TowCam Exploration for Chemosynthetic Ecosystems at the Chile Triple Junction

As well as being the juncture of diverse geological phenomena (including a rift, active
margin, , the Chile Triple Junction is a key target for exploration to understand the
biogeography and biodiversity of chemosynthetic environments in which life is fueled by
energy released from chemical reactions at the seafloor. To date, more than 100 different
hydrothermal fields have been found worldwide, with at least one site known to exist in
every major ocean basin (Baker & German, 2004). Although the global mid-ocean ridge
crest is a near-contiguous geologic feature, however, bathed in a deep ocean in which
complete mixing takes just a few thousand years, hydrothermal vent-fauna (>400 endemic
species) define at least six distinct biogeographic provinces (Van Dover et al., 2002). This is
perplexing - not least because cold-seeps (>200 endemic species), and large organic falls
(>400 species) are also now known to host chemosynthetic ecosystems (Tunnicliffe, 1998;
Smith & Baco, 2003). What, therefore - other than the release of chemically reduced
compounds (H2S, CH4) – can have caused this biodiversity and biogeography of deep-sea
chemosynthetic ecosystems to develop? One hypothesis is that biogeographic provinces
result from persistent geologic or oceanographic barriers to gen -flow (e.g., Van Dover et
al., 2002; Tyler et al., 2002; Shank et al., 2004). To test this, however, we must also
establish what similarities/differences arise between different chemosynthetic ecosystems
in the absence of any significant geological or oceanographic barriers.