Using δ15N in Fish Larvae as an Indicator of Watershed Sources of Anthropogenic Nitrogen: Response at Multiple Spatial Scales

Use of stable isotope ratios of fish larvae as indicators to assess diets and patterns of anthropogenic nitrogen pollution in estuarine ecosystems

“…This study demonstrates that water quality (ammonium, which reflects both nitrogen sources and hydrologic exchange) influences δ 15 N. Ammonium can come from domestic, industrial or agricultural pollution, and highly significant correlations between fish δ 15 N and ammonium imply a direct response to anthropogenic inputs of nitrogen. Our findings are in good agreement with Hoffman et al (2012), who reported that δ 15 N in fish larvae is a responsive indicator of watershed sources of anthropogenic nitrogen in coastal receiving water. Inferring, however, which specific nitrogen sources contribute to elevate δ 15 N is difficult, since these ecosystems contain a variety of different pollution sources that contribute to the nitrogen load to estuarine ecosystems.…”

“…Because of their short generation times (typically weeks to months), most planktonic organisms are considered to be excellent bioindicators of global change as they respond quickly to shifts in the aquatic environment where they occur. Accordingly, these consumers with nitrogen turnover rates on the scale of weeks to a few months provide nitrogen isotopic signatures that are sufficiently stable to reduce short-term noise but which respond quickly enough to detect anthropogenic nitrogen inputs to estuaries (Hoffman et al, 2012). Hoffman et al (2012) was the only study found in the literature that examined nitrogen isotope signatures among fish larvae, a novel biotic indicator of anthropogenic nutrient inputs to coast receiving waters.…”

“…Accordingly, these consumers with nitrogen turnover rates on the scale of weeks to a few months provide nitrogen isotopic signatures that are sufficiently stable to reduce short-term noise but which respond quickly enough to detect anthropogenic nitrogen inputs to estuaries (Hoffman et al, 2012). Hoffman et al (2012) was the only study found in the literature that examined nitrogen isotope signatures among fish larvae, a novel biotic indicator of anthropogenic nutrient inputs to coast receiving waters. Fish had a stable isotope response to changes in sources and their nitrogen isotopic signal has been shown to reflect nitrogen sources.…”

Long‐lived organisms provide an integrative footprint of agricultural land use

“…The linkage between land use, anthropogenic nitrogen, and the assimilation of this nitrogen into food webs shows a direct connection between the influence of humans on watersheds and the biochemical makeup of organisms. These relationships can be complex because of system-specific differences in background d 15 N, the type of N inputs, and hydrology , Hoffman et al 2012, Howarth et al 2012. Although this study does not completely agree with existing N isotope cycling models (Fry 2006, Diebel andVander Zanden 2009), our results are similar to other recent studies that show that d 15 N content of organisms track anthropogenic N inputs (Lefebvre et al 2007, Hoffman et al 2012, Spooner et al 2013.…”

Relationship between the natural abundance of soil nitrogen isotopes and condition in North Dakota wetlands

“…Natural abundances of stable isotopes have been used as an indicator of anthropogenic inputs into ecosystems (Hoffman et al, 2012;Xu and Zhang, 2012), and elevated nutrient levels have been correlated with high human impact (Elliott and Brush, 2006). Therefore, stable isotope levels in wetland soils can be used to indicate changes in land use and nutrient inputs into natural systems (Chang et al, 2002;Elliott and Brush, 2006;Merlo-Galeazzi and Zambrano, 2014).…”