Passage 34(biology)(海底珊瑚生物)
Coral reefs are one of the most fragile, biologically complex, and diverse marine ecosystem on Earth. This ecosystem is one of the fascinating(迷人的) paradoxes of the biosphere(生物圈): how do clear, and thus nutrient-poor, waters support such prolific and productive(多量且多產的) communities? Part of the answer lies within the tissues of the corals themselves. Symbiotic (共生) cells of algae(藻類) known as zooxanthellae carry out photosynthesis(光合作用) using the metabolic(新陳代謝) wastes of the coral thereby producing food for themselves, for their corals, hosts, and even for other members of the reef community. This symbiotic process allows organisms in the reef community to use sparse nutrient resources efficiently. (靠藻類行光合,靠珊瑚消化,這樣的共生系統允許在organism 在珊瑚社區中去有效率的使用稀少的資源)
Unfortunately for coral reefs, however, a variety of human activities are causing worldwide degradation(退化) of shallow marine habitats by adding nutrients to the water. Agriculture, slash-and-burn land clearing, sewage(汙染物) disposal and manufacturing that creates waste by-products all increase nutrient loads in these waters. Typical symptoms (sign) of reef decline are destabilized herbivore populations (食草動物) and an increasing abundance(豐富) of algae and filter-feeding animals(考點). Declines in reef communities are consistent with observations that nutrient input is increasing in direct proportion to growing human populations, thereby threatening reef communities sensitive to subtle changes in nutrient input to their waters.
不幸的是,人類活動是破壞coral reef 的原兇,
留意215-217三題,其餘兩題可略過