Daily accumulation rates of floating debris and attached biota on continental and oceanic island shores in the SE Pacific: testing predictions based on global models

PeerJ

article

Sabine Rech¹  Rene Matias Arias¹  Simón Vadell¹  Dennis Gordon³  Martin Thiel¹ 

[1] Departamento de Biologia Marina, Facultad de Ciencias del Mar, Universidad Catolica del Norte;Center for Ecology and Sustainable Management of Oceanic Islands ESMOI, Universidad Catolica del Norte;National Institute of Water and Atmospheric Research;Centro de Estudios Avanzados en Zonas Áridas

关键词: Anthropogenic marine debris;    Floating litter;    Marine currents;    Marine invertebrates;    Plastic pollution;    South Pacific Subtropical Gyre;    Marine debris accumulation patterns;    Invasive species;    Dispersal by rafting;    Rapa Nui (Easter Island);   

DOI  :  10.7717/peerj.15550

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

BackgroundLong-distance rafting on anthropogenic marine debris (AMD) is thought to have a significant impact on global marine biogeography and the dispersal of non-indigenous species. Therefore, early identification of arrival sites of AMD and its epibionts is crucial for the prioritization of preventive measures. As accumulation patterns along global coastlines are largely unstudied, we tested if existing oceanographic models and knowledge about upstream sources of litter and epibionts can be used as a simple and cost-efficient approach for predicting probable arrival sites of AMD-rafting biota in coastal zones.MethodsUsing the Southeast Pacific as a model system, we studied daily accumulation rates, composition, and minimum floating times of AMD with and without epibionts on seven sandy beaches, covering the oceanic environment (Rapa Nui/Easter Island) and three regions (south, centre, north) along the Chilean continental coast, over a minimum of 10 consecutive days, and we contrast our results with predictions from published models.ResultsTotal AMD accumulation rates varied from 56 ± 36 (mean ± standard deviation) to 388 ± 433 items km−1 d−1 and differed strongly between regions, in accordance with local geomorphology and socioeconomic conditions (presence of larger cities and rivers upstream, main economic activities, etc.). Daily accumulation of items with pelagic epibionts (indicators of a pelagic trajectory) ranged from 46 ± 29 (Rapa Nui) to 0.0 items km−1 d−1 (northern continental region). Minimum floating times of rafts, as estimated from the size of pelagic epibionts, were longest in the South Pacific Subtropical Gyre’s (SPSG) centre region, followed by the high-latitude continental region under the influence of the onshore West Wind Drift, and decreased along the continental alongshore upwelling current, towards lower latitudes. Apart from pelagic rafters, a wide range of benthic epibionts, including invasive and cryptogenic species, was found on rafts at the continental beaches. Similarly, we present another record of local benthic corals Pocillopora sp., on Rapa Nui rafts.DiscussionOur results agree with the predictions made by recent models based on the prevailing wind and surface current regimes, with high frequencies of long-distance rafting in the oceanic SPSG centre and very low frequencies along the continental coast. These findings confirm the suitability of such models in predicting arrival hotspots of AMD and rafting species. Moreover, storm surges as well as site-related factors seem to influence AMD arrival patterns along the Chilean continental coast and might cause the observed high variability between sampling sites and days. Our results highlight the possible importance of rafting as a vector of along-shore dispersal and range expansions along the SE Pacific continental coast and add to the discussion about its role in benthic species dispersal between South Pacific oceanic islands.

【 授权许可】

CC BY