Effects of tourism-derived sewage on coral reefs: Isotopic assessments identify effective bioindicators

Lachs L 1 , Johari NAM 2 , Le DQ 2 , Safuan CDM 2 , Duprey NN 3 , Tanaka K 4 Show all authors , Hong TC 5 , Ory NC 6 , Bachok Z 2 , Baker DM 3 , Kochzius M 7 , Shirai K 4

Affiliations 

  • 1 Marine Biology, Ecology & Biodiversity, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium; Institute of Oceanography and Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia. Electronic address: l.lachs2@newcastle.ac.uk
  • 2 Institute of Oceanography and Environment, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
  • 3 The Swire Institute of Marine Science, The University of Hong Kong, Pokfulam Rd, Hong Kong, People's Republic of China; School of Biological Sciences, The University of Hong Kong, Pok Fu Lam, Hong Kong Special Administrative Region
  • 4 The Atmosphere and Ocean Research Institute, The University of Tokyo, Kashiwa, Japan
  • 5 School of Marine and Environmental Sciences, Universiti Malaysia Terengganu, 21030 Kuala Nerus, Terengganu, Malaysia
  • 6 The Swire Institute of Marine Science, The University of Hong Kong, Pokfulam Rd, Hong Kong, People's Republic of China; School of Biological Sciences, The University of Hong Kong, Pok Fu Lam, Hong Kong Special Administrative Region; GEOMAR Helmholtz Centre of Ocean Research Kiel, Marine Evolutionary Ecology, Düsternbrooker Weg 20, 24105 Kiel, Germany
  • 7 Marine Biology, Ecology & Biodiversity, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
Mar Pollut Bull, 2019 Nov;148:85-96.
PMID: 31422307 DOI: 10.1016/j.marpolbul.2019.07.059

Abstract

Pulau Redang and Pulau Tioman have experienced huge tourism growth over the last two decades, but minimal sewage treatment may threaten the resilience of their coral reefs. This study uses stable isotope techniques to identify suitable bioindicators of sewage nutrients (δ15N) at these islands by measuring macroalgae (Lobophora spp.), gastropods (Drupella spp.), scleractinian coral (Acropora spp.), and leather coral (Sinularia spp.). At tourist hubs using seepage septic tank systems, enrichment of Acropora δ15N (Redang, +0.7‰) and Sinularia δ15N (Tioman, +0.4‰) compared to pristine background levels indicate enhanced sewage nutrient discharge. Carbon isotopes and survey data suggest that sedimentation did not confound these δ15N trends. Potential damaging effects of sewage discharge on the coral reef communities at both islands are highlighted by strong correlations between Acropora δ15N and regional variation in coral reef community structure, and exclusive occurrence of degraded reefs at regions of high sewage influence.

* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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