JASON VII Program Overview

The edge of the sea provides habitats and food for the majority of the world's population and also to many aquatic organisms. It also plays a role in many global cycles, including climate change. During the JASON VII expedition, researchers, students, and teachers will join Dr. Robert Ballard in an investigation of several interconnected shallow-water habitats in Southern Florida-the Everglades, Florida Bay, Florida Keys, the Florida reef tract, and the relic reefs on Pourtalés Terrace.

Florida lies atop the Floridian Plateau, a relatively stable structure. Through geological time, rising and falling sea levels have shaped the Plateau by overlaying it with limestone deposits from nearby coral reefs and by allowing erosion to carve valleys and cliffs. Some of these valleys, such as Lake Okeechobee, which now drains into the Everglades and Florida Bay, were filled with freshwater. The rise and fall of the sea level also led to the growth and death of coral reefs.

Before the Ice Age, present-day Portalés Terrace and other land broke away from the otherwise stable plateau and began to subside. Today, approximately 29 km (18 miles) south of Key Largo, at depths of 60-200 m (about 240-600 feet), a relic reef known as the "humps" sits at the edge of the terrace. Geologist Dr. Robert Ballard and a team of engineers including CDR. David Olivier of the U. S. Navy, Dr. Dana Yoerger and Jon Howland from Woods Hole Oceanographic Institute, and biologists Dr. Jim Bohnsack from the National Marine Fisheries Service and Dr. Bob Hueter from Mote Marine Laboratory will use the U. S. Navy's NR1 submarine, equipped with a manipulator arm, an electronic still camera, side-looking sonar and depth- profiling sonar to take images of this natural feeding station.

At the reef tract, 15 km (about 9 miles) toward shore, Dr. Jerry Wellington, from the University of Houston, will lead an Investigation on climate change using specimens of coral-which, like trees, produce annual growth rings that can give researchers a history of climate changes hundreds of years into the past. Once established, a history of natural climate change can be used to determine whether human activities affect climate change. In order to conduct his research, Dr. Wellington and his team, including Graduate Student Andrea Grottoli-Everett are required to live underwater for extended periods of time. Today, engineers have made this dream a reality, allowing scientists to conduct underwater research fulltime through saturation diving and the National Undersea Research Center's underwater habitat, the AQUARIUS.

Another 15 km (about 9 miles) inland lies a line of limestone islands, or Keys, with Florida Bay just beyond. Home to juvenile fish, sharks, spiny lobsters, pink shrimp, bottlenose dolphins, sea turtles, raccoons and other organisms, Florida Bay provides a refuge for its inhabitants with its maze of inlets, smaller bays, mangrove islands, sponges, and seagrass beds. The bay is a very dynamic area with varying salinity and temperature, caused by its shallow bottom and the freshwater delivered to it by the Everglades in the wet season. This is the research area for Dr. John Hunt and his team from the Florida Department of Environmental Protection, who are concerned about the rapid decline of turtle-grass and sponges, and the subsequent effect on other organisms in the food chain.

One of the organisms that lives directly at the Everglades-Florida Bay interface is the American crocodile, which, like its cousin the American alligator, prefers freshwater. However, the crocodile lives in Florida Bay, not in the freshwater marshes of the Everglades. It lives as close as possible to the freshwater rivers flowing into the mangrove-fringed bays, but does venture into areas of higher salinity during the nesting season, when females are able to find higher ground to lay their eggs. Laura Brandt and Dr. Frank Mazzotti from the University of Florida are worried about how recent proposals for re- routing the freshwater flow will affect the endangered American crocodile.

The future of Southern Florida will depend on managing its resources, including the ability of its water to support life and the flow of its freshwater, which connects the different habitats. It is a study site for living both in and at the edge of the sea to learn the possible effects of human activities and resource development now and into the future.


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Gene Carl Feldman (gene@seawifs.gsfc.nasa.gov) (301) 286-9428
Todd Carlo Viola, JASON Foundation for Education (todd@jason.org)
Revised: 15 Nov 1995