[3끊어쓰기] TOEFL Reading : Seagrasses 3  

3 paragraph

Since most seagrass systems _________are depositional environments, 

they eventually __________accumulate 

organic material 

that _________leads to the creation 

of fine-grained sediments 

with a much higher organic content 

than that of the surrounding unvegetated areas.

This accumulation, in turn, ____________reduces 

the water movement and the oxygen supply.

The high rate of metabolism

(the processing of energy for survival)

of the microorganisms

in the sediment 

_________causes sediments

to be anaerobic

(without oxygen)

below the first few millimeters.

According to ecologist J.W. Kenworthy, 

anaerobic processes 

of the microorganisms

in the sediment 

___________are an important mechanism 

for regenerating 

and recycling nutrients and carbon, 

ensuring the high rates of productivity

---that _________is, the amount of organic material produced---

that __________are measured 

in those beds.  

In contrast

to other productivity in the ocean, 

which __________is confined to various species of algae 

and bacteria __________dependent on nutrient concentrations

in the water column,

seagrasses _________are rooted plants

that absorb nutrients

from the sediment or substrate. 

They _______are, therefore,

capable of recycling nutrients

into the ecosystem 

that would otherwise __________be trapped 

in the bottom 

and _________rendered unavailable.