This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Global warming is often treated as synonymous with climate change, but rising temperatures are only one consequence of the human-driven phenomenon. Changes in rainfall patterns are another, but their effects on ecosystems are less understood.
In fact, rain has an outsized impact on the ecology of rivers, according to a new study led by William & Mary's VIMS & Batten School and published in the journal Ecology. Researchers found that less annual rainfall destabilizes stream ecosystems, reducing the complexity of the food webs and reorganizing the distribution of animal mass. "Climate change is fundamentally changing the structure and function of these rivers.
These shifting food webs might be an early warning sign we'll need to pay attention to,"said lead author Bradley Strickland, a former postdoctoral research associate at VIMS & the Batten School of Coastal & Marine Sciences. The study focused on nine rivers in the Gulf Coast prairie ecoregion of Texas, where dry air from the Chihuahuan Desert collides with moisture from the Gulf of Mexico to create a steep rainfall gradient. The rate of annual precipitation drops considerably over a short distance, making it ideal for measuring rain's influence on riverine ecosystems.
"Anywhere else in the U.S., if you had a rainfall gradient like that, it would usually be because of some geologic feature, like a mountain range," said co-author Chris Patrick, an associate professor at VIMS & the Batten School. "So you're not sure what's causing what. In South Texas, the only thing that's really changing is the rainfall.
That makes it a nice natural laboratory. And it's unique—there's no other place in the continental U.S. like it. There may be very few other places like it in the world." Over four years, Patrick's team sampled fish, snails, algae and other organisms and took measurements of water quality, temperature and more to build a data set that tracked both vertebrate and invertebrate communities in these riverine ecosystems.
The goal of gathering all of this data was to pin down a key metric for understanding the resilience of any ecosystem: secondary production. "Secondary production is basically the growth of new animal tissue over time," Patrick said. "It's rare that people do secondary production empirically, directly measuring it rather than modeling it, for a single species.
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