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Flashcards in 446 Aquatic Ecology Deck (279)
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smolt weight

is significantly decreased with increasing density, there is a limit to how many fish a system can produce (carrying capacity)


salmon and nutrient-foodweb dynamics

more nutrients-- larger algae-- small/inefficient grazers-- low growth, small smolts, low adult return


fertilization of lake, 1983

TP increases, algal biomass increases, daphnia size and biomass increase


impact of lake fertilization on smolt size

1yr old smolts small increase in size
2yr old smolts large increase in size


impact of lake fertilization on fry/smolt density

both increasing


fry stocking of lake, 1987

TP, algal biomass drop off, daphnia size and biomass drop, average smelt size drops off, fry and smelt density increase for a few years then drop off, change in zooplankton composition
over capacity


smolt size vs. daphnia size

positively correlated
(larger, efficient grazers = larger fish)


important factors in the highly variable growth pattern of sockeye smolts

fry density
size of zooplankton
lake features


size of 1yr old smolts and total zooplankton biomass

available food is not a good predictor of smolt size


size of 1yr old smolts and mean size of Daphnia

quality of food is a better predictor of smelt growth and size


smolt size and nutrient levels

smolt size and fry density higher in high nutrient system, but not increasingly so, systems 'level off' in all nutrient levels


photic depth vs. turbidity, and colour

photic depth rapidly drops off in both, but quicker with increased turbidity


light penetration, clear lake

euphoric depth 16.4m
secchi depth 7.2m


light penetration, stained lake

euphotic depth 7.4m
secchi depth 4.3m


light penetration, glacial lake

euphotic depth 6.5
secchi depth 1.5m


thermal traits, clear lake

max T 14º
mean T 7.8º
heat budget 11.8 kcal/cm^2


thermal traits, stained lake

max T 16.2º
mean T 6.9º
heat budget 10.8 kcal/cm^2


thermal traits, glacial lake

max T 11º
mean T 5.9º
heat budget 11.6 kcal/cm^2


vertical mixing patterns in different lakes

depth as a function of T
heat budget is area 'under the curve'


depth vs. T, clear lake

med T at surface, drop off, med T at depth


depth vs. T, stained lake

highest T as surface, rapid drop off, lowest T at depth


depth vs. T, glacial lake

coldest at surface, T remains ~constant at every depth, winds up being highest T at depth b/c other 2 drop off to lower T


Primary production in different lake types

Chl vs. TP
positively correlated, high slope in clear lake
positively correlated, med slope in stained lake
no real relationship in glacial lake


glacial lakes

lowest light penetration
lowest T's (med. heat budget)
constant T with depth
higher TP
lower Chl then clear
produces smallest fish and lowest smolt biomass


1yr old smolt weight vs. age and different lake types

age vs. weight tightly positively correlated
clear lakes - fish at whole spectrum of the best fit line
stained - ~half way up line
glacial lake- only the lowest part of the line


smolt length in lake types

clear 95mm
stained 71mm
glacial 69mm


smolt weight in lake types

clear 7.9g
stained 3.3g
glacial 2.6g


smolt biomass vs. euphotic depth

clear - positively correlated
stained, glacial - only points at small euphotic depths, euphotic depths can't be very deep in these lakes


smolt biomass vs. zooplankton biomass

clear - positively correlated
stained- positively correlated but only goes ~half way up line
glacial - only points at small smolt/zoop biomasses


SST shift study, Eastern Bering Sea

2002-2005 warm, 2006-2007 cold
use N isotopes in zooplankton to study shifts in foodwebs