No reef-associated gradient in the infaunal communities of Rapa Nui (Easter Island) – Are oceanic waves more important than reef predators?
Gusmao, J., Lee, M., MacDonald, I., Ory, N., Sellanes, J., Watling, L. and Thiel, M.
Reef-associated predators are thought to influence the distribution of invertebrates of surrounding sediment habitats. In this study, we analyzed the predation pressure and the distributional patterns of macro- and meiofaunal assemblages in soft sediments surrounding two coral reef sites at Rapa Nui (Easter Island), in the central South Pacific. We tested the hypothesis that reef-associated predators negatively affect sediment-dwelling invertebrates, causing macro- and meiofauna to be less abundant and diverse in soft sediments near the reefs. As expected, predation intensity was greater nearer the reef than farther away, but macro- and meiofaunal assemblages did not differ significantly with distance from the reef. Taxon richness of macro- and meiofaunal assemblages were similar irrespective of distance from the reef. Only meiofauna showed significant variation in total abundance with distance from the reef, but this trend was not consistent between the two study sites. No gradient in sediment texture was observed with distance from the reef. Underwater video recordings at one study site also revealed that local hydrodynamics cause frequent disturbance and resuspension of the upper sediment layers. Our results suggest that soft-sediment assemblages are constantly reshuffled by oceanic waves, thereby blurring the potential effects of predation on invertebrate assemblages closer to the reef.
Palabras claves: Easter islandSoft-bottom assemblagesMacrofaunaMeiofaunaInfaunal halosReef fishesPredation
Spatio-temporal variation of anthropogenic marine debris on Chilean beaches
Hidalgo-Ruz, V., Honorato-Zimmer, D., Gatta-Rosemary, M., Nuñez, P., Hinojosa, I. and Thiel, M.
We examined the hypothesis that in an emerging economy such as Chile the abundances of Anthropogenic Marine Debris (AMD) on beaches are increasing over time. The citizen science program Científicos de la Basura (“Litter Scientists”) conducted three national surveys (2008, 2012 and 2016) to determine AMD composition, abundance, spatial patterns and temporal trends. AMD was found on all beaches along the entire Chilean coast. Highest percentages of AMD in all surveys were plastics and cigarette butts, which can be attributed to local sources (i.e. beach users). The Antofagasta region in northern Chile had the highest abundance of AMD compared with all other zones. Higher abundances of AMD were found at the upper stations from almost all zones. No significant tendency of increasing or decreasing AMD densities was observed during the 8 years covered by our study, which suggests that economic development alone cannot explain temporal trends in AMD densities.
Palabras claves: Anthropogenic marine debrisBeachesCitizen scienceTemporal trendsAntofagastaEconomic development
Metagenomic exploration of soils microbial communities associated to Antarctic vascular plants
Molina-Montenegro, M., Ballesteros, G., Castro-Nallar, E., Meneses, C., Torres-Díaz, C. and Gallardo-Cerda, J.
Antarctica is one of the most stressful ecosystems worldwide with few vascular plants,which are limited by abiotic conditions. Here, plants such as Deschampsia antarctica (Da)could generate more suitable micro-environmental conditions for the establishment ofother plants as Colobanthus quitensis (Cq). Although, plant-plant interaction is known todetermine the plant performance, little is known about how microorganisms mightmodulate the ability of plants to cope with stressful environmental conditions. Severalreports have focused on the possible ecological roles of microorganism with vascularplants, but if the rizospheric microorganisms can modulate the positive interactions amongvascular Antarctic plants has been seldom assessed. In this study, we compared therhizosphere microbiomes associated with Cq, either growing alone or associated with Da,using a shotgun metagenomic DNA sequencing approach and using eggNOG forcomparative and functional metagenomics. Overall, results show higher diversity oftaxonomic and functional groups in rhizospheric soil from Cq+Da than Cq. On the otherhand, functional annotation shows that microorganisms from rhizospheric soil from Cq+Dahave a significantly higher representation of genes associated to metabolic functionsrelated with environmental stress tolerance than Cq soils. Additional research is needed toexplore both the biological impact of these higher activities in terms of gene transfer onplant performance and in turn help to explain the still unsolved enigma about the strategydeployed by Cq to inhabit and cope with harsh conditions prevailing in Antarctic.
Temporal Variability of MODIS Phenological Indices in the Temperate Rainforest of Northern Patagonia
Lara, C., Saldías, G., Paredes, A., Cazelles, B. and Broitman, B.
Western Patagonia harbors unique and sparsely studied terrestrial ecosystems that are threatened by land use changes and exposure to basin-scale climatic variability. We assessed the performance of two satellite vegetation indices derived from MODIS–Terra, EVI (Enhanced Vegetation Index) and NDVI (Normalized Difference Vegetation Index), over the northern and southern sectors of the Chiloé Island System (CIS) to advance our understanding of vegetation dynamics in the region. Then we examined their time-varying relationships with two climatic indices indicative of tropical and extratropical influence, the ENSO (El Niño–Southern Oscillation) and the Antarctic Oscillation (AAO) index, respectively. The 17-year time series showed that only EVI captured the seasonal pattern characteristic of temperate regions, with low (high) phenological activity during Autumn-Winter (Spring–Summer). NDVI saturated during the season of high productivity and failed to capture the seasonal cycle. Temporal patterns in productivity showed a weakened seasonal cycle during the past decade, particularly over the northern sector. We observed a non-stationary association between EVI and both climatic indices. Significant co-variation between EVI and the Niño–Southern Oscillation index in the annual band persisted from 2001 until 2008–2009; annual coherence with AAO prevailed from 2013 onwards and the 2009–2012 period was characterized by coherence between EVI and both climate indices over longer temporal scales. Our results suggest that the influence of large-scale climatic variability on local weather patterns drives phenological responses in the northern and southern regions of the CIS. The imprint of climatic variability on patterns of primary production across the CIS may be underpinned by spatial differences in the anthropogenic modification of this ecosystem, as the northern sector is strongly modified by forestry and agriculture. We highlight the need for field validation of satellite indices around areas of high biomass and high endemism, located in the southern sector of the island, in order to enhance the utility of satellite vegetation indices in the conservation and management of austral ecosystems.
Palabras claves: MODIS; primary productivity; climatic variability; vegetation index; wavelet coherence
Asymmetric connectivity of the lobster Panulirus pascuensis in remote islands of the southern Pacific: importance for its management and conservation
Meerhoff, E., Yannicelli, B., Dewitte, B., Díaz-Cabrera, E., Vega-Retter, C., Ramos, M., Bravo, L., Concha, E., Hernández-Vaca, F. and Véliz, D.
Understanding patterns of marine connectivity in oceanic islands is a fundamental element for conservation and management of fished species. In the present study, the level of connectivity of the endemic lobster Panulirus pascuensis Reed, 1954 from remote islands in the southern Pacific Ocean was estimated, focusing on the Motu Motiro Hiva Marine Park (MMH), considered here as a source of recruits to Easter Island. The connectivity of adult lobster populations between Eastern Island (EI) and Salas y Gómez Island (SG), in the center of MMH, was studied by quantifying the reciprocal migration rates using variability of microsatellite loci and a biophysical individual-based model of larval transport based on the outputs of a regional high-resolution oceanic model. Considering a system composed only of adult populations located in both islands, the genetic analysis showed that 3% of the adults from EI came from SG; however, only 0.02% in the opposite direction. Neglecting the effect of other islands (e.g., Pitcairn Island located at 2000 km west of EI), the self-recruitment was estimated at 97% in EI and 99.8% in SG. The results of the Lagrangian analysis of the oceanic model simulations are consistent with the concept of asymmetric connectivity, although there is appreciable variation in recruitment among years. Both genetic and oceanographic approaches revealed large variance in connectivity from SG to EI. The asymmetric connectivity from SG to EI emphasizes the importance of the MMH Marine Park for lobster conservation in SG, and that it also supports recruitment of P. pascuensis to EI.
Breeding of the south american tern (Sterna hirundinacea) on anchored boats in Coquimbo, northern Chile
Portflitt-Toro, M., Miranda-Urbina, D., Fernández, C., Luna, N., Plaza, P., Serratosa, J., Thiel, M., Luna-Jorquera, G.
Abstract · We report the breeding attempt of South American Terns (Sterna hirundinacea) on three boats in
Coquimbo, northern Chile. The first breeding attempt was reported in winter 2011 where at least one chick fledged. From April to June 2015, all nests on the boats were monitored. We recorded eggs and chicks during May and early June. However, towards the end of June, no eggs or chicks were recorded in the nests, and a Chimango Caracara (Phalcoboenus chimango) was observed preying on chicks in one nest. In April and May 2017, breeding attempts on boats were also monitored and nests with eggs and one chick were recorded. However, at the end of May all nests were empty. This unusual nesting site for South American Terns is apparently regularly used in the area despite its virtually null breeding success.
Resumen · Reproducción del Gaviotín Sudamericano (Sterna hirundinacea) en botes anclados en Coquimbo, norte de Chile
Reportamos el intento de reproducción del Gaviotín Sudamericano (Sterna hirundinacea) sobre tres botes en Coquimbo, norte de Chile. Un primer intento de reproducción para esta zona se registró en invierno de 2011, donde al menos un pollo dejó un nido como volantón. Entre Abril y Junio de 2015 monitoreamos los nidos en los botes de manera más intensiva. Registramos huevos y pollos durante Mayo y principios de Junio. Sin embargo, a finales de Junio, no registramos huevos en los nidos y observamos un Tiuque (Phalcoboenus chimango) depredar sobre los pollos. En Abril y Mayo de 2017, monitoreamos otros intentos de reproducción y registramos un pollo y nidos con huevos. Sin embargo, a finales de Mayo, esos nidos estaban vacíos. Este inusual sitio de nidificación parece ser utilizado de forma recurrente por el Gaviotín Sudamericano, a pesar del aparente casi nulo éxito reproductivo.
Palabras claves: Anchored boats, Chile, Nesting, Predation, South American Tern
Phenotypic plasticity at the edge: Contrasting population‐level responses at the overlap of the leading and rear edges of the geographical distribution of two Scurria limpets
Broitman, B., Aguilera, M., Lagos, N. and Lardies, M.
To examine the role of ocean temperature and chemistry as drivers of interpopulation differences in multiple phenotypic traits between rear and leading edge populations of two species of limpet.
The coast of north‐central Chile, western South America.
Mollusca, Gastropoda (Lottidae).
We used field and laboratory experiments to study the ecology and physiology of individuals from populations located at the overlap of the rear and leading edges of their respective geographical distributions. At the same time, we characterized local environmental regimes, measuring seawater physical and chemical properties.
Towards the edge of their range, individuals from the leading edge species gradually reduced their shell length, metabolic rate and thermal response capacity, and increased carbonate content in their shells. Individuals of the rear edge species showed dissimilar responses between sites. Contrasting behavioural responses to experimental heating reconciled observations of an unintuitive higher maximal critical temperature and a smaller thermal safety margin for individuals of the rear edge populations. Physical–chemical characterization of seawater properties at the site located on the core of the upwelling centre showed extreme environmental conditions, with low oxygen concentration, high pCO2 and the episodic presence of corrosive seawater. These challenging environmental conditions were reflected in reduced growth for both species.
We found different spatial patterns of phenotypic plasticity in two sister species around the leading and trailing edges of their distributions. Our results provide evidence that environmental conditions around large upwelling centres can maintain biogeographical breaks through metabolic constraints on the performance of calcifying organisms. Thus, local changes in seawater chemistry associated with coastal upwelling circulation emerge as a previously overlooked driver of marine range edges.
Palabras claves: biogeographical break, calcification, limpet, Scurria, SE Pacific, thermal physiology, upwelling
Impacts of Marine Plastic Pollution From Continental Coasts to Subtropical Gyres—Fish, Seabirds, and Other Vertebrates in the SE Pacific.
Thiel, M., Luna-Jorquera, G., Álvarez-Varas, R., Gallardo, C., Hinojosa, I., Luna, N., Miranda-Urbina, D., Morales, N., Ory, N., Pacheco, A., Portflitt-Toro, M. and Zavalaga, C.
Anthropogenic Marine Debris (AMD) in the SE Pacific has primarily local origins from land-based sources, including cities (coastal and inland), beach-goers, aquaculture, and fisheries. The low frequency of AMD colonized by oceanic biota (bryozoans, lepadid barnacles) suggests that most litter items from coastal waters of the Humboldt Current System (HCS) are pulled offshore into the South Pacific Subtropical Gyre (SPSG). The highest densities of floating micro- and macroplastics are reported from the SPSG. An extensive survey of photographic records, unpublished data, conference proceedings, and published studies revealed interactions with plastics for 97 species in the SE Pacific, including 20 species of fish, 5 sea turtles, 53 seabirds, and 19 marine mammals. Sea turtles are most affected by interactions with plastics, underlined by the fact that 4 of the 5 species suffer both from entanglement and ingestion. Reports gathered in this review suggest that interactions along the continental coast are mostly via entanglement. High frequencies of microplastic ingestion have been reported from planktivorous fish and seabirds inhabiting the oceanic waters and islands exposed to high densities of microplastics concentrated by oceanic currents in the SPSG. Our review also suggests that some species from the highly productive HCS face the risk of negative interactions with AMD, because food and plastic litter are concentrated in coastal front systems. In order to improve the conservation of marine vertebrates, especially of sea turtles, urgent measures of plastic reduction are needed.
Palabras claves: anthropogenic marine debris, impacts, biota-litter interactions, entanglement, microplastic ingestion
Relative performance of empirical and physical models in assessing the seasonal and annual glacier surface mass balance of Saint-Sorlin Glacier (French Alps)
Réveillet, M., Six, D., Vincent, C., Rabatel, A., Dumont, M., Lafaysse, M., Morin, S., Vionnet, V. and Litt, M.
This study focuses on simulations of the seasonal and annual surface mass balance (SMB) of Saint-Sorlin Glacier (French Alps) for the period 1996–2015 using the detailed SURFEX/ISBA-Crocus snowpack model. The model is forced by SAFRAN meteorological reanalysis data, adjusted with automatic weather station (AWS) measurements to ensure that simulations of all the energy balance components, in particular turbulent fluxes, are accurately represented with respect to the measured energy balance. Results indicate good model performance for the simulation of summer SMB when using meteorological forcing adjusted with in situ measurements. Model performance however strongly decreases without in situ meteorological measurements. The sensitivity of the model to meteorological forcing indicates a strong sensitivity to wind speed, higher than the sensitivity to ice albedo. Compared to an empirical approach, the model exhibited better performance for simulations of snow and firn melting in the accumulation area and similar performance in the ablation area when forced with meteorological data adjusted with nearby AWS measurements. When such measurements were not available close to the glacier, the empirical model performed better. Our results suggest that simulations of the evolution of future mass balance using an energy balance model require very accurate meteorological data. Given the uncertainties in the temporal evolution of the relevant meteorological variables and glacier surface properties in the future, empirical approaches based on temperature and precipitation could be more appropriate for simulations of glaciers in the future.
Isolation and characterization of Pb-solubilizing bacteria and their effects on Pb uptake by Brassica juncea: implications for microbe-assisted phytoremediation
Yahaghi, Z., Shirvani, M., Nourbakhsh, F., de la Peña, T.C., Pueyo, J.J., Talebi, M.
The aim of this study was to isolate and characterize lead (Pb)-solubilizing bacteria from heavy metal-contaminated mine soils and to evaluate their inoculation effects on the growth and Pb absorption of Brassica juncea. The isolates were also evaluated for their plant growth-promoting characteristics as well as heavy metal and salt tolerance. A total of 171 Pb-tolerant isolates were identified, of which only 15 bacterial strains were able to produce clear haloes in solid medium containing PbO or PbCO3, indicating Pb solubilization. All of these 15 strains were also able to dissolve the Pb minerals in a liquid medium, which was accompanied by significant decreases in pH values of the medium. Based on 16S rRNA gene sequence analysis, the Pb-solubilizing strains belonged to genera Bacillus, Paenibacillus, Brevibacterium, and Staphylococcus. A majority of the Pb-solubilizing strains were able to produce indole acetic acid and siderophores to different extents. Two of the Pb-solubilizing isolates were able to solubilize inorganic phosphate as well. Some of the strains displayed tolerance to different heavy metals and to salt stress and were able to grow in a wide pH range. Inoculation with two selected Pb-solubilizing and plant growth-promoting strains, (i.e., Brevibacterium frigoritolerans YSP40 and Bacillus paralicheniformis YSP151) and their consortium enhanced the growth and Pb uptake of B. juncea plants grown in a metal-contaminated soil. The bacterial strains isolated in this study are promising candidates to develop novel microbe-assisted phytoremediation strategies for metal-contaminated soils.
Palabras claves: Metal-solubilizing bacteria, PGPR, contaminated soils, lead, phytoremediation