Biology Now, 2e

Here and Gone ■ 387

NPP in terrestrial ecosystems NPP in aquatic ecosystems

>800

600–799

400–599

200–399

100–199

0–99

Net primary productivity

(grams per square meter per year)

Net primary productivity

(grams per square meter per year)

>90

55–90

35–54

<35

survey, which monitors the Northeast Atlantic

Ocean. The CPR survey, started in 1931, employs

a unique instrument pulled through the ocean

by commercial fishing vessels to collect millions

of samples of plankton. The CPR survey found

that over the last 20–50 years, phytoplankton

biomass increased in the Northeast Atlantic, says

Abigail McQuatters-Gollop, a former researcher

at the Sir Alister Hardy Foundation for Ocean

Science, which operates the survey.

In response, Boyce, Worm, and Lewis didn’t

get angry; they got focused. After reading the

critiques, the three researchers went back to

the data. First they applied a correction factor

suggested by the critics, in the hopes of remov-

ing any bias between the two types of data. “We

did that, and the trends remained similar,” says

Boyce. Next, they again estimated changes over

time individually for the two data sources. “That

didn’t change the trends either,” says Boyce. After

that, they incorporated additional suggestions

by their peers and created a new, expanded data-

base of chlorophyll measurements to work from.

Finally, they reestimated changes in chlorophyll

using this new database and their revised analy-

sis methods, but the phytoplankton still seemed

to be declining, independently of the type of

data or how the data were analyzed. The three

researchers published their reanalysis in a series

of three papers in 2011, 2012, and 2014, demon-

strating the same decline again and again.

But the additional work has not silenced the

critics. “It’s still pretty hotly debated,” admits

Boyce. “The story is not over by any means.” In

2011, in fact, Worm traveled to an international

plankton conference where he, McQuatters-

Gollop, and others debated the topic in front

of a live audience. “It was an amicable meet-

ing that generated loads of discussion,” says

Figure 21.9

Global variation in net primary productivity

NPP can be measured as the number of grams of new biomass made by producers each year in a square

meter of each biome’s area. NPP varies greatly across both terrestrial and aquatic ecosystems.

Q1: Which terrestrial biome has the lowest NPP? Which aquatic biome?

Q2: Where are the most productive terrestrial biomes located?

Q3: Give a possible reason for your answer to question 2.

Abigail McQuatters-Gollop was a science and policy

researcher at the Sir Alister Hardy Foundation for

Ocean Science, home of the Continuous Plankton

Recorder survey, from 2010 to 2015. She is now a

lecturer in marine conservation at Plymouth

University in the United Kingdom.

ABIGAIL MCQUATTERS-GOLLOP