Evaluation of a thoracoscopic technique using ligating loops to obtain large lung biopsies in standing healthy and heaves-affected horses

Objective— To evaluate use of pre‐tied ligating loop to perform thoracoscopic, large lung biopsy in normal and heaves‐affected horses. Study Design— Prospective clinical study. Animals— Normal (n=5) and heaves‐affected (n=6) horses. Methods— Lung biopsies, 1 from each hemithorax, were collected thoracoscopically using a pre‐tied ligating loop. Horses were either normal (C) or heaves‐affected with the latter being in remission (Ha) for the initial biopsy and in exacerbation (Hs) for the 2nd biopsy. Clinical variables, PaO₂, and PaCO₂ were used to determine the effect of surgical biopsy. Postoperative pneumothorax was monitored by serial thoracic radiographic examinations. Results— Thoracoscopic lung biopsy (n=29, 22 procedures) was well tolerated by all horses. Complication rate was 31%, including 8 ligature slippage and 1 pulmonary hemorrhage. Intranasal oxygen was administered intraoperatively to 6 horses (2 C, 1 Ha, 3 Hs) with severe hypoxemia or labored breathing. There was a significant decrease in PaO₂ during surgery in horses not supplemented with oxygen. Postoperative pneumothorax (21/22 procedures) detected radiographically resolved within 3 weeks. Conclusion— Thoracoscopic lung biopsy using pre‐tied ligating loops was minimally invasive, relatively inexpensive, and fairly efficient. Heaves‐affected horses tolerated the surgery well, even when in exacerbation; however, the technique was associated with non life‐threatening complications in 31% of the biopsies, most of which required correction with additional ligating loops or more sophisticated instrumentation. Clinical Relevance— Using laparoscopic pre‐tied ligating loop for thoracoscopically‐assisted lung biopsy can be considered in horses with normal and impaired lung function but alternative instrumentation and access to intranasal oxygen must be available to the surgeon in case of complications.     

Atypical Actinobacillus pleuropneumoniae isolates that share antigenic determinants with both serotypes 1 and 7.

In the present study, the characterization of 3 atypical isolates of Actinobacillus pleuropneumoniae is presented. Two isolates (1B and 27E) showed positive reactions in coagglutination, immunodiffusion, and indirect hemagglutination tests for serotypes 1 and 7, whereas the third isolate (26B) reacted with antisera to serotypes 1, 4, and 7. These atypical isolates of A. pleuropneumoniae possessed a capsular polysaccharide (CPS) antigenically related to serotype 1 as well as an O-chain lipopolysaccharide antigenically related to serotype 7 or to serotypes 4 and 7, as shown by the use of monoclonal antibodies. Results of toxin profile and virulence assays for mice and pigs showed them to be more related to A. pleuropneumoniae serotype 7 field isolates. All 3 isolates induced antibodies mainly against serotype 7/4 O-long-chain lipopolysaccharide (LC-LPS) and, to a lesser extent, to the CPS of serotype 1, in experimentally infected pigs. Diagnostic laboratories that use a LC-LPS-based enzyme-linked immunosorbent assay (ELISA) for serodiagnosis of A. pleuropneumoniae infection in swine would probably diagnose herds infected with these atypical isolates as being infected by A. pleuropneumoniae serotypes 7 or 4, whereas those that use a CPS-based ELISA would probably consider them as infected by A. pleuropneumoniae serotype 1.     

The scale of saproxylic beetles response to landscape structure depends on their habitat stability

Context

Forest management and disturbances cause habitat fragmentation for saproxylic species living on old-growth attributes. The degree of habitat spatiotemporal continuity required by these species is a key question for designing biodiversity-friendly forestry, and it strongly depends on species’ dispersal. The “stability–dispersal” model predicts that species using stable habitats should have lower dispersal abilities than species associated with ephemeral habitat and thus respond to habitat availability at smaller scales.

Objectives

We aimed at testing the stability–dispersal model by comparing the spatial scales at which saproxylic beetle guilds using substrates with contrasted stability (from stable to ephemeral: cavicolous, fungicolous, saproxylophagous and xylophagous guilds) are affected by landscape structure (i.e. habitat amount and aggregation).

Methods

We sampled saproxylic beetles using a spatially nested design (plots within landscape windows). We quantified habitat availability (tree cavities, polypores and deadwood) in 1-ha plots, 26-ha buffers around plots and 506-ha windows, and analyzed their effect on the abundance and diversity of associated guilds.

Results

The habitat amount within plots and buffers positively affected the abundance of the cavicolous and the fungicolous guilds whereas saproxylophagous and xylophagous did not respond at these scales. The habitat aggregation within windows only positively affected the saproxylophagous species richness within plots and also on the similarity in species composition among plots.

Conclusions

Beetle guilds specialized on more stable habitat were affected by landscape structure at smaller spatial scales, which corroborated the stability–dispersal model. In managed forests, the spatial grain of conservation efforts should therefore be adapted to the target habitat lifetime.

     

Migration behaviour and escapement of European silver eels from a large lake and wetland system subject to water level management (Grand‐Lieu Lake,France): New insights from regulated acoustic telemetry data

Current knowledge about the downstream migration of sexually mature European eels (Anguilla anguilla) remains incomplete, particularly in still water habitats such as lakes and wetlands subject to water level management. However, for the management of this endangered species, it is important to understand migration dynamics, and contribution to the breeding stock. This study aimed to assess the parameters that trigger and guide the migration of silver eels in the largest floodplain lake and associated wetlands in France (the sluice regulated Grand‐Lieu Lake). A telemetry survey of 50 acoustic and PIT‐tagged female silver eels was performed during the 2015–2016 migration period. We deployed a novel telemetric approach, using receivers to delimit several restricted virtual boxes to determine the instantaneous location of individuals and to transform simple discrete telemetric data into presence/absence data. The low numbers leaving the lake centre are probably explained by the lack of orienting water flows or other environmental clues, but whilst the fate of 34% (17/50) of the tagged eels is unknown, 18% (9/50) were caught by commercial fishermen. Modelling showed that detections were not clearly associated with environmental factors typically involved in riverine migrations (e.g. current velocity, atmospheric pressure and temperature) but they were particularly associated with higher and increasing water levels and, for eels exiting the lake, a sharp increase when sluice gates were opened to an effective gap of >75 cm. It is concluded that management of water levels and sluice gate opening during the migration period might aid escapement of silver eels.     

Effects of natural rapids and waterfalls on fish assemblage structure in the Madeira River (Amazon Basin)

Abstract – Habitat connectivity is considered a central factor shaping ecological communities, and the effects of waterway barriers such as natural waterfalls on fish movements are expected to produce differing assemblage structures in riverine ecosystems. Here, we evaluate the influence of a sequence of waterfalls on the compositional dissimilarity of fish assemblages along the Madeira River, the largest tributary of the Amazon River. We found significant differences in species composition between rivers stretches located upstream and downstream of Teotônio waterfall and, to a less extent, Jirau waterfall, independently of the hydrological period. After accounting for the relative roles of local and regional factors in explaining fish compositional dissimilarity, we still observe a significant effect of the waterfalls. We conclude that these waterfalls act as natural ecological barriers limiting fish dispersal processes and discuss aspects of these ecological filters and the potential effects of two dams currently under construction in the Madeira River.     

Mass marking of stocked European glass eels (Anguilla anguilla) with alizarin red S

This study describes a mass marking method suitable for European glass eel Anguilla anguilla, avoiding osmotic shock and reducing fish stress. During a single day, 360,000 glass eels intended for a stocking operation were bathed into an alizarin red S (ARS) solution, at a density of 346 ind.·l^?1 before being released into a freshwater marsh along with unmarked glass eels. After 15 days, examination of marked and unmarked eels kept in enclosures in the marsh showed 100% of otoliths had been successfully marked and that no excess deaths related to marking process had occurred. Seven months after stocking, results from biometric measurements and otolith analysis, carried out on a sample of 53 elvers caught by electrofishing and belonging to the size class of the 0⁺ cohort, suggest that: (i) the proportions of marked and unmarked remained unchanged, hence suggesting that the marking process had not caused excess mortality, (ii) there was no difference in length, body mass or condition factor between marked and unmarked individuals, demonstrating that marking had caused no harmful effect after 7 months, and (iii) ARS marks in otoliths remained clearly visible. The benefits of this ARS mass marking technique are discussed through a stocking operation.     

Evidence of water vapor in excess of saturation in the atmosphere of Mars

The vertical distribution of water vapor is key to the study of Mars' hydrological cycle. To date, it has been explored mainly through global climate models because of a lack of direct measurements. However, these models assume the absence of supersaturation in the atmosphere of Mars. Here, we report observations made using the SPICAM (Spectroscopy for the Investigation of the Characteristics of the Atmosphere of Mars) instrument onboard Mars Express that provide evidence of the frequent presence of water vapor in excess of saturation, by an amount far surpassing that encountered in Earth's atmosphere. This result contradicts the widespread assumption that atmospheric water on Mars cannot exist in a supersaturated state, directly affecting our long-term representation of water transport, accumulation, escape, and chemistry on a global scale.     

Spawning areas and migration patterns in the early life history of Squalius cephalus (Linnaeus, 1758): Use of otolith microchemistry for conservation and sustainable management

1. In the context of the River Rhône restoration programme, the objective of this study was to assess the dispersal and population connectivity of the European chub, Squalius cephalus (Linnaeus, 1758) in a section of the natural, free-flowing part of the lower River Rhône.
2. The elemental water signatures for Sr:Ca and Ba:Ca were measured at seven stations within the river section, including its tributaries and backwaters, to determine whether they could be differentiated by microchemistry. From August to October the signatures differed among three sectors of the study reach: the Rhône; the Ardèche; and the backwaters.
3. The elemental signatures of the otoliths of 178 young-of-the-year (YOY) chub from the stations were measured to assess spawning areas and identify early migratory life histories. Analyses of otolith microchemistry identified the natal origin of 95% of the fish. Sr:Ca signatures of otoliths showed early downstream migration for 30.4% of the YOY chub; however, 70% of the fish recruited relatively close to their spawning origin suggesting a potential inshore retention of fish.
4. The results showed (i) a non-negligible contribution of the tributaries and backwaters in the recruitment of fish into the main channel; and (ii) the ability of chub to migrate over several kilometres during their first few months of life.
5. This study shows that the combination of water and otolith microchemistry analyses of fish growth increases the understanding of fish life history. Moreover, the study revealed that half of the YOY fish from this river section came from the tributaries and the other half came from reproduction in the River Rhône (despite its high anthropization).
6. These methods offer promising future applications of otolith microchemistry for river management in the context of ecological rehabilitation, especially to assess the effectiveness of measures applied in the restoration of floodplain connectivity for riverine fish population conservation.

     

Can drifting objects drive the movements of a vulnerable pelagic shark?

1. Juvenile silky sharks (Carcharhinus falciformis) regularly associate with floating objects yet the reasons driving this behaviour remain uncertain. Understanding the proportion of time that silky sharks spend associated with floating objects is essential for assessing the impacts of the extensive use of fish aggregating devices (FADs) in the tropical tuna purse-seine fisheries, including increased probability of incidental capture and the potential of an ecological trap.
2. Previous studies provided insight into the amount of time that silky sharks spent at an individual FAD but were unable to assess neither the time spent between two associations nor the proportion of time spent associated/unassociated.
3. The percentage of time that juvenile silky sharks spend unassociated with floating objects was estimated through the analysis of horizontal movements of 26 silky sharks monitored with pop-up archival tags. Under the assumption that a high association rate with drifting FADs would align the trajectories of tracked sharks with ocean surface currents, a novel methodology is proposed, based on the comparison of shark trajectories with simulated trajectories of passively drifting particles derived using a Lagrangian model.
4. Results revealed that silky shark trajectories were divergent from surface currents, and thus unassociated with FADs, for at least 30% of their time. The potential of the methodology and the results are discussed in the context of increasing FAD densities in the Indian Ocean.

     

How anthropogenic disturbances affect the resilience of a keystone palm tree in the threatened Andean cloud forest?

To conserve tropical forests, it is crucial to characterise the disturbance threshold beyond which populations of tropical trees are no longer resilient. This approach is still not widely employed, especially with respect to the effects of moderate disturbances. Compensation effects, such as positive interactions among plants, are addressed even more rarely. We attempt to identify the extents to which the distribution of the keystone palm tree Ceroxylon echinulatum is regulated by various regimes of deforestation in a threatened tropical montane cloud forest in the North-West Andes of Ecuador. The demographic structure of this palm tree was examined in three habitats: old-growth forest, forest disturbed by selective logging, and deforested pasture. Patterns were related to stand structure, microclimate, and soil composition. Seedling desiccation owing to severe aboveground water stress led to the absence of juvenile palms in pastures, and thus was predictive of a near extinction of the species in this habitat. However, shade provided by dominant bunchgrass in pastures considerably reduced above- and belowground water stress by diminishing light intensity. Selective logging resulted in a higher density of individuals in disturbed forests than in old-growth forests, but was associated with a spoiled spatial structure. Therefore, the protection of residual old-growth forests is a prerequisite for the conservation of C. echinulatum, although secondary forests might act as provisional refuges that promote its resilience. The reduction of water stress by nurse grasses in pastures represents a promising approach to promote the resilience of tropical tree species and their associated communities after deforestation.