Characteristics of Marine Aggregates in Shallow-water Ecosystems: Implications for Disease Ecology
- 275 Downloads
Marine aggregates were evaluated for their potential role in the ecology of aquatic pathogens using underwater video surveys coupled with direct collection of aggregates in modified settling cones. Six locations, two each in New York, Connecticut, and Massachusetts, were surveyed over 8 months to explore differences in the characteristics of aggregates found in habitats populated by clams (Mercenaria mercenaria) and oysters (Crassostrea virginica). Microaggregate (<500 μm) concentrations were always greater than macroaggregate (>500 μm) concentrations, but peak concentrations of macroaggregates and microaggregates, mean size of particles, and volume fraction of aggregated material varied among the six shallow-water habitats. Concentrations (colony-forming units per ml) of total heterotrophic bacteria (THB) and total mesophilic pathogenic bacteria (MPB) from samples of aggregates were significantly different among the four locations bordering Long Island Sound (LIS). The highest concentrations and enrichment factors in aggregates were observed in August for THB and in June for MPB. Significant correlations were detected for salinity and the concentrations and enrichment factors of THB in aggregates and for the concentrations and percentages of MPB in seawater samples. Significant correlations were also detected for temperature and the concentrations of MPB in aggregates and the enrichment factors for THB and MPB (marginal significance). Bacterial species identified in association with aggregates included: Vibrio cholerea, V. parahaemolyticus, V. vulnificus, V. alginolyticus, Aeromonas hydrophila, Pseudomonas aeruginosa, Escherichia coli, and Mycobacteria sp. These results have important implications for the way in which aquatic pathogens are collected, quantified, and monitored for risk-based surveillance in shallow-water ecosystems.
KeywordsMarine snow aquatic pathogens mesophilic pathogenic bacteria enrichment factors risk-based surveillance water quality
The authors thank C. Romano, R. Bogin, M. Perrigault, and S. Dahl for laboratory assistance with processing samples and T. Marcotti, K. Uhlinger, B. Holohan, D. Kach, D. Frank, J. Thiel, and P. Bagnell for assistance with field collections. They also thank B. MacDonald and A. Bennett for recommendations on image processing and T. Getchis for assistance with outreach. This research was funded by NSF-NIH Ecology of Infectious Disease Grants to JEW (0429004), RS and JV (0429018), and BA (0429051) along with a NOAA grant to BA (R/FBF-17 award NA16RG1645) and an NRAC grant to RS.
- Alldredge AL (1979) The chemical composition of macroscopic aggregates in two neritic seas. Limnology and Oceanography 24:855–866Google Scholar
- Alldredge AL (2000) Interstitial dissolved organic carbon (DOC) concentrations within sinking marine aggregates and their potential contribution to carbon flux. Limnology and Oceanography 45:1245–1253Google Scholar
- Brzezinski MA, Alldredge AL, O’Brian LM (1997) Silica cycling within marine snow. Limnology and Oceanography 42:1706–1713Google Scholar
- Goedken M, Morsey B, Sunila I, Dungan C, De Guise S (2005) The effects of temperature and salinity on apoptosis of Crassostrea virginica hemocytes and Perkinsus marinus. Journal of Shellfish Research 24:177–183Google Scholar
- Grossart PJ, Berman T, Simon M, Pohlmann K (1998) Occurrence and microbial dynamics of macroscopic organic aggregates (lake snow) in Lake Kinneret, Israel, in fall. Aquatic Microbial Ecology 53:105–116Google Scholar
- Huq A, Sack RB, Nizam A, Longini IM, Nair GB, Ali A, Morris JG, Khan MNH, Siddique AK, Yunus M, Albert MJ, Sack DA, Colwell RR (2005) Critical factors influencing the occurrence of Vibrio cholerae in the environment of Bangladesh. Applied and Environmental Microbiology 71:4645–4654CrossRefGoogle Scholar
- Kach D, Ward JE (in review) The role of marine aggregates in the ingestion of pico-particles by suspension-feeding molluscs. Marine Biology Google Scholar
- Kiørboe T (2001) Formation and fate of marine snow: small-scale processes with large-scale implications. Scientia marina 65:57–71Google Scholar
- Lyons MM, Ward JE, Smolowitz R, Uhlinger KR, Gast RJ (2005) Lethal marine snow: Pathogen of bivalve mollusc concealed in marine aggregates. Limnology and Oceanography 50:1983–1988Google Scholar