15. What researchers such as Ransom Myers and Boris Worm have shown is just how fast things are changing.
【分析】復合句。本句中 what 引導主語從句，其中 such as Ransom Myers and Boris Worm 表列舉，is 是系動詞。
【譯文】蘭森姆·邁爾斯和鮑里斯·沃爾姆等研究者給我們展示了事情正在迅速變化。

16. Their methods do not attempt to estimate the actual biomass (the amount of living biological matter) of fish species in particular parts of the ocean, but rather changes in that biomass over time.
【分析】簡單句。本句主語是 Their methods；謂語是 do not attempt；賓語是不定式短語 to estimate the actual biomass...but rather changes。
【譯文】他們的研究方法并非試圖估計出某個特定海域中魚類生物的實際單位面積數量（目前存活的生物數量），而是隨著時間推移這些生物數量的變化。