Want to Prevent Algal Blooms? Toilet Train Birds

cormorants resting on a rock in a lake

While they may not be the sole cause, recent research shows that an increase in the population of cormorants on a lake in South Korea may have contributed to algal blooms.(Photo credit: EAGiven/iStock/Getty Images Plus/Getty Images)

Algal blooms are a rapid increase in the population of algae in a body of water. They are characterized by their bright green color. While they can be an entirely natural phenomenon, algal blooms can be very harmful. They can deplete lakes of oxygen, produce toxins, and ultimately kill much of the aquatic life. [Read more…]

Rock Snot is Nothing to Sneeze At

Though endemic to some waterways in North America and northern Europe, the algae Didymosphenia geminata is starting to become a problem in lakes, streams, and other waterways where it has inadvertently been introduced.

Didymo covers rocks and twigs at the bottom of a waterway. (Photo credit: S. Spaulding / U.S. Geological Survey)

Didymosphenia geminata is a single-cell alga commonly referred to as rock snot due to its grayish-brown color and clumpy appearance. This alga also goes by the name “didymo” for short. Though it looks slimy, it actually only feels like wet cotton or wool.

While many species of algae float on top of the water surface, didymo instead clings to rocks in river bottoms and other waterways. What starts as a few dots on a rock eventually turns into a massive clump of algae that remains attached to the rocks surface by a stalk. The free ends of the alga float in the water, forming white rat-tails that resemble clumpy toilet paper.

One major problem with didymo is that it can form huge blooms without warning. These blooms can have deleterious consequences for native organisms by smothering them. The algal mats that form can also be a major problem for public works when they clog water intake systems.

Research indicates that didymo can be spread from one waterway to another by contaminated fishing equipment. Felt-soled waders worn by fly fisherman and other fishing enthusiasts are of particular concern. Studies indicate that Didymo can survive for a period of at least 24 hours outside of water. If they remain in a damp and cool environment, the alga can survive for up to 90 days. The use of felt-soled waders has been banned in New Zealand. Didymo was first discovered in a stream in New Zealand in 2004, and has since spread to over 120 rivers and streams in the country’s South Island. Protecting the country’s waterways from infiltration by didymo is a high-priority in New Zealand; anyone convicted of knowingly transferring didymo from one waterway to another may face up to five years in prison and/or a fine of up to $100,000.

In the United States, fishers are encouraged to use rubber-soled waders. Fishers are also encouraged to check their equipment before they leave the fishing site to remove any visible pieces of algae. Afterward, they should let their equipment dry completely before entering any other waterway with it. If this is not possible, officials with the U.S. EPA encourage sportsfishers to dip their fishing equipment into a solution made of bleach and water to sanitize their equipment and kill any didymo cells.

Didymo is a major problem in New Zealand waterways. (Photo credit: David Newton / Alamy)

Thus far there is no recommended method to remove or kill didymo in affected waterways. Scientists in New Zealand tested one potential control agent but found its use was not yet warranted and required further study. It is in the best interest of fishers to ensure they do not aid in the spread of didymo, as the algae has been implicated in habitat loss for the very fish the sportsfishers aim to catch. Didymo algal blooms often choke out insects such as stoneflies and worms that species such as trout depend on as a food source. Reducing the spread of didymo will help ensure that adequate habitat is available for these species of game fish.

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Deep-Sea Fish Uses Unusual Method to See

The brownsnout spookfish Dolichopteryz longipes uses mirrors to focus its eyes. (Photo Credit: David Shale/NPL)

The brownsnout spookfish is found in tropical to temperate waters of the Atlantic, Pacific, and Indian oceans. The spookfish lives in the deep-sea, about 1000 meters beneath the ocean’s surface, where light does not penetrate. Although the existence of this deep-sea fish was discovered 120 years ago, it was not until recently that scientists were able to observe the fish up-close. Prof. Hans-Joachim Wagner of Tbingen University in Germany caught a live specimen off the island of Tonga in the Pacific Ocean. While examining the fish, scientists made an exciting discovery–the spookfish uses mirrors, rather than lenses, to focus its eyes. Flash photography was used to verify that the fish focuses its eyes with the use of mirrors. Dissection studies helped to confirm the scientists’ discovery.

Organisms that live in the deep-sea must have adaptations that let them find food and avoid predators in their low-light habitat. Deep in the ocean, the only light that exists comes from flashes of light given off by bioluminescent organisms. Bioluminescence refers to a light made by a chemical reaction within an organism. Most deep-sea bioluminescent creatures give off a blue shade of light, since that color is most easily transmitted in a marine environment. One example of a bioluminescent animal is the anglerfish. This deep-sea fish has a lighted “lure” attached to its head to attract prey.

Although the spookfish looks like it has four eyes, it actually only has two. Each eye is split into two connected halves. One half of the eye points upward, which gives the fish a view of the ocean above. The bottom half of the eye points downward, into the darkness of the abyss below.

As shown in this photo, the spookfish’s eye is made of two-connected parts. (Photo Credit: Dr. Tamara Frank)

The mirrors in the spookfish’s eyes are made up of tiny plates of guanine crystals, arranged in a stack made up of many layers. The arrangement and orientation of the crystals direct any light that enters the spookfish’s eye into a focus. The mirrors let the spookfish quickly produce bright, high-contrast images, giving it an immediate picture of what is around it. In contrast to mirrors, lenses are less efficient because they do not reflect all the light that hits them, and instead absorb some of the light.

Additional work to corroborate this discovery was conducted by Prof. Julian Partridge of Bristol University in England. Partridge developed a computer simulation that illustrates how the orientation of the plates within the spookfish’s eyes are perfectly adapted for focusing reflected light on the fish’s retina.

The scientists’ findings are reported in the January 27 edition of the journal Current Biology. The article, titled “A Novel Vertebrate Eye Using Both Refractive and Reflective Optics,” was co-authored by Hans-Joachim Wagner, Ron H. Douglas, Tamara M. Frank, Nicholas W. Roberts, and Julian C. Partridge.

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Mussels Wreaking Havoc in American Waterways

Quagga mussels, native to Ukraine, are causing numerous problems in American waterways. (Photo credit: USGS)

Move over, zebra mussels. There’s a new invasive mollusk species in town. While biologists have been trying to quell the spread of the zebra mussels, quagga mussels, bivalves native to Ukraine, have quietly been taking over waterways from the Great Lakes to the Colorado River.

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