how the decline of ocean species threatens human well-being how the decline of ocean species...
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How the decline of ocean species How the decline of ocean species threatens human well-beingthreatens human well-being
How the decline of ocean species How the decline of ocean species threatens human well-beingthreatens human well-being
Emmett DuffyEmmett DuffyVirginia Institute of Marine ScienceVirginia Institute of Marine ScienceThe College of William and MaryThe College of William and Mary
Emmett DuffyEmmett DuffyVirginia Institute of Marine ScienceVirginia Institute of Marine ScienceThe College of William and MaryThe College of William and Mary
Human society
Marine ecosystem services• Water quality control• Seafood production• Tourism and recreation• Ecosystem resilience
Linkage?
Marine biodiversity• Genetic• Species• Ecosystem
Impacts
Linkage?
Marine ecosystem processes• Carbon & nutrient cycling• Primary and secondary productivity• Food and habitat provision• Processing of wastes
Benefits
Theory: Biodiversity should increase productivity
More species use greater fraction of resources, thus produce more
Source: Tilman D (2000) Causes, consequences and ethics of biodiversity. Nature 405: 208-211.
P1 P6P5P4P3P2
““Horizontal” biodiversity Horizontal” biodiversity
PLANTS PLANTS
Plant species richness
Pla
nt c
over
(%
)
Exp’t: Diversity increases productivity
11
““Vertical”Vertical”biodiversity biodiversity
C1
O1 O2
H2H1
33
22
TOP CARNIVORE
HERBIVORES
OMNIVORES
Source: Duffy JE, et al. (2007) The functional role of biodiversity in ecosystems: incorporating trophic complexity. Ecology Letters 10: 522-538.
P1 P6P5P4P3P2
““Horizontal” biodiversity Horizontal” biodiversity
EDIBLE PLANTS INEDIBLE PLANTS
Predators
Consumers, Omnivores
Herbivores, DetritivoresZooplanktivores, Zooplankton
Algae, Plants, Detritus
Source: Byrnes JE, Reynolds PL, Stachowicz JJ (2007) Invasions and Extinctions Reshape Coastal Marine Food Webs. PLoS ONE 2: e295.
~70% extinctions
at high levels
~70% extinctions
at high levels
~70% Invasions at intermediate
levels
~70% Invasions at intermediate
levels
Trophic skew: Top consumers lost first in sea
SF BAY INVASIONS
GLOBAL & REGIONALEXTINCTIONS
Consumers exert strong top-down control in sea
Source: Cyr H, Pace ML (1993) Magnitude and patterns of herbivory in aquatic and terrestrial ecosystems. Nature 361: 148-150.
Most marine production is grazed
~70%
<20%
Gre
at
sh
ark
sE
las
mo
bra
nc
hm
es
op
red
ato
rsS
ca
llo
ps
Consumer loss ripples through food web
Source: Myers RA, Baum JK, Shepherd TD, Powers SP, Peterson CH (2007) Cascading effects of the loss of apex predatory sharks from a coastal ocean. Science 315: 1846-1850.
Healthy scallop fisheries depend on top predators
How does 2-D Biodiversity affect ecosystems?
1. Diversity increases production and resource use
2. Diversity increases stability: resistance to top-down control
3. Diversity enhances trophic transfer
1. Diversity increases production and resource use
2. Diversity increases stability: resistance to top-down control
3. Diversity enhances trophic transfer
1. Diversity increases production and resource use
2. Diversity increases stability: resistance to top-down control
3. Diversity enhances trophic transfer
1. Diversity increases production and resource use
2. Diversity increases stability: resistance to top-down control
3. Diversity enhances trophic transfer
How does 2-D Biodiversity affect ecosystems?
Diversity increases resource use and production
BIOMASSPRODUCTION
RESOURCEDEPLETION
(1) Diversity increases biomass production and resource use
(2) Patterns are similar across trophic levels (and habitats)
PH
DC
Mean MeanMax Max
Source: Cardinale BJ, Srivastava DS, Duffy JE, Wright JP, Downing AL, et al. (2006) Effects of biodiversity on the functioning of trophic groups and ecosystems. Nature 443: 989-992.
N = 111 experiments
Ln
(m
ixtu
re/a
vera
ge
mo
no
cult
ure
)
How does 2-D Biodiversity affect ecosystems?
1. Diversity increases production and resource use
2. Diversity increases stability: resistance to top-down control
3. Diversity enhances trophic transfer
1. Diversity increases production and resource use
2. Diversity increases stability: resistance to top-down control
3. Diversity enhances trophic transfer
Diversity & top-down control: the general pattern
Source: Hillebrand H, Cardinale BJ (2004) Consumer effects decline with prey diversity. Ecology Letters 7: 192-201.
Lo
g (
gra
zed
/co
ntr
ol)
Diversity confers resistance to grazing in aquatic algae
N = 172 experiments
How does 2-D Biodiversity affect ecosystems?
1. Diversity increases production and resource use
2. Diversity increases stability: resistance to top-down control
3. Diversity enhances trophic transfer
1. Diversity increases production and resource use
2. Diversity increases stability: resistance to top-down control
3. Diversity enhances trophic transfer
• All types of habitats
• singly sp. vs mixture
Source: Worm B, Barbier EB, Beaumont N, Duffy JE, Folke C, et al. (2006) Impacts of biodiversity loss on ocean ecosystem services. Science 314: 787-790.
Diversity & trophic transfer: the general pattern
N = 32 experiments
Prey (algal) & consumer diversity both increase consumer performance
Ln
(m
ixtu
re/a
vera
ge
mo
no
cult
ure
)
CONSUMER RICHNESS
PRODUCER RICHNESS
The real world: Resilience in global fisheries
Production & stability of fisheries increase with diversity
Source: Worm B, Barbier EB, Beaumont N, Duffy JE, Folke C, et al. (2006) Impacts of biodiversity loss on ocean ecosystem services. Science 314: 787-790.
Mechanism? Redundancy and stability inn fisheries
Source: Myers RA, Worm B (2003) Nature 423: 280-283.
Source: Chavez et al. (2003) Science 299: 217-221.
Diversity provides functional redundancy, i.e., “insurance”
One (of several) solutions: Marine Protected Areas
Source: Worm B, Barbier EB, Beaumont N, Duffy JE, Folke C, et al. (2006) Impacts of biodiversity loss on ocean ecosystem services. Science 314: 787-790.
Marine biodiversity has horizontal and vertical dimensionsMarine biodiversity has horizontal and vertical dimensionsTop-down control is strong in seaTop-down control is strong in seapredator loss ripples through food webpredator loss ripples through food web
Real world evidence is generally concordant with experimentsReal world evidence is generally concordant with experiments
Large fishes often maintain desirable ecosystem statesLarge fishes often maintain desirable ecosystem states
Restoration of marine biodiversity recovers ecosystem servicesRestoration of marine biodiversity recovers ecosystem services
Marine biodiversity has horizontal and vertical dimensionsMarine biodiversity has horizontal and vertical dimensionsTop-down control is strong in seaTop-down control is strong in seapredator loss ripples through food webpredator loss ripples through food web
Real world evidence is generally concordant with experimentsReal world evidence is generally concordant with experiments
Large fishes often maintain desirable ecosystem statesLarge fishes often maintain desirable ecosystem states
Restoration of marine biodiversity recovers ecosystem servicesRestoration of marine biodiversity recovers ecosystem services
Concluding thoughts
Restoration: ocean health care
mangrovesmangroves
Coral reefsCoral reefs
seagrassesseagrasses
Oyster reefsOyster reefs
Loss of diversity
Source: Worm B, Barbier EB, Beaumont N, Duffy JE, Folke C, et al. (2006) Impacts of biodiversity loss on ocean ecosystem services. Science 314: 787-790.
Loss of services
Source: Worm B, Barbier EB, Beaumont N, Duffy JE, Folke C, et al. (2006) Impacts of biodiversity loss on ocean ecosystem services. Science 314: 787-790.