CO-OCORRÊNCIA DE ESPÉCIES DE PEIXES NAS ÁREAS RASAS DA FOZ DO RIO SÃO FRANCISCO SE/AL

CO-OCURRENCE OF FISH SPECIES IN THE SHALLOW AREAS OF SÃO FRANCISCO RIVER MOUTH. The "rules of community assemblage" indicate that competitive interactions would be the main influencing factor in the structuring of biological communities, which generates a non-random pattern of co-occurrence caused by competitive exclusion. Thus, the present study aimed to investigate the co-occurrence patterns in the shallow environments of the mouth of the São Francisco River. Ichthyofauna data from the area were obtained through manual trawling carried out monthly on its banks between May 2017 and April 2018. The data were tabulated in presence/absence matrices and the analyzes were performed through comparisons with null models (random) in a computational environment R, with the EcoSimR package, and through 5000 randomizations. To quantify the co-occurrence patterns, the C-score metric was used, which calculates the species segregation pattern. The results obtained from the simulations showed that the general pattern found did not differ significantly from what was expected at random, indicating that competitive interactions were not the greatest influencing force in the structuring of ichthyofauna in the studied area.

Network-based analysis reveals differences in plant assembly between the native and the invaded ranges.

Associated with the introduction of exotic species in a new area, interactions with other native species within the recipient community occur, reshaping the original community and resulting in a unique assemblage. Yet, the differences in community assemblage between native and invaded ranges remain unclear. Mediterranean grasslands provide an excellent scenario to study community assembly following transcontinental naturalisation of plant species. Here we compared the community resemblance of plant communities in Mediterranean grasslands from both the native (Spain) and invaded (Chile) ranges. We used a novel approach based on network analysis applied to co-occurrence analysis in plant communities, allowing us to study the coexistence of native and alien species in central Chile. This useful methodology is presented as a step forward in invasion ecology studies and conservation strategies. We found that community structure differed between the native and the invaded range, with naturalised species displaying more significant interactions and playing a key role within the invaded community. In addition, alien species displayed positive interactions among them within the communities in the invaded range. Alien species acting like keystones within the Chilean grassland communities might exacerbate the threat posed by biological invasions for the native biodiversity assets. We suggest controlling the spread of the alien species identified as keystones and developing early detection strategies in surrounding areas as management guidelines.

Microbial assemblages and methanogenesis pathways impact methane production and foaming in manure deep-pit storages

Foam accumulation in swine manure deep-pits has been linked to explosions and flash fires that pose devastating threats to humans and livestock. It is clear that methane accumulation within these pits is the fuel for the fire; it is not understood what microbial drivers cause the accumulation and stabilization of methane. Here, we conducted a 13-month field study to survey the physical, chemical, and biological changes of pit-manure across 46 farms in Iowa. Our results showed that an increased methane production rate was associated with less digestible feed ingredients, suggesting that diet influences the storage pit’s microbiome. Targeted sequencing of the bacterial 16S rRNA and archaeal mcrA genes was used to identify microbial communities’ role and influence. We found that microbial communities in foaming and non-foaming manure were significantly different, and that the bacterial communities of foaming manure were more stable than those of non-foaming manure. Foaming manure methanogen communities were enriched with uncharacterized methanogens whose presence strongly correlated with high methane production rates. We also observed strong correlations between feed ration, manure characteristics, and the relative abundance of specific taxa, suggesting that manure foaming is linked to microbial community assemblage driven by efficient free long-chain fatty acid degradation by hydrogenotrophic methanogenesis.

Color of Pan Trap Influences Sampling of Bees in Livestock Pasture Ecosystem

The decline in insect pollinators has increased the importance of accurately monitoring pollinator diversity and abundance over time. Sampling techniques include the use of passive insect traps such as pan traps, yet there is still discussion over their utility and effectiveness in different ecosystems. The objective was to examine four different colors of pan traps (blue, green, yellow, and purple) for their utility in sampling bees in native forages rotationally grazed by sheep and to compare the relative abundance, richness, similarity, and community assemblage patterns among the four trap colors. Most bees were from the Halictidae family (89%). The most abundant species were Lasioglossum imitatum (42.2%), Augochlorella aurata (8.3%), L. subviridatum (6.8), Agapostemon texanus (6.4), and L. birkmani (4.1%). Blue color traps exhibited the highest rates of bee capture and species accumulation. Purple and yellow colored traps were moderately effective in capturing bees, while the green color pan traps were least effective. Similarly, observed and extrapolated species richness was highest in blue trap, followed by purple, yellow, and green. Notably, the blue trap captured the highest number of unique species, followed by purple, yellow and green traps. Considering the total number of insects collected (including bees and other insects), yellow and green traps captured a significantly higher number of insects than other colored traps. The light reflectance from blue, purple, green and yellow pan traps had peaks at ~450, 400, 550, and 600 nm, respectively. Since different insects respond to different light intensities, wavelengths, and reflectivity, these results could be used to guide future trapping protocols targeting certain insect groups in livestock pasture and similar ecosystems.

Nematodes as bio-indicators of physical disturbance of marine sediments following polychaete bait harvesting

Sediment disturbance in marine environments is caused by activities including polychaete bait harvesting, trawling, dredging, sediment erosion and treading. These activities affect the benthic communities by changing the densities, community assemblage and diversity. The aim of this study was to evaluate the potential of nematodes as indicators of sediments disturbance following polychaete bait harvesting. The study was conducted in three sites experiencing different bait harvesting intensities in Mida Creek, Kenya. Sediment samples were collected from the mudflats during low tide, preserved in 5% formalin and transported to the laboratory for processing and identification of nematodes. The highly disturbed site recorded the lowest nematode genus richness while the less disturbed sites had the highest. Overall, the most abundant nematode genera in the non-disturbed (Dabaso) and less disturbed sites (Kirepwe) were selective deposit feeders (Spirinia and Terschellingia), while most disturbed sites (e.g. Mayonda) had predators/omnivores (Pheronus, Aporcelaimellus) and selected members of the genus Spirinia. The disturbed site was characterised by low nematode diversity (H’) and low dominance (D) while the non-disturbed and less disturbed sites had higher diversity and dominance. Clearly, nematode community assemblage, diversity and feeding guilds changed following disturbance to a low diversity that favoured higher proportions of predator/omnivore taxa.

Scale-dependent contribution of host-specificity and environmental factors to wood-boring longhorn beetle community assemblage in SW China

Longhorn beetles are extremely rich wood-boring insects possessing larvae that feed on the xylem of trees and/or lianas, which have detrimental effects on plants; in turn, the hosting plants may play a fundamental role in shaping the longhorn beetle community assemblage. However, factors determining the community assemblage of wood-boring longhorn beetles, particularly along the multiple spatial scales is still in need of further exploration. In this study, we designed an experiment across several spatial scales (from local to macro scales) from tropical to temperate climate gradients in Yunnan province, southwest China to examine to what extend the attributes of host-specificity is shaping the community assemblage along different spatial scales. This study concludes that (1) the wood-boring longhorn beetles showed attributes of host-specificity to a certain degree at the community level, (2) biotic (host plant specificity) and abiotic (climatic gradients) factors jointly shaped community composition of this species along the multiple spatial scales, (3) biotic interactions have a prominent effect on the community composition of this species at local-scale while macroclimatic gradients impose the major control on it at macro-scale. Thus, this study highlights the significance of host specificity in affecting the wood-boring longhorn beetle community assemblage, particularly at local scales.