. The ecological impact of man on the south Florida herpetofauna . Figure 7. Regrowth of hydrilla in a recently-dredged canal. Continued removal is necessary to prevent clogging of waterways. (LP) "today water hyacinths blanket as many as 200,000 acres of Florida canals and lakes," which together with the even more prolific hydrilla "cost at least 15 million dollars a year to ; Hydrilla may eventually cause more problems than water hy- acinths. The plant was imported into Dade County for aquarium use in the 1950's and became introduced into waterways in 1959 (Austin
. The ecological impact of man on the south Florida herpetofauna . Figure 7. Regrowth of hydrilla in a recently-dredged canal. Continued removal is necessary to prevent clogging of waterways. (LP) "today water hyacinths blanket as many as 200,000 acres of Florida canals and lakes," which together with the even more prolific hydrilla "cost at least 15 million dollars a year to ; Hydrilla may eventually cause more problems than water hy- acinths. The plant was imported into Dade County for aquarium use in the 1950's and became introduced into waterways in 1959 (Austin in Morris 1977). Its rapid growth (an inch a day) allows it to blanket an area quickly (Fig. 7). It also spreads easily by becoming attached to "boat propellers, bird's feet, and other objects that move from lake to lake. . Consequently, in only a few years it has clogged some 150,000 acres of waterways, and has moved into most other southern states. So far it has been found as far north as Iowa, and biologists fully expect it to spread throughout the country" (Gore 1976). Only a minor fraction of the introduced plants growing in south Florida have become escapees, but these few have combined to create grave environmental problems. They are all characterized by rapid growth, which interrupts normal successional patterns. The two aquatic weeds can reproduce vegetatively. The three trees have efficient means of seed dispersal, some are self-seeding, and all can sprout from the cut trunk. Another factor that causes vegetational change in south Florida is the increased frequency of fires due to the reduction of the water storage capacity of the Kissimmee-Okeechobee-Everglades system.
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Keywords: ., bookcentury1900, bookcollectionbiodiversity, bookcontributorharv
