Temporal and spatial distribution of floating objects in coastal waters of central–southern Chile and Patagonian fjords |
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| Authors: | Iván A Hinojosa Marcelo M Rivadeneira Martin Thiel |
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| Institution: | 1. Universidad Católica del Norte, Larrondo 1281, Coquimbo, Chile;2. Centro de Estudios Avanzados en Zonas Áridas (CEAZA), Coquimbo, Chile;3. Center for Advanced Studies in Ecology and Biodiversity (CASEB), Departamento de Ecología, Pontificia Universidad Católica de Chile, Alameda 340, Santiago, Chile;1. Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, 93106, USA;2. Marine Science Institute, University of California, Santa Barbara, CA, 93106, USA;1. Department of Biotechnology, Achariya Arts and Science College, Puducherry, 605 110, India;2. Department of Oceanography and Coastal Area Studies, School of Marine Sciences, Alagappa University, Karaikudi- 630 003, Tamil Nadu, India;3. Department of Marine Science, Bharathidasan University, Tiruchirappalli, 620024, Tamil Nadu, India;1. Université de Toulon, UMR7294, CNRS/INSU, IRD – Mediterranean Institute of Oceanography (MIO), UM 110, 83957 La Garde, France;2. Ifremer, Immeuble Agostini, ZI Furiani, 20600 Bastia, Corsica, France;3. Association Mer-Terre, 21 Rue Montgrand, 13006 Marseille, France |
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| 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 pyrifera and Durvillaea 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. pyrifera densities increased towards the south, peaking in the Patagonian fjords, where it was dominant over D. antarctica. Densities of M. pyrifera in 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. |
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