Deep-sea coral record of humanimpact on watershed quality in the Mississippi River Basin Academic Article uri icon

abstract

  • AbstractOne of the greatest drivers of historical nutrient and sediment transport into the Gulf of Mexico is the unprecedented scale and intensity of land use change in the Mississippi River Basin. These landscape changes are linked to enhanced fluxes of carbon and nitrogen pollution from the Mississippi River, and persistent eutrophication and hypoxia in the northern Gulf of Mexico. Increased terrestrial runoff is one hypothesis for recent enrichment in bulk nitrogen isotope (15N) values, a tracer for nutrient source, observed in a Gulf of Mexico deepsea coral record. However, unambiguously linking anthropogenic land use change to whole scale shifts in downstream Gulf of Mexico biogeochemical cycles is difficult. Here we present a novel approach, coupling a new tracer of agroindustrialization to a multiproxy record of nutrient loading in longlived deepsea corals collected in the Gulf of Mexico. We found that coral bulk 15N values are enriched over the last 150200 years relative to the last millennia, and compoundspecific amino acid 15N data indicate a strong increase in baseline 15N of nitrate as the primary cause. Coral rhenium (Re) values are also strongly elevated during this period, suggesting that 34% of Re is of anthropogenic origin, consistent with Re enrichment in major world rivers. However, there are no preanthropogenic measurements of Re to confirm this observation. For the first time, an unprecedented record of natural and anthropogenic Re variability is documented through coral Re records. Taken together, these novel proxies link upstream changes in water quality to impacts on the deepsea coral ecosystem.

published proceedings

  • GLOBAL BIOGEOCHEMICAL CYCLES

altmetric score

  • 3

author list (cited authors)

  • Prouty, N. G., Roark, E. B., Koenig, A. E., Demopoulos, A., Batista, F. C., Kocar, B. D., ... Mienis, F.

citation count

  • 28

complete list of authors

  • Prouty, Nancy G||Roark, E Brendan||Koenig, Alan E||Demopoulos, Amanda WJ||Batista, Fabian C||Kocar, Benjamin D||Selby, David||McCarthy, Matthew D||Mienis, Furu

publication date

  • January 2014