noaa coral reef watch elevated nutrients the reefs are changing
TRANSCRIPT
NOAA Coral Reef Watch
NOAA Coral Reef Watch Elevated nutrients
The Reefs are Changing
1959
1988
1998
Photos by Gene Shinn (USGS)
What does it look like?
Balance in the Reef
Corals StructureAlgae fix inorganic material (C; N)Fish keep algae in check
A “Healthy” Reef
St. John USVI - Dennis Hubbard
ZooxanthellaeMaricopa Community College
Zooxanthellae•live in coral tissue•photosynthesize•need light•provide “food” for corals
Background: see http://serc.carleton.edu/eslabs/corals/index.html
A “Unhealthy” Reef
Grand Bahama Island Dennis Hubbard
St. Thomas USVI – Dennis Hubbard
To many algae:• elevated nutrients• too few fish• shade out corals• block larval settlement
Classifying Impacts
• Top Down• Bottom Up
Fish & Urchins •graze on algae•Keep reef surface “clean”• algae shade corals (light)• algae take up space (recruitment)
•Problems:• Overfishing• Diseases (urchins)
St. John USVI – Dennis Hubbard
Classifying Impacts
• Top Down• Bottom Up
This
leads to
This
In the Caribbean……
The “Healthy” Reef
From this……
to this!!
• too few fish• too many nutrients• both
ConceptualModel
MathematicalModel
CoralReefs in Netlogo
• Mathematical Simulation• Free• Runs on both Mac and PC
CoralReefs in Netlogo
Download & Install Program:• http://ccl.northwestern.edu/netlogo/download.shtml Download Model:• CoralReefs-V5.1.nlogo• Your instructor will give you a locationDouble-click model file to start (see Handout 2)