Natural populations are chronically exposed to various pollutants over many generations. It is thus crucial to understand and quantify adaptive dynamics of stressed populations in order to increase the relevance of ecotoxicological risk assessment. However, long-term consequences to population exposure are not much studied yet. The present study investigated evolutionary responses of Chironomus riparius populations exposed to uranium (heavy metal pollutant) and to assess the underlying mechanisms. To fulfil our objective, we produced data with organisms exposed to four relevant concentrations of uranium through eight successive generations. We built an individual-based (IBM) model of C. riparius population dynamics to analyse these data and to test several assumptions about the mechanisms involved in the phenotypic changes. The IBM was based on a dynamic energy budget (DEB) model for C. riparius by Pery et al. (2002). DEB models account mathematically for the acquisition and use of energy to describe and predict growth, maintenance, development and reproduction of living organisms. The IBM accounted for the influence of the test conditions on the observations over eight generations and highlighted some trait evolution such as time to emergence and adult size in control conditions. The model was then used to analyse the exposed population data. Our results showed that exposure to uranium led to a phenotypic selection via a differential survival characterised by longer time to emergence and smaller larval maximal size. As a general conclusion, IBMs based on DEB-based modelling developed to analyse multi-generation experiments are very promising for understanding and quantifying long term selection and tolerance mechanisms in a population under toxic stress.
Abstract. In aquatic ecosystems, sediments constitute a reservoir for many of the most persistent chemicals that are introduced into surface waters. Sediments provide a habitat for various benthic macroinvertebrates, which could be exposed to sediment-associated chemicals both directly and via food intake. These organisms play an important role on the structure and the functioning of aquatic ecosystems. Among the non-biologically essential metals, data concerning uranium (U) fate and effects on freshwater benthic macroinvertebrates are sparse. The present study aimed at estimating effects of a chronic U exposure on Chironomus riparius larvae. To achieve this goal, a 10-d laboratory bioassay was performed exposing, via the sediment, first instar larvae to a gradient of U concentrations (0, 2.97, 6.07, 11.44, 23.84 µg U/g dry wt). Significant negative effects on mortality, development time and growth were detected at 6.07, 6.07 and 2.97 µg U/g dry wt, respectively. The results underlined a possible impact of U at the population level at environmentally occurring U concentrations. This study confirmed the need for more research on the role of U on benthic macroinvertebrate.
Discussões acerca da conservação do meio ambiente têm sido frequentes nos últimos anos, consequentemente, os impactos ambientais gerados por resíduos sólidos está sempre em pauta. As aulas práticas possuem extrema importância na conscientização ambiental dos discentes desde o ensino escolar até a graduação, incentivando a criatividade para minimizar os impactos supracitados. O presente trabalho desenvolveu a conscientização ambiental de discentes de graduação em engenharia de pesca por meio de aulas práticas e produção artística. Os discentes foram separados em grupos e divididos em parcelas de 200 m cada, em seguida, os alunos coletaram os resíduos presentes nas áreas, pesaram e separaram parte do material para produção de um quadro por meio de colagem. Foram coletados cerca de 21 kg de resíduos com o vidro sendo mais pesado dentre eles, a pesar disto, foi identificado que plásticos, tanto fragmentados quanto inteiros foram encontrados em maior quantidade. Nas telas as equipes buscaram representar diferentes ambientes marinhos e suas diversidades, criticaram a formação dos resíduos sólidos gerados pelo consumismo, os efeitos da pesca fantasma sobre espécies marinhas e os impactos antrópicos gerados pela pesca irresponsável. O trabalho conseguiu alcançar o objetivo, incentivando a criatividade dos discentes em discutir assuntos importantes para o meio ambiente.
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