BIOL 311 PARTII Flashcards
(294 cards)
1
Q
wavelength to measure silicic acid
A
410nm by visible spectrophotometry
2
Q
silicic acid
A
Si(OH)4
3
Q
most common way to determine amount of phytoplankton in seawater
A
Chlorophyll (mostly Chl a)
4
Q
[Chl]
A
index of phytoplankton biomass
intensity of fluorescence is proportional to amount of Chl and thus biomass
5
Q
most common way to measure Chl
A
use acetone to extract Chl from filtered sample, measure fluorescent using fluoromoeter
6
Q
fluorescence
A
photosynthetic pigments absorb light at one wavelength and emit light at another
7
Q
breakdown products of chl produced by zooplankton digestion
A
phaeopigments
8
Q
nitrate
A
NO3 -
9
Q
Secondary production
A
amount of new zooplankton tissue elaborated per unit time
10
Q
zooplankton are
A
secondary producers
key link between PP and higher trophic levels
11
Q
key zooplankton species
A
copepods
12
Q
PP regulated by
A
availability of light and nutrients
13
Q
principle photosynthetic pigment in all phytoplankton
A
Chlorophyll (mostly Chl a)
14
Q
Secondary production regulated by
A
food availability
temperature
predation
15
Q
food chain in upwelling systems
A
pretty simple chain
phyto.–zoo–higher trophic levels
16
Q
NO2-
A
nitrite
17
Q
food chain in open ocean
A
more complex web
‘secondary production’ somewhat ambiguous
18
Q
estimating SP
A
TTE
Measuring (3 methods)
19
Q
TTE
A
Trophic Transfer Efficiency
TTE (Et) = Pt / Pt-1
TTE = amount of E; annual production at t / annual E in lower trophic level
20
Q
TTE assumptions
A
TTE of 10% is always a good estimate
We can account for biomass of all un-fished species in food web
21
Q
IS TTE reliable
A
TTE often 15-20% at lower levels, using 10% not always adequate, would lead to underestimates, better to measure SP directly
22
Q
Why is it easy to measure PP
A
can measure various ways: O2 production, CO2 uptake, nutrient uptake, colour w/ satellites
Rapid generation time: can estimate PP w/i few hours
23
Q
why is it not easy to measure SP
A
Much slower growth (weeks-months)
Have to focus on one species at a time
24
Q
Methods for measuring SP
A
physiologic method
cohort analysis
chitobiase method
25
The physiologic method
only certain amount of phyto. E is transferred to zoop.; calculate all inputs and outputs; requires a lot of information
26
Inputs/outputs in SP
Input: phytoplankton
Outputs: respiration, excretion, defecation, death, melting, consumption by predators
27
Cohort analysis
follow zoopl. cohort through t; must know length of life stage and weight, very difficult at sea
28
Copepod life cycle
12 stages: adult, nauplii (6?), C1-C5 copepodites
seasonal vertical migration
rise to surface as nauplii early spring
29
SP cohort analysis, abundance vs time
Abundance (m^-2) vs Time (days)
| abundance increase and decrease for each life stage, curves progress with time for successive life stages
30
Cohort analysis, 2ºP =
Σ G_i B_i
| weight-specific growth rate of stage i * biomass of stage i
31
Biomass =
```
B = X* w
X = # individuals
w = weight of individual
```
32
Production =
```
P_t = [(X1-X2) * (w1+w2)/2] + (B2-B1)
x = # individuals
w = average weight
B = biomass
```
33
Cohort analysis assumptions
populations are synchronous
sampling animals each day
not very accurate, makes difficult to use correctly
34
Landry, 1978
one of few proper cohort analyses
found production rate for single copepod species, single season, in a single lagoon
not comparable to high resolution of PP studies
35
synchronous populations
developing through life stages at the same time
36
Mesocosm
encircle large V of water + plankton
typically 2-5m wide, 3-10m deep
popularized in oceanography by Tim Parsons
37
Artificial cohort method
popular field method
| incubate specific stages/size classes for short periods
38
problems with artificial cohort method
repeated handling (damaging)
container effects (food, T)
assumes asynchrony
time consuming, laborious (have to sieve samples and separate stages)
39
Chitobiase method
Biochemical method for rapid estimation
measure chitobiase in water sample
fast and relatively simple
40
what is chitobiase
crustacean moulting enzyme that recycles chitin during moulting of an individual
amount of chitobiase is proportional to body size
41
Chitobiase method assumptions
decay rate proportional to production
42
what does chitobioase method tell
estimate of average development rate of crustacean zooplankton community
43
what is needed for chitobiase method
rate of decay of chitobiase from seawater sample
44
Chitobiase method benefits
Fast, relatively simple, versatile, high resolution over short time
45
Zooplankton food
phytoplankton
protozoans
other zooplankton
46
zooplankton food use
growth
reproduction
routine metabolism and respiration
47
how much food do zooplankton need
smaller zoop have higher weight-specific food requirements
| smaller, higher T = higher metabolic rates
48
food required (zooplankton)
inversely proportional to size
49
How much phytoplankton do zoop consume
ca. 10-40%
| occasionally nearly 100% of daily PP
50
Zoop. food limitations
in lab higher nutrition levels required than are found in ocean, at low [food] there were lower body weights
Zoop in ocean not starving, reproduction not limited, food availability doesn’t seem limiting
51
Field measurement of zoop reproductive output
usually show little-no relationship w/ food concentration
52
What does Zoop growth rate depend on
*Temperature
body size/metabolism
resources
53
max zoop growth
only occurs above threshold food concentration
| highest for youngest stages
54
zoop growth open ocean vs coastal
food-limited growth at [food] found in oceanic areas regardless of T
55
habitat T vs food concentration
Cm, Cc increase w/ decreasing T
oceanic organisms fall mostly below Cc, some above at very low T
Coastal zoop almost entirely above Cc
56
Cm
matintenance food concentration
assimilation balances respiration
below equals starvation (not enough food to meet metabolic needs)
57
Cc
critical concentration
| above which growth rate is max
58
Habitat T vs Food concentration, Juvenile, Adult
Cm, Cc increase more at low T for adults, i.e. adults have more challenges reaching max growth at low T
59
Food limitation conclusions
food limited growth most likely in oceanic conditions and large zoop
60
why do only lab studies find food availability matters for zoop growth
either erroneous results or underestimate real food availability
61
Huntley-Lopez Model (1992)
re-analyze published data, find T alone explains >90% of growth rate variation
suggest that SP can be estimated as fn of T
62
Huntley-Lopez model, SP =
B * 0.445 *e^0.111T
T = temperature
B = biomass
SP in g C m^-3 day^-1
63
criticism of Huntley-Lopez model
relies mostly on lab data collected under unrealistic condition
doesn't align with what is seen in field
64
food quality and zoop
bioindicators (e.g. fatty acids) have been shown to affect reproductive success and growth rate
65
Annual changes in temperate oceans
```
angle of sun
insolation
stratification
nutrients
compensation depth
```
66
summer in temperature oceans
sun shines straight -highest concentration of energy- high heating of water- stratification- high PP - nutrient decline- deep compensation depth
67
PP, SP patterns in temperature oceans
PP, SP high (peak) in spring, decrease in summer due to low nutrients, secondary bloom in fall due to upwelling (wind mixing, tides, etc), may be mini blooms throughout
68
why does PP decrease after bloom
decreased nutrients
| increase in SP - grazing
69
overall temperature ocean productive pattern
strong seasonality
| large export flux
70
polar ocean productivity patterns
only 1 bloom, in summer, phyto/zoo/ nutr curves all pretty tightly coupled, strong seasonality
71
tropical ocean productivity patterns
strong, permanent thermocline, barrier to mixing, low nut, low productivity year round, no blooms, very low increases/decreases (small blooms from small scale mixing), no seasonality, very little export flux
72
tropical ocean productivity relies on
remineralization - regenerated system
73
regenerated nutrients
ammonium, urea
74
exceptions to low productivity tropics
coral reefs
| equatorial and coastal upwelling zones
75
temperate ocean productivity limitations
winter - light
| spring/summer - nutrients
76
polar region limits to productivity
summer - nutrients
| all other times - light
77
tropical region limit to productivity
all seasons - nutrients
78
main grazers of 'large' phytoplankton cells
copepods
79
why are phytoplankton blooms possible if they are grazed
zoo grow slower
80
average productivity of upwelling zone
500 gC/m2/yr
81
what areas of the ocean are most productive?
depends - per m2 = coastal, but coastal zones are small… overall = open ocean (pay attention to units)
82
front
relatively narrow region characterized by large horizontal gradient in variables (e.g. T, S, D); sharp changes
83
example of a frontal system in the ocean
edge of the continental shelf – increased productivity parallel to shore
between islands - different depths, flow lines changed
84
Island effects
vertices formed downstream of a current moving past an island, disrupt nutrient patterns
85
tidal effects
moving through narrow pass (e.g. estuary) causes eddies to form - disrupt water/nutreint patterns
86
average productivity of open ocean
125 gC/m2/yr
87
Large-Scab patchiness caused by
coast, river-plumes, fronts, island effects, divergence/convergence, gyres
88
In NH net water movement is
to the right
89
Continental divergence
water moving away from shore, deep water rises to replace = upwelling; always on W side of continent because waters are moving away (NH and SH)
90
Planetary fronts
span entire ocean basins
91
average productivity of continental shelf
360gC/m2/yr
92
example of planetary front
Antarctica circumpolar current
| Between subtropic and subpolar gyres
93
anticyclonic gyre
clockwise circulation in NH (counter clockwise in SH)
water moves 'in' (to the right)
downwelling
warm water
94
average productivity of coral reef
2000gC/m2/yr
95
continental divergence =
high productivity
96
continental convergence
waters ‘pile up’, downwelling, poor productivity, generally E side of continents
97
gyre right hand rule
clockwise gyre - wrap fingers clockwise - thumb points away - water moves down
98
effects of anticyclonic gyre
downwelling - warm water-- low productivity
99
warm core ring
anticyclonic gyre
100
where reefs are generally found
continental convergent areas
101
cyclonic gyre
anticlockwise circulation in NH (clockwise in SH)
water moves up/out (to the right)
upwelling, divergent, cold (NH and SH)
102
cold core ring
cyclonic gyre
103
Small-scale patchiness
Langmuir circulation
| Deep scattering layer
104
Langmuir circulation
'streaks' formed between langmuir cells; from moderate, persistent wind producing convection cells in topmost layer of water w/ long axes
105
Deep scattering layer
result of diel vertical migration
106
CO2 over the last 20,000 yrs
slow, steady increase up to 1800s then major increase
107
effects of cyclonic gyre
upwelling - cold water - high productivity
108
CO2 in 1750
277ppm
109
CO2 in 2016
405ppm
| 46% increase since 1750
110
first daily measurements of CO2 over 400
May 2013
111
where are CO2 measurements made
Mauna Loa
112
Fossil emissions graph
CO2 emissions per year = steady incline from 1990-now
113
current CO2 emissions
9.9Gt C/yr
114
contributors to CO2 emissions
Highest to lowest: Coal, oil, gas, cement
| all have increased
115
year-to-date globally averaged land surface T
1.48ºC above 20th century average
116
year-to-date globally averaged sea surface T
0.77ºC above 20th century average
117
RCP
Representative concentration pathways
118
IPCC 5th assessment RCPs
RCP8.5 =3.2-5.4ºC
RCP6 = 2-3.7ºC
RCP4.5 = 1.7-3.2ºC
RCP2.6 = 0.9-2.3ºC
119
Ice cores can tell how far back
800,000yrs
120
RCP path we are on
likely not possible to meet RCP2.6 or RCP4.5 would have to remove CO2
121
Dominant physical changed expected in the oceans as a result of climate change
surface layer warming
surface layer freshening
shallowing of upper mixed layer
increased stratification at base of mixed layer
changes in wind patterns and storm tracks
122
physical changes to the ocean from climate change greatest
at high latitudes
123
results of increased ocean stratification
less 'diffusion' of O2 down = anoxia
| less mixing of nutrients up = lower productivity
124
freshening is the result of
increased precipitation and glacial melt
125
organisms in a changing climate, MAAD
Move
Acclimate
Adapt
Die
126
organisms in a changing climate, move
shift range poleward (or to higher elevations) following rising isotherms
127
organisms in a changing climate, acclimate
survive outside of normal range organisms previously existed
dependent on plasticity
128
organisms in a changing climate, adapt
over multiple generations
- evolve w/i existing phenotype
- evolve through genetic mutation
129
organisms in a changing climate, die
locally, regionally, or globally extinct
130
terrestrial organisms are shifting how much
2-3X faster than previously reported
17km/decade poleward
11m/decade vertically
131
marine organism range shifts
190+/- 38 km/decade SE
132
changes in fish assemblage at fixed locations
smaller, faster growing fishes increasing (sculpin, hagfish, cod)
larger fish decreasing (pout, pollock, haddock, ray)
133
changes in plankton with climate change
biomass peaks occurring earlier
| mismatch with timing of predators (migrating, reproducing)
134
what happens to the ocean with an increase in CO2
increased acidity
| CO2 + H20 - HCO3- + H+ -- CO3^2- + 2H+
135
Bjerrum plot
concentration vs. pH
| CO2 peak -- HCO3 peak -- CO3 2-
136
current seawater pH
ca. 8
137
pH =
- log [H+]
| add CO2, increase H, decrease pH
138
problems with low pH
hard on shell-builders (coccolithophores, pteropods, corals, shellfish) that are important to marine food web and economically
139
onshore vs offshore pH
Onshore regions lower pH than offshore due to upwelling of lower pH waters
140
USA shellfish economic value
$270M
3200 jobs
threatened by ocean acidification
141
Canada shellfish economic value
>12,000t oysters annually
| >$18M / yr
142
oxygen changes in the ocean
w/ increasing T and CO2 = decreasing O2
143
in low O2 environment
have to work harder to obtain O2 and to expel CO2 (lower pO2, high pCO2)
Optimum aerobic performance can not be maintained – fitness window becomes narrower, and peak performance decreases
144
most likely increase in T by 2100
3ºC
145
Increase in sea level since pre-industrial
ca. 0.25m
146
expected sea level rise by 2100
```
RCP2.6 = 0.65m
RCP8.5 = 1m
```
147
Ωarg
degree to which seawater is saturated with aragonite
148
changes in Ωarg
∆[carbonate ion] results in ∝change in Ωarg; ocean acidification = decline in Ωarg = harder for marine calcifies to precipitate skeletons/shells
149
Energy flow in marine ecosystem
sun - PP - SP - carnivores
| all stages transfer E to decomposers
150
mineral cycling in marine ecosystems
(PP - SP - Carnivores) - Decomposers - Nutrients - PP
151
What is a trophic pyramid
size of each layer represents relative biomass of organisms at that trophic level
152
trophic level
group of organisms occupying same position in a food web
153
Amount of E available to higher trophic levels depends on
Amount of PP
TTE
# of trophic levels
154
e.g. of trophic levels being dependent on PP
Highly productive waters (NW Atl) have higher fish/squid populations
low productivity waters (Baltic) have low carnivore #s
155
Types or marine food chains
oceanic type
coastal type
upwelling type
156
upwelling type food chain
microphytolankton - pelagic :(macrozoop. - zooplanktiverous fish - piscivorous fish)
benthic (benthic herbivores - benthic carnivores - piscivorous fish)
157
upwelling type food chain
macrophytoplankton - (planktiverous fish)
| megazooplankton - planktiverous whale
158
nanaoplankton
flagellates
159
oceanic piscivorous fish
tuna, squid
160
benthic herbivores
clams, mussels
161
planktiverous fish
anchovy
162
megazooplankton
krill
163
macrozooplankton
copepods
164
megazooplankton
chaetognaths
165
zooplanktiverous fish
herring
166
oceanic type food chan
nanoplankton - microzooplankton - macrozooplankton - megazooplankton --zoplanktivorous fish - piscivorous fish
167
benthic carnivores
cod
168
coastal piscivorous fish
salmon, shark
169
microphytoplankton
diatoms, dinoflagellates
170
Mean PP: Oceanic, coastal, upwelling
O: 75 gC/m2/yr
C: 300
U: 500
171
number of E transfers between trophic levels: Oceanic, coastal, upwelling
O: 5
C: 3
U: 1.5
172
Average TTE: oceanic, coastal, upwelling
O: 10%
C: 15%
U: 20%
173
mean fish production: o, c, u
O: 0.75 mgC/m2/yr
C: 1000
U: 44, 700
174
Microbes in the ocean
```
phytoplankton/algae
fungi (rare, poorly known)
protozoa (flagellates, ciliates)
archaea (poorly known)
bacteria (mainly heterotrophs)
Viruses (phages, animal viruses)
```
175
Virus size
0.01-0.2µm
176
Marine prokaryotes
Eubacteria, Archaea
single celled, no nucleus, very small
most of genetic diversity on Earth
177
where are Eubacteria found
water column
| sediments
178
where are Archaea found
in extreme environments
179
Bacterial cell densities in marine environment
Estuary: >5x10^6 cells/mL
Coastal: 1-5x106
Open ocean: 0.5-1x10^6
deep sea: less than 0.01x10^6
180
typical bacteria density in ocean
10^5-10^6/mL
181
overall concentration of bacteria in ocean
1.6x10^29
182
prokaryote sizes
0.2-1µM
| Bacteria, Archae
183
amount of bacteria that are heterotrophic
90-95%
184
amount of organic C in ocean that is heterotrophic bacterial
70%
185
amount of organic C in ocean that is bacterial
90-95%
186
eukaryote microbe sizes
1-200µM
| Algae, protozoa
187
when were marine bacteria recognized as important
1970s
188
why was it hard to recognize bacteria in the ocean
small - need microscopy
| culturing - not useful for marine
189
scientific advancements that allowed the recognition of marine bacteria
fluorescent dyes that bind to nucleic acids
190
now we count/ID bacteria using
epifluorescence microscopy
| flow cytometry
191
what happens to bacteria in the ocean
consumed by other plankton
| lysed by viruses
192
lysis
the disintegration of a cell by rupture of the cell wall or membrane
193
what do heterotrophic bacteria eat
primarily DOM
| from: phytoplankton fluid, excretory products, viral lysed cells, sloppy feeding left overs
194
DOM
dissolved organic matter
| passes through 0.45µm filter
195
DOC
dissolved organic carbon
| primary component of DOM
196
Microbial loop
fish - zooplankton - ciliates - micro flagellates - bacteria - remineralization - nutrients
197
Marine viruses
no metabolism, inject genetic material into host and force replication, most abundant life in ocean, ubiquitous
198
marine viruses known since
1990s
199
typical marine virus concentrations
10^7 - 10^11/mL
| order of magnitude more than bacteria
200
rate of marine viral infections
ca. 10^23 infections /second
201
Marine virus habitat
greatest abundance in surface (upper 200m), nearshore
202
why are the majority of viruses in the surface
because thats where the majority of hosts are
203
main marine viral infections
heterotrophic bacteria = bacteriophages
204
ecological role of marine virus
```
bacterial mortality (including HAB)
major biomass turnover
```
205
ecological role of marine heterotrophic bacteria
nutrient cycles - remineralization
microbial loop
pollution remediation
206
When did the Atlantic cod population collapse
1980
| catastrophic in 1992
207
Cod
demersal, longlived (20+yrs), early maturity (2-4yrs), omnivorous, broadcast spawn, highly fecund, soniferous, easy to dry and salt
208
demersal
living close to the floor of the sea
209
East coast high productivity
front where Gulfstream meets Labrador current
210
Georges bank prey
phytoplankton
flagellates
ciliates
copepod nauplii
211
Georges bank target species
Copepods
haddock larva
cod larva
212
Georges bank predators
```
euphausiids
hydroids
amphipods
chaetognaths
ctenophore
siphonophore
medusa
herring
mackerel
```
213
early cod fish harvesting methods
handline
longline
gillnet
214
Cod fisheries, 1700
shipped to europe
linked to slavery, sugar cane, rum
helped start American revolution ($)
215
effects of bottom trawling
total destruction of deep sea habitats
216
fishing technology
steam powered trawl vessels catch 6X faster
| diesel powered even more efficient
217
amounts of fish harvested
1920s - 1250,000t
1960- 200,000t
1965- 760,000t
populations declining 1966-1970
218
why didn't fishing stop with declining populations
weak regulations, poorly enforced, insufficient
219
solution to the overfishing
extend fishing grounds from 12-200nautifcal miles (EEZ)
220
Fish stocks 1980
haddock, yellowtail flounder stocks collapse
rely entirely on cod
landings drop from 1.6bill-220mil to 1991
221
changes to allowable fishing after 1991
```
1994 new rules
license moratorium
reduced allowable days at sea (DAS)
closed portions of Georges Banks
new fish, mesh size restrictions
designed to reduce fishing efforts 50% over 5-7yrs
```
222
total cod harvested from NWFL
100milliont
1/2 1500-1900
1/2 1900-2000
223
expected recovery after 1993 reduction in fishing effort
not yet occurred
224
why aren't cod recovering
shrimp, crab catch has gone up significantly
225
took over new niche space opened up by cod
groundfish - pelagics - crustaceans
226
coastal zone
narrow strip of ocean from edge of continental shelf to the estuaries
waters less than 200m
227
coastal zones are how much of ocean surface
7%
228
coastal zones are how much of ocean volume
much less than 0.5%
229
importance of coastal waters
most biologically productive parts of worlds ocean
nutrient-rich, high PP
major role in biogeochemical cycling
most of worlds greatest fisheries
230
anti-cyclonic retention cycle
meeting of currents = anticyclonic gyre; productivity due to frontal zone, larvae retained in gyre, make way down to rocky bottom; Nutrients not upwelled but larvae returned
231
coastal processes complicated by
shallowness
freshwater input
tidal currents
upwelling events
232
organic carbon in coastal ocean compared to open oceans
8-30X more Corg
233
coastal ocean Corg burial
80% of Corg buried in coastal zone
| large % of CaCO3 and SiO2 also deposited
234
coastal zone production
14% of total global
80-90% of new production
50% of denitrification
235
productivity of river/estuarine plume
high PP due to increased nutrs. and light levels; where fresh water meets the seawater mixing causes entrainment of particles from deeper water in to the surface = small-scale upwelling
236
increased bio activity from plumes due to river input
increased turbidity and nutrient enrichment from river (particles, sediment, nutrients)
237
increased bio activity at plumes from seawater input
nutrient entrainment and upwelling
238
increased bio activity from plumes due to stability
enhanced stability due to freshwater/dense water layering
239
importance of estuaries
```
Among most productive enviro.s on E
high PP
nursery grounds
economically relevant
important associated environments
```
240
important environments associated with estuaries
salt-marshes
| mangrove swamps
241
where are mangrove swamps
coastal zones near equator, around N half of Australia
242
where are salt marshes
N coast of Europe, Asia
E/W coasts of US
SE coast SA
243
North Atlantic conditions
```
Warm (8.5ºC at depth in winter)
Very low N in summer
No Fe limitation
Large # diatoms, photosynthetic dinofl., benthic fish
HCLN
poor phyto/zoo coupling
high phyto. export
```
244
North Pacific conditions
```
Cold (3.8ºC at depth in winter)
High nutrients yr round
Iron limited
Large # small photosyn. flagellates, large # pelagic fish
HNLC
close phyto/zoo coupling
low phyto. export
```
245
dominant N Atl copepod
Calanus finmarchicus
246
dominant N Pac copepod
Neocalanus plumchrus
247
C finmarchicus cycle
surface before fully developed (low fitness), no significant impact on phyto., feed - grow - lag in bloom; up and down through summer, lower pressure on phyto.
248
N. plumchrus
cover water = reserves = greater fitness, surface as adults, keep phyto in-check through summer, much greater impact
249
how life stage affects ability to graze bloom
C finmarchicus
| need to grow and gain energy before able to graze to full potential
250
concentration vs distance from shore
estuary/inner shelf = high nut., phyto bloom, decrease in euphotic zone depth
outer shelf/open ocean = low phyto., low nutrients, low euphotic zone depth
251
HOTS
Hawaiian Ocean Time-series Study (NPCG)
252
BATS
Bermuda Atlantic Time-series Study (Sargasso Sea)
253
HOTS/BATS
```
very low productivity
no upwelling
very stable systems
permanent thermoclines
low, but very deep productivity
```
254
subtropical gyres
anti-cyclonic flow
| convergent - water piles in center, stabilizes, warm, oligotrophic
255
subtropical gyre temperatures
surface layer: ca. 18ºC (winter) - 25ºC (summer)
256
subtropic gyre thermocline
seasonal: 50-70m
permanent: ca. 125m
257
subtropic gyre productivity
Net photosynthesis positive, nitrate depleted, phosphorus nearly depleted to ca. 125m
258
oligotrophic
low nutrients
low productivity
high oxygen
259
subtropic gyre chl max
deeper than other systems (like temperate, subarctic, coastal)
260
why is chl max deep in subtropic system
low vertical mixing leaves high nutrients at depth
| 60% of deep phytoplankton is cyanobacteria
261
why was there found to be a high % of cyanobacteria in tropical systems
N2 fixers
262
nitrogen fixing cyanobacteria
Trichodesmium
263
Why is N2 fixation high in Sargasso Sea
N Africa aeolian dust (Fe)
264
Affect of N2 fixation on redfield ratio
larger supply of N so P becomes limiting factor
| e.g. N:P Sargasso = 17:1 (BATS)
265
key feature of subtropical gyre
water column stability
266
Tropic mesozooplnkton
```
continuously active
no seasonal rest phase
diverse
low biomass
keep production nearly in balance
```
267
Normal conditions in the equatorial Western Pacific
low pressure
rising air
cloudy/rainy
trade winds come from the East
268
normal conditions in equatorial eastern pacific
high pressure
sinking air
clear, dry weather
trade winds blow to the West
269
Equatorial Pacific trade winds
southeast, move from E-->W, cause Peruvian upwelling, creates a warm 'pool' of water along W Pac
270
main places N2 fixation occurs
**Sargasso Sea
| NPCG (NP Central Gyre)
271
what happens during ENSO
winds change direction - upwelling shuts down
272
Effects of ENSO
change in productivity, fishery yield, mammals/birds, weather patterns, global climate, alter jet stream, harmful and beneficial results
273
frequency of ENSO
2-10 yrs
274
ENSO index
weighted average of atmospheric and oceanic factors, shows alternating patterns of El Niño - La Niña conditions
275
factors involved in ENSO index
atmospheric pressure, winds, SST, etc
276
TAO project
Tropical Atmosphere Ocean project
| monitors equatorial Pacific with ca. 70 moored buoys for detection, understanding, and prediction of El Niño
277
southern oscillation
atmospheric component of El Niño; oscillation in surface air pressure between E/W Pac
278
what was the strongest ENSO in recorded history?
1997/98 and 2015/16 both had ONI = 2.3
279
Anoxic/hypoxic water examples
Saanich Inlet
Norther Gulf of Mexico
The Oregon Coast
St. Lawrence Estuary
280
Saanich Inlet
hypoxia develops periodically (naturally)
| has been occurring for ca. 10,000yrs
281
hypoxia
reduced oxygen content of air or water detrimental to aerobic organisms
282
development of hypoxia
high OM production in surface - high vertical transport of OM to deep - high remineralization of OM by heterotrophic bacteria (consumes O2)
283
high productivity in SI
coastal upwelling brings dense nutrient rich water into Strait of Georgia
284
hypoxia in SI develops because
sill blocks oxygenated water from entering
285
SI renewal
eventually dense O2 water builds up, spills over sill, and re-supplies oxygen
286
Hypoxia in Gulf of Mexico caused by
excess N delivered by Mississippi (drains majority of country) + stratification of Gulf waters
287
Is Gulf of Mexico anoxia anthropogenic
yes - widespread fertilizer use = high nutrient = high PP = high OM flux..
288
Oregon coastal water
hypoxic events occurring since 2002
| upwelling zone, strengthening from intensified winds, bringing deeper water with lower O2 to surface
289
St. Lawrence estuary
waters are a mixture of N/S waters, the mixture is changing to more of the warm water/low O2 source
290
St. Lawrence water sources
LCW - Labrador coastal water (cold and oxygenated)
| NACW - North Atlantic Coastal Water (warm, low O2)
291
St. Lawrence water source ratio
1930: 72% LCW, 28% NACW
1985: 53% LCW, 47% NACW
292
Why is St. Lawrence changing
change in circulation patterns
| low O2 is exacerbated by human use of fertilizer
293
example of naturally occurring hypoxia/anoxia
SI
294
Is Oregon coast hypoxia natural
no, considered anthropogenic because wind pattern changes are a result of climate change
