Parasitological Data as Monitors of Environmental Health

When an appropriate fish host is selected, analysis of its parasites offers a useful, reliable, economical, telescoped indication or monitor of environmental health. The value of that information increases when corroborated by another non-parasitological technique. The analysis of parasites is not necessarily simple because not all hosts serve as good models and because the number of species, presence of specific species, intensity of infections, life histories of species, location of species in hosts, and host response for each parasitic species have to be addressed individually to assure usefulness of the tool. Also, different anthropogenic contaminants act in a distinct manner relative to hosts, parasites, and each other as well as being influenced by natural environmental conditions. Total values for all parasitic species infecting a sample cannot necessarily be grouped together. For example, an abundance of numbers of either species or individuals can indicate either a healthy or an unhealthy environment, depending on the species of parasite. Moreover, depending on the parasitic species, its infection, and the time chosen for collection/examination, the assessment may indicate a chronic or acute state of the environmental health. For most types of analyses, the host should be one that has a restricted home range, can be infected by numerous species of parasites, many of which have a variety of additional hosts in their life cycles, and can be readily sampled. Data on parasitic infections in the western mosquitofish (Gambusia affinis), a fish that meets the criteria in two separate studies, illustrate the usefulness of that host as a model to indicate both healthy and detrimentally influenced environments. In those studies, species richness, intensity of select species, host resistance, other hosts involved in life cycles, and other factors all relate to site and contaminating discharge.

Variation of Environmental Regulation Stringency Among the Top Ten U.S. Hog Producing States

The U.S. hog industry, once primarily made up of small owner-operated crop-hog farms, has become dominated by large specialized operations characterized by low costs and improved technologies in livestock management. Such changes have triggered concerns over the dangers large Hog Feeding Operations (HFOs) are likely to pose to the environment. In 2007, the top ten states accounted for more than 85 percent of total U.S. hog production (Iowa (IA), North Carolina (NC), Minnesota (MN), Illinois (IL), Nebraska (NE), Indiana (IN), Missouri (MO), Oklahoma (OK), Ohio (OH), and Kansas (KS)). With such domination on production, these states are often the subject of environmental debate relating to hog production. When farmers are required to incorporate environmental measures in hog production, their costs of production increase. Metcalfe (2001) found that small HFOs have found it difficult to cope with such costs and many have exited the industry, while large operations have not been affected at the same level. Due to the variation of environmental regulations among states, other operations moved to states with lax regulations (e.g. NC prior to the late 1990s). Such regulations appear to have played a major role in shaping the structure of the hog industry.