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Flashcards in Aquatic Ecology final Deck (324)
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61

larger scale effects of harvesting fish feed

taking ~85% of sea predators food; seabirds, marine mammals

62

Effects of farming on wild salmon health

smolts travelling to ocean pass by fish farms, pick up significant infections rates; many farm fish have sea lice (infestation from low diversity, close quarters)

63

forage fish

prey fish/bait fish, small pelagic fish preyed on by larger predators for food

64

areas of application for stable isotopes

paleoclimate reconstruction (O2)
paleolimnology
terrestrial aquatic linkages
food web ecology
migratory studies
individual feeding behaviour

65

paleolimnology, stable isotopes

historic patterns of productivity, mostly C, N

66

terrestrial aquatic linkages, stable isotopes

terrestrial--> aquatic (lake management)
marine derived nutrients (salmon)--> terrestrial

67

food web ecology, stable isotopes

contaminant transfer, ecology

68

migratory studies, stable isotopes

birds, fish, zooplankton, mammals, C
how much time in open/coastal ocean
algae isotope ratio highly variable in open/coastal

69

individual feeding behaviour, stable isotope

niche shift, omnivore, trophic position
within single population
ex. stickleback - some neutral all the time, some pelagic all the time, all related to evolution, studiable by isotopes

70

∂13C ratios

C fractionates during photosynthesis, little-no fractionation up food chain
determine what food sources are based on ∂13C ratio

71

∂13C determination of food source possible with following conditions

large isotopic separation (btw food sources)
over time food signatures are stable
two/few food sources

72

examples of ∂13C determination of food source

middle of lake - very highly negative
close to littoral zone (terrestrial C) - less negative

73

∂15N in food web ecology

tells trophic level, fractionated throughout trophic levels

74

trophic enrichment of ∂15N

2.92+/- 0.8 ‰

75

typical ∂15N signatures

algae 4-8‰
invertebrates 8-16‰
forage fish 10-14‰
predatory fish 10-18‰

76

typical ∂13C signatures

off-shore -28‰ (depleted)
near-shore -14‰

77

why is ∂15N fractionated up trophic level

preferential excretion of 14N

78

high ∂15N

heavy
more positive

79

atmospheric N2 ∂15N

0‰
hasn't been fractionated by organisms

80

enriched in ∂13C

heavy
less negative
∂13C never positive

81

depleted in ∂13C

light
more negative
∂13C never positive

82

inorganic fertilizer ∂15N

0‰
made from captured atmospheric N

83

fractionation

in a chemical reaction one isotope proceeds at a quicker rate than the other due to a slight difference in mass (lighter synthesized faster/easier, more efficient)

84

two types of fractionation

animals- body tissue
algae

85

animal tissue fractionation

14N is preferentially released so 15N increases relative to its food source

86

algae fractionation

photosynthetic enzyme can process 12C molecules quicker than 13C, utilize it preferentially
based on size

87

algae photosynthetic enzyme that processes carbon molecule

RUBISCO

88

isotopic composition in foodweb

sediment: ~-30, towards terrestrial
inverts: ~-33, ~50/50 terrestrial/planktonic
piscivorous fish: ~-28/-30 pretty close to terrestrial

89

littoral zone

near shore area where sunlight penetrates all the way to the sediment and allows aquatic plants (macrophytes) to grow

90

Loch Ness Zooplankton, temporal shift in C signature reflecting food source

winter- low PP, most C is detrital, POM (less - ∂13C), zoop signature matches POM
summer- higher PP, signature drops to mirror to algae ∂13C (more - )