (e.g. Larus marinus, the Great Black-Backed
Gull), Double-Crested Cormorants (Phalacrocorax auritus),
ducks (e.g. Anas rubripes, the American Black Duck), and
Osprey (Pandion halietus).
Head Ducks flying over Lake Ontario. Photo by Barry Cherriere.
can also find fish and their eggs here.
Native fish species such as Northern
Pike (Esox lucius),
Bowfin (Amia calva), Freshwater Drum (Aplodinotus grunniens),
Pumpkinseed (Lepomis gibbosus), and Yellow Perch (Perca
flavescens) can all be found here at some time in their life
fish species are also abundant, including the Carp (Cyprinus
carpio) and Alewife (Alosa pseudoharengus).
Pike. Photo by Mike Giovanetti.
the deeper, cooler waters offshore, other species of fish are more
common. These include the non-native Rainbow Smelt (Osmerus mordax)
and the native Burbot (Lota lota), Lake Trout (Salvelinus
namaycush) and Lake Whitefish (Coregonus clupeaformis).
waters are not the home for many birds, but many hunt for food farther
out than you might expect, including gulls, terns and cormorants.
Plants are also of interest in lake habitats. Because Lake Ontario
is so deep, not enough light reaches the bottom to allow plants
to grow there. Instead, small plants called algae are present, floating
freely with the currents. Algae are often referred to as phytoplankton.
is a Latin form of the word 'plant', and 'plankton'
refers to the free-floating nature of these organisms, thus
phytoplankton are free floating plant-like organisms.
ambigua, a zooplankton, is one of the smallest species of
Daphnia in North America. It is common in lakes and permanent
ponds in southern Canada. Photo by Chad Rowe and Paul Hebert,
Cladoceran Web Site, University of Guelph. www.cladocera.uoguelph.ca.
share the water with free-floating animals called zooplankton, 'zoo'
meaning animal. Together they form the basis of the aquatic food
chain. Both insects and fish eat plankton, and in turn they are
eaten by other fish, birds and mammals including us!
lakes, including reservoir lakes, have plankton. In fact an overabundance
of phytoplankton is one sign that there is too much organic pollution,
such as sewage and domestic water, going into the lake. Lakes like
this appear green because they have so much algae and are called
highly fertile and nutrient-enriched.
that are clear, without too much algae, are called 'oligotrophic'.
possibly nutrient poor, not nutrient rich, less fertile.
there are some naturally eutrophic lakes and rivers, most are oligotrophic