Stories tagged runoff

Oct
15
2010

Water issues are complex and interrelated, so it can be difficult to solve them. But because water is essential to our way of life, we gotta get to work!

Here's an example of how convoluted things can get:

A study at the University of California in Irvine found that freshwater runoff (from precipitation and ice sheet melting) into the oceans has increased significantly--18% more water flowed into the oceans in 2006 compared to 1994. The main problem with this is that the freshwater then becomes saltwater, and we have to wait for it to evaporate and rain onto the ground for it to become drinkable/cookable/agriculturable again. But with global warming, precipitation patterns have changed so that the areas that need water aren't getting as much as they used to.

Speaking of global warming, CO2 in the atmosphere does more than heat things up--it dissolves into the ocean, which makes the water more acidic. This change in pH, though subtle, could become sufficient to kill delicate creatures such as krill in the Southern Ocean within 100 years. Considering that many of the fish we like to eat dine on krill, this could pose a big problem in the future.

But it gets more complicated. The runoff from agricultural fields contains nitogren-based fertilizers, and rivers release tons of it into the ocean each year. The nitrogen fuels an overgrowth of algae, which die when the nitrogen is gone and fall to the seafloor. There, they are consumed by bacteria that thrive and gobble up all the oxygen, creating a "dead zone" where plants and animals cannot live. While human activities add double the natural amount of nitrogen into soils, about 60% of that fertilizer is never used by the plant and ends up in the ocean. Some of it also ends up in the atmosphere, where it becomes N2O--a more powerful greenhouse gas than CO2. This adds to global warming, bringing us back to increased freshwater runoff.

In short, more water is running into the ocean and that water is full of ick that kills stuff and makes more water run into the ocean. Ick.

Remember those freaky frogs first discovered by Minnesota schoolchildren in 1995? (Science Buzz did an exhibit about them, too, in early spring of 2005.) Pieter Johnson, an evolutionary biologist at the University of Colorado at Boulder (formerly of University of Wisconsin, Madison), has published his newest research: he says parasites called trematodes cause the missing and extra legs, and that runoff from farms and lawns fuels algae growth, which allows for larger snail populations, which means more trematodes and more deformed frogs....

Jan
14
2005

In August 1995, schoolchildren found deformed frogs in a wetland near Henderson, Minnesota. Some frogs had extra legs, others no legs at all. Some had missing or extra eyes, toes, or feet. And some also had problems with their internal organs. By the fall of 1996, there were over 200 reports of freakish frogs, from two-thirds of Minnesota's counties. Deformed frogs have since been found in 44 states.

Deformed frog: This frog has two right back legs. Others have been found with missing legs, missing parts of legs, or legs in unexpected places.
Deformed frog: This frog has two right back legs. Others have been found with missing legs, missing parts of legs, or legs in unexpected places.Courtesy Minnesota Pollution Control Agency

A 1997 study raised frogs in the lab, mixing pure water with water from two Minnesota sites that had lots of deformed frogs. The more pond water that was used, the more likely the lab frogs were to be deformed. Water from sites with healthy frogs produced healthy animals in the lab. The scientific conclusion was, "There's something in the water." But what could it be? Since then, several researchers have been hunting for the cause.

Scientists have proposed several explanations for the deformities. It may be parasites, chemicals, ultraviolet light, or some combination of the three. Lab studies have shown that all of these factors, alone or in combination, can cause some deformities. But no single cause seems to explain it all. The research doesn't yet add up to a neat and tidy answer, so scientists continue to puzzle out the story.

Who cares about frogs? You should. If there's something wrong with the water, it may eventually hurt all of us. But it will hurt frogs first. Frogs have thin skins, and easily absorb any contaminants in the water. Frogs seem to be in trouble all around the world. There are more and more reports of deformities. And some species have disappeared, or no longer live in their old habitats. It's a wide-spread problem that may affect us all.