Publicaciones
Effects of isolation and fishing on the marine ecosystems of Easter Island and Salas y Gómez, Chile.
Friedlander, A., Ballesteros, E., Beets, J., Berkenpas, E., Gaymer, C., Gorny, M., & Sala, E.
An expedition to Salas y Gómez and Easter islands was conducted to develop a comprehensive baseline of the nearshore marine ecosystem, to survey seamounts of the recently created Motu Motiro Hiva Marine Park (MMHMP) – a no-take marine reserve of 150 000 km2 – and to compare these results with Easter Island where the marine ecosystem is similar but has no marine protection.
Live coral cover was surprisingly high at both Easter Island (53%) and Salas y Gómez (44%), especially considering their sub-tropical location, high wave energy environments, and geographic isolation.
Endemic and regionally-endemic species comprised 77% of the fish abundance at Easter Island and 73% at Salas y Gómez. Fish biomass at Salas y Gómez was relatively high (1.2 t ha-1) and included a large proportion of apex predators (43%), whereas at Easter Island it was almost three times lower (0.45 t ha-1) with large predators accounting for less than 2% of the biomass, despite good habitat quality.
The large cohort of small sharks and the absence of larger sharks at Salas y Gómez suggest mesopredator release consistent with recent shark fishing. The fish fauna at the seamounts between Easter Island and Salas y Gómez, outside of MMHMP, harboured 46% endemic species, including a new species of damselfish (Chromis sp. nov.) and probably a new species of Chimaera (Hydrolagus). Numerous seamounts adjacent to Salas y Gómez are currently not included in the MMHMP.
This expedition highlights the high biodiversity value of this remote part of the Pacific owing to the uniqueness (endemicity) of the fauna, large apex predator biomass, and geographic isolation.
Año: 2013
Palabras claves: Coral; biodiversity; no-take marine reserve; algae; fish; fishing.
Zoning of the Mejillones Peninsula marine protected coastal area of multiple uses, northern Chile.
Ulloa, R., Vargas, A., Hudson, C., & Rivadeneira, M.
Marine protected areas of multiple uses (MPA-MU), are an important management tool to protect biodiversity and regulate the use of coastal marine resources. However, robust conservation plans require an explicit consideration of not only biological but also social components, balancing the protection of biodiversity with a sustainable exploitation of marine resources. Here we applied the decision-making algorithm MARXAN to provide a zoning analysis at the Mejillones Peninsula MPA-MU in northern Chile, one of largest MPA's of the Humboldt Current Marine Ecosystem. We set conservation goals for coarse and fine-filter conservation targets that were crossed out against different threats and pressure factors from human activities across the area. We identified a portfolio of sites for conservation, within the Mejillones Peninsula MPA-MU, representing different ecological systems with different levels of human impacts and vulnerability. These results may serve as a foundational guideline for the future administration of the MPA-MU.
Año: 2013
Palabras claves: MPA-MU, MARXAN, conservation plans, marine coastal ecosystems, northern Chile.
Ecophysiological plasticity and local differentiation help explain the invasion success of Taraxacum officinale (dandelion) in South America.
Molina-Montenegro, M., Palma-Rojas, C., Alcayaga-Olivares, Y., Oses, R., Corcuera, L., Cavieres, L., & Gianoli, E.
Plasticity and local adaptation have been suggested as two main mechanisms that alien species use to successfully tolerate and invade broad geographic areas. In the present study, we try answer the question if the mechanism for the broad distributional range of T. officinale is for phenotypic plasticity, ecotypic adaptation or both. For this, we used individuals of T. officinale originated from seeds collected in five localities along its latitudinal distribution range in the southern-hemisphere. Seedlings were acclimated at 5 and 25°C for one month. After the acclimation period we evaluated ecophysiological and cytogenetic traits. Additionally, we assessed the fitness at each temperature by recording the seed output of individuals from different localities. Finally, we performed a manipulative experiment in order to assess the tolerance to herbivory and competitive ability between T. officinale from all origins and Hypochaeris scorzonerae a co-occurring native species. Overall, individuals of T. officinale showed high plasticity and ecotypic adaptation for all traits assessed in this study. Changes both in physiology and morphology observed in T. officinale from different origins were mostly correlated, enhancing their ecophysiological performance in temperatures similar to those of their origin. Additionally, all localities showed the same chromosome number and ploidy level. On the other hand, all individuals showed an increase the seed output at 25°C, but those from northern localities increased more. T. officinale from all origins was not significantly affected by herbivory while native showed a negative effect. On the other hand, T. officinale exerted a strong negative effect on the native species, but this former not effected significantly to the invasive T. officinale. High plasticity and local adaptation in all ecophysiological traits, seed-set and the low cytogenetic variability in T. officinale suggests that both strategies are present in this invasive plant species and are not mutually exclusive. Finally, higher tolerance to herbivory and competitive ability suggests that T. officinale could perform successfully in environments with different climatic conditions, and thus colonize and invade South-America.
Año: 2013
Palabras claves:
Within-population genetic diversity of climbing plants and trees in a temperate forest in central Chile.
Torres-Díaz, C., Ruiz, E., Salgado-Luarte, C., Molina-Montenegro, M., & Gianoli, E.
The climbing habit is a key innovation in angiosperm evolution: climbing plant taxa have greater species richness than their non-climbing sister groups. It is considered that highly diversified clades should show increased among-population genetic differentiation. Less clear is the expected pattern regarding within-population genetic diversity in speciose lineages. We tested the hypothesis of greater within-population genetic diversity in climbing plants compared to trees in a temperate forest in central Chile. The assumption underlying this hypothesis is that higher among-population differentiation in climbers compared to trees should reflect higher genetic diversity as well. AFLP markers from 167 individual plants from 14 species (seven climbers and seven trees) were used to estimate the following indices of within-population genetic diversity: mean unbiased expected heterozygosity (He), percentage of polymorphic loci (PPL), Shannon information index (I), and the effective number of alleles (Ne). Overall, within-population genetic diversity did not differ between climbing plants and trees. The He for climbing plants was slightly higher than that of trees (0.247 vs. 0.231), and PPL was higher in trees (93.6) than in climbers (81.8), but these differences were not statistically significant. Both I and Ne were very similar for both groups. The expected greater genetic diversity in climbers might have been counterbalanced by tree-related ecological factors that turned to be relevant in the species assemblages studied. Results of this preliminary study should be further confirmed with a broader approach including several forest sites and larger sample sizes.
Año: 2013
Palabras claves: AFLP, climbers, evolution, genetic variability, key innovation.
Positive interactions between the lichen Usnea antarctica (Parmeliaceae) and the native flora in Maritime Antarctica.
Molina-Montenegro, M., Ricote-Martínez, N., Muñoz-Ramírez, C., Gómez-González, S., Torres-Díaz, C., Salgado-Luarte, C., & Gianoli, E.
Eight out of 13 species were positively associated with cushions of the widespread lichen U. antarctica, while only one species (U. aurantiaco-atra) showed a negative association with U. antarctica. Survival of Deschampsia was enhanced when growing associated with U. antarctica cushions. Our results indicate that cushions ameliorated the extreme conditions of Antarctic islands through increased temperature and soil moisture, decreased radiation and evaporative water loss and increased nutrient availability.
Año: 2013
Palabras claves: Antarctica; Deschampsia antarctica ; Facilitation; Global warming; Lichens; Mosses; Nurse effect.
Distribution and abundance of small plastic debris on beaches in the SE Pacific (Chile): A study supported by a citizen science project.
Hidalgo-Ruz, V. & Thiel, M.
The accumulation of large and small plastic debris is a problem throughout the world's oceans and coastlines. Abundances and types of small plastic debris have only been reported for some isolated beaches in the SE Pacific, but these data are insufficient to evaluate the situation in this region. The citizen science project "National Sampling of Small Plastic Debris” was supported by schoolchildren from all over Chile who documented the distribution and abundance of small plastic debris on Chilean beaches. Thirty-nine schools and nearly 1000 students from continental Chile and Easter Island participated in the activity. To validate the data obtained by the students, all samples were recounted in the laboratory. The results of the present study showed that the students were able to follow the instructions and generate reliable data. The average abundance obtained was 27 small plastic pieces per m2 for the continental coast of Chile, but the samples from Easter Island had extraordinarily higher abundances (>800 items per m2). The abundance of small plastic debris on the continental coast could be associated with coastal urban centers and their economic activities. The high abundance found on Easter Island can be explained mainly by the transport of plastic debris via the surface currents in the South Pacific Subtropical Gyre, resulting in the accumulation of small plastic debris on the beaches of the island. This first report of the widespread distribution and abundance of small plastic debris on Chilean beaches underscores the need to extend plastic debris research to ecological aspects of the problem and to improve waste management.
Año: 2013
Palabras claves: Small plastic debris; Anthropogenic litter; Plastics; Citizen Science; SE Pacific; Chile; Easter Island; Marine debris.
Effects of sympatric predatory crabs Romaleon polyodon and Cancer plebejus (Decapoda, Brachyura, Cancridae) on sublittoral macrobenthic communities.
Pacheco, A., Thiel, M., Uribe, R., Campos, L., & Riascos, J.
Although large crabs are recognized as important sediment disturbers influencing the structure of benthic communities, the role of dominant predatory crabs in soft-bottom habitats along the Humboldt Current Ecosystem, remains largely unknown. A field study was conducted, hypothesizing that the digging activity of these predators disturbs the habitat thereby leading to a reduction in individual abundance, biomass and species richness; these changes result in a modified structure of macrobenthic communities. A directed sampling (crab pits vs. reference areas) showed significant reductions in total abundances in pits compared to reference areas, but no differences were observed in taxonomic richness or benthic biomass. Short-term cage experiment showed significant decreases in total abundance and biomass of macroinvertebrates in predator inclusion treatments compared to exclusions and controls. In consequence, our results confirmed that burrowing activities and the generation of small disturbed sediment patches influence the community structure. These results highlight the importance of large cancrid crabs in soft-bottom habitats, where their modification of the physical configuration of the sediment affects community structure over small spatial scales. Crabs are thus an important source of spatial heterogeneity of the sea-floor landscape. This ecological role must be considered in management strategies of the extensive artisanal fishery for these crabs, as current evidence is showing increasing populations of intermediate predators (like cancrid crabs) in many benthic habitats in response to the depletion of top predators.
Año: 2013
Palabras claves: Bioturbation; Burrowing; Cage experiment; Northern Chile; Predation; Small-scale disturbance; Soft bottom.
Identification of self-reported user behavior, education level, and preferences to reduce littering on beaches – A survey from the SE Pacific.
Eastman, L., Núñez, P., Crettier, B., & Thiel, M.
Beach litter is an environmental, health, and economic burden around the world. Reducing or eliminating beach litter requires a sound understanding of the beach users that often produce the litter. Education has consistently been promulgated as positively influencing environmental behaviors, though this is not well-investigated for the beach environment. In this citizen science project, school children surveyed the population in their various coastal communities in Chile, garnering over 900 responses nationwide. The survey included several domains concerning the problem of beach litter: demographic profiles of beach users (including education level), their littering behavior, and their disposition and preference towards solutions. Nearly half of the participants admitted to having littered in some way while the majority of those with college or graduate school education said they never litter, significantly more than lower education groups. A vast majority of the population endorsed a fine for beach littering. Community-level environmental education (for the entire population, including litterers) was the most common solution proposed by beach users, but was significantly less popular the more often the participant self-reported littering. Based on these results it is suggested that beach managers create multifaceted and localized solutions that involve several strategies (environmental education, fines, more trash cans) and also take into account the demographic profile of the beach users (including their education level), which could influence their littering behavior and support of potential solutions.
Año: 2013
Palabras claves:
Dispersal of post-larval macrobenthos in subtidal sedimentary habitats: Roles of vertical diel migration, water column, bedload transport and biological traits’ expression.
Pacheco, A., Uribe, R., Thiel, M., Oliva, M., & Riascos, J.
Post-larval dispersal along the sediment–water interface is an important process in the dynamics of macrobenthic populations and communities in marine sublittoral sediments. However, the modes of post-larval dispersal in low energy sublittoral habitats have been poorly documented. Herein we examined the specific dispersal mechanisms (diel vertical migration, water column, and bedload transport) and corresponding biological traits of the dispersing assemblage. At two sublittoral sites (sheltered and exposed) along the northern coast of Chile, we installed different trap types that capture benthic organisms with specific modes of dispersal (active emergence and passive water column drifting) and also by a combination of mechanisms (bedload transport, passive suspension and settlement from the water column). Our results show that even though there were common species in all types of traps, the post-larval macrobenthic assemblage depended on specific mechanisms of dispersal. At the sheltered site, abundant emerging taxa colonized sediments that were placed 0.5 m above the bottom and bedload-transported invertebrates appeared to be associated to the passive drifting of macroalgae. At the exposed site, assemblage dispersal was driven by specific mechanisms e.g. bedload transport and active emergence. At both sites the biological traits “small size, swimming, hard exoskeleton, free living and surface position” were associated to water column and bedload dispersal. This study highlights the importance of (i) the water–sediment interface for dispersal of post-larvae in sublittoral soft-bottom habitat, and (ii) a specific set of biological traits when dispersing either along the bottom or through the water column.
Año: 2013
Palabras claves: Emerging Benthos; Bottom Currents; Soft-bottom Communities; Humboldt Current Ecosystem.
Seasonal variation in floating persistence of detached Durvillaea antarctica (Chamisso) Hariot thalli.
Graiff, A., Karsten, U., Meyer, S., Pfender, D., Tala, F., & Thiel, M.
Several large kelp species are capable of long-distance dispersal via rafting. However, seasonal changes in environmental conditions at the sea surface may variably affect the physiological status of the floating thalli; challenging conditions during summer may accelerate disintegration and cause rapid sinking. We used the bull kelp Durvillaea antarctica from northern-central Chile (30°S) to test seasonal variation in floating persistence. Experiments with tethered specimens were conducted in all seasons to assess how variable environmental conditions influence the morphology and photosynthetic characteristics of floating D. antarctica. Floating specimens stayed afloat at the surface for more than 1 month during moderate environmental conditions that prevailed in winter, spring, and fall. However, higher water temperatures and intense solar radiation in summer resulted in significant biomass losses and rapid disintegration of the floating kelps; consequently, they sank within <1 month. These strong seasonal effects were reflected in decreasing maximal quantum yield as well as in maximum relative electron transport rates of photosynthesis. Understanding physiological responses of floating algae is important because increasing global temperatures and shifts in solar radiation may strongly affect the survival of floating algae, potentially reducing the distances and frequencies of rafting dispersal.
Año: 2013
Palabras claves: Durvillaea antarctica; floating persistence; rafting; temperature; UV radiation.