Fertilizer-derived N in opportunistic macroalgae after flooding of agricultural land

Sandra Walløe Thorsen*, Erik Kristensen, Thomas Valdemarsen, Mogens R. Flindt, Cintia Organo Quintana, Marianne Holmer

*Corresponding author for this work

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Abstract

Managed realignment by deliberate flooding of coastal areas is an adaptation to sea level rise but may risk enriching the coastal zone with nutrients when seawater floods agricultural soil. This study focuses on the early development of macroalgae and their sources of nitrogen (N) in Gyldensteen Coastal Lagoon, Denmark. The lagoon was claimed for agricultural purposes in 1871 and reflooded by managed realignment 143 yr later (2014). Our hypotheses were: (1) that nutrients of agricultural origin from the newly flooded soil initiate opportunistic macroalgal blooms; and (2) that the isotopic composition of green algae rapidly reflects the origin of nutrient sources. We monitored macroalgal cover and conducted stable isotope (δ 15 N) analyses to assess the origin of N sources. Intense green macroalgal blooms occurred during the first summer after flooding and diminished in the 2 following years as a result of rapid water exchange. Low δ 15 N in macroalgae in the first year (mean ± SE, 4.2 ± 0.3) increased significantly in the next year (8.0 ± 0.1). A laboratory experiment tested the δ 15 N response of opportunistic green macroalgae (Ulva spp.) exposed to organic manure and synthetic inorganic fertilizers. Higher δ 15 N (11.1 ± 0.1) characterized manure-treated algae compared to fertilizer-treated algae (2.7 ± 0.2). Based on these field and laboratory results, we accept both hypotheses and conclude that the major N source supporting macroalgal growth in 2014 was derived from synthetic fertilizers; however, rapid tidal flushing during the following years resulted in nutrient limitation and lower macroalgal growth.

Original languageEnglish
JournalMarine Ecology Progress Series
Volume616
Pages (from-to)37-49
ISSN0171-8630
DOIs
Publication statusPublished - 1. Jan 2019

Fingerprint

managed realignment
algae
macroalgae
agricultural land
flooding
fertilizer
fertilizers
nutrient
manure
algal bloom
nutrients
alga
flooded soil
nutrient limitation
coastal lagoon
water exchange
flushing
green alga
agricultural soil
coastal zone

Keywords

  • Coastal
  • Gyldensteen Coastal Lagoon
  • Macroalgal bloom
  • Nitrogen
  • Nutrient sources
  • Realignment
  • Sea level rise

Cite this

@article{dcb06fc48ad8452b9e803ea363b95406,
title = "Fertilizer-derived N in opportunistic macroalgae after flooding of agricultural land",
abstract = "Managed realignment by deliberate flooding of coastal areas is an adaptation to sea level rise but may risk enriching the coastal zone with nutrients when seawater floods agricultural soil. This study focuses on the early development of macroalgae and their sources of nitrogen (N) in Gyldensteen Coastal Lagoon, Denmark. The lagoon was claimed for agricultural purposes in 1871 and reflooded by managed realignment 143 yr later (2014). Our hypotheses were: (1) that nutrients of agricultural origin from the newly flooded soil initiate opportunistic macroalgal blooms; and (2) that the isotopic composition of green algae rapidly reflects the origin of nutrient sources. We monitored macroalgal cover and conducted stable isotope (δ 15 N) analyses to assess the origin of N sources. Intense green macroalgal blooms occurred during the first summer after flooding and diminished in the 2 following years as a result of rapid water exchange. Low δ 15 N in macroalgae in the first year (mean ± SE, 4.2 ± 0.3) increased significantly in the next year (8.0 ± 0.1). A laboratory experiment tested the δ 15 N response of opportunistic green macroalgae (Ulva spp.) exposed to organic manure and synthetic inorganic fertilizers. Higher δ 15 N (11.1 ± 0.1) characterized manure-treated algae compared to fertilizer-treated algae (2.7 ± 0.2). Based on these field and laboratory results, we accept both hypotheses and conclude that the major N source supporting macroalgal growth in 2014 was derived from synthetic fertilizers; however, rapid tidal flushing during the following years resulted in nutrient limitation and lower macroalgal growth.",
keywords = "Coastal, Gyldensteen Coastal Lagoon, Macroalgal bloom, Nitrogen, Nutrient sources, Realignment, Sea level rise",
author = "Thorsen, {Sandra Wall{\o}e} and Erik Kristensen and Thomas Valdemarsen and Flindt, {Mogens R.} and Quintana, {Cintia Organo} and Marianne Holmer",
year = "2019",
month = "1",
day = "1",
doi = "10.3354/meps12927",
language = "English",
volume = "616",
pages = "37--49",
journal = "Marine Ecology - Progress Series",
issn = "0171-8630",
publisher = "Inter Research",

}

Fertilizer-derived N in opportunistic macroalgae after flooding of agricultural land. / Thorsen, Sandra Walløe; Kristensen, Erik; Valdemarsen, Thomas; Flindt, Mogens R.; Quintana, Cintia Organo; Holmer, Marianne.

In: Marine Ecology Progress Series, Vol. 616, 01.01.2019, p. 37-49.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Fertilizer-derived N in opportunistic macroalgae after flooding of agricultural land

AU - Thorsen, Sandra Walløe

AU - Kristensen, Erik

AU - Valdemarsen, Thomas

AU - Flindt, Mogens R.

AU - Quintana, Cintia Organo

AU - Holmer, Marianne

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Managed realignment by deliberate flooding of coastal areas is an adaptation to sea level rise but may risk enriching the coastal zone with nutrients when seawater floods agricultural soil. This study focuses on the early development of macroalgae and their sources of nitrogen (N) in Gyldensteen Coastal Lagoon, Denmark. The lagoon was claimed for agricultural purposes in 1871 and reflooded by managed realignment 143 yr later (2014). Our hypotheses were: (1) that nutrients of agricultural origin from the newly flooded soil initiate opportunistic macroalgal blooms; and (2) that the isotopic composition of green algae rapidly reflects the origin of nutrient sources. We monitored macroalgal cover and conducted stable isotope (δ 15 N) analyses to assess the origin of N sources. Intense green macroalgal blooms occurred during the first summer after flooding and diminished in the 2 following years as a result of rapid water exchange. Low δ 15 N in macroalgae in the first year (mean ± SE, 4.2 ± 0.3) increased significantly in the next year (8.0 ± 0.1). A laboratory experiment tested the δ 15 N response of opportunistic green macroalgae (Ulva spp.) exposed to organic manure and synthetic inorganic fertilizers. Higher δ 15 N (11.1 ± 0.1) characterized manure-treated algae compared to fertilizer-treated algae (2.7 ± 0.2). Based on these field and laboratory results, we accept both hypotheses and conclude that the major N source supporting macroalgal growth in 2014 was derived from synthetic fertilizers; however, rapid tidal flushing during the following years resulted in nutrient limitation and lower macroalgal growth.

AB - Managed realignment by deliberate flooding of coastal areas is an adaptation to sea level rise but may risk enriching the coastal zone with nutrients when seawater floods agricultural soil. This study focuses on the early development of macroalgae and their sources of nitrogen (N) in Gyldensteen Coastal Lagoon, Denmark. The lagoon was claimed for agricultural purposes in 1871 and reflooded by managed realignment 143 yr later (2014). Our hypotheses were: (1) that nutrients of agricultural origin from the newly flooded soil initiate opportunistic macroalgal blooms; and (2) that the isotopic composition of green algae rapidly reflects the origin of nutrient sources. We monitored macroalgal cover and conducted stable isotope (δ 15 N) analyses to assess the origin of N sources. Intense green macroalgal blooms occurred during the first summer after flooding and diminished in the 2 following years as a result of rapid water exchange. Low δ 15 N in macroalgae in the first year (mean ± SE, 4.2 ± 0.3) increased significantly in the next year (8.0 ± 0.1). A laboratory experiment tested the δ 15 N response of opportunistic green macroalgae (Ulva spp.) exposed to organic manure and synthetic inorganic fertilizers. Higher δ 15 N (11.1 ± 0.1) characterized manure-treated algae compared to fertilizer-treated algae (2.7 ± 0.2). Based on these field and laboratory results, we accept both hypotheses and conclude that the major N source supporting macroalgal growth in 2014 was derived from synthetic fertilizers; however, rapid tidal flushing during the following years resulted in nutrient limitation and lower macroalgal growth.

KW - Coastal

KW - Gyldensteen Coastal Lagoon

KW - Macroalgal bloom

KW - Nitrogen

KW - Nutrient sources

KW - Realignment

KW - Sea level rise

U2 - 10.3354/meps12927

DO - 10.3354/meps12927

M3 - Journal article

AN - SCOPUS:85065477710

VL - 616

SP - 37

EP - 49

JO - Marine Ecology - Progress Series

JF - Marine Ecology - Progress Series

SN - 0171-8630

ER -