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Freshwater Biology
Bacteria
• Freshwater bacteria can be cool, but they
can also be harmful
• Bacteria love warm, wet environments
– Many freshwater locations are perfect
• Harmful bacteria in freshwater
environments can infect humans
Bacteria
• How do they get there?
– Many bacteria come from animal feces (poo)
and earth around the water source
– Bacteria can come from infected swimmers
– Can also come from infected animals
– Strong or large amounts of rain will definitely
wash bacteria into the water source
• Bacteria can enter humans through
inhalation, digestion, and open wounds
Bacteria
• While there are plenty of helpful bacteria in
freshwater environments, but many of
them can cause harmful symtoms for
swimmers;
– Cough, rash, diarrhea.. And EVEN DEATH!
• So..
– Don’t swim if pregnant
– Don’t swim if you’re old (Mr. B)
Freshwater Fish
• Physiology
– Freshwater fish must be able to diffuse water
through their gills (to eliminate impurities)
– Freshwater fish must be able to hold onto
salts with a large kidney
– Freshwater fish release large amounts of
urine
– Freshwater fish have to have enough scales
to reduce diffusion, fish that loose too many
scales will die
Freshwater Fish
• Migration
– Potamodromous
– Oceanodromous
– Diadromous
• Anadromous
• Catadromous
• 1% of all fish are able to live in both salt and
fresh water
• Freshwater fish can withstand .05% salinity
Freshwater Fish
• Freshwater fish are much more readily
adaptable than saltwater fish
– This is because their environments are
usually always changing
• There are more freshwater fish in rivers
and streams than in lakes
• 42% of known fish species live in
freshwater
Freshwater Mammals
• Freshwater mammals include not only
cetaceans (river dolphin), but land animals
as well
• Freshwater mammals often have large
tails (Ex. Beavers, manatees, etc.) to aid
them in swimming
• Many freshwater mammals have fur (lots
of it) to keep them warm
Freshwater Mammals
• Why do they need fur?
– Freshwater environments are often colder
than salt water environments so they need
insulation
• What do they eat?
– Crustaceans, other fish/animals, freshwater
vegetation
Freshwater Mammals
• Freshwater species are often used as
indicator species for scientists
– Scientists can study the population size
around a water source to determine if the
ecosystem is healthy
• Freshwater mammals are also
endangered by the same things as
saltwater mammals;
– Sewage, boating accidents, stupid people