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Temporal and spatial distribution of floating objects in coastal waters of central–southern Chile and Patagonian fjords
Published Date
Continental Shelf Research 1 March 2011, Vol.31(3):172–186,doi:10.1016/j.csr.2010.04.013 Fjord Oceanography of the Chilean Patagonia Author
Iván A. Hinojosa a
Marcelo M. Rivadeneira a,b,c
Martin Thiel a,b,,
aUniversidad Católica del Norte, Larrondo 1281, Coquimbo, Chile
bCentro de Estudios Avanzados en Zonas Áridas (CEAZA), Coquimbo, Chile
cCenter for Advanced Studies in Ecology and Biodiversity (CASEB), Departamento de Ecología, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile
Received 23 December 2009. Revised 16 April 2010. Accepted 26 April 2010. Available online 9 June 2010.
Abstract Floating objects are suggested to be the principal vector for the transport and dispersal of marine invertebrates with direct development as well as catalysts for carbon and nutrient recycling in accumulation areas. The first step in identifying the ecological relevance of floating objects in a specific area is to identify their spatio-temporal distribution. We evaluated the composition, abundance, distribution, and temporal variability of floating objects along the continental coast of central–southern Chile (33–42°S) and the Patagonian fjords (42–50°S) using ship surveys conducted in austral winter (July/August) and spring (November) of the years 2002–2005 and 2008. Potential sources of floating items were identified with the aid of publicly available databases and scientific reports. We found three main types of floating objects, namely floating marine debris (mainly plastic objects and Styrofoam), wood (trunks and branches), and floating kelps (Macrocystis pyriferaandDurvillaea antarctica). Floating marine debris were abundant along most of the examined transects, with markedly lower abundances toward the southern fjord areas. Floating marine debris abundances generally corresponded to the distribution of human activities, and were highest in the Interior Sea of Chiloé, where aquaculture activities are intense. Floating wood appeared sporadically in the study area, often close to the main rivers. In accordance with seasonal river run-off, wood was more abundant along the continental coast in winter (rainy season) and in the Patagonian fjords during the spring surveys (snow melt). Densities of the two floating kelp species were similar along the continental coast, without a clear seasonal pattern.M. pyriferadensities increased towards the south, peaking in the Patagonian fjords, where it was dominant overD. antarctica. Densities ofM. pyriferain the Patagonian fjords were highest in spring. Correlation analyses between the abundances of floating objects and the distance to the nearest sources were generally non-significant, suggesting that post-supply processes affect the distribution of the floating objects in the study region. The identification of several major retention zones supports this idea. Accumulation areas of floating objects appear to be more common in the fjord zones. In general, the results underscore the abundance of floating objects throughout the study region and the fact that floating marine debris sources are mostly local, whereas floating algae may be dispersed over greater distances. Future studies should focus on the ecological role of floating objects in biota dispersal and nutrient cycling. Keywords
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