Temporal and Spatial Variation of Benthic Intertidal Community of a Sandstone Reef in Pernambuco—Brazil as a Tool to Evaluate Bioinvasion

In this study,the superior and inferior intertidal areas of hard substrate were sampled during the rainy season(June and August)and dry season(October and December)of 2015 at Piedade Beach.The percent cover of Chthamalus bisinuatus,Brachidontes solisianus,Isognomon bicolor,Ulva spp.and filamentous green algae were measured with a 20×20 cm quadrat with one hundred intersections.The quadrats were placed randomly at the sampling sites of Piedade reef.One-way ANOVAs(Analyses of Variance)were used to test the temporal variation of the studied organisms.Chthamalus bisinuatus occurred only in the superior mesolitoral where they had an increase in percent cover during the dry season,which wasn’t statistically significant.Brachidontes solisianus occurred in both superior and inferior levels and had a significant decrease in the superior intertidal during the dry season.Isognomon bicolor occurred only in the inferior level and decreased to almost zero in the December.Ulva spp.and green filamentous algae had an opposite pattern in the inferior intertidal although only the filamentous algae showed a significant decrease in the dry season.Organisms such as Chthamalus bisinuatus resists better the heat and are dominant in the superior intertidal levels of reefs and rocky coasts.Brachidontes solisianus didn’t change much in the lower intertidal and showed that can coexist with the invasive Isognomon bicolor.While the filamentous green showed a decrease in the dry season probably more affected by desiccation than Ulva spp.at Piedade reef.

The Role of Natural and Human-Mediated Pathways for Invasive Agricultural Pests:A Historical Analysis of Cases from Brazil

Information about the geographic distribution of agricultural pests is the basis for all pest-related agricultural and environmental protection policies. However, often the pest’s records are incomplete and uncertain. Even with limitations, the pest records are needed for any country to organize a system for agriculture protection and to mobilize surveillance efforts. The first point is to identify the imminence of biological invasions, which can be accomplished through the collection of data on pest distribution. The basic information to evaluate the predictability of an invasion is geographic distribution and the identification of pathway types associated with the potential invader. Thus, the level of the risk of introduction is assessed more objectively. In this article, cases of introduction of pests were analyzed from published reports in Brazil in terms of their geographic distribution at the time of their introduction. Taking into consideration the country’s extensive terrestrial borders, this study attempts to elucidate the role played by different pathways in each bioinvasion. This analysis recognized the limitations of the historical method and underlying uncertainties of each invasion event. Human-mediated pathways were the main source of agricultural pest invasions in Brazil and the country was more a disperser than a receptor of exotic agricultural pests and diseases in South America. A new geographical hotspot (Northern South America and Caribbean Region) for possible invasions was identified.

Mechanisms of invasive population establishment and spread of pinewood nematodes in China

This paper summarizes the results of our study of the pinewood nematode(Bursaphelenchus xylophi-lus).By population genetic analysis,it was determined that there was no genetic bottle caused by the founder effect and genetic drift in the Chinese invasive population.Multiple invasions with large amounts of nematodes from different sources led to rich genetic diversity in the invasive population.Keeping high genetic diversity in the invasive process may be one of the genetic mechanisms in its successful invasion.By testing interspecies competition,it was shown that,with high fecundity and a strong competitive ability,B.xylophilus outcompeted the native species B.mucronatus in the natural ecosystem during the invasion process.Competitive displacement may be one of the ecological mechanisms of B.xylophilus's invasion.In addition,an unequal interspecific hybridization with intro-gress was in favor of the invasive species which also accelerated the replacement of B.mucronatus by B.xylophilus.The structures,functions and evolutions of a few important genes that are closely related to the ecological adaptation of pinewood nematodes were studied to explore the molecular mechanism of its ecological adaptations.Further,the resistance and resilience mechanism of the pine ecosystem invaded by pinewood nematodes was also investigated.The results of these studies uncovered a portion of the genetic and ecological mechanisms of PWN's successful invasion and laid a foundation for further study to obtain a comprehensive interpretation of the mechanisms of the nematode invasion.The results also provided a scientific basis for effectively controlling the occurrence and spread of pine wilt disease which is caused by nematodes.Various aspects requiring further investigation are considered.

Shifting chemical defence or novel weapons? A review of defence traits in Agarophyton vermiculophyllum and other invasive seaweeds

Seaweed bioinvasions increasingly affect coastal environments around the world, which increases the need for predictive models and mitigation strategies. The biotic interactions between seaweed invaders and invaded communities are often considered a key determinant of invasion success and failure and we here revise the current evidence that the capacity of seaweed invaders to deter enemies in newly reached environments correlates with their invasion success. Particularly efficient chemical defences have been described for several of the more problematic seaweed invaders during the last decades. However, confirmed cases in which seaweed invaders confronted un-adapted enemies in newly gained environments with deterrents that were absent from these environments prior to the invasion (so-called “novel weapons”) are scarce, although an increasing number of invasive and non-invasive seaweeds are screened for defence compounds. More evidence exists that seaweeds may adapt defence intensities to changing pressure by biological enemies in newly invaded habitats. However, most of this evidence of shifting defence was gathered with only one particular model seaweed, the Asia-endemic red alga Agarophyton vermiculophyllum, which is particularly accessible for direct comparisons of native and non-native populations in common garden experiments. A. vermiculophyllum interacts with consumers, epibionts and bacterial pathogens and in most of these interactions, non-native populations have rather gained than lost defensive capacity relative to native conspecifics. The increases in the few examined cases were due to an increased production of broad-spectrum deterrents and the relative scarcity of specialized deterrents perhaps reflects the circumstance that seaweed consumers and epibionts are overwhelmingly generalists.