【推荐2】Limiting kids’ recreational (消遣的) screen time to less than two hours a day, along with enough sleep and physical activity, is associated with improved cognition (认知) , according to a study published in The Lancet Child & Adolescent Health.

The study included about 4 ,500 US children aged 8 to11 and measured their habits against the Canadian 24 – Hour Movement Guidelines for Children and Youth. It found that 51% of the children got the recommended (建议的) 9 to 11 hours of uninterrupted sleep per night; 37% met the recreational screen time limit of two hours or less per day, while 18% met the physical activity recommendation of at least 60 minutes of accumulated physical activity a day. Only 5% of the children in the study met all three recommendations; 30% met none at all.

The researchers found that as each recommendation was met by a participant, there was a positive association with global cognition, which includes memory, attention, processing speed and language. Those who met all three had the most “superior” global cognition, followed by those meeting the sleep and screen time recommendation and finally the screen time recommendation alone, according to the study.

Other organizations, such as the American Academy of Pediatrics – have guidelines in place to help with the management of children’s screen time. The organization suggests putting realistic rules or limits in place for how long your children are on their screens, knowing who they are talking to and what they are doing. The amount recommended screen time depends on the age of the child. Besides, parents should also make sure to encourage physical activity and have bedroom rules such as creating “ tech-free zones”.

【推荐3】The California sea otter (海獭), once hunted to the edge of extinction, has staged a thrilling comeback in the last century. Now, scientists have discovered that the otters’ success story has led to something just as remarkable: the restoration of their declining coastal marsh (沼泽) habitat.

Elkhorn Slough, a coastal marsh within Monterey Bay, had been experiencing severe damage. The root cause was a growing population of shore crabs, which fed heavily on the marsh plants, weakening the structural integrity of the habitat. Coastal marshes like these are not only natural defenses against storm waves but also serve as important carbon storage areas and water-cleaning systems.

The conservation-driven comeback of the sea otter has been crucial. California’s coastlines were once alive with sea otters. Sadly, they were nearly wiped out at the hands of fur traders. In the 1980s, conservation efforts aided these otters in re-occupying large areas of their former range. Now, Elkhorn Slough has the highest concentration of sea otters in California, with a population of about 100. By naturally feasting on crabs, the otters have helped a significant regrowth of plant life. Brent Hughes, a scientist working alongside Angelini, led a three-year study. Their findings were clear: in areas with sea otters, crab numbers fell markedly. This led to a resurgence in plant growth, which in turn stabilized the soil and lowered the rate of soil washing away.

As the sea otter population continues to restore, their positive impact on coastal ecosystems is likely to increase. It not only showcases the sea otter as a central species—a species that has a significant effect on its natural environment—but also highlights the essential nature of top predators (捕食者) in preserving ecological harmony. “My honest reaction was—this could become a classic in the literature,” says scientist Lekelia Jenkins. She reveals marsh restoration also helps people by reducing flooding. “Suddenly, sea otters go from just cute things we like to something that can protect our livelihoods and our properties.”