Effects of watershed land use on coastal marine environments: A multiscale exploratory analysis with multiple biogeochemical indicators in fringing coral reefs of Okinawa Island

Takashi Sakamaki; Akiko Morita; Shouji Touyama; Yasushi Watanabe; Shouhei Suzuki; Takashi Kawai

doi:10.1016/j.marpolbul.2022.114054

Effects of watershed land use on coastal marine environments: A multiscale exploratory analysis with multiple biogeochemical indicators in fringing coral reefs of Okinawa Island

Mar Pollut Bull. 2022 Oct:183:114054. doi: 10.1016/j.marpolbul.2022.114054. Epub 2022 Aug 22.

Authors

Takashi Sakamaki¹, Akiko Morita², Shouji Touyama³, Yasushi Watanabe⁴, Shouhei Suzuki⁵, Takashi Kawai⁶

Affiliations

¹ Department of Civil and Environmental Engineering, Tohoku University, Sendai 980-8579, Japan; Department of Civil Engineering and Architecture, University of the Ryukyus, Okinawa 903-0213, Japan. Electronic address: takashi.sakamaki.a5@tohoku.ac.jp.
² Department of Civil and Environmental Engineering, Tohoku University, Sendai 980-8579, Japan; Department of Civil Engineering and Architecture, University of the Ryukyus, Okinawa 903-0213, Japan; Oriental Consultants Co., Ltd., Tokyo 151-0071, Japan.
³ Department of Civil Engineering and Architecture, University of the Ryukyus, Okinawa 903-0213, Japan; Stargate Entertainment, Okinawa 905-0005, Japan.
⁴ GIS Okinawa Laboratory, Okinawa 901-0401, Japan.
⁵ Department of Civil Engineering and Architecture, University of the Ryukyus, Okinawa 903-0213, Japan.
⁶ Department of Civil Engineering and Architecture, University of the Ryukyus, Okinawa 903-0213, Japan; Tokyo Kyuei Co., Ltd., Tokyo 101-0032, Japan.

PMID: 36007269
DOI: 10.1016/j.marpolbul.2022.114054

Abstract

The analytical spatial scale and selection of biogeochemical indicators affect interpretations of land-use impacts on coastal marine environments. In this study, nine biogeochemical indicators were sampled from 36 locations of coral reefs fringing a subtropical island, and their relationships with watershed land use were assessed by spatial autoregressive models with spatial weight matrixes based on distance thresholds of a few to 30 km. POM-relevant indicators were associated with agricultural and urban lands of watersheds within relatively small ranges (6-14 km), while the concentrations of inorganic nutrients were associated with watersheds within 20 km or more. The macroalgal δ¹⁵N showed a strong relationship with agricultural lands of watersheds within 7 km and urban/forest lands of watersheds within 24 km. These results demonstrate significant effects of land use on the coral reef ecosystems of the island, and the importance of appropriate combinations of analytical scales and biogeochemical indicators.

Keywords: Anthropogenic nitrogen; Coral reef conservation; Land–sea connection; Multiscale buffers; Primary production; Stable isotopes.

MeSH terms

Agriculture
Animals
Anthozoa*
Coral Reefs*
Ecosystem