The blooms of red tide, dinoflagellates, and reef algae are seasonal and in some cases geographically restricted. There has been some suggestion that nutrient additions to marine waters may affect size of blooms, frequency, and seasonality of occurrence (see Appendix A). Scromboid is believed to be due to improper handling of shellfish after harvest and no association with polluted marine waters has been suggested.

In the United States, rarely are monitoring programs designed to determine level of pathogenic agents in marine waters. The bacteriological indicator system has been used primarily to determine the microbial quality of estuaries and recreational waters. No information is available on the occurrence of enteric protozoa in marine waters. Specialized studies have been directed at specific pathogenic bacteria, but the greatest amount of information on the occurrence of pathogens in marine waters has been reported for the enteric viruses. There may be several reasons for this. Viruses have