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Confirmed: Stress Gradient Hypothesis: How Plant Communities Endure Stress

By Guest PostFebruary 5, 2013Natureandrew altieri, barnacles, brown university ecologist, caribbean coral reefs, China, climatic zones, ecology letters, ecosystem, environmental stress, global meta analysis, growth responses, heat stress, high stress, highly competitive species, hypothesis in 1994, iology at brown, jiao tong university, less competitive species, mark bertness, mussel beds, negative interactions, organisms, patagonia, predictive value, qiang he, ray callaway, reduction in competition, rhode island, rule of thumb, salt marshes, santa barbara, sardinian sand dunes, sea grass beds, seaweeds, shanghai, shift to facilitation, shores, soil moisture, stress gradient hypothesis, stress increase, stress types, survival responses, university of california, university of montana

The Stress Gradient Hypothesis holds that as stress increases in an ecosystem, mutually supportive interactions become more significant and negative interactions, such as competition, become less so. The idea has been hotly debated but is now backed by a review of hundreds of studies co-authored in Ecology Letters by Mark Bertness, professor of biology at Brown, who first formally proposed the hypothesis in 1994. The time has come, he said, to test its application and predictive value.

PROVIDENCE, R.I. [Brown University] — Ecology is rife with predation, competition, and other dramatic “negative interactions,” but those alone do not determine the course life on Earth. Organisms sometimes benefit each other, too, and according to the Stress Gradient Hypothesis, their “positive interactions” become measurably more influential when ecosystems become threatened by conditions such as drought. Ecologists have argued about the hypothesis ever since Brown University ecologist Mark Bertness co-proposed it in 1994; Bertness says a large new global meta-analysis he co-authored in Ecology Letters definitively shows that it is true. (more…)

Recreational Fishing Brings Salt Marsh Die-Off

As recreational fishing activity has reduced predators in many of Cape Cod’s salt marsh ecosystems, Sesarma crabs have feasted on grasses, causing dramatic die-offs of the marshes, according to a new study. The researchers assessed the “trophic cascade” in several experiments that also ruled out alternative explanations for the problem.

PROVIDENCE, R.I. [Brown University] — Recreational fishing is a major contributor to the rapid decline of important salt marshes along Cape Cod because it strips top predators such as striped bass, blue crabs, and smooth dogfish out of the ecosystem, according to new research by Brown University ecologists.

With far fewer predators in areas where recreational fishing is prevalent, native Sesarma crabs have had relatively free rein to eat salt marsh grasses, causing the ecosystem to collapse, said Mark Bertness, chair of Brown’s Department of Ecology and Evolutionary Biology and the paper’s senior author. He led a series of experiments and measurements published online in the journal Ecology that he said unavoidably implicate recreational fishing in marsh die-off. (more…)

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Confirmed: Stress Gradient Hypothesis: How Plant Communities Endure Stress

Recreational Fishing Brings Salt Marsh Die-Off