The ecology of crocodylus acutus in florida - a thesis in ecology (endangered species, osmoregulation)
Philadelphia, Pa., Pennsylvania State Univ., Diss., 1983
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| Sprache: | eng |
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Tag hinzufügen | Zusammenfassung: | Philadelphia, Pa., Pennsylvania State Univ., Diss., 1983 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-hatching 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 showed increased tolerance to sea water 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. |
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| Beschreibung: | 177 S. |