Sponges on Florida Coral Reefs: Demographics and Impacts on Water Quality

Sponges on Florida Coral Reefs: Demographics and Impacts on Water Quality

Principal Investigator: Dr. Joseph Pawlik, UNCW
Co-Principal Investigator: Dr. Christopher Finelli, UNCW
Training: May 12 - 15
Saturation: May 16 - 25

Sponges are now the dominant habitat-forming animals on Caribbean coral reefs. Among them, the giant barrel sponge, Xestospongia muta, has the greatest biomass on Florida coral reefs. Despite its importance to habitat complexity and reef health, few data existed regarding the basic biology of this massive sponge prior to the start of the PIs’ research program at ARB, including rates of mortality and recruitment, reproduction, growth and age. Like reef corals, this sponge is subject to mortality from anthropogenic impacts (climate change, oil spills), bleaching, and diseases. Additional threats include fishing line debris, which can cleanly slice through sponges during storm events and in high-flow environments. Conservation and management efforts require basic long-term monitoring data on reef sponges to establish baseline demographic information. Moreover, preliminary data suggest that specimens of X. muta filter water at a rate of 97 ml-H2O h-1 ml-tissue-1. With sponges ranging in size from < 100 ml to > 200,000 ml, potential population filtration rates are considerable and demographic changes in sponge populations could have profound effects on reef water quality.

Beginning in 1997, Pawlik and students established and began monitoring 12 permanent circular plots (16 m diameter) at Conch and Pickles reefs containing over 650 marked X. muta to document sponge mortality, recruitment, bleaching, growth, disease, and damage by debris. Past awards from NOAA have been remarkably productive, resulting in 16 peer-reviewed publications since 2006. Modeling studies have resulted in age estimates of large X. muta within plots at >100 years, and some at other sites at over 2000 years old, placing these sponges among the oldest animals on earth. Stage-based matrix models indicate that populations of X. muta are increasing on Florida’s reefs. Studies of sponge chemical ecology have resulted in a revision of our understanding of Caribbean reef ecosystems and the isolation and identification of bioactive metabolites involved in antipredatory and allelopathic interactions.

Coral

Objectives

  • Rates of mortality, recruitment, and growth of Xestospongia muta will be monitored in 12 permanent plots at 2 reef locations and at three depths. The same data will be monitored for two additional long-lived sponge species, Geodia neptuni and Agelas conifera, at the same sites, thereby providing a comparative basis for understanding sponge demography on reefs.
  • Pumping and clearance rates of healthy X. muta, G. neptuni, and A. conifera across a range of sizes will be measured to estimate population filtration rates and impacts on coral reef ecosystems.
  • The impact of anthropogenic debris, oil and disease on sponges within permanent transects will be monitored and quantified.
  • The importance of plankton food availability on sponge distribution and abundance will be tested.