PROVIDENCE, R.I. [Brown University] There's been a rich debate in marine ecological circles about what happens to a key food source along rocky coastlines dominated by upwelling. The literature is filled with studies suggesting that the larvae of simple prey organisms such as barnacles and mussels hitch a ride on the coast-to-offshore currents typical of upwelling and are thus mostly absent in the coastal tidal zones.
That theory is getting a major challenge. In a paper in Ecological Monographs, Brown University marine ecologist Jon Witman and colleagues report that a key thread in the food web, the barnacle the popcorn of the sea flourishes in zones with vertical upwelling. Working at an expansive range of underwater sites in the Galapagos Islands, Witman and his team found that at two subtidal depths, barnacle larvae had latched onto rock walls, despite the vertical currents. In fact, the swifter the vertical current, the more likely the barnacles would colonize a rocky surface, the team found.
The finding "is counter to the prevailing notion about how marine communities are influenced by upwelling," said Witman, professor of biology in the Department of Ecology and Evolutionary Biology.
Barnacle communities thrived in the vertical-current sites, the team also found. The group routinely found specimens that had grown from one field season to the next to 3 centimeters (about 1 inch) in diameter "big enough to make soup out of," Witman said. The researchers also documented the presence of whelks and hogfish, which feast on barnacles. This predator-prey relationship shows that vertical upwelling zones are "much more dynamic ecosystems in terms of marine organisms than previously believed," Witman said.
Witman and his team, including Brown graduate student Margarita Brandt and Franz Smith of CSIRO Marine and Atmospheric Research in Australia, chose a dozen sites of underwater cliffs, ledges and slopes along a
|Contact: Richard Lewis|