Realizing their unique opportunity, the scientists quickly changed gears and within days were back on the beaches to reassess their study sites in the catastrophe's aftermath. They have returned many times since, diligently documenting the ecological recovery and long-term effects of the earthquake and tsunami on these coastlines, in both natural and human-altered settings.
The magnitude and direction of land-level change brought the greatest impact, drowning beaches especially where the tsunami exacerbated earthquake-induced subsidence and widening and flattening beaches where the earthquake brought uplift. The drowned beach areas suffered mortality of intertidal life; the widened beaches quickly saw the return of plants and animals that had vanished due to the effects of coastal armoring.
"With the study in California and our study here, we knew that building coastal defense structures, such as seawalls, decreases beach area, and that a seawall results in the decline of intertidal diversity," said lead author Eduardo Jaramillo, of Universidad Austral de Chile. "But after the earthquake, where significant continental uplift occurred, the beach area that had been lost due to coastal armoring has now been restored. And the re-colonization of the mobile beach fauna was under way just weeks after."
With responses varying so widely depending on land-level changes, mobility of flora and fauna, and shore type, the findings show not only that the interactions of extreme events with armored beaches can produce surprising ecological outcomes but also suggest that landscape alteration, including armoring, can leave lasting footprints in coastal ecosystems.
"When someone builds a seawall, not only is beach habitat covered up with the wall itself, but, over time, sand is lost in front of the wall until the
|Contact: Shelly Leachman|
University of California - Santa Barbara