Outline

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Outline
Soft-sediment ecosystems

• The deep sea
• Processes in shallow water assemblages
• Detecting impacts of multiple disturbances

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Sandy shores/beaches
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Muddy shores/bays, estuaries, and lagoons
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Competition as a force in soft-sediments

• Competition usually for food

• Competition rarely causes displacement. Instead,
  effects growth, reproduction, and survival

• Competition has a big effect on community
  structure- depth distribution, population
  dynamics but not species composition

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Pete Peterson (1979)
Does the IDH hold in soft-sediments?
Worked in tidal mudflats and lagoons (Mugu Lagoon)
Intermediate disturbance hypothesis (IDH) Joe
Connell (1978)
Not in soft-sediments
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Shallow subtidal soft-bottoms
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Benthic diatoms
Foraminiferans
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Polychaete worms
crustaceans
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heart urchins
pycnogonids
brittle stars
scallops
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Many types of predators
Predators have a big effect on community
composition
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bat ray feeding pits
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Types and scales of disturbances in soft-sediments
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Physical disturbances in Antarctic soft-bottoms
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Soft-sediment infauna
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Natural physical disturbances
Iceberg scouring
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Recently scoured
Recovered
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Anchor ice formation and uplift
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Resulting zonation of species
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Process of recovery controlled by succession

• Directional sequence of species replacement
  following disturbance
• Influenced by species life histories, disturbance
  regime, and characteristics of free space

• Models (1) Connell Slatyer (1977)
• Facilitation
• Inhibition
• Tolerance

Models (2) Sutherland (1974) Multiple stable
states
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Physical disturbance caused by organic enrichment
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Pollution a major problem in all marine systems
Two generic forms of contaminants
Eutrophication
Toxic contamination
Metals, organic compounds (PCBs, Dioxin,
pesticides)
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Assessing biological impacts of chemical
stressors in marine soft-sediment habitats

• gt1 Billion US spent annually worldwide to
  monitor pollution and biological effects
• Tripartite approach to assessments
• Produced few models that predict community
  responses to specific contaminant types
• Do not know the how to differentiate biological
  impacts of different contaminant types

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Two generic forms of marine contaminants often
covary in space and time
What is the effect of organic enrichment and
toxics on marine communities?
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Predictions based on life history traits of
soft-sediment organisms
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Predictions
Annelids
Arthropods
Echinoderms
Organic enrichment
little change slight decrease
little change slight increase
Metal contamination
little change
Both
How will biotic interactions influence these
reponses?
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Why test hypotheses in Antarctica?

• Pristine habitats with little background
  contamination
• Well-described and species rich communities
• Sea ice cover drastically reduces disturbances
• Few epibenthic predators reduces biological
  disturbance

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Maniuplative field experiment
0 TOC / 0 ppm Cu
0 TOC / 100 ppm Cu
0 TOC / 500 Cu
1 TOC / 0 Cu
1 TOC / 100 Cu
Same treatments But caged to exclude predators
1 TOC / 500 Cu
2 TOC /500 Cu
2 TOC / 0 Cu
2 TOC /100 Cu
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Community response
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Population demographic responses to stressors
Total annelids
No. Individuals/0.04 m2
Capitella capitata
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5
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Growth (mm in length/month)
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2
1
0
TOC
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Preliminary model
Annelids
Arthropods
Echinoderms
Organic enrichment
Copper contamination
Both
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How general are responses of high taxa?Do
responses vary with environmental conditions?
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Meta-analyses of data from pollution monitoring
stations

• 414 US EPA, NOAA, and CSBPP monitoring stations
  located
• in temperate latitudes
• New York-Florida (Atlantic coast) and
  Oregon-California
• (Pacific coast)
• Bays, estuaries, and nearshore coastal habitat
• 1997-98 data for 56 chemical contaminants,
  sediment characteristics,
• and macrofauna
• Multiple stepwise backward regression
• analyses

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Applications

• Community index based on high taxonomic responses
  
• can streamline pollution monitoring programs
• Reduce pollution monitoring costs
• Improve understanding of cause and effect-
• finally a model!