Early stages of Margaritifera margaritifera glochidiosis in Atlantic salmon: Morphopathological characterization

Freshwater mussels of the order Unionida encyst into the fish mucosa to metamorphose and complete their life cycle, causing a parasitic disease known as glochidiosis. This parasitic stage represents a bottleneck for the survival of naiads, particularly for critically endangered species as Margaritifera margaritifera; however, little is known about the events occurring during this critical stage. Therefore, this study aimed to histologically characterize the development of M. margaritifera glochidiosis in Atlantic salmon to get insight into the pathogenesis of this interaction. Fish exposed to glochidia were sampled during the first 44 days post-exposure, and organs were observed by stereomicroscopy and light microscopy. Glochidia attached to the gills by pinching the lamellar epithelium, whereupon an acute proliferative branchitis engulfed most of the larvae. However, during the first 14 days, a severe detachment of unviable glochidia occurred, associated with the presence of pleomorphic inflammatory infiltrate and epithelial degeneration. In the cases where larvae remained attached, a chronification of the lesions with none to scarce inflammation was observed. These results provide key information to better understand the complex host–parasite interaction during the early stages of glochidiosis and provide valuable information to optimize artificial rearing of naiads in conservation of threatened freshwater mussel populations.     

Shedding light on the migratory patterns of the Amazonian goliath catfish,Brachyplatystoma platynemum,using otolith 87Sr/86Sr analyses

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Climate‐induced vulnerability of fisheries in the Coral Triangle: Skipjack Tuna thermal spawning habitats

We investigated projected changes in sea surface temperature (SST) and the associated impacts on spawning habitat for skipjack tuna (Katsuwonus pelamis) in the Coral Triangle region (CT). A multimodel aggregate of SST CMIP5 models for the CT region, based on a comprehensive skill validation assessment, was used to identify the five best performing of 36 models tested for inclusion in a regional multimodel ensemble. Monthly 1° SST multimodel aggregate projections for the CT region under RCP8.5 show that increases in SST, as high as 2.8°C (mean value), will likely occur by the end of this century. Using these estimates of SST change, we applied three parameterizations of skipjack tuna spawning temperatures to assess the potential for change in spawning habitat within the CT region. The three spawning temperature parameterizations were as follows: (a) a square‐wave function derived from catch data with boundaries at 26 and 30°C; (b) a symmetric Gaussian function derived from the SEAPODYM models; and (c) an asymmetric Gaussian function that modifies the SEAPODYM curve in (b) to include the results of relevant physiological experiments. All three parameterizations show similar geographic patterns, with the amount of favourable spawning habitat decreasing throughout the central, equatorial CT region and increasing at higher latitudes. However, the three parameterizations show marked differences in the modelled magnitude of change, with an asymmetric Gaussian function (ASGF) showing a regionwide average of 66.1% decline in favourable spawning habitat between 2015 and 2099. These projected changes in tuna spawning habitats are likely to have important consequences on local and regional fisheries management in the CT region.     

Thermal comfort indices assessed in integrated production systems in the Brazilian savannah

The objective was to evaluate the animal thermal comfort indices from two integrated crop-livestock-forestry (ICLF) systems. For this, temperature–humidity index (THI), black globe temperature and humidity index (BGHI), and the radiant thermal load (RTL) were assessed. Two ICLF (ICLF-1 and ICLF-2) systems and one control system were established. On the ICLF systems, the arboreal component was the eucalyptus tree (Eucalyptus grandis × Eucalyptus urophylla; H13 clone), planted in simple wide-spaced rows. The ICLF-1 system had a tree spacing of 14 × 2 m with 357 trees per hectare, and the ICLF-2 had a tree spacing of 22 × 2 m with 227 trees per hectare. The control system had five scattered native trees per hectare, pertaining to Gochnatia and Dipteryx species. The forage component in all three systems was piatã-grass (Brachiaria brizantha cv. BRS Piatã). The experimental design was a randomized block in a sub-subplot design scheme with four replications. The presence of shade provided by the trees offered better conditions of animal comfort when compared with the condition of full sun. The ICLF-1 system, with higher tree density, provided better indicators for thermal comfort, THI, BGHI, and RTL when compared with the condition of full sun, while ICLF-2 was no different than ICLF-1 for BGHI.     

First description of a natural infection with spleen and kidney necrosis virus in zebrafish

Zebrafish has become a popular research model in the last years, and several diseases affecting zebrafish research facilities have been reported. However, only one case of naturally occurring viral infections was described for this species. In 2015, infectious spleen and kidney necrosis virus (ISKNV) was detected in zebrafish from a research facility in Spain. Affected fish showed lethargy, loss of appetite, abnormal swimming, distention of the coelomic cavity and, in the most severe cases, respiratory distress, pale gills and petechial haemorrhages at the base of fins. Cytomegaly was the most relevant histopathological finding in organs and tissues, sometimes associated to degenerative and necrotic changes. ISKNV belongs to the relatively newly defined genus Megalocytivirus, family Iridoviridae, comprising large, icosahedral cytoplasmic DNA viruses. This is the first case of naturally occurring Megalocytivirus infection in zebrafish research facilities, associated with morbidity. The virus has been identified based on both pathologic and genetic evidence, to better understand the pathogenesis of the infection in zebrafish and the phylogenetic relationship with other iridoviruses. Given the ability of megalocytiviruses to cross‐species boundaries, it seems necessary to implement stringent biosecurity practices as these infections may invalidate experimental data and have major impact on laboratory and cultured fish.     

Simple estimation of available water capacity in soils of semiarid and subhumid environments

Soil available water capacity (AWC) is an important factor affecting soil productivity in semiarid and subhumid environments and is mainly determined by the soil textural composition. As the soils of these environments usually present fairly uniform textures across depth, we hypothesized that it would be possible to accurately estimate the whole-profile AWC using surface information. Our objective was to test this hypothesis in the Argentine Semiarid Pampas. Information was collected from 152 sites where AWC was measured in 20?cm layers up to a depth of 140?cm or up to the upper limit of the petrocalcic horizon, when present. In each case, whole profile AWC was estimated using a one-step and a two-step approach, comparing multiple regression and artificial neural networks as modeling techniques. Both modeling methods were effective (R²?>?0.76, P?相似文献   

Devices to detect red palm weevil infestation on palm species

The date palm (Phoenix dactylifera L.) and other palm species have recently been threatened by the red palm weevil (RPW) Rhynchophorus ferrugineus Olivier, which is very difficult to be detected at early stage. This research tested non invasive approaches to detecting RPW including: a TreeRadarUnit? (TRU); a densitometer, a penetrometer used for evaluation of the standing trees stability; a thermal camera and a digital camera. The technologies were applied in Italy on 715 palms (173 P. dactylifera, 453 Phoenix canariensis Chabaud and 311 of other palm species), and on 86 adult date palms in Saudi Arabia. In Italy, the thermal camera showed a high accuracy (96.29%) compared to close visual observation over the following nine months. The digital camera did almost as well (92.57%). Tree Radar Unit and densitometer also showed good accuracy (83.33 and 88.89% respectively). In the Kingdom of Saudi Arabia, the thermal camera showed a good accuracy (77.73%) when compared to invasive diagnosis (i.e. cutting down and opening up palm trunks). The digital camera showed a lower accuracy of 66.67% due to the fact that the red weevil mainly attacks the base of the stem and therefore there are no visible symptoms on the crown shape that would be picked up in image analysis. TRU gave good results (74.73% compared to invasive diagnosis), with the best accuracy at ground level (80.65%). The densitometer results were similar to the TRU case, with higher accuracy (82.26% compared to invasive diagnosis) and the highest at ground level (87.10%).     

Performance of wick irrigation system using self-compensating troughs with substrates for lettuce production

Subirrigation systems in which water and nutrients are supplied to the substrate through wick strips for upward nutrient solution (NS) movement can be a feasible alternative to improve lettuce quality with low environmental pollution, enabling production with reduced labor and electricity or in regions with high air temperature. The objective of this study was to compare the performance of two wick irrigation systems using self-compensating troughs filled with either pine bark (WPB) or coconut coir (WCC) with nutrient film technique (NFT) hydroponic system for greenhouse lettuce production. The daily monitoring of electrical conductivity (EC) and pH allowed the experiment management according to the recommended values for optimal lettuce growth. The EC showed variation among troughs and salt accumulation in substrates, with WPB exhibiting two times greater EC than WCC (ranging from 0.95 to 7.57 and from 0.68 to 3.67 dS·m^?1, respectively), while the pH values were stable over time. The WCC promoted greater root length and shoot diameter, while WPB produced shorter plants compared to the other two treatments. NFT resulted in an 83% lower leaf area and 44% lower root volume than WPB and WCC. The fresh and dry shoot masses with NFT were 58% and 24% lower than with WPB and WCC, respectively. The fresh root mass was also reduced in NFT plants, which was 67% smaller than WCC and 59% smaller than WPB. Root dry mass of NFT was 35% lower than the average of WPB and WCC. Nitrate (NO₃)-nitrogen (N), ammonium (NH₄)-N, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sulfur (S), boron (B), copper (Cu), iron (Fe), manganese (Mn), and zinc (Zn) concentrations in plant shoot and root at the end of the experiment as well as the same nutrients, chloride, sodium, and bicarbonate concentrations in substrate and NS determined weekly differed among the treatments (P < 0.01). The EC and nutrient concentration in the substrates increased over time. The wick irrigation system with both substrates resulted in higher productivity than NFT, with higher yield and plant quality in WCC, indicating its feasibility as an alternative system for lettuce production in greenhouses. However, due to the salinity buildup, water and nutrition management needs to be optimized for self-compensating troughs to avoid an increase in substrate EC over time.