446 Aquatic Ecology Flashcards
(279 cards)
1
Q
why study aquatic ecology
A
aquatic ecosystems & resources critical to human survival, health, well being
2
Q
ecosystem processes
A
hydrologic flux, storage biological productivity biogeochemical cycling, storage decomposition maintenance of biological diversity
3
Q
ecosystem “goods”
A
food construction materials medicinal plants wild genes for domestic plants and animals tourism and recreation
4
Q
ecosystem “services”
A
maintain atmospheric gaseous composition regulate cimate cleanse water/air pollinate crops generate/maintain soils store/cycle nutrients absorbe/detoxify pollutants maintain hydro. cycles provide beauty, inspiration, research
5
Q
human disturbances affecting coastal ecosystems
A
- Fishing, Pollution, Mechanical habitat destruction, introductions, climate change
(fishing always preceded other disturbances, others change in order)
6
Q
inputs and concerns
A
organic (livestock), fertilizer, rain, pollutants, pathogens, pharma-care, invasive species, nitrate leaching
7
Q
adverse effects of eutrophication
A
increased biomass of plankton shifts in phytoplankton (may be to toxic) increased epiphytes coral reef loss decreased water transparency oxygen depletion increased fish kills loss of desirable fish species reduction in fish/shellfish harvest decreased aesthetic value
8
Q
chemical characteristics of aquatic ecosystems
A
nutrients
9
Q
biological characteristics of aquatic ecosystems
A
foodweb
10
Q
limnology
A
the study of inland waters - lakes (both freshwater and saline), reservoirs, rivers, streams, wetlands, and groundwater - as ecological systems interacting with their drainage basins and the atmosphere.
11
Q
algal biomass vs nutrient
A
chl vs. Total phosphorus (TP)
increasing on log scale but large variation above/below the line
12
Q
why measure TP as nutrient load?
A
most limiting resource
13
Q
high nutrient, lower than expected Chl (algae)
A
more large fish, preying on large grazers
14
Q
small algae
A
larger, efficient grazers
larger biomass
larger planktivorous fish
system is more efficient
15
Q
system with lots of small planktivorous fish
A
prey upon small grazers
larger algae
16
Q
high density of small fish
A
low density of large zooplankton
higher Chl (algae)
greener water, lower O2
17
Q
small grazer, shallow lake, Chl vs. TP
A
high productivity, but less than small grazer system in med-large lake- less O2, less insolation, less space…
18
Q
empirical data
A
observational
19
Q
experimental data
A
manipulate variable
20
Q
response of lake ecosystem to nutrient loading experiment
A
same [nutrient], #large fish vary
w/o large fish = small zooplankton = more algae
21
Q
epilimnion
A
the upper layer of water in a stratified lake, ~constant T, mixed layer
22
Q
lakes with high grazing, low TP
A
clear water, more light penetration, more heat deeper, larger metalimnion, less steep T gradient, deeper O2 max, photosynthesis can occur throughout metalimnion
23
Q
metalimnion
A
thermocline, T changes more rapidly with depth than it does in the layers above or below, highest density, layer of ‘stuck’ algae
24
Q
indicator of water transparency
A
secchi depth
25
lake with low grazing, high TP
high Chl = low transparency = low O2, higher and smaller metalimnion, less light penetration, steeper T slope in metalimnion, light just barely penetrates meta., photosynthesis cannot occur throughout metalimnion, O2 goes to 0, system is reducing (like saanich inlet)
26
zooplankton size under high fish density
~80% less than 0.2mm
27
zooplankton size under low fish density
~40% less than 0.2mm
28
hypolimnion
the lower layer of water in a stratified lake, typically cooler than the water above and relatively stagnant, ~constant T, O2
29
algae biomass with time
low grazing= increased biomass w/ t
| intense grazing = very low slope, barely increasing
30
TP with time
low grazing = increased TP w/ t
intense grazing = very low slope, barely increasing
low grazing = more algae = more TP
31
dissolved P with time
low grazing = very low slope, barely increasing
| intense grazing = high slope, increasing
32
why is there higher dissolved P with intense grazing
high grazing = lots of dissolved P b/c not being taken up by algae
size of fish controls [algae] which controls [dissolved vs. particulate P]
33
length of algae as a function of biomass of algae in large grazer system
as biomass increases, size increases (more removed = more nutrients available to the fewer)
34
length of algae as a function of biomass in small grazer system
increased biomass = smaller size (more biomass means higher quantity means less nutrients available to each)
35
algae size and phosphate turnover time
```
small algae (large grazer system) = slower nutrient turnover = long phosphate turnover time
large algae (small grazer system) = faster Phosphate turnover time
```
36
when you have large particles, the overall particle load
is made up of more large particles, median is higher
| large particles = less small particles
37
add nutrients
overall particle size shift to larger particles
| = long phosphate turnover time
38
add nutrients and fish
shift to more smaller particles
| = shorter phosphate turnover time
39
so... as average size of plankton declines..
larger slope, uptake efficiency increases, turnover time is shorter
AND transparency declines
40
how changes in biology = changes in physics
thermal structure, penetration of light, accumulated energy/heat content
41
fetch
longest open length of a water body through which wind can blow
42
change in epilimnion with fetch
increased fetch = increased depth of epilimnion (more wind = more wind mixing)
43
downward heating intensity vs. penetration of solar radiation
increasing surface area of water body (fetch) vs. increasing water transparency
44
increasing fetch & transparency
deeper epilimnion, more heat, more energy, greater depth for photosynthesis, more O2
45
role of biology on mixing rate
affects clarity of lake which affects insolation absorption which affects stratification
46
sedimentation, total phosphorus rates highest in
+N (nutrients added, no small fish, large zooplankton)
47
secchi depth highest in
control then +N
| deepest when no small fish
48
chlorophyll highest in
+NF (nutrients, small fish, small zooplankton grazers, larger algae)
49
summer O2 profile, control vs. +F
+F higher O2 in epilimnion
lower O2 in metalimnion and hypolimnion
O2 max is higher in water column in +F and goes to 0 with depth
50
summer O2 profile, +N, +NF
+N higher O2 at all depths
| +NF goes to 0 in hypolimnion
51
lake St. George
```
large # planktivorous fish
low secchi depth
smaller daphnia
shallower epilimnion depth
higher TP
higher Chl
strongly eutrophic
```
52
Haynes lake
```
less planktivorous fish
deeper secchi depth
deep epilimnion depth
larger daphnia length
lower TP
lower Chl
```
53
Julian days
continuous count of days since the beginning of the day starting at noon on January 1
54
hypolimnetic oxygen changes with season
oxygen depletion from spring -- summer (lowest O2 with +F)
55
hypolimnetic oxygen chantes in Haynes lake and lake StGeorge
both reach min. in June, S.G. stays at ~0 for rest of summer, H. increases to second max in late July-early August. Lake H. never goes to 0
56
algae size and relative sedimentation rate
small grazer system = short phosphate turnover time = lower relative sedimentation
57
why larger grazer system has higher relative sedimentation
large things sediment more, greater proportion sink, heavier, less efficiently used (P turnover)
58
absolute sedimentation rates
would be higher in small grazer system because there's so much more
59
toxic algal groups
cyanobacteria, dinoflagellates, diatoms
60
problems with algal blooms
toxins, anoxia, habitat loss, recreational loss, health risks
61
anthropogenic P, N to aquatic systems lead to
```
eutrophication
algal blooms
fatal algal toxins
anoxia- loss of diversity/habitat
proliferation of waterborne pathogens
increased chlorination byproducts in drinking water
```
62
waterborne pathogens especially important in
tropical/subtropical regions, can be related to cholera
63
forms of land-use
```
agriculture
farming
waste disposal
fertilizer
harvesting
hydrology
```
64
effects of N,P loading are different
depending on structure of system
shallow vs. deep
large vs. small fish
65
population growth
increasing pop., more mouths to feed, more land-use required, world fertilizer growth, more N,P loading,
66
obtaining N, P for fertilizer
N atmospherically available, easier to obtain. P not atmospherically available, geological nutrient, limited
67
problem with speed of population growth
available, cultivatable agricultural land is NOT increasing, need GMOs to keep up with pop. increase
68
GMOs to keep up w/ pop. increase
rices that can grow through floods - multiple crops/year
69
problem with GMOs that allow us to increase agricultural yield
leaching soil nutrients, more and more fertilizer
70
population growth and water shortage
water hungry plants and animals (and nutrient loading)
71
examples of water hungry crops
```
70L/apple
3400L/kg rice
140L/cup of coffee
120L/glass of wine
15,500L/ kg of beef
```
72
changes in atmospheric NH4
30% increase in urea use as fertilizer (1960-1990)
73
observed relationship between N,P and Chl
positively correlated
| nitrogen more tightly correlated
74
eutrophication defined as
excessive growth of algae, often associated with bluegreen and other harmful algal blooms
75
determines types of algal bloom
amount of nutrients, composition of nutrients (TN:TP)
76
N:P ratios for different runoff types
```
unfertilized field N:P 250
forests 75
rainfall 25
manure seepage 9
sewage 5
```
77
nutrient composition ratio
dependent on where nutrients come from
| dictates algal bloom
78
bluegreen algae associated with what nutrient composition
low N:P ratio (towards the manure, sewage deposits)
79
differential response to increased [P] in N limited vs. P limited ecosystem
N limited systems does not respond as strongly to increased P
80
increasing phosphorus concentration =
increased dominance of cyanobacteria
81
other controls on levels and types of algal biomass blooms
seasonality of nutrient inputs (coastal and freshwater ecosystem)
physical properties of receiving system
structure of foodweb
82
N:P ratio as a control in number of red tides
as N:P decreases, #red tides increases, highest below 16
| duration of blooms longer when N:P
83
redfield ratio
N:P
16:1
84
increasing nutrient, increasing algal biomass
responses are not proportional in all systems, dependent on structure of foodweb (small vs. large grazers) and physical structure of ecosystem
85
physical lake structure and response to changes in nutrients
deeper lakes can take more 'abuse' before showing response (less likely to become eutrophic)
86
algae harmful to animals, humans
cyanobacteria (bluegreen)
dinoflagellates
some diatoms
87
types of algal toxins
neurotoxins
hepatotoxins
lipo-polysaccharides
88
neurotoxins
alkaloids, b/g algae
| cause neurodegenerative symptoms through disruption in communication between neutrons and muscles
89
neurotoxin examples
anatoxin-a, saxotoxin, neosaxotoxins, Nostoc, Anabaena, Oscillatoria, Aphanizomenon
90
hepatotoxins
peptides
| affect liver, cause weakness, vomiting, diarrhea, respiratory blockages
91
hepatotoxin examples
Anatoxin-a, saxotoxin, neosaxotoxins, Nostoc, Anabaena, Oscillatoria, Microcystis
92
Lipo-polysaccharides
cause skin irritation (dissolve skin)
93
neurotoxin bioaccumulation
accumulate in nervous system (cerebral), show up with age
94
fertilizer use and red tides
increased fertilizer use tightly correlated with increased # of red tides
95
TP, TN and toxin forming algae concentration
both positive correlations
| steeper increase in toxin forming algae with increased TP then increased TN
96
concentration of microcystin vs. toxigenic biomass
increasing. the more biomass present, the more of the toxic variety
97
microcystin
class of toxins produced by certain freshwater cyanobacteria
98
ubiquity of cyanobacteria
terrestrial, freshwater, brackish, marine, widespread = potential for widespread human exposure
99
β-N-methylamino-L-alanine
BMAA- novel neurotoxic amino acid from cyanobacteria (and many algal taxa around the world), ubiquitous, accumulate and slowly release through time, found in brain tissues of people who die of ALS and other neurodegenerative disease
100
BMAA in guam
high concentration in coralloid roots of cycad trees-- concentrated in fleshy seed-- flying fox forage on seed-- accumulate-- Chamorro people eat them-- die of ALS-PDC. 50-100X incidence rate anywhere else
101
BMAA biomagnification
free BMAA--cyanobacteria 0.3µg/g--- cycad 37µg/g -- flying foxes 3556µg/g -- Chamorro people
102
Chamorro people
highest rate of neurodegenerative disease in the world
103
water categories based on nutrient richness
Oligotrophic- nutrient poor
Mesotrophic- good clarity, average nutrient
Eutrophic- enriched with nutrients, good plant growth, possible algal blooms
Hypertrophic- excessively enriched with nutrients, poor clarity, devastating algal blooms
104
lake Taihu
went from oligotrophic (1960) to eutrophic-hypertrophic in 90's
population growth, livestock growth
toxins produced
105
ALS
amyotrophic lateral sclerosis
106
BMAA exposure in desert dust
soldiers found to have high levels of BMAA, suffering from neurodegenerative disease from Iraq desert pools. dormant until rain season. inhaled, especially around Gulf War.
107
sporadic ALS in Annapolis, Maryland
found to come from Chesapeake Bay blue crabs, BMAA in Chesapeake Bay food web common risk factor
108
fa cai, Mandarin; and fat choy, Cantonese
Nostoc grown and harvested to make soup during New Years celebration. Banned now, mostly artificial, but some still contain Nostoc (BMAA).
109
driving force in aquatic system
foodweb
| changes to food web have cascading effects
110
ecosystem productivity depends on
transfer efficiency of nutrients and energy along foodweb- affected by changes in predators and prey- any affects = cascading changes
111
shifts in food web structure and function, implications for
predator/prey effects
contaminant transfer
biodiversity
productivity
112
energy transfer efficiency in small plankton, small fish system
less efficiency transfer
113
predatory invertebrates
comets with small fish for prey, added system complexity
114
food web views
bottom-up - ratio dependent, more inputs = more outputs
| top-down - limits bottom up, predators self regulate
115
predator self regulation
eat too much and use up all resources
116
k
carrying capacity of system
117
low k
low resources, nutrients, space
118
predator/prey biomass vs. carrying capacity models
R-O model: predator increase w/ k, prey constant
A-G: both increase but predator growth is smaller than prey growth
Getz: both increase parallel to each other, prey higher
predator self limitation: prey increases, predator constant
119
Fretwell trophic level biomass vs environmental productivity
alternate trophic levels have parallel relationships
| level 3 grazes down level 2 which helps increase level 1
120
Fretwell-Oksanen trophic level biomass vs environmental productivity
predators keep prey constant
levels 1&3 parallel increase, 2 constant while they increase
when 2 is increasing, level 1 is constant
121
Ginzburg-Getz-Ardith trophic level biomass vs environmental productivity
all increasing
ratio dependent
highly contradicted system, level can't increase at a ratio dependent manner, would self restrict
122
Persson trophic level biomass vs environmental productivity
looks the same as F-O only 2 trophic levels exist. one is increasing while the other is constant
123
length of food chain
affects accumulation process and efficiency
124
each food web interaction (energy transfer)
- 10-15% of E
| shorter food chain = more efficient
125
Menge and Sutherland, views on top down regulation in food webs
physical disturbance shortens food chains, most organisms will shift diet depending on food availability
126
Hairston, Smith, Slobodkin , views on top down regulation in food webs
predator/prey interaction bring in self regulatory processes. predators regulate herbivores, releasing plants to become resource limited
127
Freewill and Oksanen, views on top down regulation in food webs
top trophic levels and even numbered steps below are resource limited, trophic levels odd numbered steps below are predator limited
128
McQueen, views on predator and resource co-limitation in food webs
top-down diminishes efficiency at bottom of food chain, but both affect each other
129
Getz, views on top down regulation in food webs
inference hypothesis- predators interfere with each other- prevent efficient exploitation of resources, prey can increase
130
Mittelbach, views on top down regulation in food webs
predators require different resources as they grow (ontogenetic shift)
131
Lei bold, views on top down regulation in food webs
control of prey by consumer is not always consistent (shifts to less edible species)
132
Sinclair and Norton, views on top down regulation in food webs
starvation-weakened prey become more vulnerable to predation or disease
133
predator negative feedback, self regulation
interference competition
exploitative competition
depletion of nutritious, palatable, accessible prey
134
algal biomass vs. potential productivity, even link system (hypothetical)
2-link (algae, zooplankton), increased productivity will not increase algal biomass
135
algal biomass vs. potential productivity, odd links system (hypothetical)
potential productivity can increase, 3rd link consumes 2nd link and allows 1st link to grow
136
TP, indicator of
productivity
137
fishing down top of foodweb
shifting average trophic level (down)
significant decline in average trophic level of fish catch, average size of fish becoming smaller
crowding down foodweb?
138
how to define trophic level
analyze gut content
139
as average catch increases
average trophic level decreases, Pauley et al., 1998
140
cascading effects of the loss of apex predatory sharks from a coastal ocean
11 species of shark- all declining from overfishing
different species of mesopredators - all increasing
termination of scallop fishery
141
effects of fish in river food webs
one of first experiments on river ecosystem to demonstrate cascading effect of predators on lower trophic levels are consistent w/ observations from other ecosystem (remove large fish, small fish dominant, algal biomass increased, odd/even # trophic level limitations)
142
major change in food web concept theories
foodwebs are not closed systems. local interaction in one ecosystem may reverberate into another.
ex. aquatic system affecting terrestrial
143
aquatic system affecting terrestrial example
fish eating larval dragonfly-- decrease dragonfly abundance -- increase honeybee abundance -- increase pollination
no fish-- pollination significantly decreased
144
shrimp stocking theory
add more food, they will produce more
145
shrimp stocking results
reduced number of spawner, reduces numbers of bears and eagles
146
what happened with the shrimp stocking?
the introduced shrimp (Mysis) come up in water column at nigh and prey on the kokanee/trouts food but stay at the bottom of the lake during the day- reducing fish prey
147
Lake Victoria changes
introduced Nile Perch (1954) to increase European sport fishing; HAD extremely high diversity before; major shift to invasive species, basically replaced natives, loss of diversity and food web interactions
148
stability and diversity
higher diversity = higher stability
149
Haplochromis
zooplanktivorous cichlid, significantly decreased since introduction of nile perch
150
one positive side to nile perch introduction
more protein for Kenyan people
151
trophic downgrading
apex consumers were ubiquitous for my's, extensive cascading effects as diverse as disease, wildfire, carbon sequestration, invasive species, biogeochemical cycles: process, function, resilience
152
trophic cascades: see otter populations
eat sea urchins- sea urchins destroy roots of kelp- kelp bed declines harm many species (home to many species, similar to corals)
153
trophic cascade: sea star
absence of sea star= loss of diversity in tidal community; sea stars increase species diversity by preventing competitive dominance of mussles
154
trophic cascade: Long Lake, Michigan experiment
large mouth bass - prey on minnows-- graze on algae. right side of lake has bass = clear lake, left side has no bass = decrease clarity. bass indirectly reduce phytoplankton, indirectly increase clarity
155
trophic cascade: sharks
without sharks/apex predators don't have complex food web, can't have clear water, can't have coral reefs
156
trophic cascades: Brier Creek
predatory bass extirpate herbivorous minnows, promote growth of benthic algae, alter colour of water
157
trophic cascade: arctic fox
preys on birds, decrease bird population-- decrease nutrient input (poop)-- grasslands turn to tundra
158
trophic cascades: predatory cats
remove large predators-- herbivores increase and 'clean up' forest floor (less leaf litter and forest floor plants)
159
trophic cascade: wolf
wolf-- elk-- more, greener riparian vegetation
160
trophic cascade: wildebeest
eradication of virus-- recovery of native ungulates-- decline of woody vegetation in Serengeti
161
sea otters absent
fish abundance decreased
mussel growth decreased
gulls- diet shift from fish to invertebrates
bald eagles- diet shift-- decrease in mammals, fish; increase in birds
162
trophic cascades: fire
rinderpest (viral) decreases wildebeest which decreases vegetation control which increases fire risk
40% more burn with virus
163
trophic cascade: disease
fishing decreases lobster-- decreases sea urchin density-- increases epidemics
~30% increase in epidemic without fishing
164
trophic cascade: atmosphere
bass decrease minnow, decrease zooplankton, decrease phytoplankton, increase atmospheric C influx
165
trophic cascade: soil
fox decreases seabirds, which decrease soil nutrients
166
trophic cascade: water
spawning salmon decrease particulate suspension, decreases stream particulate load
167
trophic cascade: invasive species
predatory birds decrease non-indigenous spiders
168
trophic cascades: biodiversity
coyotes decrease mesopredators which decrease small vertebrates
169
preceded all other human disturbance
overfishing -- ecological extinction
170
fishing and nile perch
type of fishing determine survivorship (age), survivorship determines prey taken by nile perch
171
nile perch predation on haplochromines
decreasing: no fishing, gill nets, beach seines, gill nets + seines
172
salmon life cycle
freshwater- eggs, rearing of juveniles
estuary- smolt (0-1yr)
ocean- juvenile, growth (1-4yrs)
estuary- returning to freshwater to spawn
freshwater - spawning, death- contribute nutrients
173
importance of salmon in the ocean
orca
harbour seal
commercial fishery
174
importance of salmon in freshwater
sport fishery
cultural fishery
bear, eagle, gull, coyote, otter, raven, crow, trout
175
simplified salmon life cycle
incubation-- fry-- smolt-- adult-- return
176
salmon fry
recently hatched, very young
177
smolt
young salmon, ~2yrs, ready to return to sea, changes to system for saltwater life
178
salmon return related to
size of smolts
179
~2inch smolts
4-8% return rate
180
~6inch smolt
10-20% return rate
181
smolt weight
is significantly decreased with increasing density, there is a limit to how many fish a system can produce (carrying capacity)
182
salmon and nutrient-foodweb dynamics
more nutrients-- larger algae-- small/inefficient grazers-- low growth, small smolts, low adult return
183
fertilization of lake, 1983
TP increases, algal biomass increases, daphnia size and biomass increase
184
impact of lake fertilization on smolt size
1yr old smolts small increase in size
| 2yr old smolts large increase in size
185
impact of lake fertilization on fry/smolt density
both increasing
186
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
187
smolt size vs. daphnia size
```
positively correlated
(larger, efficient grazers = larger fish)
```
188
important factors in the highly variable growth pattern of sockeye smolts
fry density
size of zooplankton
lake features
189
size of 1yr old smolts and total zooplankton biomass
available food is not a good predictor of smolt size
190
size of 1yr old smolts and mean size of Daphnia
quality of food is a better predictor of smelt growth and size
191
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
192
photic depth vs. turbidity, and colour
photic depth rapidly drops off in both, but quicker with increased turbidity
193
light penetration, clear lake
euphoric depth 16.4m
| secchi depth 7.2m
194
light penetration, stained lake
euphotic depth 7.4m
| secchi depth 4.3m
195
light penetration, glacial lake
euphotic depth 6.5
| secchi depth 1.5m
196
thermal traits, clear lake
max T 14º
mean T 7.8º
heat budget 11.8 kcal/cm^2
197
thermal traits, stained lake
max T 16.2º
mean T 6.9º
heat budget 10.8 kcal/cm^2
198
thermal traits, glacial lake
max T 11º
mean T 5.9º
heat budget 11.6 kcal/cm^2
199
vertical mixing patterns in different lakes
depth as a function of T
| heat budget is area 'under the curve'
200
depth vs. T, clear lake
med T at surface, drop off, med T at depth
201
depth vs. T, stained lake
highest T as surface, rapid drop off, lowest T at depth
202
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
203
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
204
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
```
205
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
206
smolt length in lake types
clear 95mm
stained 71mm
glacial 69mm
207
smolt weight in lake types
clear 7.9g
stained 3.3g
glacial 2.6g
208
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
209
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
210
SST shift study, Eastern Bering Sea
2002-2005 warm, 2006-2007 cold
| use N isotopes in zooplankton to study shifts in foodwebs
211
Eastern Bering Sea sampling
cruises in sep. 2003, 2007
collected juvenile salmon, forage fish, zooplankton
186 stations
13,000 fish, 600 zooplankton samples analyzed for N, C isotopes
212
juvenile salmon studied in eastern Bering Sea
sockeye, pink, chum, coho, chinook
213
change in abundance of juvenile salmon
in cold years juvenile salmon distribution decreased in all species types
pacific cod abundance increased
214
∂13C tells
```
where food comes from in relation to shore
more depleted (more - ) = off-shore
less depleted (less - ) = near-shore
```
215
∂15N vs ∂13C
trophic enrichment of 15N up foodweb
216
algae ∂15N
4-8‰
217
∂15N, inverts.
8-14‰
218
∂15N, forage fish
10-14‰
219
predatory fish, ∂15N
10-18‰
220
why trophic enrichment of 15N?
organisms preferentially utilize the lower molecular weight isotope leading to enrichment of the heavier one
221
∂15N in plankton
must be determined for every group of plankton to set a baseline, then this baseline can be used to determine trophic level in the fish
222
juvenile salmon trophic position above zooplankton
2005 ~2
| 2007
223
why were juvenile salmon higher in trophic level in warm years
more food available, growing bigger/faster, consuming fish
224
why juvenile salmon lower in trophic level in cool years
less nutrients available, less food available
225
differences in N vs. S Eastern Bering Sea (EBS)
S: large shift in trophic level from warm - cold years
N: little change in trophic level
226
increasing nutrients of a system
may enhance smolt production through enhanced 1º, 2º productivity (but only up to k)
227
survival of smolts
can increase with increasing size of smolts
228
adults returns/recruits per spawner
may increase with increasing smolt size
229
high density of salmon fry
can dampen impacts of nutrients on smolt size and production by:
limiting resources available,
reducing efficiency of nutrient/energy transfer,
reducing growth/survival of fry and smolts
230
anadromous
fish, born in fresh water, spend most of life in the sea and returns to fresh water to spawn. Salmon, smelt, shad, striped bass, and sturgeon
231
management of anadromous fisheries
integrate ecological and fishery science to better understand and quantify linkages between freshwater and marine phases
232
challenges facing sustainable fisheries
- conflicting interests of stake holders and end users
| - stocking/fertilization of lakes/streams beyond carrying capacity
233
to develop meaningful management models
- synthesize long-term data to determine carrying capacity and relate to spawners and production of smolts
- develop better long-term data on fry/smolt production and relation with adult return
234
upwelling systems
less than 2% of the ocean
contribute 7% to global marine PP
contribute 20% of global fish catch
235
CCS
California Current System
from the top of VI down
wind moves water south, causes upwelling, huge economic value to BC
236
Subarctic Current, Alaska Current
North of VI
| boundary between varies in position, strength, and timing throughout the year and year-year
237
current system changes
affect fish catch
238
economic value of upwelling systems
ex-vessel value at least $200million
economic spin-off orders of magnitude larger
sport fishing ~$2billion
recreational, shipping value
239
ex-vessel value
post-season adjusted price/lb for first purchase of commercial harvest, usually established by determining average price for an individual species, harvested by a specific gear, in a specific area
240
Important biological processes in the CCS
```
basin conditions:
PDO
NPGO
ENSO
local conditions:
upwelling
Temperature
Salinity
```
241
PDO
pacific decadal oscillation, oscillates between warm and cool phases,
leading principal component of North Pacific monthly sea surface temperature variability
242
NPGO
northern pacific gyre oscillation
243
ENSO
El Niño - Southern Oscillation
244
High PDO effects (generally)
high salmon survival in Alaska
lower salmon survival here and N US (lower nutrients)
inverse production regimes
245
Inverse production regimes
"portfolio effect"
provide stability
diverse stock responses = lower variability overall
246
recruitment
abundance of fish entering a targeted population determined by growth, abundance, and survival
247
classes of study in fisheries oceanography
1.determination of parameters that
define habitats of different life-history stages
2.integrated assessment of the “health” of the ecosystems
3. assessment of
the effects of climate variability on recruitment
248
first few weeks that young salmon spend at sea
appears to be when year class strength is set, critical survival period
249
Oceanic Niño Index (ONI)
3month running mean of SST anomalies in Niño 3.4 region of equatorial Pacific
(5°N–5°S, 120°–170°W).
An El Niño event is defined to occur when ONI > 0.5°C for 5 consecutive months
250
copepod diversity
```
summer: low- sub-Arctic
waters dominate, naturally
contain low diversity
winter: highly diverse assemblage of subtropical copepods
negative PDO: less diversity
positive PDO: more diversity
indicator/sentinel species
```
251
ENSO characteristics
large scale climate patterns
warm anomaly across equator
fish that are expected to come back, don't
252
ENSO now
safely say one of the 3 strongest on record
likely to be the strongest on record
~60% chance it will revert to La Niña mid2016
253
NPGO affected by
regional and basin-scale variations in wind-driven up welling and horizontal advection
254
NPGO affects
salinity, nutrient concentrations
255
NPGO fluctuations cause
changes in phytoplankton concentrations and variability up trophic level
256
NPGO now
variability is increasing
| bad NPGO year = bad fish stocks everywhere, little-no portfolio effect
257
warm-water copepods
small, not high quality energy reserves
258
cold-water copepods
larger, adapted to survive cool T's, large lipid reserves, more energetic food source
259
effects of local conditions on salmon, primary production
increase Chl = increased resident fish yield
| but.. salmon aren't resident, don't appear to be driven by Chl
260
PDO cool phase, copepods
transport boreal coastal copepods into california current from gulf of alaska
261
PDO warm phase, copepods
transport sub-tropical copepods into NCC from transition zone offshore
262
mechanisms that bring copepods to shore dictated by
physics
263
why do salmon care about copepod species
early marine life mortality is size-selective (predation, gape limitation), smolts 99% mortality,
growth in early marine life is critical, large fish = higher survival
264
quality of prey and growth
high quality prey = more energy = grow faster
smolts feeding on low quality of prey reach ~1/2 size of smolts on high quality prey in 1yr
quality vs. quantity appears to drive fish stock
265
linking climate to salmon survival
Bayesian networks- can use quantitative, qualitative, expert opinion, to test various scenarios. provide probabilistic framework in addition to hypothesis testing.
266
testing WCVI chinook
fish tissue samples fall of 2000-2009
stable isotope analysis to geneticallyy ID (make sure local)
remain resident w/i few hundred km of natal stream until winter
analyze stomach content
267
∂13C offshore
depleted (more negative)
| low productivity
268
∂13C indicator
strong indicator for salmon survival - can predict how many salmon will return based on ∂13C
269
difficulties of examining isotope records
~months worth of data to distinguish
shifting diet and habitat with growth
interannual effects
270
results of WCVI chinook study
find NPGO to be driving factor affecting survival
271
why does NPGO affect survival
directly impacts ∂13C
| indirectly: SST--copepods--zooplankton--∂13C--survival
272
what does PDO affect?
leads to ∂15N (trophic level), not connected to survival
273
effects of changing SST
shift species distribution, bring new species, new copepods, effect salmon species?
274
climate change effects
intensify winds, stronger upwelling - may increase productivity, change migration patterns, affect precipitation patterns
275
effects of changes in precipitation
warm dry summers lethal to salmon stock
| truck fish from lake to river/ocean?
276
ocean acidification
```
CO2 sink
CO2 + H2O -- HCO3 + H
decreasing pH
affect critical life stages
killing VI shellfish stocks
```
277
jack salmon
Chinooks that return to the fresh water one or two years earlier than their counterpart
278
most consisten eutrophication effects
shifts in algal species composition
| increased frequency/intensity of nuisance blooms
279
carrying capacity definition
maximum number of individuals of a given species that an area's resources can sustain indefinitely without significantly depleting or degrading those resources
