the explorers journal the global adventure issue - The Explorers Club

We returned from our cruise enthusiastic aboutthe preliminary results from the expedition, whichshowed that icebergs have a significant influenceon the surrounding pelagic ecosystem. BenTwining (USC) joined our efforts at this stageto study the impact of collected iceberg detritalmaterial on laboratory phytoplankton incubations.Phytoplankton grown in media enriched withiceberg-borne terrigenous material we collectedgrew at significantly higher levels than thosegrown in unenriched media, strongly suggestingthat the iron-rich material was indeed responsiblefor the high growth rates we observed aroundthe icebergs. The next step was to estimate howimportant this study was regarding the wholepopulation of icebergs in the studied region of theWeddell Sea. The “biological halo” around the twoicebergs studied extended out to about four kilometers,substantially increasing the pelagic areainfluenced by these drifting islands of ice. A radarsatellite image taken about the time of our studyand covering more than 11,000 square kilometersof the sea surface, contained 962 detectible icebergs.Only 89 of these were within the same sizerange as those we studied. If we extrapolate thesize of each of these to include a four-kilometer radiushalo around them, their total area of influencerepresents some 39 percent of the total area of50