Workshop Report - Ridge 2000 Program

Dispersal of Organisms
What are the biological and physical characteristics
responsible for the dispersal and life histories of organisms at
deep-sea hydrothermal vents?
A concerted effort must be devoted to defining the range of
reproductive strategies encountered among vent species and to
obtaining a detailed understanding of the reproductive responses
of vent organisms to environmental signals. Vent spacing, ridge
segmentation, offset distances, and interposing land masses may
provide barriers to gene exchange allowing chance events and
local selection to influence the genetic composition of populations
and species. The role of chance events and natural selection
in the development of vent ecosystems will be understood
through study of dispersal stages and genetic differentiation of
populations.
Vent chemistry and fluctuations in vent flow need to be
related to life history features such as rate of growth, time to
maturity, reproduction and mortality, and selective survival of
post-settlement stages. The influence of hydrothermal plume
dynamics andI or physical currents (mesoscale eddies, along-ridge
transport, etc.) on the transport of various life history stages
of vent organisms needs intense study, as does the distribution
of such stages within both the water column and the benthic
boundary layer. To address these problems it is paramount to
know the duration of vent activity.
Necessary sampling and analytical approaches include in situ
chemical characterization of hydrothermal systems, measurements
of rates of tissue accretion and skeletal deteriorationl
dissolution, in situ organism manipulations, and efficient
sampling of the plankton. In addition it is necessary to
undertake physical oceanographic measurements, settlement and
colonization substrate experiments, interpretative analyses of
larval morphological features, studies of mitochondrial DNA, and
gel electrophoretic studies.
Speciation and Evolution
What is the role of geographic isolation in the evolution of
vent communities on ocean ridges?
Evolution of vent communities is a reflection of long-term
geological processes governing ridge and hydrothermal evolution.
Linear spacing of vents and the isolation of entire ridge
systems results in evolutionary processes on several spatial
scales: separation of populations and species, evolution of one
species into another, introduction of new species to the vent
habitat. and co-evolution of the community members.
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