contribution of 6.0% to the diet of the sample population. The most common plant 
species in the diet were equally represented in males and females. Adult and juvenile 
animals differed only with respect to the consumption of Syringodium filiforme, 
Panicum hemitomon, and algae. Seagrass made large contributions to the diets of 
animals on the coasts, while Hydrilla verticillata and Panicum hemitomon made the 
largest contributions to the diets of animals in Central Florida. Halodule wrightii 
contributed the greatest percentage to the diet by percent composition in summer and 
winter, while Syringodium filiforme and Thalassia testudinum values were highest in 
the winter and spring, and spring respectively. The terrestrial grass Panicum 
hemitomon, and freshwater plant species contributed the most to the diets of the 
animals during the fall. Subsurface portions of plants contributed more to the diet for 
salt water species (mean ratio of surface/subsurface portions = 46/54) than for 
freshwater species (86/14). Ratios of surface/subsurface portions of plants were 
essentially equal for males and females, and for juveniles and adults. Manatees 
collected on the coasts consumed more subsurface portions of plants than those 
collected from Central Florida. More subsurface portions of plants were consumed in 
winter and summer than in the spring and fall. 
1977 - 1981 
Mazzotti, F. J. (1983) The ecology of Crocodylus acutus in Florida. Ph. D. Dissertation. The 
Pennsylvania State University, University Park, PA. 161 pp. 
Crocodylus acutus formerly occupied a much broader range in southeastern Florida. 
Aerial and boat surveys showed that the current core distribution of C. acutus is the 
extreme southern Florida mainland and northern Key Largo. Most sightings were in 
bays, ponds, rivers, and canals in mangrove swamps. All known nesting sites are 
within this area. Approximately 50% of the sightings and captures of non-hatchling 
crocodiles were of immature animals. Thus recruitment into the breeding population 
appears to be occurring. Seventy-four percent of the known crocodile mortalities that 
occurred between 1971 and 1981 were related to human activities such as shooting or 
collision with automobiles. Preservation of the crocodile population will require 
increasing attention to reducing the adverse effects of man and protection of remaining 
habitats from disturbance. Crocodiles nest on exposed shoreline beaches, creek banks, 
and canal banks. The substrate may be composed of marl, peat, or sand. Failure of eggs 
to hatch is primarily caused by desiccation and flooding, and the nesting period is timed 
to avoid the driest and wettest periods of the year. Approximately 200 hatchlings are 
produced each year in Everglades National Park. Hatchlings usually disperse rapidly 
from their nests, and it was not possible to distinguish between death and dispersal. 
However, some hatchling crocodiles survived for at least a year in Everglades National 
Park, on northern Key Largo and at the Turkey Point power plant site. Turkey Point 
hatchling crocodiles were found in the cooling canal system. Here, as in other parts of 
southern Florida, hatchlings not only tolerated saline water but gained mass under 
hypersaline conditions. They grow to the size (200 g) at which they show increased 
tolerance to seawater by the onset of the dry season in October. Hatchling C. acutus 
have rates of body sodium and water turnovers similar to those of hatchling Alligator 
mississippiensis. Both species appear less specialized for life in saline water than C. 
porosus. In the laboratory, C. acutus held in seawater can osmoregulate behaviorally by 
drinking brackish water made available by simulating rainfall. The drinking of brackish 
water combined with rapid growth to a more salt tolerant size seems to be one of the 
primary specializations of C. acutus for life in saline water. 
235 
