222 College of Forestry 



SUMMARY AND CONCLUSIONS 



In llie i)revious pages we have attempted to ascertain the 

 amount of animal Hfe present on tlie bottom of Lower South 

 Iiay and vicinity. It was found that this bay contained several 

 diverse habitats and that the animals and the vegetation showed 

 a corresponding variation. A feature brought out in the inves- 

 tigations is the fact that tlic greatest develnpjuent of plant and 

 anhnal life on the bottom is found wilJii)i the 6- foot contour. 

 Of the 1,164 'icres examined about 88 percent of the number 

 of individual invertibrate animals were found within the 0-foot 

 contour, and only 12 percent outside this area, or in round 

 numbers 6,^86 million individuals inside this line, and p^J 

 inillion beyond this line. From the standpoint of area this 

 means a population of almost seven billion individuals in 205 

 acres, within the 6- foot contour, and beyond this line a popu- 

 lation of less than one billion individuals in 959 acres. Per 

 acre, this also means that an average of 33 million individuals 

 live in one acre in water 6 feet or less in depth, while but one 

 million individuals per acre live in water deeper than 6 feet. 

 The drop in density of population from the 6- foot area to the 

 6-12 foot area is striking, the population of the deeper area 

 being but 11 percent of the shallower area. Beyond the 6-12 

 foot area the decrease in number of individuals is much less 

 marked, amounting to 59 percent of the population of the 

 6-12 foot area. When we remember that fish are more abun- 

 dant within the 6-foot contour, where the majorit}' of young 

 fish live and most adult fish breed, the significance of this rich- 

 ness of bottom life in the shallow water is at once realized, and 

 indicates that this is the most important depth for the culture 

 of fish. 



Of the different kinds of bottom areas examined in Lower 

 South Bay, it was found that the sand liottom was the richest 

 in animal life and the boulder bottom the poorest. In per- 

 centage this may be expressed as follows, the sand bottom 

 being valued at 100 percent : sandy clay 87 percent, clay 66 

 percent, gravel 57 percent, mud 42 percent, and boulder 46 



