Project Overview

The Florida Coastal Everglades (FCE), like many coastal ecosystems, is changing due to human influences. Because conditions in the Everglades vary widely over time and across habitats, the area serves as an ideal natural laboratory for understanding what drives the movements of large animals in shifting environments.

In nutrient-poor places like the Everglades, animals that move between habitats can play a vital role in moving nutrients across the landscape. When these nutrients reach new areas, they can boost the growth of phytoplankton — the tiny, plant-like organisms that use sunlight to grow and form the base of the aquatic food web. This process, known as primary productivity, fuels the entire ecosystem by providing energy for fish, crustaceans, and other marine life. By studying how animals move and what they eat before and after environmental changes, scientists can better understand how this flow of nutrients connects different parts of the ecosystem and how it might change in the future.

Bull sharks are key predators in coastal ecosystems like the FCE. Because they can live in both freshwater and saltwater, they may help move nutrients between these environments, especially in the nutrient-poor estuaries of the Everglades. Building on research since 2007 tracking bull sharks in the FCE, this project uses new technologies and large data approaches to explore how young bull sharks use this nursery habitat.

Researchers monitor juvenile bull sharks using acoustic tags, tissue and fecal samples, and animal-borne dataloggers to:

1. Understand how movement patterns relate to what the sharks are eating.
2. Determine whether bull sharks use tides to conserve energy during travel.
3. Examine how changing environmental conditions influence fine-scale movements and activity.
4. Link movement and feeding behaviors to survival and when sharks leave the nursery.

Understanding what drives animal movements helps scientists explain how species interact with one another and with their environment. Understanding these movement patterns is also key to predicting how animal behavior may change as natural conditions or human activities alter the environment. Animals may move to find better temperatures, oxygen levels, or food, or to balance the trade-off between gaining energy and avoiding predators.

While many studies have explored how animals move in response to prey, food-safety tradeoffs, or environmental changes, scientists are now paying more attention to energy landscapes — or spatial maps that show how much energy it costs an animal to move through or reside in different parts of its environment. These costs can change with tides, currents, or temperature. Because animals often try to save energy or get the most out of what they spend, their movement paths, speeds, and timing can all be shaped by these invisible energy maps.

This research explores how energy landscapes influence the movements and feeding habits of juvenile bull sharks in the Shark River Estuary, and what these behaviors mean for the Everglades ecosystem over time.