Antagonistic interplay between pH and food resources affects copepod traits and performance in a year-round upwelling system

Autores:

Aguilera, V., Vargas, C., & Dam, H.

Resumen:

Linking pH/pCO2 natural variation to phenotypic traits and performance of foundational species provides essential information for assessing and predicting the impact of ocean acidification (OA) on marine ecosystems. Yet, evidence of such linkage for copepods, the most abundant metazoans in the oceans, remains scarce, particularly for naturally corrosive Eastern Boundary Upwelling systems (EBUs). This study assessed the relationship between pH levels and traits (body and egg size) and performance (ingestion rate (IR) and egg reproduction rate (EPR)) of the numerically dominant neritic copepod Acartia tonsa, in a year-round upwelling system of the northern (23° S) Humboldt EBUs. The study revealed decreases in chlorophyll (Chl) ingestion rate, egg production rate and egg size with decreasing pH as well as egg production efficiency, but the opposite for copepod body size. Further, ingestion rate increased hyperbolically with Chl, and saturated at ~1 µg Chl. L−1. Food resources categorized as high (H, >1 µg L−1) and low (L, <1 µg L−1) levels, and pH-values categorized as equivalent to present day (≤400 µatm pCO2, pH > 7.89) and future (>400 µatm pCO2, pH < 7.89) were used to compare our observations to values globally employed to experimentally test copepod sensitivity to OA. A comparison (PERMANOVA) test with Chl/pH (2*2) design showed that partially overlapping OA levels expected for the year 2100 in other ocean regions, low-pH conditions in this system negatively impacted traits and performance associated with copepod fitness. However, interacting antagonistically with pH, food resource (Chl) maintained copepod production in spite of low pH levels. Thus, the deleterious effects of ocean acidification are modulated by resource availability in this system.

Año: 2020

Palabras claves:

Can hydraulic traits help to explain the current distributional limits in two Nothofagus species in the Chilean Andes?

Autores:

Carrasco-Urra, F., Saldaña, A., Molina-Montenegro, M.A.

Resumen:

The Andes of central Chile is a geographical gradient with a marked variation in its climatic conditions. Along its
slopes, are distributed the evergreen Nothofagus dombeyi and deciduous Nothofagus pumilio species that show
differences in their leaf habits, range extensions, and in their limits of latitudinal distribution. Plant ecology
proposes that unfavorable climatic conditions are limiting factors that determine the tree species distributions
and that the functional hydraulic traits responses allow understanding the mechanisms underlying the current
distribution of them. We hypothesize that both species will have lower mean values of KL and KS in populations
near to distribution limits compared with middle populations due that unfavorable climatic conditions are
predominant in the latitudinal range limits. We quantify in situ the leaf (KL) and xylem (KS) specific hydraulic conductivities in populations of N. dombeyi and N. pumilio near their northern and southern limits of distribution
as well as in a middle population along Chilean Andes. Results showed that both species had lower mean values
in populations near northern and southern limits compared to populations distributed in middle sites. Also, we
found that the hydraulic performance population of N. pumilio distributed in the middle site had higher than
N. dombeyi. We concluded that lower hydraulic conductivity associated with distribution limits for both study
species implies a lower probability of being affected by embolism, independently of their leaf habits, showing a
functional hydraulic convergence to low water availability or cold.

Año: 2019

Palabras claves: embolism, evergreen vs deciduous, hydraulic traits, Nothofagus , species distribution.

An analysis of modern pollen rain on an elevational gradient in the High-Andes of Central Chile (33°)

Autores:

Fernández Murillo, M.P., Cuevas, J.G., Maldonado, A.

Resumen:

The superficial pollen records are tools for the vegetal reconstruction of a certain area. Like a plant record,
pollen can be used to classify plant formations and determine plant diversity. Although some studies show the
relationship between pollen and vegetation in Chile, few have explored the pollen diversity in an altitudinal
gradient and its sensitivity as a marker of altitudinal belts. Consequently, we used pollen samples of surface soil
and by means of morphological identification, cluster analysis and zonation we determined the pollen groups
that represent the vegetation floors in an altitudinal gradient. Moreover, we compared pollen diversity among
these floors for three basins of the Chilean Central Andes as a comprehensive index of the pollen composition
and abundance. In the Laguna del Viento basin, four pollen groups coincided with the plant floors previously defined in the literature: sub Andean, Andean, and High Andean. The latter one was subdivided into two groups.
In the El Yeso basin, two pollen groups were determined, all corresponding to the Andean floor, and finally in
the El Volcán basin, two pollen groups were recorded that are related to the sub Andean and Andean vegetation
floors. On the other hand, only in one basin the pollen diversity decreased with the altitude. These results
showed that pollen assemblages can distinguish plant floors, but with a lower resolution than when using
established flora, probably due to the pollen taxonomic resolution, differential production and dispersal factors.

Año: 2019

Palabras claves: Altitude, Andes of Central Chile, diversity, pollen, vegetal distribution.

Molecular characterization and expression patterns of two LPS binding /bactericidal permeability-increasing proteins (LBP/BPIs) from the scallop Argopecten purpuratus.

Autores:

González, R., Brokordt, K., Rojas, R., & Schmitt, P.

Resumen:

Lipopolysaccharide-binding proteins (LBPs) and bactericidal permeability-increasing proteins (BPIs) are effec-
tors of the innate immune response which act in a coordinated manner to bind and neutralize the LPS present in

Gram negative bacteria. The structural organization that confers the function of LBPs and BPIs is very similar,
however, they are antagonistic to each other. In this work, we characterized two LBP/BPIs from the scallop
Argopecten purpuratus, namely ApLBP/BPI1 and ApLBP/BPI2. The molecular and phylogenetic analyses of
ApLBP/BPIs indicated that both isoforms display classic characteristics of LBP/BPIs from other invertebrates.

Additionally, ApLBP/BPIs are constitutively expressed in scallop tissues and their transcript expression is up-
regulated in hemocytes and gills in response to an immune challenge. However, some structural characteristics

of functional importance for the biological activity of these molecules, such as the net charge differ substantially
between ApLBP/BPI1 and ApLBP/BPI2. Furthermore, each isoform displays a specific profile of basal expression
among different tissues, as well as specific patterns of expression during the activation of the immune response.
Results suggest that functional specialization of ApLBP/BPIs might happen, with potential role as LBP or BPI in
this species of scallop. Further research on the biological activities of ApLBP/BPIs are necessary to elucidate their
participation in the scallop immune response.

Año: 2020

Palabras claves: Innate immunity, Antimicrobial effectors, Mollusks, Scallops, Aquaculture

Biochemical composition as a function of fruit maturity stage of bell pepper (Capsicum annum) inoculated with Bacillus amyloliquefaciens

Autores:

Cisternas-Jamet, J., Salvatierra-Martínez, R., Vega-Gálvez, A., Stoll, A., Uribe, E., & Goñi, M.

Resumen:

The use of growth promoting bacteria in sweet pepper plants (Capsicum annuum), such as some Bacillus strains,
has previously been related to increased yields and plant resistance. However, it is also important to evaluate the
effect that inoculation has on the ripening process and on the nutritional composition of the fruits. In the present
work, the effect of root inoculation of sweet pepper plants with Bacillus amyloliquefaciens on the composition of
sweet peppers harvested at different stages of maturation is evaluated. It was possible to determine a clear effect
of inoculation on the fixation of Ca and Fe, and the content of vitamin C and compounds with antioxidant
capacity. Root inoculation with Bacillus amyloliquefaciens generated an increase in the concentration of calcium,
iron and vitamin C of 561 mg kg−1, 182 mg kg−1 and 561 μg 100 g−1 d.m., respectively in Red II and Green I
compared to the control samples. An increase in antioxidant capacity was generated, which is reflected in an
increase in the ORAC test of 1618 umol TE 100 g−1 d.m. and in 587 umol TE 100 g−1 d.m. for Green I and Red I
crops respectively. On the other hand, the effect of the fruit ripening process was significant, especially in
relation to the development of natural pigments and phenolic compounds, with high antioxidant potential. An
increased of extractable pigments of 57 color units with respect to the control sample in Red II is highlighted,
which enhances the organoleptic attractiveness of the fruit. These results would allow producers to determine
the time at which to harvest to maximize the nutritional contribution of sweet peppers.

Año: 2020

Palabras claves: Bacillus, Biofertilizer, Nutraceutical, Antioxidants, Vitamin C

Modeling the reproductive impact of aquaculture-produced sexually fertile triploids on conspecific diploid populations

Autores:

Winkler, F., Concha, M., & Concha, C.

Resumen:

The use of artificially produced triploid (3n) organisms has been proposed as a strategy to produce total or partial sterility in a number of species in order to prevent the potential negative effects of escapees on the genetic structure and integrity of wild conspecific populations or to avoid having alien species become feral in a new environment. When infertility is incomplete, triploid organisms are able to produce gametes that compete with those produced by wild diploid populations or crops that share the same habitat during reproductive periods, which may adversely affect the reproductive success of the wild population. In the present study, a model was developed in order to estimate the effects of the production of gametes by triploid organisms on the reproductive efficiency of a sympatric diploid population of the same species. The chance of the production of balanced gametes by triploids rapidly reduced with the increase of haploid number of the species. It was concluded that, in most aquatic species, this effect depends on the relative contribution of gametes derived from triploid individuals ( pet), which is determined by the proportion of triploids in the population and their relative fecundity relative to normal diploids. The variation of the reproductive efficiency in a mixed population of diploids and triploids will be directly proportional to pet if only one sex is fertile in triploids but will have a logarithmic relationship if both sexes are fertile.

Año: 2019

Palabras claves: Triploids, Risk assessment, Reproductive success, Sterility, Chromosome manipulation, Fecundity

Long-term persistence of the floating bull kelp Durvillaea antarctica from the South-East Pacific: Potential contribution to local and transoceanic connectivity

Autores:

Tala, F., López, B., Velásquez, M., Jeldres, R., Macaya, E., & Mansilla, A., Ojeda, J., Thiel, M.

Resumen:

Current knowledge about the performance of floating seaweeds as dispersal vectors comes mostly from mid latitudes (30°–40°), but phylogeographic studies suggest that long-distance dispersal (LDD) is more common at high latitudes (50°–60°). To test this hypothesis, long-term field experiments with floating southern bull kelp Durvillaea antarctica were conducted along a latitudinal gradient (30°S, 37°S and 54°S) in austral winter and summer. Floating time exceeded 200d in winter at the high latitudes but in summer it dropped to 90d, being still higher than at low latitudes (<45d). Biomass variations were due to loss of buoyant fronds. Reproductive activity diminished during long floating times. Physiological changes included mainly a reduction in photosynthetic (Fv/Fm and pigments) rather than in defence variables (phlorotannins and antioxidant activity). The observed long floating persistence and long-term acclimation responses at 54°S support the hypothesis of LDD by kelp rafts at high latitudes.

Año: 2019

Palabras claves: Chile, Durvillaea antarctica, Floating persistence, Rafting, Dispersal, Floating seaweeds, Temperature

How Does the Diversity of Divers Affect the Design of Citizen Science Projects?

Autores:

Hermoso, M., Martin, V., Stotz, W., Gelcich, S., & Thiel, M.

Resumen:

Divers have widely participated in citizen science (CS) projects and are one of the main groups of marine citizen scientists. However, there is little knowledge about profiles of, and incentives for potential divers to join CS projects. To date, most studies have focused on the SCUBA diving industry; nevertheless, there is a diversity of divers, not all using SCUBA, who engage in different activities during their dives. Differences in diver profiles could affect their willingness and ability to contribute to CS. In this study, we compare the diving profile, interests, preferences and motivations to participate in CS of five diver types (artisanal fishermen, recreational divers, instructors, scientific divers, and others). All divers have strong interests in participating in CS projects, with no major differences among diver types. In general, they are interested in a wide variety of themes related to CS but they prefer simple sampling protocols. Divers are motivated to participate in CS to learn about the sea and contribute to science. Some important differences among diver types were found, with artisanal fishermen having significantly more dive experience than other diver types, but less free time during their dives and limited access to some communication channels and technologies. These characteristics make them ideal partners to contribute their local ecological knowledge (LEK) to local CS projects. In contrast, recreational divers have the least experience but most free time during their dives and good access to cameras and communications channels, making them suitable partners for large-scale CS projects that do not require a high level of species knowledge. Instructors and scientific divers are well-placed to coordinate and supervise CS activities. The results confirm that divers are not all alike and specific considerations have to be taken into account to improve the contribution of each diver type to CS. The findings provide essential information for the design of different types of CS projects. By considering the relevant incentives and opportunities for diverse diver groups, marine CS projects will make efficient gains in volunteer recruitment, retention, and collaborative generation of knowledge about the marine environment.

Año: 2019

Palabras claves: Participatory science, subtidal, SCUBA, fishermen, recreational divers.

Uncovering population structure in the Humboldt penguin (Spheniscus humboldti) along the Pacific coast at South America

Autores:

Dantas, G., Oliveira, L., Santos, A., Flores, M., Melo, D., Simeone, A., González-Acuña, D., Luna-Jorquera, G., Le Bohec, C., Valdés-Velásquez, A., Cardeña, M., Morgante, J.S., Vianna, J.A.

Resumen:

The upwelling hypothesis has been proposed to explain reduced or lack of population structure in seabird species specialized in food resources available at cold-water upwellings. However, population genetic structure may be challenging to detect in species with large population sizes, since variation in allele frequencies are more robust under genetic drift. High gene flow among populations, that can be constant or pulses of migration in a short period, may also decrease power of algorithms to detect genetic structure. Penguin species usually have large population sizes, high migratory ability but philopatric behavior, and recent investigations debate the existence of subtle population structure for some species not detected before. Previous study on Humboldt penguins found lack of population genetic structure for colonies of Punta San Juan and from South Chile. Here, we used mtDNA and nuclear markers (10 microsatellites and RAG1 intron) to evaluate population structure for 11 main breeding colonies of Humboldt penguins, covering the whole spatial distribution of this species. Although mtDNA failed to detect population structure, microsatellite loci and nuclear intron detected population structure along its latitudinal distribution. Microsatellite showed significant Rst values between most of pairwise locations (44 of 56 locations, Rst = 0.003 to 0.081) and 86% of individuals were assigned to their sampled colony, suggesting philopatry. STRUCTURE detected three main genetic clusters according to geographical locations: i) Peru; ii) North of Chile; and iii) Central-South of Chile. The Humboldt penguin shows signal population expansion after the Last Glacial Maximum (LGM), suggesting that the genetic structure of the species is a result of population dynamics and foraging colder water upwelling that favor gene flow and phylopatric rate. Our findings thus highlight that variable markers and wide sampling along the species distribution are crucial to better understand genetic population structure in animals with high dispersal ability.

Año: 2019

Palabras claves: Penguins, Population genetics, Animal sociality, Chile (country), Gene flow, Islands, Seabirds, Haplotypes

Esculturas de acero: observaciones de corrosión e inhibición mediante una cámara de niebla salina, sensores y un microscopio de bajo costo

Autores:

Novoa Jerez, J., Alfaro Guerra, M., & Alfaro Alcaíno, I.

Resumen:

La presencia de partículas de NaCl en el aerosol marino produce corrosión en esculturas de acero de interés patrimonial, valor artístico y arquitectónico. Es aquí donde la observación de la corrosión utilizando una cámara de neblina, sensores y un microscopio de bajo costo podría permitir su estudio, junto con la ventaja de poder desarrollar proyectos en conjunto entre carreras de Pedagogía en Química con carreras de Pedagogía en Historia y Geografía y Pedagogía en Matemáticas y Computación, además del estudio de las propiedades anticorrosivas de Metamizol frente al acero al carbono sometido al aerosol marino en la cámara de neblina mediante la utilización de fotomicrografías.

Año: 2019

Palabras claves: Corrosión atmosférica, Aerosol marino, Esculturas de acero, Cámara de neblina, Sensores, Microscopio de bajo costo.