Center for Marine Science, University of North Carolina Wilmington, Wilmington, NC 28409, USA.
Water Res. 2013 Jun 15;47(10):3455-66. doi: 10.1016/j.watres.2013.03.047. Epub 2013 Apr 6.
Fecal microbial pollution of recreational and shellfishing waters is a major human health and economic issue. Microbial pollution sourced from stormwater runoff is especially widespread, and strongly associated with urbanization. However, non-point source nutrient pollution is also problematic, and may come from sources different from fecal-derived pollution (i.e. fertilization of farm fields, lawns and gardens, and ornamental urban areas). Fecal bacteria require nutrients; thus the impact of such nutrient loading on survival and abundance of fecal coliform bacteria in ambient waters was experimentally investigated in a constructed wetland in coastal North Carolina, USA. A series of nutrient-addition bioassays testing impacts of inorganic and organic nitrogen and phosphorus demonstrated that additions of neither organic nor inorganic nitrogen stimulated fecal coliform bacteria. However, phosphorus additions provided significant stimulation of fecal coliform growth at times; on other occasions such additions did not. Dilution bioassays combined with nutrient additions were subsequently devised to assess potential impacts of microzooplankton grazing on the target fecal bacteria populations. Results demonstrated grazing to be a significant bacterial reduction factor in 63% of tests, potentially obscuring nutrient effects. Thus, combining dilution experiments with nutrient addition bioassays yielded simultaneous information on microzooplankton grazing rates on fecal bacteria, fecal bacterial growth rates, and nutrient limitation. Overall, when tested against a non-amended control, additions of either organic or inorganic phosphorus significantly stimulated fecal coliform bacterial growth on 50% of occasions tested, with organic phosphorus generally providing greater stimulation. The finding of significant phosphorus stimulation of fecal bacteria indicates that extraneous nutrient loading can, at times, augment the impacts of fecal microbial pollution of shellfishing and human contact waters.
休闲和贝类捕捞水域的粪便微生物污染是一个主要的人类健康和经济问题。雨水径流带来的微生物污染尤其广泛，与城市化密切相关。然而，非点源营养污染也是一个问题，可能来自与粪便来源污染不同的来源（即农田、草坪和花园以及观赏性城市地区的施肥）。粪便细菌需要营养物质；因此，在美国北卡罗来纳州沿海的一个人工湿地中，实验研究了这种营养负荷对环境水中粪大肠菌群存活和丰度的影响。一系列测试无机和有机氮和磷影响的营养添加生物测定表明，有机氮和无机氮的添加都没有刺激粪大肠菌群。然而，磷的添加有时会显著刺激粪大肠菌群的生长；在其他情况下，这种添加并没有。随后设计了稀释生物测定与营养添加相结合，以评估微型浮游动物摄食对目标粪便细菌种群的潜在影响。结果表明，摄食在 63%的测试中是一个重要的细菌减少因素，这可能掩盖了营养物质的影响。因此，将稀释实验与营养添加生物测定相结合，可以同时获得微型浮游动物对粪便细菌的摄食率、粪便细菌的生长率和营养限制的信息。总的来说，与未经处理的对照相比，在 50%的测试中，有机磷或无机磷的添加显著刺激了粪大肠菌群的生长，而有机磷通常提供更大的刺激。粪便细菌受磷刺激的发现表明，外来营养负荷有时会增强贝类捕捞和人类接触水域的粪便微生物污染的影响。
