2009 Winners

2008 Winners

2009 PILOT PROJECTS AWARDEES

Specific Aims

The overall goal of this project is to determine the growth and detachment dynamics of mixed species biofilms on intertidal beach sediments and the potential for these biofilms to serve as a refugia for indicator or pathogenic microbes. This goal will involve the synthesis of several smaller

Objectives:

(1) Quantification of the total microbial abundance as well as fecal indicator bacteria of beach sediments and their flux into marine waters under simulated conditions of groundwater seepage and mechanical abrasion within the swash and breaker zones.

(2) Quantification of sediment extracellular polymeric substances (EPS), the structural component of biofilms, and their flux into marine waters under simulated conditions of groundwater seepage and mechanical abrasion within the swash and breaker zones.

(3) Visual characterization of sediment biofilms and the microspatial distribution of attached microbes using confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM).

Relevance to UM Oceans and Human Health Center

The current proposal seeks to better understand the extent to which biofilm formation impacts the mobility of fecal indicator bacteria such as enterococci from sand grains into coastal waters. This is directly related to the UM OHH core research project; “Recreational Microbes”. OHH investigations are currently underway to develop a predictive model of the human health risks associated with exposure at recreational beaches. This developing model will bring together the physical attributes and microbial characteristics of the coastal environment with epidemiologic studies of reported human health effects (Bonilla et al 2007). The ability to link the complex physical characteristics of the coastal environment with concentrations of fecal indicator bacteria and human health risks requires a mechanistic understanding of how these bacteria are residing and being sourced into the marine environment. We believe biofilms are the fundamental link between microbes and the sedimentary environment. We see the proposed study as a first step in understanding the role of biofilms as a refugia for both indicator and pathogenic microbes and their release from sediments into the marine environment. Further collaborative research will be required to understand the importance of grain mineralogy (carbonate vs. silicate), grain size, moisture content, and organic carbon content in biofilm formation and microbial colonization. Natural beaches in south Florida are predominately quartz sand whereas many of the filled or renourished beaches are rich in carbonate grains dredged from offshore. This distinction is yet to be investigated as a factor in explaining variation in the microbial dynamics of local beaches. The current proposal and potential future directions of this research are designed to meet the strategic goals outlined by the National Institute of Environmental Health Sciences (NIEHS). We propose integrative and collaborative research focused on better understanding Human diseases with a strong environmental component and potential for a large public health impact.

Beach Sediment Biofilms: A Refugia for Indicator and Pathogenic Microbes?

Dr. Maria Josephina Olascoaga - Assistant Professor of Physical Oceanographer
Dr. Shuxiu Liang – Associate Professor of Harbor, Coastal and Offshore Engineering

Abstract:

Karenia brevis exists in low concentrations in large areas of the Gulf of Mexico, but it occasionally forms blooms along the north coast of the Gulf of Mexico to the Florida panhandle. The largest and most frequent harmful algal blooms (HABs) occur along the West Florida Shelf (WFS), between Tampa Bay and Sanibel Island. Recent statistical analysis of historical data of K. brevis abundance and distribution off west Florida, river flow discharge, and the application of dynamical systems methods to simulate surface ocean currents have suggested that circulation constraints and nutrient load into coastal waters due to land runoff are the most important factors leading to HAB development on the WFS. To acquire a deeper understanding of the role of land runoff, we propose to undertake a thorough investigation of the dynamics of the West Florida river plumes. A first phase of this investigation will involve appropriately configuring a coastal ocean circulation model to include realistic river outflow, rather than climatological river outflow as previously considered. The potential role of river plume on circulation pattern on the inner WFS will be analyzed thoroughly. A second phase will involve coupling the above ocean circulation model with an ecosystem model, which will aim at assessing the importance of West Florida main river outflow on HAB development. These tasks will be mainly carried out by S. Liang (Visiting Investigator) in collaboration with the PI.