446 Aquatic Ecology Flashcards
why study aquatic ecology
aquatic ecosystems & resources critical to human survival, health, well being
ecosystem processes
hydrologic flux, storage biological productivity biogeochemical cycling, storage decomposition maintenance of biological diversity
ecosystem “goods”
food construction materials medicinal plants wild genes for domestic plants and animals tourism and recreation
ecosystem “services”
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
human disturbances affecting coastal ecosystems
- Fishing, Pollution, Mechanical habitat destruction, introductions, climate change
(fishing always preceded other disturbances, others change in order)
inputs and concerns
organic (livestock), fertilizer, rain, pollutants, pathogens, pharma-care, invasive species, nitrate leaching
adverse effects of eutrophication
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
chemical characteristics of aquatic ecosystems
nutrients
biological characteristics of aquatic ecosystems
foodweb
limnology
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.
algal biomass vs nutrient
chl vs. Total phosphorus (TP)
increasing on log scale but large variation above/below the line
why measure TP as nutrient load?
most limiting resource
high nutrient, lower than expected Chl (algae)
more large fish, preying on large grazers
small algae
larger, efficient grazers
larger biomass
larger planktivorous fish
system is more efficient
system with lots of small planktivorous fish
prey upon small grazers
larger algae
high density of small fish
low density of large zooplankton
higher Chl (algae)
greener water, lower O2
small grazer, shallow lake, Chl vs. TP
high productivity, but less than small grazer system in med-large lake- less O2, less insolation, less space…
empirical data
observational
experimental data
manipulate variable
response of lake ecosystem to nutrient loading experiment
same [nutrient], #large fish vary
w/o large fish = small zooplankton = more algae
epilimnion
the upper layer of water in a stratified lake, ~constant T, mixed layer
lakes with high grazing, low TP
clear water, more light penetration, more heat deeper, larger metalimnion, less steep T gradient, deeper O2 max, photosynthesis can occur throughout metalimnion
metalimnion
thermocline, T changes more rapidly with depth than it does in the layers above or below, highest density, layer of ‘stuck’ algae
indicator of water transparency
secchi depth
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)
zooplankton size under high fish density
~80% less than 0.2mm
zooplankton size under low fish density
~40% less than 0.2mm
hypolimnion
the lower layer of water in a stratified lake, typically cooler than the water above and relatively stagnant, ~constant T, O2
algae biomass with time
low grazing= increased biomass w/ t
intense grazing = very low slope, barely increasing
TP with time
low grazing = increased TP w/ t
intense grazing = very low slope, barely increasing
low grazing = more algae = more TP
dissolved P with time
low grazing = very low slope, barely increasing
intense grazing = high slope, increasing
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]
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)
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)
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
when you have large particles, the overall particle load
is made up of more large particles, median is higher
large particles = less small particles
add nutrients
overall particle size shift to larger particles
= long phosphate turnover time
add nutrients and fish
shift to more smaller particles
= shorter phosphate turnover time
so… as average size of plankton declines..
larger slope, uptake efficiency increases, turnover time is shorter
AND transparency declines
how changes in biology = changes in physics
thermal structure, penetration of light, accumulated energy/heat content
fetch
longest open length of a water body through which wind can blow
change in epilimnion with fetch
increased fetch = increased depth of epilimnion (more wind = more wind mixing)
downward heating intensity vs. penetration of solar radiation
increasing surface area of water body (fetch) vs. increasing water transparency
increasing fetch & transparency
deeper epilimnion, more heat, more energy, greater depth for photosynthesis, more O2
role of biology on mixing rate
affects clarity of lake which affects insolation absorption which affects stratification
sedimentation, total phosphorus rates highest in
+N (nutrients added, no small fish, large zooplankton)
secchi depth highest in
control then +N
deepest when no small fish
chlorophyll highest in
+NF (nutrients, small fish, small zooplankton grazers, larger algae)
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
summer O2 profile, +N, +NF
+N higher O2 at all depths
+NF goes to 0 in hypolimnion
lake St. George
large # planktivorous fish low secchi depth smaller daphnia shallower epilimnion depth higher TP higher Chl strongly eutrophic
Haynes lake
less planktivorous fish deeper secchi depth deep epilimnion depth larger daphnia length lower TP lower Chl
Julian days
continuous count of days since the beginning of the day starting at noon on January 1
hypolimnetic oxygen changes with season
oxygen depletion from spring – summer (lowest O2 with +F)
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
algae size and relative sedimentation rate
small grazer system = short phosphate turnover time = lower relative sedimentation
why larger grazer system has higher relative sedimentation
large things sediment more, greater proportion sink, heavier, less efficiently used (P turnover)
absolute sedimentation rates
would be higher in small grazer system because there’s so much more
toxic algal groups
cyanobacteria, dinoflagellates, diatoms
problems with algal blooms
toxins, anoxia, habitat loss, recreational loss, health risks
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
waterborne pathogens especially important in
tropical/subtropical regions, can be related to cholera
forms of land-use
agriculture farming waste disposal fertilizer harvesting hydrology
effects of N,P loading are different
depending on structure of system
shallow vs. deep
large vs. small fish
population growth
increasing pop., more mouths to feed, more land-use required, world fertilizer growth, more N,P loading,
obtaining N, P for fertilizer
N atmospherically available, easier to obtain. P not atmospherically available, geological nutrient, limited
problem with speed of population growth
available, cultivatable agricultural land is NOT increasing, need GMOs to keep up with pop. increase
GMOs to keep up w/ pop. increase
rices that can grow through floods - multiple crops/year
problem with GMOs that allow us to increase agricultural yield
leaching soil nutrients, more and more fertilizer
population growth and water shortage
water hungry plants and animals (and nutrient loading)
examples of water hungry crops
70L/apple 3400L/kg rice 140L/cup of coffee 120L/glass of wine 15,500L/ kg of beef
changes in atmospheric NH4
30% increase in urea use as fertilizer (1960-1990)
observed relationship between N,P and Chl
positively correlated
nitrogen more tightly correlated
eutrophication defined as
excessive growth of algae, often associated with bluegreen and other harmful algal blooms
determines types of algal bloom
amount of nutrients, composition of nutrients (TN:TP)
N:P ratios for different runoff types
unfertilized field N:P 250 forests 75 rainfall 25 manure seepage 9 sewage 5
nutrient composition ratio
dependent on where nutrients come from
dictates algal bloom
bluegreen algae associated with what nutrient composition
low N:P ratio (towards the manure, sewage deposits)
differential response to increased [P] in N limited vs. P limited ecosystem
N limited systems does not respond as strongly to increased P
increasing phosphorus concentration =
increased dominance of cyanobacteria
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
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
redfield ratio
N:P
16:1
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
physical lake structure and response to changes in nutrients
deeper lakes can take more ‘abuse’ before showing response (less likely to become eutrophic)
algae harmful to animals, humans
cyanobacteria (bluegreen)
dinoflagellates
some diatoms
types of algal toxins
neurotoxins
hepatotoxins
lipo-polysaccharides
neurotoxins
alkaloids, b/g algae
cause neurodegenerative symptoms through disruption in communication between neutrons and muscles
neurotoxin examples
anatoxin-a, saxotoxin, neosaxotoxins, Nostoc, Anabaena, Oscillatoria, Aphanizomenon
hepatotoxins
peptides
affect liver, cause weakness, vomiting, diarrhea, respiratory blockages
hepatotoxin examples
Anatoxin-a, saxotoxin, neosaxotoxins, Nostoc, Anabaena, Oscillatoria, Microcystis
Lipo-polysaccharides
cause skin irritation (dissolve skin)
neurotoxin bioaccumulation
accumulate in nervous system (cerebral), show up with age
fertilizer use and red tides
increased fertilizer use tightly correlated with increased # of red tides
TP, TN and toxin forming algae concentration
both positive correlations
steeper increase in toxin forming algae with increased TP then increased TN
concentration of microcystin vs. toxigenic biomass
increasing. the more biomass present, the more of the toxic variety
microcystin
class of toxins produced by certain freshwater cyanobacteria
ubiquity of cyanobacteria
terrestrial, freshwater, brackish, marine, widespread = potential for widespread human exposure
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
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
BMAA biomagnification
free BMAA–cyanobacteria 0.3µg/g— cycad 37µg/g – flying foxes 3556µg/g – Chamorro people
Chamorro people
highest rate of neurodegenerative disease in the world
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
lake Taihu
went from oligotrophic (1960) to eutrophic-hypertrophic in 90’s
population growth, livestock growth
toxins produced
ALS
amyotrophic lateral sclerosis
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.
sporadic ALS in Annapolis, Maryland
found to come from Chesapeake Bay blue crabs, BMAA in Chesapeake Bay food web common risk factor
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).
driving force in aquatic system
foodweb
changes to food web have cascading effects
ecosystem productivity depends on
transfer efficiency of nutrients and energy along foodweb- affected by changes in predators and prey- any affects = cascading changes
shifts in food web structure and function, implications for
predator/prey effects
contaminant transfer
biodiversity
productivity
energy transfer efficiency in small plankton, small fish system
less efficiency transfer
predatory invertebrates
comets with small fish for prey, added system complexity
food web views
bottom-up - ratio dependent, more inputs = more outputs
top-down - limits bottom up, predators self regulate
predator self regulation
eat too much and use up all resources
k
carrying capacity of system
low k
low resources, nutrients, space
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
Fretwell trophic level biomass vs environmental productivity
alternate trophic levels have parallel relationships
level 3 grazes down level 2 which helps increase level 1
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
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
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
length of food chain
affects accumulation process and efficiency
each food web interaction (energy transfer)
- 10-15% of E
shorter food chain = more efficient
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
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
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
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
Getz, views on top down regulation in food webs
inference hypothesis- predators interfere with each other- prevent efficient exploitation of resources, prey can increase
Mittelbach, views on top down regulation in food webs
predators require different resources as they grow (ontogenetic shift)
Lei bold, views on top down regulation in food webs
control of prey by consumer is not always consistent (shifts to less edible species)
Sinclair and Norton, views on top down regulation in food webs
starvation-weakened prey become more vulnerable to predation or disease
predator negative feedback, self regulation
interference competition
exploitative competition
depletion of nutritious, palatable, accessible prey
algal biomass vs. potential productivity, even link system (hypothetical)
2-link (algae, zooplankton), increased productivity will not increase algal biomass
algal biomass vs. potential productivity, odd links system (hypothetical)
potential productivity can increase, 3rd link consumes 2nd link and allows 1st link to grow
TP, indicator of
productivity
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?
how to define trophic level
analyze gut content
as average catch increases
average trophic level decreases, Pauley et al., 1998
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
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)
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
aquatic system affecting terrestrial example
fish eating larval dragonfly– decrease dragonfly abundance – increase honeybee abundance – increase pollination
no fish– pollination significantly decreased
shrimp stocking theory
add more food, they will produce more
shrimp stocking results
reduced number of spawner, reduces numbers of bears and eagles
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
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
stability and diversity
higher diversity = higher stability
Haplochromis
zooplanktivorous cichlid, significantly decreased since introduction of nile perch
one positive side to nile perch introduction
more protein for Kenyan people
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
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)
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
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
trophic cascade: sharks
without sharks/apex predators don’t have complex food web, can’t have clear water, can’t have coral reefs
trophic cascades: Brier Creek
predatory bass extirpate herbivorous minnows, promote growth of benthic algae, alter colour of water
trophic cascade: arctic fox
preys on birds, decrease bird population– decrease nutrient input (poop)– grasslands turn to tundra
trophic cascades: predatory cats
remove large predators– herbivores increase and ‘clean up’ forest floor (less leaf litter and forest floor plants)
trophic cascade: wolf
wolf– elk– more, greener riparian vegetation
trophic cascade: wildebeest
eradication of virus– recovery of native ungulates– decline of woody vegetation in Serengeti
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
trophic cascades: fire
rinderpest (viral) decreases wildebeest which decreases vegetation control which increases fire risk
40% more burn with virus
trophic cascade: disease
fishing decreases lobster– decreases sea urchin density– increases epidemics
~30% increase in epidemic without fishing
trophic cascade: atmosphere
bass decrease minnow, decrease zooplankton, decrease phytoplankton, increase atmospheric C influx
trophic cascade: soil
fox decreases seabirds, which decrease soil nutrients
trophic cascade: water
spawning salmon decrease particulate suspension, decreases stream particulate load
trophic cascade: invasive species
predatory birds decrease non-indigenous spiders
trophic cascades: biodiversity
coyotes decrease mesopredators which decrease small vertebrates
preceded all other human disturbance
overfishing – ecological extinction
fishing and nile perch
type of fishing determine survivorship (age), survivorship determines prey taken by nile perch
nile perch predation on haplochromines
decreasing: no fishing, gill nets, beach seines, gill nets + seines
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
importance of salmon in the ocean
orca
harbour seal
commercial fishery
importance of salmon in freshwater
sport fishery
cultural fishery
bear, eagle, gull, coyote, otter, raven, crow, trout
simplified salmon life cycle
incubation– fry– smolt– adult– return
salmon fry
recently hatched, very young
smolt
young salmon, ~2yrs, ready to return to sea, changes to system for saltwater life
salmon return related to
size of smolts
~2inch smolts
4-8% return rate
~6inch smolt
10-20% return rate
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
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
juvenile salmon studied in eastern Bering Sea
sockeye, pink, chum, coho, chinook
change in abundance of juvenile salmon
in cold years juvenile salmon distribution decreased in all species types
pacific cod abundance increased
∂13C tells
where food comes from in relation to shore more depleted (more - ) = off-shore less depleted (less - ) = near-shore
∂15N vs ∂13C
trophic enrichment of 15N up foodweb
algae ∂15N
4-8‰
∂15N, inverts.
8-14‰
∂15N, forage fish
10-14‰
predatory fish, ∂15N
10-18‰
why trophic enrichment of 15N?
organisms preferentially utilize the lower molecular weight isotope leading to enrichment of the heavier one
∂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
juvenile salmon trophic position above zooplankton
2005 ~2
2007
why were juvenile salmon higher in trophic level in warm years
more food available, growing bigger/faster, consuming fish
why juvenile salmon lower in trophic level in cool years
less nutrients available, less food available
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
increasing nutrients of a system
may enhance smolt production through enhanced 1º, 2º productivity (but only up to k)
survival of smolts
can increase with increasing size of smolts
adults returns/recruits per spawner
may increase with increasing smolt size
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
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
management of anadromous fisheries
integrate ecological and fishery science to better understand and quantify linkages between freshwater and marine phases
challenges facing sustainable fisheries
- conflicting interests of stake holders and end users
- stocking/fertilization of lakes/streams beyond carrying capacity
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
upwelling systems
less than 2% of the ocean
contribute 7% to global marine PP
contribute 20% of global fish catch
CCS
California Current System
from the top of VI down
wind moves water south, causes upwelling, huge economic value to BC
Subarctic Current, Alaska Current
North of VI
boundary between varies in position, strength, and timing throughout the year and year-year
current system changes
affect fish catch
economic value of upwelling systems
ex-vessel value at least $200million
economic spin-off orders of magnitude larger
sport fishing ~$2billion
recreational, shipping value
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
Important biological processes in the CCS
basin conditions: PDO NPGO ENSO local conditions: upwelling Temperature Salinity
PDO
pacific decadal oscillation, oscillates between warm and cool phases,
leading principal component of North Pacific monthly sea surface temperature variability
NPGO
northern pacific gyre oscillation
ENSO
El Niño - Southern Oscillation
High PDO effects (generally)
high salmon survival in Alaska
lower salmon survival here and N US (lower nutrients)
inverse production regimes
Inverse production regimes
“portfolio effect”
provide stability
diverse stock responses = lower variability overall
recruitment
abundance of fish entering a targeted population determined by growth, abundance, and survival
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
first few weeks that young salmon spend at sea
appears to be when year class strength is set, critical survival period
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
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
ENSO characteristics
large scale climate patterns
warm anomaly across equator
fish that are expected to come back, don’t
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
NPGO affected by
regional and basin-scale variations in wind-driven up welling and horizontal advection
NPGO affects
salinity, nutrient concentrations
NPGO fluctuations cause
changes in phytoplankton concentrations and variability up trophic level
NPGO now
variability is increasing
bad NPGO year = bad fish stocks everywhere, little-no portfolio effect
warm-water copepods
small, not high quality energy reserves
cold-water copepods
larger, adapted to survive cool T’s, large lipid reserves, more energetic food source
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
PDO cool phase, copepods
transport boreal coastal copepods into california current from gulf of alaska
PDO warm phase, copepods
transport sub-tropical copepods into NCC from transition zone offshore
mechanisms that bring copepods to shore dictated by
physics
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
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
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.
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
∂13C offshore
depleted (more negative)
low productivity
∂13C indicator
strong indicator for salmon survival - can predict how many salmon will return based on ∂13C
difficulties of examining isotope records
~months worth of data to distinguish
shifting diet and habitat with growth
interannual effects
results of WCVI chinook study
find NPGO to be driving factor affecting survival
why does NPGO affect survival
directly impacts ∂13C
indirectly: SST–copepods–zooplankton–∂13C–survival
what does PDO affect?
leads to ∂15N (trophic level), not connected to survival
effects of changing SST
shift species distribution, bring new species, new copepods, effect salmon species?
climate change effects
intensify winds, stronger upwelling - may increase productivity, change migration patterns, affect precipitation patterns
effects of changes in precipitation
warm dry summers lethal to salmon stock
truck fish from lake to river/ocean?
ocean acidification
CO2 sink CO2 + H2O -- HCO3 + H decreasing pH affect critical life stages killing VI shellfish stocks
jack salmon
Chinooks that return to the fresh water one or two years earlier than their counterpart
most consisten eutrophication effects
shifts in algal species composition
increased frequency/intensity of nuisance blooms
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
