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Flashcards in Aquatic Ecology final Deck (324)
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211

% of total catch vs year (Lake Victoria)

haplochromines (cichlid) majority of prey catch until ~'74
1974-1980 majority is haplo. and omena
after 1980 majority is Nile perch and omena

212

Omena

anchovy-like minnow

213

Standing stock estimates, Lake Victoria
Kg/ha vs year

Native - ~60 in 1970's down to ~0 in 80's, 90's
Introduced- ~30 in 80's --> ~70 in 90's
almost entirely introduced species

214

Oxygen in Lake victoria
O2 (mg/L) vs Month

surface ~10 all year
bottom: less than 5 all year, anoxic in winter, highest in summer
loss of haplochromines (algal readers) changed oxygen structure
bottom up control

215

Eastern Bullfrog

widely introduced for aquaculture (restaurants) Europe, Asia, Japan
replace/consume prey of/ infect native amphibians

216

spread of Eastern Bullfrog

California 1905
Burnaby 1940
Elk Lake 1960's

217

Eastern Bullfrog diet

omnivores
insects, fish, ducklings, rodents

218

Invasive Zooplankton

Daphnia lumholtzii (Europe-NA)
Bythotrepes (NA)
Cercopagus (black sea-baltic)
Mysis relicta (Ghost shrimp, glacial relict)

219

Success of invasive species

distinct features that give them the advantage
ex. sharp spine, anti predator mechanisms, larger T/resource/habitat ranges

220

Mysis relicta foodweb changes

introduced to Flathead river-lake ecosystem to increase kokanee population. Only feed at night, competition for kokanee's resources.. decreases kok. pop., lake trout, bears, eagles, copepods, cladocerans (water flea)

221

Invasive filter feeders

Zebra, Quagga mussels
introduced from ship ballast from E Europe, 1988
few predators (dicks, 1 fish)
widespread through Mississippi
major financial impact
larvae continue to spread with boats

222

Why are so many eggs released in St. Lawrence seaway

ships have to release ballast to rise in canal

223

Effects of increased mussles

clog water pipes, make great lakes more oligotrophic, affect fish productivity

224

Origin of foreign fish

mostly from:
South America, Asia, Africa, Central America

225

Laurentian Great Lakes

most important NA water source
SA 244,000km^2
V 23,000km^3
21% worlds water
84% NA water
1/3 of Canadian Population

226

Great Lakes fish introductions

1600's Carp
1930's Lamprey, alewife
1960's Pacific Salmon
Rainbow smelt, reffe, goby (ballast water), zebra mussels

227

Lamprey, alewife introduction great leaks

1930's
upper lakes via Welland canal
loss of lake trout, whitefish
alewife - zooplanktiverous--> anoxia

228

Welland Canal

waterways connecting Atlantic ocean to great lakes

229

Pacific Salmon introduction to great lakes

1960's
chinook, coho
introduced to deal with alewife (biological control)
salmon spawn upstream, don't go to ocean, very contaminated

230

VI fish introductions

Sunfish
Rainbow Trout
Small Mouth Bass
Yellow Perch

231

Other introduced species

Asian carp/Grass carp
Cormorants
Bang
Nutria
Didymospenia

232

Asian Carp, Grass carp

introduced to control aquatic plants, took over
biological control

233

Cormorants

Lake Ontario
efficient gobies consumer (invasive fish)
fewer sport fish

234

Bangia

filamentous algae forming extensive growth

235

Nutria

'river rat' -kinda looks beaver/marmot like
very efficient foragers
cause enormous damage
from SA

236

Didymospenia

filamentous diatom
choking river beds
decrease use of rivers as spawning grounds

237

Caulerpa taxifolia

mediterranean
1984 first discovered
1990 1ha authorities informed (in writing)
1994 declared major threat 1500Ha
1998 UN law to battle invader 4600Ha
1999 covers 97% of suitable surfaces France, Monaco, Italy

238

Invasive cats

feral populations, one of worst invasive mammalian predators
direct predation
competition
hybridization
disease transmission
ecologic process alteration
behavioural change

239

Google Earth/GIS

can be used to study introduction/coverage of invasive w/ time
google earth found to be 84% accurate at detection

240

fate of invasives, possible outcomes

Transport-- introduction -- success (fail) --spread (fast/slow) -- impact (nuisance/non-nuisance)