Campylobacters are emerging as one of the most significant causes of human infections worldwide, and the role that waterfowl and the aquatic environment have in the spread of disease is beginning to be elucidated. On a world scale campylobacters are possibly the major cause of gastrointestinal infections. Campylobacters are common commensals in the intestinal tract of many species of wild birds, including waterfowl. They are also widely distributed in aquatic environments where their origins may include waterfowl as well as sewage effluents and agricultural runoff. Campylobacters have marked seasonal trends. In temperate aquatic environments they peak during winter, whereas spring-summer is the peak period for human infection. Campylobacter species may survive, and remain potentially pathogenic, for long periods in aquatic environments. The utility of bacterial fecal indicators in predicting the presence of campylobacters in natural waters is questionable. Viable but nonculturable Campylobacter cells may occur, but whether they have any role in the generation of outbreaks of campylobacteriosis is unclear. The routine detection of Campylobacter spp. in avian feces and environmental waters largely relies on conventional culture methods, while the recognition of a particular species or strain is based on serotyping and increasingly on molecular methods. Thus, PCR combined with selective enrichment enhances the detection of campylobacters in water and feces, while DNA sequencing facilitates recognition of particular species and strains.

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Concentrations and glucose mineralization potentials (Vmax) of attached and free bacteria in waters from the Humber estuary were determined. The waters had high concentrations of suspended solids. Most bacteria were attached to suspended solids and Vmax of attached bacteria was greater than that of free bacteria. These observations suggest that breakdown of organic matter is carried out mainly by attached bacteria. Examination of samples from other estuaries which contained less suspended solids than the Humber suggested that in these estuaries free bacteria might be more abundant than attached bacteria.

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During a neap-spring-neap tidal cycle in the Humber estuary concentrations of suspended solids and oxygen depletion were greatest at spring tides. Most bacteria were attached to particles and attached bacteria (counted using epifluorescence microscopy) increased as solids increased. Concentrations of free bacteria however were unrelated to suspended solids. Heterotrophic activities of bacteria per unit volume of water (measured using C glucose uptake and Michaelis-Menton kinetics) varied irregularly and were not related to bacterial crops, suspended solids or oxygen depletion. Activity per bacterium however decreased as suspended solids increased.