Temporal and spatial distribution of floating objects in coastal waters of central-southern Chile and Patagonian fjords

• Published in: Continental Shelf Research
• Main Authors: Hinojosa Toledo, IA, Rivadeneira, MM, Thiel, M
• Format: Article in Journal/Newspaper
• Language: English
• Published: Pergamon-Elsevier Science Ltd 2011
• Subjects: Environmental Sciences; Environmental Science and Management; Conservation and Biodiversity; Antarc*; Antarctica
• Online Access: https://doi.org/10.1016/j.csr.2010.04.013; http://ecite.utas.edu.au/88826

Floating objectsaresuggestedtobetheprincipalvectorforthetransportanddispersalofmarineinvertebrateswithdirectdevelopmentaswellascatalystsforcarbonandnutrientrecyclinginaccumulationareas.Thefirststepinidentifyingtheecologicalrelevanceoffloatingobjectsinaspecificarea istoidentifytheirspatio-temporaldistribution.Weevaluatedthecomposition,abundance,distribution,andtemporalvariabilityoffloatingobjectsalongthecontinentalcoastofcentralsouthernChile (33421S) andthePatagonianfjords(42501S) usingshipsurveysconductedinaustralwinter(July/August)andspring(November)oftheyears20022005and2008.Potentialsourcesoffloatingitems wereidentifiedwiththeaidofpubliclyavailabledatabasesandscientificreports.Wefoundthreemain typesoffloatingobjects,namelyfloatingmarinedebris(mainlyplasticobjectsandStyrofoam),wood (trunksandbranches),andfloatingkelps(Macrocystispyrifera and Durvillaea antarctica).Floatingmarinedebriswereabundantalongmostoftheexaminedtransects,withmarkedlylowerabundancestowardthesouthernfjordareas.Floatingmarinedebrisabundancesgenerallycorrespondedtothedistributionofhumanactivities,andwerehighestintheInteriorSeaofChiloe , whereaquacultureactivitiesareintense.Floatingwoodappearedsporadicallyinthestudyarea,oftenclosetothemainrivers. Inaccordancewithseasonalriverrun-off,woodwasmoreabundantalongthecontinentalcoastin winter(rainyseason)andinthePatagonianfjordsduringthespringsurveys(snowmelt).Densitiesofthe twofloatingkelpspeciesweresimilaralongthecontinentalcoast,withoutaclearseasonalpattern.M. pyrifera densitiesincreasedtowardsthesouth,peakinginthePatagonianfjords,whereitwasdominantover D. antarctica. Densitiesof M. pyrifera in thePatagonianfjordswerehighestinspring.Correlationanalysesbetweentheabundancesoffloatingobjectsandthedistancetothenearestsourceswere generallynon-significant,suggestingthatpost-supplyprocessesaffectthedistributionofthefloating objectsinthestudyregion.Theidentificationofseveralmajorretentionzonessupportsthisidea.Accumulationareasoffloatingobjectsappeartobemorecommoninthefjordzones.Ingeneral,the resultsunderscoretheabundanceoffloatingobjectsthroughoutthestudyregionandthefactthatfloating marinedebrissourcesaremostlylocal,whereasfloatingalgaemaybedispersedovergreaterdistances.Futurestudiesshouldfocusontheecologicalroleoffloatingobjectsinbiotadispersalandnutrientcycling.