Identifying sources of nitrogen to Hanalei Bay, Kauai, utilizing the nitrogen isotope signature of macroalgae
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Abstract
Sewage effluent, storm runoff, discharge from polluted rivers, and inputs of groundwater have all been suggested as potential sources of land derived nutrients into Hanalei Bay, Kauai. We determined the nitrogen isotopic signatures (δ15N) of different nitrate sources to Hanalei Bay along with the isotopic signature recorded by 11 species of macroalgal collected in the Bay. The macroalgae integrate the isotopic signatures of the nitrate sources over time, thus these data along with the nitrate to dissolved inorganic phosphate molar ratios (N:P) of the macroalgae were used to determine the major nitrate source to the bay ecosystem and which of the macro-nutrients is limiting algae growth, respectively. Relatively low δ15N values (average −0.5‰) were observed in all algae collected throughout the Bay; implicating fertilizer, rather than domestic sewage, as an important external source of nitrogen to the coastal water around Hanalei. The N:P ratio in the algae compared to the ratio in the Bay waters imply that the Hanalei Bay coastal ecosystem is nitrogen limited and thus, increased nitrogen input may potentially impact this coastal ecosystem and specifically the coral reefs in the Bay. Identifying the major source of nutrient loading to the Bay is important for risk assessment and potential remediation plans.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Identifying sources of nitrogen to Hanalei Bay, Kauai, utilizing the nitrogen isotope signature of macroalgae |
| Series title | Environmental Science & Technology |
| DOI | 10.1021/es0700449 |
| Volume | 41 |
| Issue | 15 |
| Year Published | 2007 |
| Language | English |
| Publisher | American Chemical Society |
| Contributing office(s) | Toxic Substances Hydrology Program |
| Description | 7 p. |
| First page | 5217 |
| Last page | 5223 |
| Country | United States |
| State | Hawaii |
| Other Geospatial | Kauai Island, Hanalei Bay |
| Google Analytic Metrics | Metrics page |