Freshwater Conservation Flashcards
Freshwater Diversity
1% of the total volume
41% of all fish species
Freshwater declines
83% decline since the 1970s
This is higher than terrestrial and marine
Causes of freshwater decline
Exotic introductions ~68%
Pollution ~38%
Hybridization ~38%
Overharvest ~15%
British Columbia Freshwater fisheries
81 FW species
4 extinct
Dragon Lake whitefish has 2 species that are extinct (toxaphene poison)
Hadley lake stickleback 2 species catfish invasion
15 exotic introduction
Factors for FW diversity
Isolation
Spatial heterogeneity
primary productivity
temporal scale
Substrate Alteration
most fish depend on substrate complexity
snags removed for human use
snags are 4% of the area but, 60% of invertebrate biomass (4x more food-mass)
Serves as nursing habitat
Channelization
reduce fish/biomass and productivity
Mining and tailing ponds
sedimentation, heavy metal contamination
trillions of liters in candada
Deforestation of riparian
effects sedimentation, turbidity, bank stability, loss of shading
Dams
Influence habitat and migration
sometimes use fish ladders
large reductions to migrating salmon in NA
Aswan Dam
Reduces sardines in mediterranean
Volga river
90% catch loss in caspian sea
Hells Gate Rockslide
This increased water flow velocity
100% block of salmon
Introduced species
Transplants within a country and exotics from outside
160 FW introduced species
in all cases introductions lead to declines or extinctions
Brazilian introductions
Naturalization of invasives for aquaculture
Asian carp
Placed by US gov into sewage ponds to eat the algae
Flooded into Mississippi River where they now dominate
They have migrated up and detected into the Great Lakes
Dam Removal vs Invasive Management
Dam removal and fixing the flow characters of the river is valuable, but the removal of invasives is more important
Great Lakes
200 native fishes
Canal from Lake Ontario to Lake Erie allows for the invasion of many marine species
Lamprey have decimated lake trout population
Zebra mussel covers most of the benthos
180 species introduced
Lake Winnipeg
largest intact watershed
commercial fishing and 25% of Canadas FW catch
major shoreline development and input from many rivers across prairies has led to eutrophication
Teck Mines
Zinc and lead smelters in Trail
10 million tonnes of slag per year into the Columbia river
60 million dollars in fines last 20 years
Overfsihig
Larely unrecognized and poorly understood
