EE BIOL 123 - Marine Ecology
EE BIOL 148 - Biology of Marine Plants
EE BIOL 194B - Research Group or Internship Seminars: Ecology and Evolutionary Biology
Simulation modeling at the population, community and ecosystem process levels; macroalgal, seagrass, and coral reef community structure; nutrient dynamics; disturbance ecology; restoration ecology; experimental design and statistical analysis. My main interest is disturbance ecology. In my work I have tried to assess the importance of disturbance in controlling community structure in three very different ecosystems: algal communites in estuaries and lagoons in southern California, coral and algal communities in coral reefs of the Florida Reef Tract, and coral communities in the Eastern Pacific. Algal communites in estuaries and lagoons in southern California have been heavily impacted by anthropogenic disturbance. We think that most of these systems were probably seasonal estuaries, with a dry-season lagoonal phase. Seasonal lagoons were formed when the estuarine connection to the ocean was cut off by long shore drift forming a sand bar. Now, with upstream diversion of seasonal floodwater, many are permanently cut off from the ocean, and serve as sinks of nutrients and toxins from the watershed. Many undergo seasonal blooms of ""nuisance"" algae in response to nutrient inputs. The composition of these blooms may be one of two species of opportunistic green macroalgae, phytoplankton, or benthic mats of cyanobacteria. My research has focused on the factors that control the magnitude, duration, and composition of these algal blooms. To accomplish this research I use three approaches: field studies; manipulative experiments in the field and lab; and numerical simulation modeling. One offshoot of this work is that I am currently collaborating with scientists at the University of Hawaii to try to determine the cause of a bloom of green macroalgae that is impacting the reefs and beachs of Maui. During my post-doc at the University of Miami, Hurricane Andrew hit the Florida pennisula. Andrew was the most powerful storm to hit Florida for over 50 years, and left behind wide-scale devastation. The coral reefs of BiscayneNational Park were directly impacted by the hurricane. The eye-wall of the hurricane passed over this region, creating enormous storm waves and surge with enough force to damage reef communities. Hurricane-damaged reef (pictures) 1 2 3 4 Although coral reefs are hurricane-adapted, as they evolved within the hurricane-belt, our concern was whether anthropogenic disturbance may act to compound the natural disturbance and effect both the amount of damage and potential recovery processes. Ecological theory predicts that large-scale disturbances in ecotonal regions may cause a long-term shift in the ""state"" of an ecosystem. In the case of the northern Florida Reef Tract, this would mean a shift from a coral dominated ecosystem to one dominated by macroalgae. The primary objective of this portion of the project was to quantify the direct and indirect damage to the coral reef community due to the passage of Hurricane Andrew, and to assess initial rates of recovery. There were four basic results of this research. First, we discovered that the direct damage to coral reef communities due to Hurricane Andrew was less than expected given the level of damage sustained in other areas after hurricanes of similar or lesser magnitude. We hypothesize that this was due to the relatively fast forward motion of Andrew. There was time for the corals to be ""fractured,"" but many were not broken. Second, the level of indirect damage was at least as significant as the direct damage. Winter storms of average intensity knocked the fractured corals over, and the tumbling action shattered them into fragments. Third, the algal community changed immediately after the Hurricane as an opportunistic species of green macroalgae colonized the injured coral. However, this change was transitory, lasting only a few weeks. Last, we found that the most heavily damaged species of coral was Acropora palmata , a branching coral. We documented several adaptations to hurricane damage evidenced by this species, including rapid wound healing, high survival of hurricane-generated fragments, and reproduction of new individuals from fragments. For the last project, a simulation model was developed from a long-term data set of a subpopulation of Gardineroseris planulata in the eastern Pacific relating size-specific schedules of growth and partial mortality to minimum temperature, predation by Acanthaster planci , and El Nio-Southern Oscillation (ENSO) related elevation of water temperature. Predation by Acanthaster planci was of overwhelming importance; even the least frequent predation scenario skewed the population toward smaller colonies. We compared model predictions to field data for population size structure across the region (Uva Island, the Pearl Islands, and the Galapagos Islands). Model predictions for ENSO-associated mortality, re-growth and recovery were predicted by the model across the thermal gradient represented by these sites. 100 year scenarios varying frequency of ENSO were run to determine the long-term effect of repeated warming events on the size structure of Gardineroseris planulata populations across the region. Results suggested that the importance of ENSO in structuring the Gardineroseris planulata population increased as thermal stability decreased.
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