Dissolved organic matter from tropical peatlands reduces shelf sea light availability in the Singapore Strait, Southeast Asia

Shelf seas provide valuable ecosystem services, but their productivity and ecological functioning depend critically on sunlight transmitted through the water column. Anthropogenic reductions in underwater light availability are thus a serious threat to coastal habitats. The flux of light-absorbing c...

Full description

Saved in:
Bibliographic Details
Main Authors: Martin, Patrick, Sanwlani, Nivedita, Lee, Tiffany Wan Qi, Wong, Joel Meng Cheng, Chang, Kristy Yi Wen, Wong, Elizabeth Wing-See, Liew, Soo Chin
Other Authors: Asian School of the Environment
Format: Article
Language:English
Published: 2022
Subjects:
Online Access:https://hdl.handle.net/10356/153716
Tags: Add Tag
No Tags, Be the first to tag this record!
Institution: Nanyang Technological University
Language: English
id sg-ntu-dr.10356-153716
record_format dspace
spelling sg-ntu-dr.10356-1537162023-02-28T16:41:08Z Dissolved organic matter from tropical peatlands reduces shelf sea light availability in the Singapore Strait, Southeast Asia Martin, Patrick Sanwlani, Nivedita Lee, Tiffany Wan Qi Wong, Joel Meng Cheng Chang, Kristy Yi Wen Wong, Elizabeth Wing-See Liew, Soo Chin Asian School of the Environment Science::Geology Coral Reefs Optical Water Quality Shelf seas provide valuable ecosystem services, but their productivity and ecological functioning depend critically on sunlight transmitted through the water column. Anthropogenic reductions in underwater light availability are thus a serious threat to coastal habitats. The flux of light-absorbing coloured dissolved organic matter (CDOM) from land to sea may have increased world-wide, but how this has altered the availability and spectral quality of light in shelf seas remains poorly known. We present time-series data from the Sunda Shelf in Southeast Asia, where the monsoon-driven reversal in ocean currents supplies water enriched in CDOM from tropical peatlands for part of the year, resulting in 5- to 10-fold seasonal variation in light absorption by CDOM. We show that this terrigenous CDOM can dominate underwater light absorption at wavelengths up to 500 nm, and shift the underwater irradiance spectrum towards longer wavelengths. The seasonal presence of terrigenous CDOM also reduces the 10% light penetration depth by 1-5 m, or 10-45%. We estimate that on average 0.6 m, or 25%, of this terrigenous CDOM-mediated shoaling might be attributable to the enhanced input of dissolved organic matter following peatland disturbance. The seasonal change in the light environment is correlated with changes in phytoplankton absorption spectra that suggest a photo-acclimation response, and we infer that terrigenous CDOM likely contributes to limiting the depth distribution of photosynthetic corals. The results reveal an ecologically important but largely overlooked impact of human modifications to carbon fluxes that is likely increasingly important in coastal seas. National Research Foundation (NRF) Published version This research was supported by the National Research Foundation Singapore, Prime Minister’s Office, under the Marine Science Research and Development Program through grant MSRDP-P32 to P.M. 2022-01-17T07:01:42Z 2022-01-17T07:01:42Z 2021 Journal Article Martin, P., Sanwlani, N., Lee, T. W. Q., Wong, J. M. C., Chang, K. Y. W., Wong, E. W. & Liew, S. C. (2021). Dissolved organic matter from tropical peatlands reduces shelf sea light availability in the Singapore Strait, Southeast Asia. Marine Ecology Progress Series, 672, 89-109. https://dx.doi.org/10.3354/meps13776 0171-8630 https://hdl.handle.net/10356/153716 10.3354/meps13776 2-s2.0-85108974736 672 89 109 en MSRDP-P32 Marine Ecology Progress Series 10.21979/N9/TXYRC3 © 2021 The authors. Open Access under Creative Commons by Attribution Licence. Use, distribution and reproduction are unrestricted. Authors and original publication must be credited. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic Science::Geology
Coral Reefs
Optical Water Quality
spellingShingle Science::Geology
Coral Reefs
Optical Water Quality
Martin, Patrick
Sanwlani, Nivedita
Lee, Tiffany Wan Qi
Wong, Joel Meng Cheng
Chang, Kristy Yi Wen
Wong, Elizabeth Wing-See
Liew, Soo Chin
Dissolved organic matter from tropical peatlands reduces shelf sea light availability in the Singapore Strait, Southeast Asia
description Shelf seas provide valuable ecosystem services, but their productivity and ecological functioning depend critically on sunlight transmitted through the water column. Anthropogenic reductions in underwater light availability are thus a serious threat to coastal habitats. The flux of light-absorbing coloured dissolved organic matter (CDOM) from land to sea may have increased world-wide, but how this has altered the availability and spectral quality of light in shelf seas remains poorly known. We present time-series data from the Sunda Shelf in Southeast Asia, where the monsoon-driven reversal in ocean currents supplies water enriched in CDOM from tropical peatlands for part of the year, resulting in 5- to 10-fold seasonal variation in light absorption by CDOM. We show that this terrigenous CDOM can dominate underwater light absorption at wavelengths up to 500 nm, and shift the underwater irradiance spectrum towards longer wavelengths. The seasonal presence of terrigenous CDOM also reduces the 10% light penetration depth by 1-5 m, or 10-45%. We estimate that on average 0.6 m, or 25%, of this terrigenous CDOM-mediated shoaling might be attributable to the enhanced input of dissolved organic matter following peatland disturbance. The seasonal change in the light environment is correlated with changes in phytoplankton absorption spectra that suggest a photo-acclimation response, and we infer that terrigenous CDOM likely contributes to limiting the depth distribution of photosynthetic corals. The results reveal an ecologically important but largely overlooked impact of human modifications to carbon fluxes that is likely increasingly important in coastal seas.
author2 Asian School of the Environment
author_facet Asian School of the Environment
Martin, Patrick
Sanwlani, Nivedita
Lee, Tiffany Wan Qi
Wong, Joel Meng Cheng
Chang, Kristy Yi Wen
Wong, Elizabeth Wing-See
Liew, Soo Chin
format Article
author Martin, Patrick
Sanwlani, Nivedita
Lee, Tiffany Wan Qi
Wong, Joel Meng Cheng
Chang, Kristy Yi Wen
Wong, Elizabeth Wing-See
Liew, Soo Chin
author_sort Martin, Patrick
title Dissolved organic matter from tropical peatlands reduces shelf sea light availability in the Singapore Strait, Southeast Asia
title_short Dissolved organic matter from tropical peatlands reduces shelf sea light availability in the Singapore Strait, Southeast Asia
title_full Dissolved organic matter from tropical peatlands reduces shelf sea light availability in the Singapore Strait, Southeast Asia
title_fullStr Dissolved organic matter from tropical peatlands reduces shelf sea light availability in the Singapore Strait, Southeast Asia
title_full_unstemmed Dissolved organic matter from tropical peatlands reduces shelf sea light availability in the Singapore Strait, Southeast Asia
title_sort dissolved organic matter from tropical peatlands reduces shelf sea light availability in the singapore strait, southeast asia
publishDate 2022
url https://hdl.handle.net/10356/153716
_version_ 1759855976310112256