Controlled laboratory system to study soil solarization and organic amendment effects on plant pathogens

ABSTRACT A controlled laboratory system for simulating soil solarization, with and without organic amendment, was developed and validated using physical, chemical, and biological parameters. The system consists of soil containers that are exposed to controlled and constant aeration, and to temperature fluctuations that resemble those occurring during solarization at various depths. This system enables a separate analysis of volatiles and other components. We recorded a sharp decrease in oxygen concentration in the soil atmosphere followed by a gradual increase to the original concentration during solarization in the field and heating in the simulation system of soil amended with wild rocket (Diplotaxis tenuifolia) or thyme (Thymus vulgaris). The combined treatment of organic amendment and solarization (or heating in the controlled system) was highly effective at controlling populations of Fusarium oxysporum f. sp. radicis-lycopersici. Changes in soil pH, enzymatic activities, and microbial populations followed, in most cases, trends which were similar under both solarization and the heating system, when exposed to controlled aerobic conditions. The reliability and validity of the system in simulating physical, chemical, and biological processes taking place during solarization is demonstrated.     

Networks of inbreeding coefficients in a selected population of rabbits

The correlation between pedigree and genomic-based inbreeding coefficients is usually discussed in the literature. However, some of these correlations could be spurious. Using partial correlations and information theory, it is possible to distinguish a significant association between two variables which is independent from associations with a third variable. The objective of this study is to implement partial correlations and information theory to assess the relationship between different inbreeding coefficients using a selected population of rabbits. Data from pedigree and genomic information from a 200K SNP chip were available. After applying filtering criteria, the data set comprised 437 animals genotyped for 114,604 autosomal SNP. Fifteen pedigree- and genome-based inbreeding coefficients were estimated and used to build a network. Recent inbreeding coefficient based on runs of homozygosity had 9 edges linking it with different inbreeding coefficients. Partial correlations and information theory approach allowed to infer meaningful associations between inbreeding coefficients and highlighted the importance of the recent inbreeding based on runs of homozygosity, but a good proxy of it could be those pedigree-based definitions reflecting recent inbreeding.     

High-resolution images and drone-based LiDAR reveal striking patterns of vegetation gaps in a wooded spinifex grassland of Western Australia

Landscape Ecology - Vegetation patterns in hummock grasslands of Australia’s arid interior can be very complex. Additionally, the grasslands are interspersed with variable amounts of trees...     

Occurrence of Cryptosporidium spp. in Antillean manatees (Trichechus manatus) and Amazonian manatees (Trichechus inunguis) from Brazil

Infections by Cryptosporidium spp. in aquatic mammals is a major concern due to the possibility of the waterborne transmission of oocysts. The aim of the present study was to report the occurrence of Cryptosporidium spp. in Antillean manatees (Trichechus manatus) and Amazonian manatees (Trichechus inunguis) from Brazil. Fecal samples were collected and processed using Kinyoun's method. Positive samples were also submitted to the direct immunofluorescence test. The results revealed the presence of Cryptosporidium spp. oocysts in 12.5% (17/136) of the material obtained from the Antillean manatees and in 4.3% (05/115) of the samples from the Amazonian manatees. Cryptosporidium spp. infection was more prevalent in captive animals than in free-ranging specimens.     

Insecticidal activity of synthetic antioxidants,natural phytochemicals,and essential oils against an <Emphasis Type="Italic">Aspergillus</Emphasis> section <Emphasis Type="Italic">Flavi</Emphasis> vector (<Emphasis Type="Italic">Oryzaephilus surinamensis</Emphasis> L.) in microcosm

The purpose of this study is to investigate the insecticidal activity of two benzoic acids 2(3)-tert-butyl-4 hydroxyanisole (BHA) and 2,6-di(tert-butyl)-p-cresol (BHT); two phenolic acids 3-phenyl-2-propenoic acid (CA) and trans-4-hydroxy-3-methoxycinnamic acid (FA); and two essential oils of Eugenia caryophyllata (clove tree) and Thymus vulgaris (thyme) against Oryzaephilus surinamensis (L.) vector carrier of aflatoxigenic fungi on stored peanut. The weight loss of peanut, susceptibility of insects, Aspergillus isolation frequency from insects and peanut, and aflatoxin B₁ analyses from peanut were determined. BHA, BHT, and BHA/BHT mixture were highly effective against O. surinamensis, these chemical agents give 100% mortality at the doses assayed. Essential oil of thyme at 2,000 and 3,000 ppm were highly effective against O. surinamensis, these concentrations gave 100% mortality. No Aspergillus section Flavi contamination was observed in dead insects collected from peanut treated with BHA/BHT mixture. No differences were observed in the fresh weight of pods peanut among treatments with and without chemical agents. All samples of treated peanut pods showed complete inhibition of this toxin after 120 days of storage. Our results indicate that these substances could be evaluated further for the control of pest vectors of aflatoxigenic fungi of stored peanut.     

Impact of Antarctic Circumpolar Current development on late Paleogene ocean structure

Global cooling and the development of continental-scale Antarctic glaciation occurred in the late middle Eocene to early Oligocene (~38 to 28 million years ago), accompanied by deep-ocean reorganization attributed to gradual Antarctic Circumpolar Current (ACC) development. Our benthic foraminiferal stable isotope comparisons show that a large δ(13)C offset developed between mid-depth (~600 meters) and deep (>1000 meters) western North Atlantic waters in the early Oligocene, indicating the development of intermediate-depth δ(13)C and O(2) minima closely linked in the modern ocean to northward incursion of Antarctic Intermediate Water. At the same time, the ocean's coldest waters became restricted to south of the ACC, probably forming a bottom-ocean layer, as in the modern ocean. We show that the modern four-layer ocean structure (surface, intermediate, deep, and bottom waters) developed during the early Oligocene as a consequence of the ACC.     

Integrated toxicity evaluation of a pulp deposit using organisms of different trophic levels

Purpose

In order to assess possible adverse effects originating from pulp deposits in a Swiss lake, a sediment quality triad approach was applied with chemical, ecotoxicological and ecological assessment methods.

Materials and methods

To obtain an integrative picture of the potential ecotoxicological effects on organisms of different trophic levels, four test procedures were applied. The acute effects of pulp deposit pore water on a decomposer, the amphipod Gammarus fossarum, were monitored. Chronic toxicity of the pore water was evaluated on primary producers via a growth inhibition test with unicellular green algae (Pseudokirchneriella subcapitata) and on secondary consumers in a reproduction test with the water flea Ceriodaphnia dubia. To evaluate the effects of the pulp deposit on sediment inhabitants, a whole-life-cycle test with the non-biting midge Chironomus riparius was undertaken. Chemical assessment included dissolved organic carbon, extractable organic halogenic compounds, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs) and heavy metals. The composition of the macrozoobenthos community was analysed in order to assess the ecological effects.

Results and discussion

G. fossarum displayed increased locomotor activity at 12.5% but not at 25% sample concentration during a short-time exposure of 20 h. Chronic effects compromised the reproduction and growth of C. dubia (lowest observed effect concentration, 12.5% sample concentration) with zero population growth in 100% pulp deposit pore water. In 100% pulp deposit, C. riparius exhibited increased mortality at 10 and 17 days after oviposition. Pulp deposits of 50% and 100% concentration caused a significantly lower emergence compared with the reference treatments (lake sediment and quartz sand). Additionally, the locomotor activity of chironomids decreased significantly in 25–100% pulp deposit. No chronic effects of pulp deposit pore water on algae photosynthesis and growth could be detected. The bioassay results were in accordance with an elevated content of PAHs, PCBs and metals in the pulp deposit. Significantly more organisms known to be tolerant to organic pollution were present within the macrozoobenthos community.

Conclusions

In general, for sediment inhabitants such as chironomids, the pulp deposit has to be classified toxic. In the present test setup, the toxicity of the pulp deposit was reflected better by the chronic test systems applied than by the acute ones. The applied testing framework could be a suitable tool to assess the risk of contaminated sites, and this information will help decide whether risk mitigation measures should be taken. In addition, with a similar approach, the success of any mitigation measures taken can be assessed.     

Advances and challenges in marine conservation in Chile: A regional and global comparison

1. Despite significant progress made in Chile, and globally, in establishing marine protected areas (MPAs), the actual contribution to marine biodiversity conservation needs to be revised, to focus on representativeness and the diversity of tools alongside effective implementation, management, and enforcement.
2. This study makes progress in this direction, describing the most recent advances in marine conservation in Chile and analysing the contribution of the different conservation instruments as well as the distribution of designated areas across ecoregions. Furthermore, it examines the potential contribution of alternative area-based instruments to balance ocean protection. The advances observed in Chile were compared among four South American countries and five leading countries in ocean conservation, analysing protection levels in coastal areas, continental exclusive economic zones, and overseas territories.
3. Data on MPA boundaries and attributes were sourced from the World Database on Protected Areas and complemented the official information on MPAs and territorial user rights for fisheries and for indigenous people in South America.
4. The current level of protection in Chile is among the highest in the world in area coverage and in the proportion of the continental exclusive economic zone assigned to fully protected areas. However, it exhibits the strongest imbalances in the distribution of designated MPAs between coastal and oceanic waters, in comparison with the leading countries and also within South America (Perú, Chile, Argentina, and Uruguay), and among ecoregions.
5. The patterns observed suggest that Chile has advanced, but concentrated, conservation efforts in low-threat, remote ecoregions. There is an urgent need to progress towards high-threat ecoregions, which implies balancing the needs of nature and people. The distribution of ancillary conservation instruments can help double the level of protection in threatened coastal areas, filling gaps in marine conservation and creating an opportunity to progress and diversify conservation strategies.

     

Effects of changes in environmental factors on the non-specific immune response of Nile tilapia, Oreochromis niloticus L.

Lysozyme acts as a non‐specific defence substance and is found in the peripheral blood, cutaneous mucus and certain tissues of marine and freshwater fishes. In the present study, we examined the effect of various environmental factors (water temperature, salinity, pH and suspended sediments) on plasma lysozyme activity in the Nile tilapia, Oreochromis niloticus L. When the fish were reared at different water temperatures (18.4, 23, 28 and 33°C), plasma lysozyme activity increased at 28°C after 2 and 4 weeks. A significant decrease in lysozyme activity was found in the fish reared at 33°C for 4 weeks. These results suggest that there is a water temperature range that affects the amount of plasma lysozyme activity that can be detected. Fish cultured at 24 g L^?1 of salinity for 2 and 4 weeks and 12 g L^?1 for 4 weeks resulted in significantly increased plasma lysozyme activity, suggesting that environmental salinity also affects the amount of plasma lysozyme that can be detected. Lysozyme activity also significantly increased when the fish were held in acidic water at pH 4.0 and in suspended sediments at 2000 mg L^?1 for 2 weeks. It was concluded that changes in some aquatic environmental factors affect the non‐specific immune responses of Nile tilapia.