2篇儿疑似阅读原文，请6月考过nn帮忙鉴定。

大概结构和内容都和jj描述得差不多，请考过的nn帮忙看一下。

感觉GMAC也偷懒儿，两篇都是某论文的摘要部分，所以希望大家考试时能多记些阅读的英文标志词，这样比较好搜索。

寄生问题

Host age is one of the key factors in host–parasite relationships as it possibly affects infestation levels, parasite-induced mortality of a host, and parasite distribution among host individuals. We tested two alternative hypotheses about infestation pattern and survival under parasitism in relation to host age. The first hypothesis assumes that parasites are recruited faster than they die and, thus, suggests that adult hosts will show higher infestation levels than juveniles because the former have more time to accumulate parasites. The second hypothesis assumes that parasites die faster than they are recruited and, thus, suggests that adults will show lower infestation levels because of acquired immune response and/or the mortality of heavily infested juveniles and, thus, selection for less infested adults. As the negative effects of parasites on host are often intensity-dependent, we expected that the age-related differences in infestation may be translated to lower or higher survival under parasitism of adults, in the cases of the first and the second hypotheses, respectively. We manipulated ectoparasite numbers using insecticide and assessed the infestation pattern in adult and juvenile gerbils (Gerbillus andersoni) in the Negev
                        Desert. We found only a partial support for age-dependent parasitism. No age-related differences in infestation and distribution among host individuals were found after adjusting the ectoparasite numbers to the host’s surface area. However, age-related differences in survival under parasitism were revealed. The survival probability of parasitized juveniles decreased in about 48% compared to unparasitized hosts while the survival probability of adults was not affected by ectoparasites. Our results suggest that the effect of host age on host–parasite dynamics may not explicitly be determined by age-dependent differences in ectoparasite recruitment or mortality processes but may also be affected by other host-related and parasite-related traits

分解石油化学制剂伤害珊瑚

Chemicals used to disperse marine oil slicks may harm corals more than the off itself does, according to a new study. The finding suggests that chemical dispersants should be used near reefs only as a last resort, when oil approaches a shoreline where it might devastate wildlife and plants for decades.

In many cases, authorities first try to clean up oil spills mechanically. If weather conditions are too rough or a slick threatens to wash up on shore, dispersants are usually the next option. Made up of surfactants and solvents, dispersants act as detergents, breaking up oil into droplets that mix into water, scatter with currents, and eventually degrade. However, the dispersed oil droplets readily sink and can lethally contaminate coral.

Baruch Rinkevich of the National Institute of Oceanography in Haifa, Israel, and his colleagues tested whether chemical dispersants, as well as oil droplets, do harm to corals. They report that dispersants kill branching corals or retard their growth. The team also confirms previous research indicating that corals do better when exposed to oil that hasn't been dispersed.

"Dispersants are very toxic for corals; Rinkevich says. "It's a no-win situation, but more knowledge [will add to officials'] evaluation and decisions about what to do in unpredictable situations."

To test the effects of the dispersants, the researchers pruned 2-inch segments from the branches of two common hard coral species found in the Red Sea and grew them into several large colonies in laboratory tanks. The team then added to the tanks various concentrations of crude oil, one of six commercial dispersants mixed with oil, or one of the six dispersants alone. After allowing 24-hour exposure to the substances, researchers washed the corals, simulating what would happen in the real environment when oil and dispersants wash away. The team then measured coral survival and growth weekly for 50 days.After 1 week, more than 90 percent of one coral species and about 75 percent of the other survived in the oil-only tanks, whereas virtually all coral died in the tanks containing either the dispersant-oil mix or the dispersant alone. After 50 days, more than 90 percent of the surviving corals from the oil-only tanks continued to grow. Almost all coral from the dispersed-oil and the dispersant-only tanks experienced retarded growth.

Amy Merten, codirector of the Coastal
                Response
                Research
                Center at the National Oceanic and Atmospheric Administration in Seattle, says that the results contradict the rule of thumb that dispersants are less toxic than oil droplets. It's important for authorities in charge of spill cleanups to note that coral reacts to the dispersant itself, she says. "There needs to be more consideration of dispersants." However, Merten adds that under real conditions, coral may not be exposed to dispersants in the same amount, and for the same duration, that it was in the laboratory tests.

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还有2天了 不知道RC JJ 能看多深...

太好了。MM说的是个好办法，考过的同志们多记关键词。这种网络搜索的方式找到原文或者类似文章的几率还是很大的。

寄生这篇从前面看是原文，但是原文好像比这篇长一些