Assessing the micro-phytoplankton response to nitrate in Comau Fjord (42 S) in Patagonia (Chile), using a microcosms approach

José Luis Iriarte*, Silvio Pantoja, Humberto E. González, Gabriela Silva, Hector Paves, Pamela Labbé, Lorena Rebolledo, Murat Van Ardelan, V. Häussermann

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

Anthropogenic (aquaculture) changes in environment nutrient concentrations may affect phytoplankton (biomass and taxa composition) in marine coastal waters off the Chilean Patagonia. The effects of adding nitrate (NO3 -) to natural phytoplankton assemblages were evaluated considering biomass, cell abundance, and taxonomic composition. Microcosm experiments were performed in the spring, summer, and winter in the Comau Fjord located in Subantarctic Patagonia. At the end of the experiments, NO3 - decreased rapidly and was undetectable in treatments, indicating a strong NO3 - deficiency associated with an exponential increase in Chl-a concentrations, particulate organic nitrogen, and carbon in these treatments. Moreover, given the depleted nitrate concentrations of the spring and summer experiments, the micro-phytoplankton taxa structure shifted from mixed diatom and dinoflagellate assemblages (Ceratium spp.; Dinophysis spp.; Coscinodiscus sp.; Rhizosolenia pungens) to assemblages dominated by blooms of the classic chain-forming diatoms found in temperate and cold waters such as Chaetoceros spp.; Skeletonema spp.; and Thalassiosira spp. Thus, nitrogen sources (i.e.; nitrate, ammonia) may influence phytoplankton abundance and biomass accumulation dynamics in the northern section of Patagonia. It also emphasizes the importance of diatom taxa in regards to the short-term response of phytoplankton to changing environmental nutrient conditions due to natural (decreasing freshwater stream flow) and anthropogenic (aquaculture) events. This situation may be one of the future scenarios in the Patagonian fjords, thus stressing the needs for active environmental monitoring and impact assessment.

Original languageEnglish
Pages (from-to)5055-5070
Number of pages16
JournalEnvironmental Monitoring and Assessment
Volume185
Issue number6
DOIs
StatePublished - 2013
Externally publishedYes

Bibliographical note

Funding Information:
Acknowledgments This research was funded by FONDE-CYT 1080187 (J.L. Iriarte). We thank the Huinay Foundation for providing marine laboratories and vessel facilities, as well as phytoplankton data from the Comau Fjord, and our colleagues G. Försterra and V. Häussermann for their help at the Huinay Scientific Station. We appreciate the valuable help of Patricio Ampuero and Caroll García during the experimental work and microscopic analysis, and Pirjo Huovinen for allowing us to use her submersible Ramses-ACC2-UV-VIS hyperspectral radiometer sensor (Trios Optical Sensors). This research was also partially funded by the Centro de Investigación de Ecosistemas de la Patagonia (CIEP), Programa de Financiamiento Basal COPAS–Sur Austral, and WAFOW/NTNU–Norwegian Research Council Latin American–Norway Programme. The winter experiment was part of the MSc. Thesis of Ms. Pamela Labbe at Universidad de Concepción, who was funded by a 1-year scholarship from COPAS–Sur Austral. This is publication 55 of Huinay Scientific Field Station.

ASJC Scopus subject areas

  • General Environmental Science
  • Pollution
  • Management, Monitoring, Policy and Law

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