A mysterious killer has been destroying sea stars. Scientists had thought an infection was to blame. A new study does point to bacteria as the killer. But the bacteria appear to make those sea stars unable to breathe, not infect them.

In 2013, a disease known as sea-star wasting broke out off the U.S. Pacific Coast and the sea stars there died in massive numbers. “It is hard to figure out the complex disease,” says Ian Hewson, a marine biologist at Cornell University. First, Hewson and his group found a virus in unhealthy sea stars in 2014, but later studies found no connection between it and sea-star deaths. They then explored other factors, such as differences in water temperature. They also tried exposing the animals to bacteria. But nothing reliably caused the wasting disease.

However, when comparing bacteria living with healthy sea stars with those living with unhealthy animals, the scientists found higher levels of certain types of bacteria around sick sea stars. Some bacteria were copiotrophs, which grow rapidly in areas with lots of nutrients (营养). And some were the bacteria that survive only in environments with little to no oxygen.

To re-create these conditions in the lab, the researchers added nutrients to stimulate bacterial growth in the tubs with sea stars. Sure enough, the animals got sick. When they reduced the oxygen in the water, similarly, it caused wounds in three out of every four sea stars. However, no sea star getting normal oxygen levels got sick. The study shows that copiotrophs are stealing oxygen from the water, causing sea-star wasting. Dying sea stars produce more nutrients, which may help bacteria to grow on nearby animals. “It’s a bit of a snowball effect.” Hewson says.

“The problem may worsen with climate change, because warmer waters can hold less oxygen than colder waters. Bacteria such as copiotrophs also grow rapidly in warm water. But knowing the likely cause could help experts better treat sick sea stars,” Hewson says.

As summer temperatures around the country rise, many consumers are seeing their energy bills go up rapidly. The average monthly energy bill in the U. S. was $121 in 2021, according to the U.S. Energy Information Administration.

Consumers can keep their homes cooler by using curtains or blinds and keeping them closed during the sunniest part of the day. Turing up the temperature on air conditioners by 7℃ to 10℃ for at least eight hours a day can save as much as 10% from yearly energy costs, Energy. gov reports.

Besides, a smart thermostat (恒温器) can adjust temperature and help to reduce energy bills. A smart thermostat uses Wi-Fi to connect with an app on the owner’s phone. Some models even know when the user’s phone leaves the house and adjusts the heating or cooling accordingly.

“You can raise or lower the temperature when you’re not home, so you’re not using energy in the house when you’re not going to be around to benefit from it,” says Sara Rathner, a personal finance expert. “You can also control your heating and cooling systems from wherever you are, as long as you have your phone on you.” Not all home heating and cooling systems are suitable for smart home thermostats, though. Most thermostats work best with forced air-type systems, so they won’t work with radiant (辐射的) heating systems.

Prices for smart home thermostats start at about $100 and go up from there, while a more traditional thermostat can be purchased for under $30. Rathner suggests looking for seasonal savings like Black Friday deals. Some energy providers offer discounts on new smart thermostats, too. Energy. gov has a rebate (折扣) tool to help consumers find rebates in their own state. Other high-tech devices like smart lights connected to a smart home assistant can also enable consumers to reduce unnecessary use of electricity and cut power to those that continue to draw energy even when not in use.