A biometric and ecologic comparison between Artemia from Mexico and Chile

BACKGROUND: A preliminary biometric and ecologic database for the brine shrimp Artemia from Mexico and Chile is presented. The area abounds in small and seasonal ponds and large inland lakes, the latter mainly located in Mexico, although relatively large and isolated lakes are found in complex hydrological settings in pre-high plateau areas of Chile. This paper summarizes research efforts aimed at the localization, characterization, and evaluation of the aquaculture potential of Artemia populations in Mexico and Chile, which exhibit great habitat diversity (ponds, salterns, coastal lagoons, sea arms, coastal and inland lakes), contrasting weather conditions and different levels of isolation and human intervention. RESULTS: This study covered locations between 29° north latitude (Baja California, Mexico) to 50° south latitude (Puerto Natales, Chile). Biological characteristics considered are species name, reproductive mode, cyst diameter, chorion thickness, and nauplius length, whereas ecological data include pond size, pH, salinity, temperature, and water ionic composition. Artemia franciscana is the only species found in Mexico, it exists together with A. persimilis in Chile, though separated geographically. Ecological differences in habitat exist between both regions but also within countries, a pattern particularly clear with regard to water composition. Surprisingly, a Mexican (Cuatro Ciénegas, A. franciscana) and a Chilean location (Torres del Paine, A. persimilis) share habitat characteristics, at least for the period when data were collected. The discriminat analysis for cyst diameter and nauplius length shows that Artemia from only one location match in cyst diameter with those from San Francisco Bay (SFB) (Point Lobos), and one (Marquez) is far apart from SFB and all the others. The Chilean locations (Pampilla, Cejar, Cahuil, Llamara, Yape) share cyst diameter, but tend to differ from SFB. The remaining Mexican locations (Juchitan, Ohuira, Yavaros) are well separated from all the others. With regard to nauplii length, populations tend to distribute in a relatively random manner, being Marquez the location differing the most in cyst diameter from SFB. CONCLUSION: This database will contribute to the knowledge of radiation centers and serves as a baseline for further biogeographic studies, population characterization, management, and monitoring of Artemia biodiversity. Likewise, the impact of colonization and translocations for aquaculture purposes can be better assessed with a baseline for reference. Mexico and Chile exemplify the need to increase and further integrate regional information to tackle fundamental problems underlying practical utilization of Artemia

Effect of Herbaceous Layer Interference on the Post-Fire Regeneration of a Serotinous Pine (Pinus pinaster Aiton) across Two Seedling Ages

Herbaceous vegetation is a major source of interference with the regeneration of woody species. This is particularly the case after forest fires, as a dense herbaceous layer usually regenerates naturally. Although the competitive effect of the herbaceous vegetation upon tree seedlings has been widely studied, there are still gaps in knowledge for management related to the effect of tree seedling age and size on the outcome of the interaction. In this study, we seek to determine the response of maritime pine (Pinus pinaster Aiton) seedlings to herbaceous competition at two different seedling ages. For that, two treatments of herbaceous competition were implemented, namely unweeded (no action around pine seedlings) and weeded (herbaceous cover removed around pine seedlings). Treatments were conducted twice (2 and 4 years after the fire), and we monitored seedling survival and growth at the end of each growing season. The treatments were implemented across three adjacent landscape units that differed in the management of burned wood and that are representative of common post-fire scenarios: no intervention, salvage logging, and an intermediate degree of intervention. Weeding increased seedling survival from 44.7% to 67.8% when seedlings were 2 years old, but had no effect for four-year-old seedlings, which showed 99% survival. Seedling growth also increased in the weeding treatment, but only slightly. Moreover, growth (and survival for two-year-old seedlings) was strongly correlated with initial seedling size, particularly in the case of two-year-old seedlings. Initial pine seedling height was strongly and positively correlated with the height of the herbaceous layer, supporting the existence of microsite features that promote plant growth above competitive effects. The results support that management actions conducive to foster post-fire pine forest restoration in this Mediterranean ecosystem should reduce herbaceous competition at early stages after fire (second or third year) and focus on larger seedlings.This research was funded by projects 10/2005 from the Organismo Autónomo de Parques Nacionales (Spanish Government), CGL2008-01671 from the Spanish Ministerio de Ciencia e Innovación (Spanish Government), and P12-RNM-2705 from Junta de Andalucía (Andalusian regional Government)

Linking animal behaviour and tree recruitment: Caching decisions by a scatter-hoarder corvid determine seed fate in a Mediterranean agroforestry system

1. Seed dispersal by scatter-hoarder corvids is key for the establishment of important tree species from the Holarctic region such as the walnut (Juglans regia). However, the factors that drive animal decisions to cache seeds in specific locations and the consequences of these decisions on seed fate are poorly understood. 2. We experimentally created four distinct, replicated habitat types in a Mediterranean agricultural landscape where the Eurasian magpie (Pica pica) is a common scatter hoarder: soft bare soil; compacted bare soil; compacted soil with a dense herbaceous cover; and soft linear bare soil made up of the irrigation furrows that separated the rest of the treatments. We also experimentally placed visual landmarks (stones, sticks and bunches of dry plants) to test if magpies use them to place seed caches. Walnut dispersal from feeders to the habitats was monitored by radiotracking and camera traps. 3. A sowing experiment simulating natural caches tested the effect of caching type on seed germination and seedling emergence. Seed mass was controlled for the dispersal and sowing experiments. 4. Magpies selected the two habitats with soft soil, and avoided the one with compacted soil, to cache nuts. Seed mass did not affect dispersal distance, germination or emergence; however, heavier seeds were cached more often under litter and in the habitat with herbaceous cover, whereas lighter seeds were more often buried in the soft bare soil habitat. Seed burial under soil or litter determined seed fate, as there was virtually no emergence from unburied nuts. There was no evidence of any effect of the visual landmarks. 5. Synthesis. The consequences of seed caching for seedling early establishment are driven by a fine decision-making process of the disperser. Magpies seemed to ponder the characteristics of the habitat and the seed itself to determine where and how to cache each nut. By doing so, magpies reinforced the quality of seed dispersal effectiveness, as they cached walnuts in locations that enhanced both seed survival and seedling emergence.Ministry of Science and Innovation, Spain (MICINN)Instituto de Salud Carlos III Spanish Government IJC2018-036411- Spanish Government PID2019-106806GB-I00RTI2018-096187-J-I00REMEDINAL S2018/EMT-4338SS2018/EMT-4338Spanish Government CGL2014-53308-PUniversidad de Alcala CCG2014/BIO-02 UAH-GP2019-

Massive and effective acorn dispersal into agroforestry systems by an overlooked vector, the Eurasian magpie (Pica pica)

Oak regeneration and the expansion of forested sites in Eurasia rely on acorn dispersal by animals, especially the Eurasian jay (Garrulus glandarius). However, in open agroforestry systems where jays are absent, such as old fields far from acorn sources, oak recruitment still occurs. We hypothesize that the Eurasian magpie (Pica pica), an abundant corvid in this system, substitutes the jay in its seed dispersal function. By ringing 169 magpies, video recording >7500 acorn removal events with trail cameras, and radiotagging 337 acorns, we quantified that (1) magpies cached 41–56% of the annual acorn production of Quercus ilex trees in single caches on the ground; (2) breeding pairs, and especially males, were the main acorn dispersers; (3) each breeding magpie cached 169–1372 acorns in 6 weeks; and (4) the effectiveness of dispersal (percentage of cached acorns resulting in seedlings) was 0.6–2.4%, which (5) yielded a high density of emerged seedlings (56–439 seedlings/ha). We evidence that magpie could be a key species in the regeneration of oak agroforestry mosaics because they massively and effectively dispersed acorns. However, in our particular study site, effectiveness was low probably due to herbivory and summer drought stress (i.e., a context limitation rather than an intrinsic limitation of the disperser). As the distributions of magpies and oaks overlap widely in Eurasia, effective acorn dispersal by magpies could have a significant role in largescale oak forest recovery in strongly fragmented landscapes.This study was funded by the Spanish Ministerio de Ciencia y Tecnología (CGL2014-53308-P), the REMEDINAL network of the Madrid Autonomous Government (S2013/MAE-2719 and S2018/EMT-4338), and the University of Alcalá (CCG2014/BIO-02, UAH-GP2019- 6). LMB was supported by an FPI fellowship from the Ministerio de Ciencia y Tecnología (BES-2015-075276). ABL acknowledges Juan de la Cierva postdoctoral fellowship and project RTI2018-096187-J-100 from Ministerio de Ciencia, Innovación y Universidades

Revegetation through seeding or planting: A worldwide systematic map

Roughly 2 billion ha of land are degraded and in need of ecological restoration worldwide. Active restoration frequently involves revegetation, which leads to the dilemma of whether to conduct direct seeding or to plant nursery-grown seedlings. The choice of revegetation method can regulate plant survival and performance, with economic implications that ultimately feed back to our capacity to conduct restoration. We followed a peerreviewed protocol to develop a systematic map that collates, describes and catalogues the available studies on how seeding compares to planting in achieving restoration targets. We compiled a database with the characteristics of all retrieved studies, which can be searched to identify studies of particular locations and habitats, objectives of restoration, plant material, technical aspects, and outcomes measured. The search was made in eight languages and retrieved 3355 publications, of which 178 were retained. The systematic map identifies research gaps, such as a lack of studies in the global South, in tropical rainforests, and covering a long time period, which represent opportunities to expand field-based research. Additionally, many studies overlooked reporting on important technical aspects such as seed provenance and nursery cultivation methods, and others such as watering or seedling protection were more frequently applied for planting than for seeding, which limits our capacity to learn from past research. Most studies measured outcomes related to the target plants but avoided measuring general restoration outcomes or economic aspects. This represents a relevant gap in research, as the choice of revegetation method is greatly based on economic aspects and the achievement of restoration goals goes beyond the establishment of plants. Finally, we identified a substantial volume of studies conducted in temperate regions and over short periods (0–5 y). This research cluster calls for a future in-depth synthesis, potentially through meta-analysis, to reveal the overall balance between seeding and planting and assess whether the response to this question is mediated by species traits, environmental characteristics, or technical aspects. Besides identifying research clusters and gaps, the systematic map database allows managers to find the most relevant scientific literature on the appropriateness of seeding vs. planting for particular conditions, such as certain species or habitats.Spanish Ministerio de Ciencia, Innovacion y Universidades/FEDER RTI 2018-096187-J-100 RYC 2020-029407-IMinistry of Science and Innovation, Spain (MICINN) TED2021.130976 B.I00Consejeria de Economia, Conocimiento, Empresas y Universidad de la Junta de Andalucia/FEDER P18-RT-1927Universidad de Granada / CBU

Deadwood Decay in a Burnt Mediterranean Pine Reforestation

Dead wood remaining after wildfires represents a biological legacy for forest regeneration, and its decay is both cause and consequence of a large set of ecological processes. However, the rate of wood decomposition after fires is still poorly understood, particularly for Mediterranean-type ecosystems. In this study, we analyzed deadwood decomposition following a wildfire in a Mediterranean pine plantation in the Sierra Nevada Natural and National Park (southeast Spain). Three plots were established over an elevational/species gradient spanning from 1477 to 2053 m above sea level, in which burnt logs of three species of pines were experimentally laid out and wood densities were estimated five times over ten years. The logs lost an overall 23% of their density, although this value ranged from an average 11% at the highest-elevation plot (dominated by Pinus sylvestris) to 32% at an intermediate elevation (with P. nigra). Contrary to studies in other climates, large-diameter logs decomposed faster than small-diameter logs. Our results provide one of the longest time series for wood decomposition in Mediterranean ecosystems and suggest that this process provides spatial variability in the post-fire ecosystem at the scale of stands due to variable speeds of decay. Common management practices such as salvage logging diminish burnt wood and influence the rich ecological processes related to its decay.This study was supported by Project 10/2005 from the Organismo Autónomo de Parques Nacionales (Spanish Government), CGL2008-01671 from the Spanish Ministerio de Ciencia e Innovación, and P12-RNM-2705 from Junta de Andalucía. A.B.L. acknowledges funding from Juan de la Cierva grant by Ministerio de Economía y Competitividad (FJCI-2015-23687). C.R.M-G. had a Ph.D. grant from the National University of Asunción (Paraguay) and Carolina Foundation (Spain)

A semiempirical quantum approach to possible structures of copper electrodeposits at submonolayer and monolayer levels on Pt(100) and Pt(111) clusters

The development and reconstruction of surface structures formed by underpotential deposition (UPD) of Cu atoms on Pt(100) and Pt(111) clusters are approached through extended Hückel molecular orbital (EHMO) calculations applied to a statistical Cu atom deposition. These results allow us to obtain a qualitative description of the different stable configurations of Cu atoms on the Pt cluster surfaces in terms of the corresponding binding energies.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Does post-disturbance salvage logging affect the provision of ecosystem services?

Background: Forest fires, insect outbreaks, and windstorms are common forest disturbances that are expected to increase in importance in coming decades. Post-disturbance management often involves salvage logging, i.e. the felling and removal of the affected trees. However, harvesting these biological legacies may represent a second disturbance whose effects on ecosystem processes add on those of the initial disturbance. Many of the potentially affected processes, such as soil erosion and stream water quality, represent regulating and supporting ecosystem services important for human society. In the last 15years, much empirical evidence has been gathered on the ecological consequences of this management practice, and it has now become necessary to synthesise this evidence in meaningful ways for managers and decision-makers. Methods: With this systematic review we aim to synthesise the literature on the effects of salvage logging on ecosystem services and determine the effects of major effect modifiers such as disturbance type and intensity, the timing and method of logging, and the type of forest. We will conduct searches of the primary scientific literature, which will be selected and categorised according to its relevance to the topic and its quality. Each relevant article will be read in full to obtain the necessary data for meta-analysis and to identify its main conclusions. Mixed-effects models will be performed to assess the effects of the identified effect modifiers on the effect sizes of the salvage intervention on ecosystem services and to account for random effects arising from studies being performed in the same area. Sensitivity analyses will test the potential effects of study quality, and publication bias will be assessed with the trim and fill method. We will present the results as a narrative review and a meta-analysis

Microelementos en nauplios de Artemia franciscana (Kellog, 1906) de seis poblaciones mexicanas y su relación con peces y crustáceos

This study describes the concentrations of iron (Fe), copper Cu, cinc (Zn), and manganese Mn for the nauplius stage of Artemia franciscana from six populations: Salinas de Hidalgo in the State of San Luis Potosi; Texcoco in the State of Mexico; Tres Hermanos, from Yavaros, State of Sonora; La Esperanza in Ohuira, State of Sinaloa; and Las Coloradas and Juchitán, State of Oaxaca. The determination of these elements was made from nauplii obtained from decapsulated and hatched cysts. The resulting nauplii were dried, pulverized and submitted to acid digestion. The determination was made by using an atomic absorption spectrum. The nauplii from San Luis Potosi showed the highest concentration of the four elements. Fe was the most abundant element in the nauplii of all six populations (506.91-1,469.16 mg/L). Zinc was in second place in quantity (75.30-155.47 mg/L). Copper was detected in all nauplii at high levels of concentration (24.23-101.76 mg/L) with respect to desirable amounts for catfish and peneid shrimp. Manganese was present in smaller amounts (15.88-28.76 mg/L) in all six populations and met the diet requirements of fish in general (20 to 50 mg/kg in thediet), only nauplii from Ohuira, and from the State of San Luis Potosí were able to cover their needs. Information on requirements for fish and shrimp larvae that feed on Artemia nauplii is scarce, therefore it is necessary to carry out more studies on this topic to support the development of suitable diets for cultivated these species.En este trabajo se presentan las concentraciones de fierro (Fe), cobre (Cu), zinc (Zn) y manganeso (Mn) en la etapa naupliar de Artemia franciscana de seis poblaciones mexicanas: las Salinas de Hidalgo, San Luis Potosí (SLP); Texcoco, Estado de México; Tres Hermanos, Yavaros, Sonora; La Esperanza, Ohuira, Sinaloa; Las Coloradas, Oaxaca y Juchitán, Oaxaca. La determinación de estos elementos se hizo a partir de nauplios eclosionados de quistes previamente descapsulados, los cuales se secaron y pulverizaron para posteriormente ser sometidos a una digestión ácida. Para la lectura de los datos, se utilizó un espectro de absorción atómica. Los nauplios de SLP fueron los que presentaron mayor concentración de los cuatro elementos. El Fe fue el elemento más abundante en los nauplios de las seis poblaciones (506.911469.19 mg/L). El zinc se encontró en segundo lugar en cuanto a cantidad (75.30155.47 mg/L). El cobre detectado en todos los nauplios alcanzó niveles altos (24.23101.76 mg/L), en relación con los requerimientos en peces como el bagre o los camarones peneidos. El manganeso se presentó en menor cantidad (15.8828.76 mg/L), en las seis poblaciones y de acuerdo con la demanda que tienen los peces en general (20 a 50 mg/kg en la dieta), solamente los nauplios de Ohuira, y de SLP, podrían cubrir los requisitos. La información es escasa sobre las necesidades de minerales que tienen las larvas de peces y camarones, que se alimentan de nauplios de Artemia; por lo que se considera necesario realizar más estudios sobre este tema y así poder desarrollar dietas adecuadas para estos organismos

Small strain stiffness within logarithmic contractancy model for structured anisotropic clay.

ABSTRACT: Stiffness of soils in the small strain region is high and it decays nonlinearly with increasing shear strains or with mobilization of shear stresses. However, the commonly used critical state based constitutive models use a simple elastic formulation at small strains that falls short in the prediction of the small strain nonlinearity and anisotropy. This paper proposes a simple way for rendering the existing constitutive models with the capability to capture the small strain behaviour of soils. This is illustrated by proposing a new model for structured anisotropic clay extending an existing model that uses the framework of logarithmic contractancy called ESCLAY1S. The proposed model is implemented into a Finite Element program as a user-defined soil model. The model predictions are compared with experimental data for various clays. Furthermore, the effect of nonlinearity is investigated for an excavation in soft clay