11 research outputs found
Diapause as escape strategy to exposure to toxicants: response of Brachionus calyciforus to arsenic
Invertebrate organisms commonly respond to environmental fluctuation by entering diapause. Production of diapause in monogonont rotifers involves a previous switch from asexual to partial sexual reproduction. Although zooplankton have been used in ecotoxicological assays, often their true vulnerability to toxicants is underestimated by not incorporating the sexual phase. We experimentally analyzed traits involved in sexual reproduction and diapause in the cyclically parthenogenetic freshwater rotifer, Brachionus calyciflorus, exposed to arsenic, a metalloid naturally found in high concentrations in desert zones, focusing on the effectiveness of diapause as an escape response in the face of an adverse condition. Addition of sublethal concentrations of arsenic modified the pattern of diapause observed in the rotifer: investment in diapause with arsenic addition peaked earlier and higher than in non-toxicant conditions, which suggests that sexual investment could be enhanced in highly stressed environmental conditions by increased responsiveness to stimulation. Nevertheless, eggs produced in large amount with arsenic, were mostly low quality, and healthy-looking eggs had lower hatching success, therefore it is unclear whether this pattern is optimum in an environment with arsenic, or if rather arsenic presence in water bodies disturbs the optimal allocation of offspring entering diapause. We observed high accumulation of arsenic in organisms exposed to constant concentration after several generations, which suggests that arsenic may be accumulated transgenerationally. The sexual phase in rotifers may be more sensitive to environmental conditions than the asexual one, therefore diapause attributes should be considered in ecotoxicological assessment because of its ecological and evolutionary implications on lakes biodiversity
Effects of trash box design on solid waste segregation behavior in university of the philippines diliman
Despite the presence of segregation bins, the solid wastes collected by maintenance personnel in UP Diliman are still unsorted. Because of this, this study was conducted to determine if the trash box design will greatly affect the decision of the waste generators to segregate. It also aims to assess the condition of solid waste segregation and to propose improvements on the existing solid waste segregation schemes. This is done by selecting four buildings in UP with different trash bin design, namely, the Melchor Hall, Benitez Hall, Palma Hall Annex, and Alonso Hall. Waste characterization and survey were conducted in the selected buildings and findings show that the segregation is not that efficient with waste characterization results of 64.17% and survey results of 53.15%. Majority of the students responded that they are segregating; however, the waste sorting survey results show that they are confused in classifying the wastes. The reasons for not segregating can be classified into four major factors: time, trash bin design and appearance, environment, and behaviour towards segregation. Majority of the students responded that their decision to segregate is affected by the trash bin design. Respondents preferred multi-colored trash bins with waste classification and pictures as label on the face of the bin. The proposed trash bins have four classifications consistent with the guidelines regarding the solid waste management in UP Diliman. An affirmative instruction was also posted to encourage the waste source to segregate. It is further suggested that a specific color should be fixed for each type of waste for easy identification. However, no matter how colorful or detailed the design is, it will only be effective with strict compliance of its implementation and monitoring. The education of students and staff regarding the classification of wastes should also be taken into account