Use of historical isoscapes to develop an estuarine nutrient baseline

Frontiers in Marine Science

Marine Science

Farzana I. Rahman¹  Paula Zelanko¹  Lena K. Champlin¹  Audrey Rittenhouse¹  Nadine B. Quintana Krupinski²  Elizabeth B. Watson³  Andrew B. Gray⁴  Rikke Jeppesen⁵  Andrea Woolfolk⁵  John Haskins⁵  Kerstin Wasson⁶  Autumn J. Oczkowski⁷ 

[1]Department of Biodiversity, Earth & Environmental Sciences and the Academy of Natural Sciences of Drexel University, Philadelphia, PA, United States

[2]Department of Earth and Planetary Sciences, University of California Santa Cruz, Santa Cruz, CA, United States

[3]Department of Ecology and Evolution, Stony Brook University, Stony Brook, NY, United States

[4]Department of Environmental Sciences, University of California Riverside, Riverside, CA, United States

[5]Elkhorn Slough National Estuarine Research Reserve, Royal Oaks, CA, United States

[6]Elkhorn Slough National Estuarine Research Reserve, Royal Oaks, CA, United States

[7]Ecology and Evolutionary Biology, University of California Santa Cruz, Santa Cruz, CA, United States

[8]U.S. Environmental Protection Agency (EPA), Atlantic Ecology Division, Narragansett, RI, United States

关键词: nitrogen;    eutrophication;    stable isotopes;    isoscapes;    sediment cores;    baseline;   

DOI  :  10.3389/fmars.2023.1257015

 received in 2023-07-11, accepted in 2023-08-21,  发布年份 2023

来源: Frontiers

【 摘 要 】

Coastal eutrophication is a prevalent threat to the healthy functioning of ecosystems globally. While degraded water quality can be detected by monitoring oxygen, nutrient concentrations, and algal abundance, establishing regulatory guidelines is complicated by a lack of baseline data (e.g., pre-Anthropocene). We use historical carbon and nitrogen isoscapes over ~300 years from sediment cores to reconstruct spatial and temporal changes in nutrient dynamics for a central California estuary, Elkhorn Slough, where development and agriculture dramatically enhanced nutrient inputs over the past century. We found strong contrasts between current sediment stable isotopes and those from the recent past, demonstrating shifts exceeding those in previously studied eutrophic estuaries and substantial increases in nutrient inputs. Comparisons of contemporary with historical isoscapes also revealed that nitrogen sources shifted from a historical marine-terrestrial gradient with higher δ15N near the inlet to amplified denitrification at the head and mouth of the modern estuary driven by increased N inputs. Geospatial analysis of historical data suggests that an increase in fertilizer application – rather than population growth or increases in the extent of cultivated land – is chiefly responsible for increasing nutrient loads during the 20th century. This study demonstrates the ability of isotopic and stoichiometric maps to provide important perspectives on long-term shifts and spatial patterns of nutrients that can be used to improve management of nutrient pollution.

【 授权许可】

Unknown   
Copyright © 2023 Champlin, Woolfolk, Oczkowski, Rittenhouse, Gray, Wasson, Rahman, Zelanko, Quintana Krupinski, Jeppesen, Haskins and Watson