Recovery of black-necked swans, macrophytes and water quality in a Ramsar wetland of southern Chile: Assessing resilience following sudden anthropogenic disturbances

Eduardo Jaramillo, Nelson A. Lagos, Fabio A. Labra, Enrique Paredes, Emilio Acuña, Daniel Melnick, Mario Manzano, Carlos Velásquez, Cristian Duarte

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)

Abstract

In 2004 migration and mortality for unknown reasons of the herbivorous Black necked swan (Cygnus melancorhyphus (Molina, 1782)) occurred within the Río Cruces wetland (southern Chile), a Ramsar Site and nature sanctuary. Before 2004, this wetland hosted the largest breeding population of this water bird in the Neotropic Realm. The concurrent decrease in the spatial occurrence of the aquatic plant Egeria densa Planch. 1849 - the main food source of swans - was proposed as a cause for swan migration and mortality. Additionally, post-mortem analyses carried out on swans during 2004 showed diminished body weight, high iron loads and histopathological abnormalities in their livers, suggesting iron storage disease. Various hypotheses were postulated to describe those changes; the most plausible related to variations in water quality after a pulp mill located upstream the wetland started to operate in February 2004. Those changes cascaded throughout the stands of E. densa whose remnants had high iron contents in their tissues. Here we present results of a long-term monitoring program of the wetland components, which show that swan population abundance, body weights and histological liver conditions recovered to pre-disturbance levels in 2012. The recovery of E. densa and iron content in plants throughout the wetland, also returned to pre-disturbance levels in the same 8-year time period. These results show the temporal scale over which resilience and natural restoring processes occur in wetland ecosystems of temperate regions such as southern Chile.

Original languageEnglish
Pages (from-to)291-301
Number of pages11
JournalScience of the Total Environment
Volume628-629
DOIs
Publication statusPublished - 1 Jul 2018

Keywords

  • Aquatic macrophytes
  • Herbivorous water birds
  • Industrial waters
  • Ramsar site
  • Southern Chile
  • Wetlands

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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