Identifying likely sources of fecal contamination in Little Lagoon, Alabama

1. Identifying likely sources of fecal contamination in Little Lagoon, Alabama Dr. Alice Ortmann University of South Alabama Dauphin Island Sea Lab Image: AL.com, Mobile Press Register

2. Project Background • Water quality sampling suggested an issue with fecal coliforms (FCB) in Little Lagoon • Not correlated with any measured variables

3. Sea Grant Funded Project • Identify the source of the fecal contamination so an appropriate management plan can be developed • Contamination from humans • higher health risk • can be managed • Contamination from wildlife • low health risk • much harder to manage

4. Use two DNA-based approaches to identify sources • Comparison of E. coli communities within the lagoon to communities in inflowing water. • Quantify total Bacteroidalesin the lagoon and determine what percentage came from humans, dogs and cows.

5. Bon Secour Bay Sample Sites within Little Lagoon 1 2 3 5 4 Pass Gulf of Mexico Sample each site from March 2011-February 2012 Collect 40 ‘random’ samples throughout the year for E. coli analysis Google Earth Image

6. Approach

7. FCB were often above the regulatory limit during the study

8. E. coli communities through out the lagoon are simple and well mixed Standard mdh communities from Little Lagoon

9. Lagoon communities are significantly different than inflow communities

10. E. coli communities analysis does not indicate a specific source of contamination • Inflow sites included: • small pond • sediment • streams • drainage • freshwater vs. saltwater • E. coli and close relatives can survive in aquatic environments, so these may represent naturally occurring organisms

11. Use qPCR to identify the host of the Bacteroidales • They are a family (multiple species) of Bacteria that live in animal guts • obligate anaerobes • do not grow in aquatic environments • high abundances in feces • quantitative PCR (qPCR) • sensitive with good detection • very specific, using DNA sequences

12. We used four different assays to determine the host of Bacteroidales • BacUni→ detect all members of the Bacteroidales regardless of their host • BacHum→ detect only Bacteroidalesfrom human hosts • BacDog→ detect only Bacteroidalesfrom dog (maybe cat) hosts • BacCow→ detect only Bacteroidalesfrom cow (maybe horse) hosts

13. Bacteroidales genes were detected at all sites throughout the year **8 samples missing from analysis

14. The abundance of BacUni did not correlate with the abundance of FCB

15. Bacteroidales from cows and dogs was much lower than BacUni estimates ***BacDog, extremely high: Site1 January and Site5 February 1.61072.3106

16. Together, they represent a small fraction of the total Bacteroidales

17. And they do not correlate well with FCBs

18. BacHum was always detected in Little Lagoon

19. BacHum was also not correlated with the abundance of FCB

20. Most of the time, a small number of the BacUni could be accounted for by human Bacteroidales

21. A significant amount of Bacteroidales genes are not accounted for by humans, dogs or cows

22. Bacteroidales analysis suggests human fecal contamination at low levels • Like reflects the fact there are humans using the lagoon • Maximum estimate: 0.08 g of fecal material/L • Local maximums: reflect recent use • Humans not likely the source of the large increases in FCB • Estimates do not correlate with FCB • Naturally occurring strains/relatives of E.coli

23. Acknowledgements • Daniel Presley-E. coli analysis and qPCR • Chris Lee-new BacUni analysis • Justin Liefer-sample collection • LLPS-sample collection analysis • Lei Wang and Natalie Ortell-working with Chris Image from: http://www.mygulfshoresrentalhouse.com