Ocean circulation change suffocating Gulf of St. Lawrence
Estuaries are among the most nutrient-rich and biologically productive areas of the ocean, and the Gulf of St. Lawrence, where freshwater from the Great Lakes and the St. Lawrence River meets the salty Atlantic Ocean in eastern Canada, is the largest estuary in the world. But the biodiversity and long-thriving fisheries of the Gulf of St. Lawrence could be threatened by declines in oxygen levels over the last half century.
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Spawning salmon engineer landscapes
All animals depend on their ecosystems for habitat. And, in turn, many animals impact their ecosystems by engineering the landscape to suit their needs. Beavers provide an iconic example of ecosystem engineering when they build dams, which influence streams and wetlands. The engineering efforts of salmon, meanwhile, can even shape the bedrock of the watersheds in which they live, according to a recent study that modeled the evolution of those watersheds over several million years.
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Evolution of eyes, not limbs, led fish onto land
In the Middle Devonian, roughly 385 million years ago, the first vertebrates began making their way out of water. For these pioneering fish, the adaptation of fins into limbs facilitated the transition. But in a new study, researchers have found that millions of years before fully functional terrestrial limbs evolved, some fish were developing better eyesight — an evolutionary adaptation they suggest gave an advantage to fish hunting insects near the shore.
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The mackerel year: Tambora changed how New England fished
The 1815 eruption of Indonesia's Tambora Volcano led to a 1- to 1.5-degree-Celsius drop in the average global temperature, prompting 1816 to be called the "year without a summer." New research analyzes weather data and historical records from New England to explain why, in the northeast U.S., 1816 was also called the "mackerel year." As eruption-induced extreme weather triggered food scarcity in some areas, including a reduction in alewife numbers along the U.S. Atlantic coast, fishermen in the Gulf of Maine turned to mackerel fisheries farther offshore that had been neglected while more easily fished coastal and freshwater species were available.
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Tiny fish illuminates tooth fairy mystery
When kids lose their milk teeth, the roots shrivel up and just the outer enamel falls out — a process known as basal resorption. Now, the discovery of a tiny jawbone from a 424-million-year-old fossil fish is shedding light on the origin of our modern mode of tooth replacement.
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Coral Reef Roundup: December 2016
With multiple threats facing our coral reefs — from climate change to overfishing — and scientists continually studying the coral reefs beneath the waves, new findings are announced often. Here are a few of the latest updates.
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Tully monster mystery solved
In 1958, an amateur fossil collector named Francis Tully found a strange fossil in a quarry near Morris, Ill., southwest of Chicago. Thousands more of the worm-like Tullimonstrum gregarium, better known as the "Tully monster," were recovered from the same deposit — now a National Historic Landmark called Mazon Creek fossil beds. But the creature's full appearance and just what sort of animal the Tully monster was have remained mysteries. In a new study, researchers have now finally identified it as a jawless fish, similar to modern lampreys.
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Jawless fish more like jawed fish than thought
Vertebrates come in all shapes and sizes, but the one thing almost all have in common are jaws, which developed early in vertebrate evolution. Jawless fish, which evolved about 530 million years ago and are thought to be more primitive than their jawed relatives, are an exception. According to a new study, however, the brains of jawless fish have more in common with the brains of jawed vertebrates than previously thought.
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Fish evolved quickly after earthquake
Evolution is often thought of as occurring over very long timescales, but as a tiny Alaskan fish demonstrates, significant changes can take place in just a few generations.
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Counting 'tree' rings in fish skulls provides climate clues
Most fish have little structures in their skulls that record growth patterns — periods of feast and famine — just like tree rings. Now, scientists are using these structures, called otoliths, to show how fish size may decrease as a result of a changing ocean.
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