Biogeochemical typology and temporal variability of lagoon waters in a coral reef ecosystem subject to terrigeneous and anthropogenic inputs (New Caledonia)

Renaud Fichez; S. Chifflet; Pascal Douillet; P. Gerard; F. Gutierrez; A. Jouon; Sylvain Ouillon; Christian Grenz

Biogeochemical typology and temporal variability of lagoon waters in a coral reef ecosystem subject to terrigeneous and anthropogenic inputs (New Caledonia)

Renaud Fichez ^{1, 2} S. Chifflet ^{2, 3} Pascal Douillet ⁴ P. Gerard ^{2, 5} F. Gutierrez ⁶ A. Jouon ⁵ Sylvain Ouillon ⁷ Christian Grenz ⁸

1 CAMELIA - Caractérisation et modélisation des échanges dans des lagons soumis aux influences terrigènes et anthropiques

2 COM - Centre d'océanologie de Marseille

3 IRD - IRD, Universidad Autonoma Metropolitana Iztapalapa

4 OPLC

MIO - Institut méditerranéen d'océanologie

5 IRD [Nouvelle-Calédonie] - Institut de Recherche pour le Développement

6 DCBS - Universidad Autonoma Metropolitana Iztapalapa

7 ECOLA LEGOS

LEGOS - Laboratoire d'études en Géophysique et océanographie spatiales

8 LOPB - Laboratoire d'Océanographie Physique et Biologique

Abstract : Considering the growing concern about the impact of anthropogenic inputs on coral reefs and coral reef lagoons, surprisingly little attention has been given to the relationship between those inputs and the trophic status of lagoon waters. The present paper describes the distribution of biogeochemical parameters in the coral reef lagoon of New Caledonia where environmental conditions allegedly range from pristine oligotrophic to anthropogenically influenced. The study objectives were to: (i) identify terrigeneous and anthropogenic inputs and propose a typology of lagoon waters, (ii) determine temporal variability of water biogeochemical parameters at time-scales ranging from hours to seasons. Combined ACP-cluster analyses revealed that over the 2000 km2 lagoon area around the city of Nouméa, "natural" terrigeneous versus oceanic influences affecting all stations only accounted for less than 20% of the spatial variability whereas 60% of that spatial variability could be attributed to significant eutrophication of a limited number of inshore stations. ACP analysis allowed to unambiguously discriminating between the natural trophic enrichment along the offshore-inshore gradient and anthropogenically induced eutrophication. High temporal variability in dissolved inorganic nutrients concentrations strongly hindered their use as indicators of environmental status. Due to longer turn over time, particulate organic material and more specifically chlorophyll a appeared as more reliable nonconservative tracer of trophic status. Results further provided evidence that ENSO occurrences might temporarily lower the trophic status of the New Caledonia lagoon. It is concluded that, due to such high frequency temporal variability, the use of biogeochemical parameters in environmental surveys require adapted sampling strategies, data management and environmental alert methods.

Keywords : Coral reef lagoon Nutrients Hydrology Typology Temporal variability Trophic status

Document type :

Journal articles

Domain :

Sciences of the Universe [physics] / Earth Sciences / Oceanography

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https://hal.archives-ouvertes.fr/hal-00765976
Contributor : Nadia Ayoub <>
Submitted on : Monday, December 17, 2012 - 12:53:53 PM
Last modification on : Friday, October 11, 2019 - 8:23:08 PM

Biogeochemical typology and temporal variability of lagoon waters in a coral reef ecosystem subject to terrigeneous and anthropogenic inputs (New Caledonia)

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Biogeochemical typology and temporal variability of lagoon waters in a coral reef ecosystem subject to terrigeneous and anthropogenic inputs (New Caledonia)

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