Aquatic Ecology final Flashcards
Aquaculture impacts
escapement waste discharge fish health water quality coastal activities global feedfish populations marine foodwebs
Captured/farmed fishery products flow chart
aquatic production (PP)– capture fisheries (discarded bycatch, human consumption)- fish meal - aquaculture (livestock) -human consumption (terrestrial agriculture)
Captured/farmed fishery products flow chart, negative feedbacks
- feedbacks on PP
capture fisheries, fish meal, aquaculture
Captured/farmed fishery products flow chart, aquaculture negative feedback
waste, habitat modification, pollution, impacts on population/food web dynamics, escaping feral species
PP proportion division from capture fisheries
approximately:
1/4 bycatch (waste)
1/4 fish meal
1/2 human consumption (straight)
PP proportion division from fish meal
1/6 Aquaculture
2/6 (1/3) livestock
3/6 (1/2) human consumption
changes in total capture
increased substantially
human consumption from aquaculture & capture fisheries, 1997
~95 million metric tonnes (worldwide)
environment issues from aquaculture
discharge degrades water quality
alter/degrade natural habitat
pressure from multi-uses on water system
Biological issues with aquaculture
over-exploitation of organisms - food web consequences
chemical use (health concern)
introduction/transmission diseases, parasites, aliens
contamination
production quantity and value vs. year
exponential increase
huge increase since 1980’s
2004 quantity: ~60million tonnes
2004 value: $70 billion US
aquaculture production, china/asia/rest of world
China by far the hugest proportion and largest increase (50million tonne increase in 30yr), Asia ~20million tonne increase in 30 yrs, rest of world increased less than 10million tonne (an IS less than 10)
world population 1950-2002
2.56billion –6.23billion
now ~7billion
consumption per capita, 1950-2002
~doubled since 1950 (10-22kg per person/per year)
changes in marine fish catch, 1950-2002
~20million tonnes – 80/90million tonnes
Utilization of fish, 2000’s
40% fresh 30% non-food (feed) 18% frozen 7% cured 8% canned
Changes in utilization of fish since 1960’s
increase in fresh fish- better transportation, maintenance
increase in frozen fish
Canada’s Atlantic cod
1980-1990 catch was ~500,000 tonnes, 1995 drops off to nothing, overexploited to population collapse, still can not recover b/c niche space taken over
human fish consumption as a percent of total animal protein
worldwide 16%
N America 6.6%
Africa 21%
Far East 28% (Asia, healthier, cheaper, less fresh water needed)
World farm salmon production, 1980-2003
BC, Norway, Chile, UK all increase in production
Norway MAJOR increase
Changes in world farm salmon production, 1996-2002
Chile +235%
Norway +71% (but highest total value)
Scotland +89%
BC +96% (but lowest total value)
Changes in wild salmon, US + Canada, 1988-2002
chinook, chum, coho, sockeye- all decrease in production roughly 30%, decrease in at-vessel price/lb ~70%
pink production +11%
Changes in farmed Atlantic Salmon, US + Canada, 1988-2002
production: +895,000%
price: -61%
mariculture
cultivation of marine organisms for food and other products in the open ocean
aquaculture by environment (2004)
Brackish 6%
Freshwater 43%
mariculture 51%
what is grown in aquaculture
very diverse: crustaceans (shrimp, crab), finishes (carps, tilapia), filter feeders (mussels, oysters, scallops..), aquatic plants, carnivorous fish (salmon, bass, bream)
World aquaculture production by volume, by country/continent, 2004 (the main players)
China 70%
Rest of Asia 22%
Other 9%
w/i Other: W Europe 3.5%, Latin America 2%, NA 1.27%
World aquaculture production by value, by country/continent, 2004 (the main players)
China 51%
Rest of Asia 29%
Other 20%
w/i other: WE 8%, LA 7.5%, NA 1.86%
fastest growing food producing industry
aquaculture
problem of rapidly increasing aquaculture
demand for feed ingredients increasing rapidly, supply limited
feed used in BC, 2000
65 million kg
to produce 49million kg farmed fish
what happens to feed
20% deposited as feces
unused feed deposited as solid
excretory release of dissolved material
chemical components of aquaculture feed
45-65% is Carbon
6-10% is N, 1-2% is P
total system loading unknown
whats so important about increased N, P
two most important nutrients responsible fro eutrophication
Estimated loading to BCs coastal water from aquaculture
7.1 million kg of C
1.3 million kg of N
236,000kg P
all per year
may not be significant for entire system, but definitely important in enclosed bays
how salmon are unlike other ‘farm’ animals
carnivorous, feed is 45% fishmeal, 25% fish oil
cost of producing farm fish
2.8kg wild fish = 1kg farm fish
area required to produce the feed = 40-50,000X production area
Amount of PP being used for aquaculture
European industry - ~90% of North Seas’s PP
BC - 7.8million ha of ocean (278X area of all terrestrial BC horticulture)
what’s underneath a fish farm???
black sediment - highly organic material, reductive, lacking oxygen
taxa richness vs [sulfide] (µM)
negative linear
appears well correlated, but also a pretty wide spread in the data
whats happening with the sulfide
increased Cord – increased sulfide accumulation– kill benthic inverts.
rockfish near farms
found to have higher Hg content closer to fish farms
why rockfish?
not very migratory, good proxy for local condition
why higher Hg near fish farms?
oxygen reduction due to C loading = anoxic sediment– Hg methylated and converted to usable form (methyl mercury)– accumulates in tissues– produces neurological effects
levels of contaminants in farm produced, store bought, wild salmon
farmed & most of store bought ~ equal in all of the contaminants/carcinogens tested (PCB, dioxin, toxaphene, dieldrin), wild lower
some store bought appears to be wild but more is farmed
fish utilization and supply (excluding China), trend
1950-2002
population linear increasing
food supply non changing
changes in fishmeal use, 1988-2002
1988: Poultry 59%, aquaculture 10%, pigs 20%
2002: poultry 22%, aquaculture 46%, pigs 25%
what are poultry being fed now
bluegreen algae (more deeply coloured yolk, carotenoids)
fish oil use
1990: edible 76%, aquaculture 16%, industrial 8%
2002: edible 14%, aquaculture 81%, industrial 5%
Other sources of fish feed
by-catch
fish processing by-products
plant products
livestock by-products
Canada salmon feed
lowest fishmeal and oil inclusion rate
SA fish feed
41% of all fish used in feed, including: Anchoret, Chilean jack mackerel, South American pilchard
very important low trophic level fishes!!
top marine capture, 2002
anchoveta (9.7mt) pollock (2.7mt) tuna (2.0mt) capelin (2.0mt) herring (1.9mt)
changes in salmon fishmeal/fish oil use
fishmeal +185%
fish oil +577%
changes in carp fishmeal/fish oil use
fishmeal 750%
oil 70%
changes in crustacean fishmeal/oil use
fishmeal 1363% increase
fish oil 2660% increase!
overexploited species for fish feed
Peruvian anchovy- 6.2mt harvested 2003, recovering, overfished
Chilean jack mackerel- 1.7mt harvest 2003, fully fished, overfished
up to 11 species in this list are fully fished, unsustainable!
SA harvest of feed fish
1960-70’s exploit anchoveta– collapse– SA pilchard takes over niche– exploit them– collapse– chilean jack mackerel moves in..
natural cause of population decline in fish species
El Niño- huge decrease 1998
capture-reduction
how much is caught relative to time vessel spends out (? maybe) .. lowest in El Niño yrs
larger scale effects of harvesting fish feed
taking ~85% of sea predators food; seabirds, marine mammals
Effects of farming on wild salmon health
smolts travelling to ocean pass by fish farms, pick up significant infections rates; many farm fish have sea lice (infestation from low diversity, close quarters)
forage fish
prey fish/bait fish, small pelagic fish preyed on by larger predators for food
areas of application for stable isotopes
paleoclimate reconstruction (O2) paleolimnology terrestrial aquatic linkages food web ecology migratory studies individual feeding behaviour
paleolimnology, stable isotopes
historic patterns of productivity, mostly C, N
terrestrial aquatic linkages, stable isotopes
terrestrial–> aquatic (lake management)
marine derived nutrients (salmon)–> terrestrial
food web ecology, stable isotopes
contaminant transfer, ecology
migratory studies, stable isotopes
birds, fish, zooplankton, mammals, C
how much time in open/coastal ocean
algae isotope ratio highly variable in open/coastal
individual feeding behaviour, stable isotope
niche shift, omnivore, trophic position
within single population
ex. stickleback - some neutral all the time, some pelagic all the time, all related to evolution, studiable by isotopes
∂13C ratios
C fractionates during photosynthesis, little-no fractionation up food chain
determine what food sources are based on ∂13C ratio
∂13C determination of food source possible with following conditions
large isotopic separation (btw food sources)
over time food signatures are stable
two/few food sources
examples of ∂13C determination of food source
middle of lake - very highly negative
close to littoral zone (terrestrial C) - less negative
∂15N in food web ecology
tells trophic level, fractionated throughout trophic levels
trophic enrichment of ∂15N
2.92+/- 0.8 ‰
typical ∂15N signatures
algae 4-8‰
invertebrates 8-16‰
forage fish 10-14‰
predatory fish 10-18‰
typical ∂13C signatures
off-shore -28‰ (depleted)
near-shore -14‰
why is ∂15N fractionated up trophic level
preferential excretion of 14N
high ∂15N
heavy
more positive
atmospheric N2 ∂15N
0‰
hasn’t been fractionated by organisms
enriched in ∂13C
heavy
less negative
∂13C never positive
depleted in ∂13C
light
more negative
∂13C never positive
inorganic fertilizer ∂15N
0‰
made from captured atmospheric N
fractionation
in a chemical reaction one isotope proceeds at a quicker rate than the other due to a slight difference in mass (lighter synthesized faster/easier, more efficient)
two types of fractionation
animals- body tissue
algae
animal tissue fractionation
14N is preferentially released so 15N increases relative to its food source
algae fractionation
photosynthetic enzyme can process 12C molecules quicker than 13C, utilize it preferentially
based on size
algae photosynthetic enzyme that processes carbon molecule
RUBISCO
isotopic composition in foodweb
sediment: ~-30, towards terrestrial
inverts: ~-33, ~50/50 terrestrial/planktonic
piscivorous fish: ~-28/-30 pretty close to terrestrial
littoral zone
near shore area where sunlight penetrates all the way to the sediment and allows aquatic plants (macrophytes) to grow
Loch Ness Zooplankton, temporal shift in C signature reflecting food source
winter- low PP, most C is detrital, POM (less - ∂13C), zoop signature matches POM
summer- higher PP, signature drops to mirror to algae ∂13C (more - )
reconstruct historic salmon runs with ∂15N
sedimentary ∂15N correlated to number of spawners
250,000spawners ~ 6‰
1mill spawners ~ 8.5‰
∂15N sediment signature change in 1900
dramatically drops off, commercial fishing
significantly different ∂15N signatures along the river
higher ∂15N signature in root feeders, omnivores, detritivores, predators.. BELOW falls (input of high ∂15N source, salmon)
Class 1 lake
lack preferred lake trout prey, pelagic forage fish, causing lake trout to feed on zooplankton and zoobenthos
class 2 lake
contain at least one species of pelagic forage fish, resulting in piscivory
class 3 lake
pelagic forage fish and glacis-marine relict invertebrate predator Myis relicta - elevates lake trout to fifth trophic level
measuring trophic level by ∂15N ratio
gut contents
digestibility highly variable
assumptions made
pelagic
Any water in a sea or lake that is neither close to the bottom nor near the shore
pelagic zooplankton signatures
variable! needs to be established as a baseline
study found differences in calanoid copepods, Daphnia, Holopedium
lake to lake isotope signatures
highly variable depending on inputs (human, animal, fertilizer, salmon)
PCB (ng/g wet mass) vs trophic position
liner increasing
class 1 at low end
class 2 in middle
class 3 at top end (most trophic positions)
appears to be due to increased % lipid with increased trophic level
PCBs and lipids
lipophilic contaminants, accumulate in fat (lipophilicity)
unnatural, remain in bodies
∂15N trophic position vs. dietary trophic position
highly correlated = N good measure of trophic position
Hg (µg/g) vs. Lake class
higher in higher class higher if smelt present in each individual class
∂15N vs ∂13C, Arctic Lake System, Lake Trout
LT top predator - highest ∂15N, ~middle of ∂13C spread- consumes pelagic and littoral fish
Log Hg (µg/g wet weight) vs. ∂13C
decreasing
terrestrial source has lower level of Hg
if LT feed more on nearshore/benthic than offshore/pelagic they will have lower Hg
Hg consumption guideline
0.5µg/g
one meal per week (non pregnant adults)
[Hg] (µg/g) vs. ∂15N (‰) in Ontario, Quebec lakes
all Class 2 and 3 fish are above consumption guideline level of Hg
sport fishing species, widely consumed
US Hg blood levels
300,000-600,000 children/yr cord blood Hg level > 5.8µg/L, a level associated with loss of IQ
cost of methyl mercury toxicity
lost productivity (lower IQ) $8.7bill/yr
Daphnia spp. ∂15N (‰) vs levels of land-use (low, high)
low land use (Sooke lake) - 0-5‰
high land use (Shawnigan lake) - 6-13‰
Sooke lake
our drinking water
fully protected
Shawnigan lake
developed
lots of septic
highly enriched in ∂15N
Caffeine (ng/L) vs. ∂15N in Mussel Tissue
linear positive
caffeine from septic contamination
robust indicator of fecal contamination
Caffeine (ng/L) vs. Shoreline Development (lots/km^2), Shawnigan lake
linear positive
denser housing = more septic = fecal input = more caffeine
∂15N (‰) vs. year, Sooke Lake and Shawnigan lake sediment cores
Shawn. has increased from ~1-3 as a result of human development
Sooke- has some spikes from building new dams/raising the dam- inundating land
EBS
Eastern Bering Sea
EBS 2002-2005
large-scale warming event
followed by 2yrs cooling event (2006-07)
EBS sampling
zooplankton from 186 stations each year
13,000 fish
600 zooplankton
change in abundance of juvenile salmon and forage fish
increase in warm years
decrease in cold years
in salmon, juveniles, forage fish
EBS zooplankton ∂15N
must be determined for baseline
higher in N EBS- upwelling? predatory?
Juvenile Sockeye Salmon ∂15N, EBS
warm years- up to 2 levels above zoop. = piscivory
cool years- remain small, stay near shore, can’t grow enough to move up food chain
Juvenile Pink Salmon Trophic position above zooplankton, EBS
pink salmon normally zooplanktivorous..
in wam years- up to 2 levels above zoop., piscivorous
Juvenile Chum Salmon trophic position above zooplankton, EBS
chum usually feed on jellies
warm event- up to 2levels above zoop., piscivorous
Signatures in northern Bering Sea
warm year- less negative ∂13C, near terrestrial loading (from Yukon river)
cool year- more negative ∂13C, pelagic source
not really a pattern in ∂15N
Signatures in Southern Bering sea
Warm- higher ∂15N, higher trophic position, trophic enrichment
Cool- lower ∂15N, lower trophic position
sediment ∂15N profiles from NH lakes
26 profiles, almost all show drop in ∂15N since 1900 = depleted N signature from fertilizer use! recall (fertilizer is from atmospheric N2)
global fresh water
3%
99.7% of that 3% is unavailable (glaciers, deep aquifers)
Where is our available water
80% is in 20 large lakes
95% is in 145 lakes