Bacaan 10. Question 57-60 are based on the following passage.

    In their latest paper, published in the journal Nature Climate Change, Prof. Philip Munday and colleagues report world-first evidence that high CO₂ levels in sea water disrupts a key brain receptor in fish, causing marked changes in their behavior and sensory ability. They began by studying how baby clown and damsel fishes performed alongside their predators in CO₂ enriched water. They found that, while the predators were somewhat affected, the baby fish suffered much higher rates of attrition.

    "Our early work showed that the senses of smell of baby fish were harmed by higher CO₂ in the water, meaning they found it harder to locate a reef to settle on or detect the warning smell of a predator fish. But we suspected there was much more to it than the loss of ability to smell," says Prof. Munday. The team then examined whether fishes' senses of hearing which is used to locate and hone in on reefs at night, and avoid them during the day was affected. "The answer is, yes it was. They were confused and no longer avoided reef sounds during the day. Being attracted to reef during daylight would make them easy meat for predators."

     Their work showed the fish also tended to lose their natural instinct to turn or right which is an important factor in schooling behaviour which also makes them more vulnerable, as lone fish are easily eaten by predators. Prof. Munday further explains, "All this led us to suspect it wasn't simply damage to their individual senses that was going on but rather, that higher levels of carbon dioxide were affecting their whole central nervous system."

60. Regarding higher levels of carbon dioxide in sea water is, the author seems to feel very _____.