Good afternoon everyone. Well, with some of you about to go out on field work it's timely that in this afternoon's session. I'll be sharing some ideas about the reasons why groups of whales and dolphins sometimes swim ashore from the sea right onto the beach and, most often, die in what are known as 'mass strandings'.
Unfortunately, this type of event is a frequent occurrence in some of the locations that you'll be travelling to, where sometimes the tide goes out suddenly,【Q31】 confusing the animals. However, there are many other theories about the causes of mass strandings.
The first is that the behaviour is linked to parasites. It's often found that stranded animals were infested with large numbers of parasites. For instance, a type of worm is commonly found in the ears of dead whales. Since marine animals rely heavily on their hearing to navigate, this type of infestation has the potential to be very harmful.【Q32】
Another theory is related to toxins, or poisons. These have also been found to contribute to the death of many marine animals. Many toxins, as I'm sure you're aware, originate from plants, or animals.【Q33】 The whale ingests these toxins in its normal feeding behaviour but whether these poisons directly or indirectly lead to stranding and death, seems to depend upon the toxin involved.
In 1988, for example, fourteen humpback whales examined after stranding along the beaches of Cape Cod were found to have been poisoned after eating tuna that contained saxitoxin, the same toxin that can be fatal in humans.
Alternatively, it has also been suggested that some animals strand accidentally by following their prey ashore in the confusion of the chase. In 1995 David Thurston monitored pilot whales that beached after following squid ashore. However, this idea does not seem to hold true for the majority of mass strandings because examination of the animals stomach contents reveal that most had not been feeding as they stranded.【Q34】
There are also some new theories which link strandings to humans. A growing concern is that loud noises in the ocean cause strandings. Noises such as those caused by military exercises are of particular concern and have been pinpointed as the cause of some strandings of late.【Q35】
One of these, a mass stranding of whales in 2000 in the Bahamas coincided closely with experiments using a new submarine detection system. There were several factors that made this stranding stand out as different from previous strandings. This led researchers to look for a new cause. For one, all the stranded animals were healthy.【Q36】 In addition, the animals were spread out along 38 kilometres of coast,【Q37】 whereas it's more common for the animals to be found in a group when mass strandings occur.
A final theory is related to group behaviour, and suggests that sea mammals cannot distinguish between sick and healthy leaders and will follow sick leaders, even to an inevitable death. This is a particularly interesting theory since the whales that are thought to be most social - the toothed whales – are the group that strand the most frequently.【Q38】
The theory is also supported by evidence from a dolphin stranding in 1994. Examination of the dead animals revealed that apart from the leader, all the others had been healthy at the time of their death.【Q39】
Without one consistent theory however it is very hard for us to do anything about this phenomenon except to assist animals where and when we can. Stranding networks have been established around the world to aid in rescuing animals and collecting samples from those that could not be helped. I recommend John Conner's Marine Mammals Ashore as an excellent starting point if you're interested in finding out more about these networks,【Q40】 or establishing one yourself.
Complete the notes below.
Write NO MORE THAN TWO WORDS for each answer.
听前预测：定位词为Common in areas ；提示词为the，can，此处应填名词。
题目解析：本题根据“…some of the locations that you’ll travelling to…”进行定位，出题句为“…where sometimes the tide goes out suddenly…”，其中suddenly 对应题干quickly，核心名词 tide 或tides 为本题答案。
听前预测：定位词为e.g.，some parasites ；提示词为animals’，此处应填名词。
题目解析：本题难度不大，题干定位词some parasites 文中替换为large number of parasites ； e.g. 替换为for instance，出题句为“Since marine animals rely heavily on their hearing to navigate…”其中核心名词hearing 为本题最佳答案。
听前预测：定位词为Toxins，Poisons ；提示词为or，此处应填名词。
题目解析：本题定位简单，所听即所得，出题句为“Many toxins, as I’m sure you’re aware, originate from plants, or animals”，所以最佳答案为plants。
听前预测：定位词为majority of animals ；提示词为were not，此处应填形容词。
题目解析：雅思听力考试中，转折之后往往是重要信息，本题However 作为明显的提示词， 定位词随之出现，出题句为“…examination of the animals’ stomach contents reveal that most had not been feeding as they stranded”，根据题干提示词were not，否定词not 后feeding 为本题答案。
听前预测：定位词为小标题Human Activity ；提示词为from military tests，are，此处应填名词（复数）。
题目解析：本题根据“…some new theories which link strandings to humans”定位，出题句为“Noises such as those caused by military exercises are of particular concern…”，其中主语noises 为本题最佳答案。
听前预测：定位词为Bahamas，2000 ；提示词为were all，此处应填名词。
题目解析：本题难度不大，容易定位，出题句为“…all the stranded animals were healthy”。其 中healthy 为本题答案。
听前预测：定位词为and/or 等并列结构（由上一题中的were 即可判断）；提示词为a，此处应 填名词（单数）。
题目解析：原文中In addition 是一个很明显的递进定位词，“…whereas it’s more common for the animals to be found in a group when mass strandings occur（集体搁浅发生时，普通的动物以群体为单位更加常见）”的言外之意是Bahamas 与众不同，故not in a group，答案为group。
听前预测：定位词为Group Behaviour ；提示词为the most，此处应填形容词。
题目解析：根据定位词找到文章出题点：This is a particularly interesting theory since the whales that are thought to be most social…，然后根据题干提示词the most，很容易抓住本题答案为social。
听前预测：定位词为1994，only ；提示词was，此处应该名词（单数）。
题目解析：本题根据定位词找到文章出题点：…apart from the leader, all the others had been healthy at the time of their death，其中“apart from”意为“除了”，故核心名词leader 为本题答案。
听前预测：定位词为Marine Mammals Ashore（Connor）；提示词为about stranding，此处应填名词。
题目解析：本题难度不大，很容易定位，出题句为“…if you’re interested in finding out more about these networks…”，所听即所得，核心名词networks 为本题的最佳答案。
