Project: Ecological responses to large-scale climate disturbance: Could the interaction of overfishing and disturbance initiate phase-shifts in tropical seagrass ecosystems?

This project was funded by an NSF RAPID award and it is thematically related to the Florida Coastal Everglades Long Term Ecological Research (FCE LTER) project.

Project Data: Project data have been submitted to the FCE LTER Information Management (IM) office. To search for data from this project, please see the FCE LTER data repository at http://fcelter.fiu.edu/data/core/ and select "Mike Heithaus" from the "Dataset Originator" menu. Direct links to several datasets include:

• Percent cover, species richness, and canopy height data of seagrass communities in Shark Bay, Western Australia, with accompanying abiotic data, from October 2012 to July 2013: http://fcelter.fiu.edu/data/core/metadata/?datasetid=LT_PP_Heithaus_001;
• Capture data for sharks caught in standardized drumline fishing in Shark Bay, Western Australia, with accompanying abiotic data, from February 2008 to July 2014: http://fcelter.fiu.edu/data/core/metadata/?datasetid=LT_PP_Heithaus_002;
• Capture data for sharks caught in standardized drumline fishing in Shark Bay, Western Australia, with accompanying abiotic data, from January 2012 to April 2014: http://fcelter.fiu.edu/data/core/metadata/?datasetid=LT_PP_Heithaus_003;
• Marine turtles captured during haphazard at-sea surveys in Shark Bay, Australia from February 2008 to December 2013: http://fcelter.fiu.edu/data/core/metadata/?datasetid=LT_PP_Heithaus_004;
• Count data of air-breathing fauna from visual transect surveys including water temperature, time, sea and weather conditions in Shark Bay Marine Park, Western Australia from February 2008 to July 2013: http://fcelter.fiu.edu/data/core/metadata/?datasetid=ST_TDCS_Heithaus_002;
• Fish community data obtained from Antillean-Z fish trap deployment in the Eastern Gulf of Shark Bay, Australia from June 2013 to August 2013: http://fcelter.fiu.edu/data/core/metadata/?datasetid=ST_TDCS_Heithaus_001;
• Stationary camera observations, set, and environmental data from Shark Bay Marine Park, Western Australia from July 2011 to June 2012: http://fcelter.fiu.edu/data/core/metadata/?datasetid=ST_TDCS_Heithaus_003;
• Fish trap catch, set, and environmental data from Shark Bay Marine Park, Western Australia from May 2010 to July 2012: http://fcelter.fiu.edu/data/core/metadata/?datasetid=ST_TDCS_Heithaus_004

Description from NSF award abstract:
Large-bodied marine predators have both direct and indirect effects on other members of their communities through predation-related removals and intimidation-related (that is, non-consumptive) changes in behavior of other organisms, respectively. Thus, large-bodied predators can produce cascading effects on other aspects of the ecosystem. Understanding the nuances of top predator effects on ecosysytem structure and function is a topic of keen ecological interest with strong implications for conservation and management. The PIs have been working for 15 years in the pristine seagrass ecosystem of Shark Bay, western Australia. Their work has shown that tiger sharks induce a reduction in seagrass grazing by dugongs which allows a slow-growing but highly palatable seagrass (Amphibolis antarctica) to persist and even dominate. The slow-growing seagrass has recently experienced a widespread die-off, and two important questions are: (1) what are the immediate effects on the ecosystem; and (2) how does the presence or absence of sharks affect re-establishment of this species, with long-term consequences for the system?

The natural die-back of A. Antarctica provides a unique opportunity to study these questions of diversity, structure, and persistence, and to examine the effects of a natural disturbance in a pristine ecosystem that has been studied for many years. A RAPID award is needed to take advantage of this situation shortly after disturbance.