Computer Modeling of Dolphin Habitat Use
By Damon Gannon, PhD

Elizabeth Berens, Janet Gannon, Randy Wells, Ari Friedlander (Duke University), and Damon Gannon are working to create predictive habitat use models for the bottlenose dolphins of Sarasota Bay. The goals of the project are to (1) identify patterns of habitat selection, (2) determine which environmental factors (e.g., prey abundance) drive these patterns of habitat selection, and (3) create computer models that can identify areas of high use by dolphins. A tremendous amount of data will be incorporated into the models. These data have been collected in the field by SDRP biologists and by remote sensing. This project relies heavily on Geographic Information System (GIS) and statistical modeling software. These models can then be used to predict how human-induced changes to the habitat will affect the health of the Sarasota Bay dolphin community and to identify potentially important habitats in other geographic regions where little is known about the local dolphins. The amount and quality of data that we can bring to bear on these models is unprecedented in marine mammal habitat modeling and will hopefully result in the models having superior predictive powers.

Abiotic Factors

• Bathymetry
• Habitat
  1. Seagrass
  2. Pass
  3. Sand/Mud flat (unvegetated bottom, ›2.5 m)
  4. Open Bay (›2.5 m)
  5. Gulf
  6. Channel
  7. Mangrove
• Distance to Each Habitat Type
• Distance to Shoreline Features
  1. Mangroves
  2. Bulkhead/seawall
  3. Beach
  4. Soft Bank
• Navigation Channels
• Distance to Navigation Channels
• Distance to Artificial Structures
  1. Artificial reefs
  2. Piers/bridges
  3. Marina docks
  4. Mooring fields
• Substrate
  1. Sand
  2. Mud
• Tidal State
• Water Quality
  1. Salinity
  2. Temperature
  3. Dissolved oxygen
  4. Turbidity

Biotic Factors

• Occurence of Ambient Sounds:
  1. All fish
  2. Fish by species
  3. Boats
• Karenia brevis cell concentration
• Prey Density ("prey" defined in a variety of ways)
• Predator Density
• Dolphin Density
  1. Overall
  2. By demographic group
• Tidal State