THE SPONGES OF THE WEST -CENTRAL PACIFIC 



271 



TEXAS 



Text Figure No. 186. Diagram to show (by a star) displacement by currents (arrows) 

 of the area of greatest sponge abundance. 



account, it is clear that the Gulf of Mexico presents a pattern of sponge 

 abundance which (on a large scale) is in complete harmony with that exhibit- 

 ed (on a small scale) at Hungry Bay, Bermuda. The region most favorable 

 to sponges is displaced eastward about 600 kilometers from the mouth of the 

 river. 



The only region of greater sponge abundance than that of Western 

 Florida is that about the Aegean Islands of the Eastern Mediterranean Sea. 

 Here again a huge river, the Nile, empties into an inland sea, and the region 

 of maximum abundance is about 600 kilometers out beyond the river mouth. 

 This distance must, of course, be greater for a large river than for a small 

 one and be also influenced by the strength of the prevailing currents. 



The hypothesis is here definitely advanced, that the world's greatest 

 sponge beds, those of Greece and Asia Minor, are built up by the River Nile, 

 and the second greatest, those of Western Florida, are built up by the Miss- 

 issippi-Missouri Rivers. These are two of the world's greatest rivers. Yet how 

 about such another one as the Congo? At 600 kilometers from its mouth, the 

 ocean is some 4000 meters deep. The same is true for that greatest of all 

 rivers, the Amazon. Yet it is noteworthy that the deep sea dredgings of the 

 "Challenger" yielded especially numerous deep sea sponges off shore from the 

 Amazon mouth. 



For ideal sponge conditions, land drainage should debouch into an en- 

 closed area of fairly shallow depth and of moderate currents. This ecological 

 situation exists in the lagoons all around Ponape. 



What is the favorable item, or what are the favorable items? Full 



