Reproductive biology of the white marlin (Kajikia albida) in the southwestern and equatorial Atlantic Ocean

The present work describes the reproductive biology of the white marlin (Kajikia albida) caught in the southwestern and equatorial Atlantic Ocean. The gonads of 924 fish were collected by observers on board Brazilian tuna longliners, between November 2004 and December 2006. The spawning season was assessed by the monthly frequency distribution of distinct stages of maturity and monthly mean female gonadosomatic index GSI. Sixty-one percent (n = 656) of the fish examined were female, with a Lower Jaw Fork Length (LJFL) between 83 and 236 cm (mean = 155.5 ± 16.63). The 268 males had a LJFL between 90 and 220 cm (mean = 152.3 ± 34.62). Although the northeastern region of Brazil does not appear to be a significant spawning area for the species, the results suggest a higher reproductive activity in the third quarter of the year. Using a Bayesian logistic model approach, length at 50% maturity was estimated at 145.04 cm (credibility interval of 95%, 143.94–146.09 cm), for females, and at 140.03 cm (credibility interval of 95%, 137.28–142.52 cm), for males.     

Streptomyces brasiliscabiei,a new species causing potato scab in south Brazil

Antonie van Leeuwenhoek - This study aimed to characterize six Streptomyces strains associated with potato scab in south Brazil through polyphasic taxonomy involving morphology, pathogenicity and...     

Habitat and host associations of the fish‐burrowing parasite Artystone minima (Cymothoidae: Isopoda) in eastern Amazonia

Cymothoid fish parasites settle on hosts in ways that may impact fish health and energetics. High abundances of Artystone minima observed in Nannostomus beckfordi from the Jeju River in eastern Amazonia were investigated to answer the following questions: (a) What factors are associated with the high prevalence at this locality?; (b) Is high abundance associated with co‐infestation of alternative hosts?; and (c) Is parasite presence associated with host species growth and/or reproduction? Fish assemblages were sampled quarterly (August 2017–May 2018) from five habitats along with environmental data. Parasitic indices were calculated, and parasite presence used to evaluate differences in growth of hosts using analysis of covariance considering host sex and sampling season (wet vs. dry). Parasites were only abundant in one of the habitats, a large, shallow backwater bay with macrophytes. Abiotic environmental factors (flow and depth) likely impact parasite transmission and are, therefore, particularly important in producing these local patterns. Two secondary hosts, Hyphessobrycon cf. rosaceus and Moenkhausia collettii, were found in the wet season. Based on host biology compared to other fish in the habitat, parasite infestation is inferred to be depth associated and long‐term infestation is apparently limited in alternative hosts. Parasite presence was significantly associated with reduced weight (standardized for length) of female Nannostomus beckfordi in the wet season. Furthermore, ovaries of non‐parasitized females from the wet season presented a range of maturation stages, while parasitized females were all immature, indicating a significant association of parasites with host reproductive capacity. Abstract in Portuguese is available with online material     

Developing of a model to predict lying behavior of dairy cows on silvopastoral system during the winter season

International Journal of Biometeorology - Lying behavior is an important indicator of the cows’ welfare and health. In this study, we evaluate the effect of the physical environment on dairy...     

Environmental variables responsible for Zebu cattle thermal comfort acquisition

International Journal of Biometeorology - The aim of this study was to estimate, using data mining, which microclimate and behavioral variables affect the behavior of animals to seek shaded or...     

Testing the short-term effects of a fish invader on the trophic ecology of a closely related species

The effects of invaders on native species are usually tested using species mean trait values over long time scales. However, considering individual variation over short timescales can help us better understand the interaction between invaders and native species. We compared trophic traits of the non-native guppy (Poecilia reticulata) and the native Brazilian poeciliid Phalloceros harpagos using experiments simulating the early stages of an invasive process. We used short-term mesocosms to simulate an early invasion scenario, where the two species were placed together, and a pre-invasion scenario, where species were kept separated, and analyzed interspecific and intraspecific trophic variability. We also compared the foraging efficiency of species in laboratory experiments. We found no differences on the mean diet of both species between pre and early invasion treatments. At the individual level, in the early invasion scenario, individuals of both species reduced their trophic niche as a probable effect of the presence of the heterospecific. Phalloceros harpagos had higher consumption rates than guppies indicating greater efficiency in feeding on invertebrates. Our results suggest that non-native species were not intrinsically better consumers of high-quality resources. Instead, intraspecific variation might be playing an overlooked role in shaping interactions between species during the early stages of invasion.

     

Spatial cognitive abilities of a tide-pool fish show resilience to noise pollution

Journal of Ethology - Noise pollution may impair the cognitive performances of several animal species, producing suboptimal behavioral responses. Involuntary shifts in attention from noise...     

Aporphine Alkaloids from Ocotea puberula with Anti-Trypanosoma Cruzi Potential – Activity of Dicentrine-β-N-Oxide in the Plasma Membrane Electric Potentials

One new aporphine, dicentrine-β-N-oxide ( 1 ), together with five related known alkaloids dehydrodicentrine ( 2 ), predicentrine ( 3 ), N-methyllaurotetanine ( 4 ), cassythicine ( 5 ), and dicentrine ( 6 ) were isolated from the leaves of Ocotea puberula (Lauraceae). Antiprotozoal activity of the isolated compounds was evaluated in vitro against trypomastigote forms of Trypanosoma cruzi. Among the tested compounds, alkaloid 1 exhibited higher potential with EC₅₀ value of 18.2 μM and reduced toxicity against NCTC cells (CC₅₀>200 μM – SI>11.0), similar to positive control benznidazole (EC₅₀ of 17.7 μM and SI=10.7). Considering the promising results of dicentrine-β-N-oxide ( 1 ) against trypomastigotes, the mechanism of parasite death caused by this alkaloid was investigated. As observed, this compound reached the plasma membrane electric potential directly after 2 h of incubation and triggered mitochondrial depolarization, which probably leads to trypomastigote death. Therefore, dicentrine-β-N-oxide ( 1 ), reported for the first time in this work, can contribute to future works for the development of new trypanocidal agents.