Chapter 6: Ecology of the Everglades Protection Area

SUMMARY The studies and findings discussed in this chapter of the 2006 South Florida Environmental Report – Volume I are presented within four main fields: (1) wildlife ecology, (2) plant ecology, (3) ecosystem ecology, and (4) landscape ecology. Programs of study were based on the short-term and long-term needs of the South Florida Water Management District (District or SFWMD) including operations, regulations, permitting, environmental monitoring, Everglades Forever Act mandates, and the Comprehensive Everglades Restoration Plan. Wildlife: Monitoring of wading bird nesting success is a coordinated effort between the District, Everglades National Park, the Florida Fish and Wildlife Conservation Commission, University of Florida, the National Audubon Society, and the U.S. Fish and Wildlife Service. Each year, this coordination results in the production of the Annual Wading Bird Report. The estimated number of wading bird nests in South Florida in 2005 was 31,869. This is a 41 percent reduction in nest numbers from last year’s relatively successful season and a 54 percent decrease from the banner year of 2002, which was the best nesting year on record in South Florida since the 1940s. While the 2005 estimate is relatively high compared to the average of recent decades, it represents a sharp divergence from the general rising trend in annual numbers of wading bird nests recorded since 1999, and this decline in nest numbers was observed among all wading bird species. Reduced prey availability, as a result of anthropogenic changes in hydrology, is considered the primary factor responsible for the decline in Everglades wading bird populations. This year, two new programs to evaluate how aquatic organisms interact with hydrology were initiated. A crayfish study conducted at the Loxahatchee Impoundment Landscape Assessment (LILA) research facility at the Arthur R. Marshall Loxahatchee Wildlife Refuge found that crayfish respond to the seasonal drawdown by remaining on the ridges and safe from wading bird foraging until water levels become extremely low. As water levels continue to decline, they move into the sloughs where they subsequently become more available to foraging wading birds. The second new program, a spatially intensive survey of exotic fishes in the vicinity of the L-67 canal, suggests that at least two species – and possibly a third – are using marsh habitat for refuge or feeding, and that future studies will be needed to focus on the ecological factors determining the distribution of nonindigenous fish species and to reevaluate species-specific physiological tolerances to seasonal minimum temperature.