Dr. Myers and Dr. Worm argue that their work gives a correct baseline, which future management efforts must take into account. They believe the data support an idea current among marine biologists, that of the “shifting baseline.”

1. which 是关系代词，指代baseline（基线）；在定语从句中作take 的宾语。词组：take something into account“对某事加以考虑 ; 考虑某事”。

2. that用来代替前面已出现的名词idea（观点），以避免重复。the “shifting baseline”跟that又是同位关系。例如：

The area of the bedroom is larger than that of the sitting room.卧室的面积比起居室的面积大。