Marine life and roughness:
examples from coral reefs and coasts
Clifford Hearn, Ph.D.
Oceanography, UNSW, Canberra, ACT 2600, Australia
Wednesday, April 24, 2002
3:00 p.m.–Pacific Forum
Roughness in the ocean occurs at many spatial scales and generates
turbulence that greatly affects marine life. A good example is a coral
reef, one of the roughest surfaces in the ocean The extreme roughness of
reefs causes currents and waves to dissipate energy at rates that far
exceed values elsewhere in the ocean. Hence, the extreme roughness of
reefs is the paramount reason that coral reefs can maintain high
productivity in low nutrient tropical waters. Furthermore, causal
relationships between nutrient-uptake rates and dissipation of energy
support general observations on reef zonation and reef metabolic rates.
Turbulence is also generated by the large-scale roughness associated with
the coastal margins and assists coastal trapping of many types of larvae.
Most roughness, and associated particle trapping, is accentuated by
oscillatory motions such as waves (on reefs) and tides (on the coast). A
good example is the eutrophication of the North Sea.
Next: Evolution and biogeography of hydrothermal vent organisms