Spatial Versus Nonspatial Variance in Fecal Indicator Bacteria Differs Within and Between Ponds.

Area of Science:

• Environmental microbiology
• Water quality assessment
• Spatial statistics

Background:

• Surface water environments exhibit inherent heterogeneity, leading to variations in microbial water quality.
• Understanding spatial and non-spatial drivers of microbial contamination in ponds is crucial for effective water resource management.

Purpose of the Study:

• To investigate the spatial variation of microbial water quality within and between Virginia ponds.
• To identify key factors influencing total coliform (TC) and Escherichia coli (EC) levels across different spatial scales.

Main Methods:

• Collected 600 grab samples from 30 sites across nine Virginia ponds over time.
• Enumerated total coliform (TC) and Escherichia coli (EC) levels.
• Utilized Bayesian models of coregionalization and mixed-effects Bayesian regressions to analyze spatial and non-spatial influences.

Main Results:

• Spatial factors explained more variance in TC and EC levels when considering multiple ponds (interpond analysis).
• Non-spatial factors explained more variance within individual ponds (intrapond analysis), with significant variation between ponds.
• Microbial levels were spatially independent at distances of 56-87m within ponds, indicating distinct water quality at different sites.
• Rainfall positively correlated with microbial levels, while pH showed a negative association.

Conclusions:

• Microbial dynamics in ponds are pond-specific and scale-dependent.
• Distinct water quality at sites within the same pond necessitates localized risk management.
• Environmental factors like rainfall and pH play a significant role, but their influence varies.