Transcript 14520_2808RossVander Vorstex

Storage effects in intermittent river ecology:
implications for coexistence, biotic interactions
and colonization dynamics
Hydrobaenus sp. (Chironomidae)
diapause in desiccation-resistant case
Ross Vander Vorste
Virginia Water Resources Research Institute, Virginia Tech
@RiversRossV
Thibault Datry
IRSTEA, Villeurbanne, France
Society for Freshwater Science 2016
Biodiversity and community assembly
Community assembly
Environment
Dispersal
Biotic interactions
“Filters”
Regional species pool
Local community
(Poff 1997 JNABS, HilleRisLambers et al. 2012 Annu. Rev. Ecol. Evol. Syst.)
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Biodiversity and community assembly
How is diversity maintained in a fluctuating environment?
Harsh environmental conditions
Environmental fluctuations
Harsh
Favorable
Time
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Storage effects can maintain species diversity
Population growth during favorable environmental conditions is stored
and buffers species from the negative effects of harsh conditions
(Chesson 2000 Annu. Rev. Ecol. Evol. Syst.)
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Storage effects can maintain species diversity
Population growth during favorable environmental conditions can be
stored and buffer species from the negative effects of harsh conditions
1 Species have different responses to the environment
High
Species 1
Abundance
Low
Species 2
Low
High
Water availability
(Chesson 2000 Annu. Rev. Ecol. Evol. Syst.)
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Storage effects can maintain species diversity
Population growth during favorable environmental conditions can be
stored and buffer species from the negative effects of harsh conditions
1 Species have different responses to the environment
2 Covariance between environment and competition
High
Competition
Low
Low
High
Water availability
(Chesson 2000 Annu. Rev. Ecol. Evol. Syst.)
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Storage effects can maintain species diversity
Population growth during favorable environmental conditions can be
stored and buffer species from the negative effects of harsh conditions
1 Species have different responses to the environment
2 Covariance between environment and competition
3 Species traits limit the impact of the environment and competition
the seedbank
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(Chesson 2000 Annu. Rev. Ecol. Evol. Syst.)
How can “storage” influence communities?
1 Colonization dynamics
Early colonizing taxa can have priority effects
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How can “storage” influence communities?
1 Colonization dynamics
Early colonizing taxa can have priority effects
2 Biotic interactions
Could reduce competition and predation pressure
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How can “storage” influence communities?
1 Colonization dynamics
Early colonizing taxa can have priority effects
2 Biotic interactions
Could reduce competition and predation pressure
3 Species coexistence
Trade-off between resistant and resilient strategies
How can “storage” influence communities?
1 Colonization dynamics
Early colonizing taxa can have priority effects
2 Biotic interactions
Could reduce competition and predation pressure
3 Species coexistence
Trade-off of resistant and resilient strategies
Examples in the literature:
?
Durden images
Adler et al. 2006 PNAS
Angert et al. 2009 PNAS
Usinowicz et al. 2009 ECOLOGY
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Intermittent rivers as a model system
Environmental fluctuations
Roubion River, France
Before drying
During drying
Bertrand Launay
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Intermittent rivers as a model system
Environmental fluctuations
Found globally and increasing in abundance
Danube (Germany)
Manganui (NZ)
McMurdo Valley (Antarctica)
Tete (Mozambique)
Kapoeta (Soudan)
Rio Grande (US)
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Intermittent rivers as a model system
Environmental fluctuations
Found globally and increasing in abundance
Threatened by climate change, water
abstraction and other human activities
Narmada River, India
Colorado River, USA
Pete McBride
Chandravir Singh
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Invertebrate storage in intermittent rivers
Hyporheic zone use during drying
Gammarus pulex
(Gammaridae)
S. Luk
Leuctra sp.
(Leuctridae)
Baetis sp.
(Baetidae)
Hyporheic zone
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Invertebrate storage in intermittent rivers
Hyporheic zone use during drying
Gammarus pulex
(Gammaridae)
S. Luk
Leuctra sp.
(Leuctridae)
Baetis sp.
(Baetidae)
Hyporheic zone
Resistance forms prevent desiccation
Eggs, body armoring (cases), diapause/dormancy
Hydrobaenus sp.
(Chironomidae)
M. Billard
Stenophylax latipenis
(Limnephilidae)
M. Bogan
Mesocapnia arizonensis
(Capniidae)
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Storage effects and colonization dynamics
No
Non-dispersing
colonizers
Before
During
After
Vander Vorste et al. 2015 FWB
Dispersing
colonizers
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Storage effects and colonization dynamics
No
Non-dispersing
colonizers
Before
During
After
Dispersing
colonizers
Invertebrates from the seedbank colonize first
and could have ‘priority’ over dispersing colonizers
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Storage effects and biotic interactions
Prey
Large predator
Before
During
After
Cybister tripunctatus
(Dytiscidae)
Gammarus pulex
(Gammaridae)
Predator
Prey
Prey can use hyporheic zone to avoid biotic interactions
and drying can remove top predators
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Storage effects and species coexistence
Resilient species
Resistant species
Before
During
After
Invertebrate storage can lead to establishment of
‘early’ and ‘late’ season communities
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Key research questions
Colonization dynamics
• Are there priority effects related to colonization via
invertebrate storage?
Study design: species additions to mimic ‘early’ and ‘late’ arriving
taxa
Mesocosm experiments
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Key research questions
Biotic interactions
• Does invertebrate storage reduce competition and
predation pressure during harsh environmental
conditions?
Study design: measure biotic interactions w/ and w/o hyporheic zone
Manipulative field experiments
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Implications for IRES management
Species coexistence
• Can invertebrate populations increase from low
population size in the presence of a competing taxa?
Study design: long-term population dynamics
Population modeling
Species 1
Abundance
Field observations
Species 2
Time
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Broader implications for freshwater ecology
Temporal vs spatial dispersal
• Storage could reduce connectivity among meta-communities
• Alteration of gene flow among populations
Intermittent river management
• Increased duration will reduce importance of storage effects
• Importance of protecting invertebrate storage
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In summary
@RiversRossV
Contact: [email protected]
• Similar to terrestrial systems, storage occurs through
the combined use of the hyporheic zone and
desiccation-resistance forms by invertebrates in IRES.
• Circumstantial evidence suggests that storage
influences colonization dynamics, biotic interactions
and species coexistence.
• Research should be directed towards addressing
several key research questions related to storage
effects to advance IRES ecology.
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