Biogeography

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Biogeography
Bria Harvey Vanessa Page
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Outline

• Species and Distribution
• Population Sizes
• Environmental Structure
• Gradients
• Dispersal
• Limitations

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Species and Distribution

• The deep sea is divided into 3 main regions
• Atlantic
• Indo-Pacific
• Antarctic

(Vinogradova, 1979)
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Species and Distribution

• There are two general types of species
  distributions
• Endemic
• Cosmopolitan
• Endemic species have many genera
• Cosmopolitan species have few genera

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Species and Distribution

• There are two forms of species that are
  distinguishable based on their vertical
  distribution
• Stenobathic
• Eurybathic

(Vinogradova, 1979)
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Species and Distribution

• The geographic distribution is influenced by
  tropic relations
• Physical, Chemical, Geological, and Biological
  processes
• Phytoplankton and zooplankton zones

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Species and Distribution

• The deep sea has a high diversity and low density
  of benthic fauna and the species are
  predominantly small in size
• All benthic marine invertebrate groups occur in
  the deep sea

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Population Sizes

• Abyssal fauna diminishes in density with depth
  and distance from coastline
• Challenger Expedition

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Population Sizes

• Population size is an important factor in
  determining species divergence
• Aggregated distributions

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Population Sizes

• Ranges tend to contract rather than to expand
  with increasing depth

(Vinogradova, 1979)
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Environmental Structure

• Relief of the bottom restricts distributions
• Submarine Mountain Chains
• Mid-Atlantic Ridge
• Trenches
• Self-contained hadal provinces

(Vinogradova, 1959)
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Environmental Structure

• Relief of the bottom restricts distributions
• Elevations
• Eddies and Taylor Columns
• Bering Strait
• Currents
• Western Boundary
• Under Current (WBUC)

(Cutler, 1975)
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(Cutler, 1975)
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Gradients

• Depth related gradients
• Greatest along continental slopes
• Sediment and erosion
• Boundary currents
• Limited depth ranges
• Isopod distribution

(Hessler et al., 1979)
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Gradients
(Hessler et al., 1979)
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Dispersal

• Larvae are the primary dispersal phase
• Direct development
• Lecithotrophy
• Planktotrophy

(Young et al., 1997)
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Limitations

• Cost
• Scale
• Knowledge

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Conclusions

• General ideas about the biogeography of the deep
  sea
• Latitudinal and meridional distributions
• Depth related gradients
• Bathymetric constraints
• Disperal
• Population studies

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References

• Allen, J.A. 1979. The adaptations and radiation
  of deep-sea bivalves. Sarsia. 64 19-27. 
• Bouchet, P., Waren, A. 1979. The abyssal
  molluscan fauna of the Norwegian Sea and its
  relation to other faunas. Sarsia. 64 211-243.
• Cutler, E.B. 1975. Zoogeographical barrier on
  the continental slope off Cape Lookout, North
  Carolina. Deep-sea Research. 22 893-901.
• Hessler, R.R., Wilson, G.D., Thistle, D. 1979.
  The deep-sea isopods a biogeography and
  phylogenetic overview. Sarsia. 64 67-76.
• Sibuet, M. 1979. Distribution and diversity of
  asteroids in Atlantic abyssal plains. Sarsia.
  64 85-92.
• Vinogradova, N.G. 1959. The zoogeographical
  distribution of the deep-water bottom fauna in
  the abyssal zone of the ocean. Deep-sea
  Research. 5 205-208.
• Vinogradova, N.G. 1979. The geographical
  distribution of the abyssal and hadal
  (ultra-abyssal) fauna in relation to the vertical
  zonation of the ocean. Sarsia. 64 41-50.
• Wilson, G.D.F., Hessler, R.R. 1987. Speciation
  in the deep sea. Annual Review Ecology and
  Systematics. 18 185-207.
• Young, C.M., Sewell, M.A., Tyler, P.A., Metaxas,
  A. 1997. Biogeographic and bathymetric ranges
  of Atlantic deep-sea echinoderms and ascidians
  the role of larval dispersal. Biodiversity and
  Conservation. 6 1507-1522/