TY - JOUR
T1 - Effects of watershed land-cover on the biogeochemical properties of estuarine tidal flat sediments
T2 - A test in a densely-populated subtropical island
AU - Morita, Akiko
AU - Touyama, Shouji
AU - Kuwae, Tomohiro
AU - Nishimura, Osamu
AU - Sakamaki, Takashi
N1 - Funding Information:
We thank Y. Watanabe for assistance with the GIS data analyses. We also thank N. Chiba and C. Maruo for assistance with the chemical analyses. This research was funded by the Japan Society for the Promotion of Science (Grants-in-Aid for Scientific Research #20681023 and #24370016 ; NEXT program #GR083 ).
Publisher Copyright:
© 2016 Elsevier Ltd
PY - 2017/1/5
Y1 - 2017/1/5
N2 - The effects of watershed land cover on the biogeochemical properties of estuarine tidal flat sediment were examined in estuarine tidal flats of 16 watersheds in a densely populated, subtropical island of Japan. Despite the small sizes of the watersheds (<16.5 km2), a redundancy analysis showed that river water quality explained 62% of the cross-estuary variation in the biogeochemical properties of estuarine tidal flat sediment by the first two ordination axes. We also found that the dissolved nutrient concentrations of river water and pheophytin a content of tidal flat sediment were positively related to agricultural and urbanized land cover in the watersheds. These results indicate that human nutrient inputs significantly increase algae-derived deposits in estuaries with relatively more developed watersheds. The δ13C of particulate organic matter (POM) was negatively related to watershed forest cover. This suggests that terrestrially derived-origin POM deposits are substantial in the estuaries connected to watersheds with relatively high forest cover. However, the chemical properties of tidal flat sediment were not related to chemical indicators of POM in the base flow. We hypothesize that substantial terrestrially derived POM is discharged to estuaries of high-forest-cover watersheds during high flow, and this partially controls the chemical properties of estuarine sediments. Our results demonstrate that the chemical properties of estuarine tidal flats are associated with watershed land cover, and that the dominant processes controlling estuarine sediment properties differ among watersheds depending on land cover composition.
AB - The effects of watershed land cover on the biogeochemical properties of estuarine tidal flat sediment were examined in estuarine tidal flats of 16 watersheds in a densely populated, subtropical island of Japan. Despite the small sizes of the watersheds (<16.5 km2), a redundancy analysis showed that river water quality explained 62% of the cross-estuary variation in the biogeochemical properties of estuarine tidal flat sediment by the first two ordination axes. We also found that the dissolved nutrient concentrations of river water and pheophytin a content of tidal flat sediment were positively related to agricultural and urbanized land cover in the watersheds. These results indicate that human nutrient inputs significantly increase algae-derived deposits in estuaries with relatively more developed watersheds. The δ13C of particulate organic matter (POM) was negatively related to watershed forest cover. This suggests that terrestrially derived-origin POM deposits are substantial in the estuaries connected to watersheds with relatively high forest cover. However, the chemical properties of tidal flat sediment were not related to chemical indicators of POM in the base flow. We hypothesize that substantial terrestrially derived POM is discharged to estuaries of high-forest-cover watersheds during high flow, and this partially controls the chemical properties of estuarine sediments. Our results demonstrate that the chemical properties of estuarine tidal flats are associated with watershed land cover, and that the dominant processes controlling estuarine sediment properties differ among watersheds depending on land cover composition.
KW - Carbon and nitrogen stable isotope
KW - Estuarine tidal flat
KW - Okinawa Island
KW - Particulate organic matter
KW - Watershed land cover
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U2 - 10.1016/j.ecss.2016.11.019
DO - 10.1016/j.ecss.2016.11.019
M3 - Article
AN - SCOPUS:85002648090
SN - 0272-7714
VL - 184
SP - 207
EP - 213
JO - Estuarine, Coastal and Shelf Science
JF - Estuarine, Coastal and Shelf Science
ER -
