Specifications

Section 2 Existing Conditions/Affected Environment
EAA Storage Reservoirs Revised Draft PIR and EIS February 2006
2-33
with the number of eggs carried being a function of the size of the individual
(Gilmore and Gilbert 1992). Newly released larvae must have brackish
oligohaline-mesohaline conditions (18 ppt salinity) to survive, and are adapted
for downstream transport to estuarine and marine environments during the wet
season (Frias-Torres, 2002). Juveniles subsequently move offshore, where they
become associated with pelagic rafts of floating vegetation, in which they remain
for an indeterminate length of time. Opossum pipefish are carnivorous, preying
on crustaceans and small fish as ambush predators in dense vegetation.
Major threats to the opossum pipefish are habitat destruction, declining water
quality, and an increase in disease. Vegetation elimination destroys adult
pipefish breeding and feeding habitat.
2.11.5.12 Okeechobee Gourd
The Okeechobee gourd (Cucurbita okeechobeensis) is the only federally-listed
plant species occurring in the vicinity of the EAA. This endangered plant once
grew extensively in the pond apple swamps south of Lake Okeechobee; however,
conversion of these habitats for agriculture has eliminated most (95%) of the
natural habitat. The vine is restricted to eleven sites along the southern shore of
Lake Okeechobee in Palm Beach County and nine sites in Volusia County. Lake
level fluctuations seem to be required to facilitate dispersal and destroy
competition from weed species. The Okeechobee gourd requires trees or shrubs
(typically pond apple, but also willow or cypress) to support vines above rising
water levels during the wet season. The gourd also occurs on elevated, sunny
alligator nests along Lake Okeechobee. The occurrence of gourds is temporary;
therefore, they may disappear from a known location and reoccur when suitable
conditions occur.
2.11.5.13 Johnson’s Seagrass
The threatened Johnson’s seagrass (Halophila johnsonii) has been found growing
only along approximately 200 km of coastline in southeastern Florida from
Sebastian Inlet, Indian River County to northern Key Biscayne. This narrow
range and apparent endemism indicates that Johnson’s seagrass has the most
limited geographic distribution of any seagrass in the world.
Johnson’s seagrass occurs in dynamic and disjunct patches throughout its range.
Growth appears to be rapid and leaf pairs have short life spans while
horizontally spreading from dense apical meristems (Kenworthy 1997).
Kenworthy suggested that horizontal spreading rapid growth pattern and a high
biomass turnover could explain the dynamic patches observed in distribution
studies. New information reviewed in Kenworthy (1999, 1997) confirms H.
johnsonii’s limited geographic distribution in patchy and vertically disjunct
areas between Sebastian Inlet and northern Biscayne Bay.